自动缩放TextView文本以适合边界

我正在寻找一个最佳的方式来调整在TextView包装文本，以便它将适合其getHeight和getWidth范围内。 我不是简单地寻找一种方式来包装文本 – 我想确保它包装，并足够小，完全适合在屏幕上。

我在StackOverflow上看到了一些需要自动resize的例子，但是它们或者是非常特殊的黑客解决scheme，没有解决scheme，或者是recursion地TextView直到它足够小（这是内存激烈和强制用户每次recursion观看文本缩小步骤）。

但是我确定有人在那里find了一个不涉及我所做事情的好方法：编写几个沉重的例程来分析和测量文本，调整文本的大小，并重复，直到find适当的小尺寸。

TextView使用哪些例程来包装文本？ 难道不能以某种方式来预测文字是否足够小？

tl; dr ：是否有一个最佳实践的方式来自动resize的TextView适合，包装，在其getHeight和getWidth范围？

Answer 1

使用Android 8.0（Api等级26），这是一个默认function。 https://developer.android.com/guide/topics/ui/look-and-feel/autosizing-textview.html

Answer 2

作为一名移动开发者，我很遗憾地发现没有支持自动resize的本机。 我的search没有发现任何对我有用的东西，最后，我度过了周末的一半时间，并创build了自己的自动调整文本视图。 我会在这里发布代码，希望对别人有用。

这个类使用原始文本视图的文本颜色的静态布局来测量高度。 从那里，我下降2字体像素，并重新测量，直到我有一个适合的大小。 最后，如果文本仍然不合适，我附加一个省略号。 我有要求animation的文本和重用意见，这似乎在我有的设备上运行良好，似乎运行速度足够我。

 /** * DO WHAT YOU WANT TO PUBLIC LICENSE * Version 2, December 2004 * * Copyright (C) 2004 Sam Hocevar <[e-mail]> * * Everyone is permitted to copy and distribute verbatim or modified * copies of this license document, and changing it is allowed as long * as the name is changed. * * DO WHAT YOU WANT TO PUBLIC LICENSE * TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION * * 0. You just DO WHAT YOU WANT TO. */ import android.content.Context; import android.text.Layout.Alignment; import android.text.StaticLayout; import android.text.TextPaint; import android.util.AttributeSet; import android.util.TypedValue; import android.widget.TextView; /** * Text view that auto adjusts text size to fit within the view. * If the text size equals the minimum text size and still does not * fit, append with an ellipsis. * * @author Chase Colburn * @since Apr 4, 2011 */ public class AutoResizeTextView extends TextView { // Minimum text size for this text view public static final float MIN_TEXT_SIZE = 20; // Interface for resize notifications public interface OnTextResizeListener { public void onTextResize(TextView textView, float oldSize, float newSize); } // Our ellipse string private static final String mEllipsis = "..."; // Registered resize listener private OnTextResizeListener mTextResizeListener; // Flag for text and/or size changes to force a resize private boolean mNeedsResize = false; // Text size that is set from code. This acts as a starting point for resizing private float mTextSize; // Temporary upper bounds on the starting text size private float mMaxTextSize = 0; // Lower bounds for text size private float mMinTextSize = MIN_TEXT_SIZE; // Text view line spacing multiplier private float mSpacingMult = 1.0f; // Text view additional line spacing private float mSpacingAdd = 0.0f; // Add ellipsis to text that overflows at the smallest text size private boolean mAddEllipsis = true; // Default constructor override public AutoResizeTextView(Context context) { this(context, null); } // Default constructor when inflating from XML file public AutoResizeTextView(Context context, AttributeSet attrs) { this(context, attrs, 0); } // Default constructor override public AutoResizeTextView(Context context, AttributeSet attrs, int defStyle) { super(context, attrs, defStyle); mTextSize = getTextSize(); } /** * When text changes, set the force resize flag to true and reset the text size. */ @Override protected void onTextChanged(final CharSequence text, final int start, final int before, final int after) { mNeedsResize = true; // Since this view may be reused, it is good to reset the text size resetTextSize(); } /** * If the text view size changed, set the force resize flag to true */ @Override protected void onSizeChanged(int w, int h, int oldw, int oldh) { if (w != oldw || h != oldh) { mNeedsResize = true; } } /** * Register listener to receive resize notifications * @param listener */ public void setOnResizeListener(OnTextResizeListener listener) { mTextResizeListener = listener; } /** * Override the set text size to update our internal reference values */ @Override public void setTextSize(float size) { super.setTextSize(size); mTextSize = getTextSize(); } /** * Override the set text size to update our internal reference values */ @Override public void setTextSize(int unit, float size) { super.setTextSize(unit, size); mTextSize = getTextSize(); } /** * Override the set line spacing to update our internal reference values */ @Override public void setLineSpacing(float add, float mult) { super.setLineSpacing(add, mult); mSpacingMult = mult; mSpacingAdd = add; } /** * Set the upper text size limit and invalidate the view * @param maxTextSize */ public void setMaxTextSize(float maxTextSize) { mMaxTextSize = maxTextSize; requestLayout(); invalidate(); } /** * Return upper text size limit * @return */ public float getMaxTextSize() { return mMaxTextSize; } /** * Set the lower text size limit and invalidate the view * @param minTextSize */ public void setMinTextSize(float minTextSize) { mMinTextSize = minTextSize; requestLayout(); invalidate(); } /** * Return lower text size limit * @return */ public float getMinTextSize() { return mMinTextSize; } /** * Set flag to add ellipsis to text that overflows at the smallest text size * @param addEllipsis */ public void setAddEllipsis(boolean addEllipsis) { mAddEllipsis = addEllipsis; } /** * Return flag to add ellipsis to text that overflows at the smallest text size * @return */ public boolean getAddEllipsis() { return mAddEllipsis; } /** * Reset the text to the original size */ public void resetTextSize() { if (mTextSize > 0) { super.setTextSize(TypedValue.COMPLEX_UNIT_PX, mTextSize); mMaxTextSize = mTextSize; } } /** * Resize text after measuring */ @Override protected void onLayout(boolean changed, int left, int top, int right, int bottom) { if (changed || mNeedsResize) { int widthLimit = (right - left) - getCompoundPaddingLeft() - getCompoundPaddingRight(); int heightLimit = (bottom - top) - getCompoundPaddingBottom() - getCompoundPaddingTop(); resizeText(widthLimit, heightLimit); } super.onLayout(changed, left, top, right, bottom); } /** * Resize the text size with default width and height */ public void resizeText() { int heightLimit = getHeight() - getPaddingBottom() - getPaddingTop(); int widthLimit = getWidth() - getPaddingLeft() - getPaddingRight(); resizeText(widthLimit, heightLimit); } /** * Resize the text size with specified width and height * @param width * @param height */ public void resizeText(int width, int height) { CharSequence text = getText(); // Do not resize if the view does not have dimensions or there is no text if (text == null || text.length() == 0 || height <= 0 || width <= 0 || mTextSize == 0) { return; } if (getTransformationMethod() != null) { text = getTransformationMethod().getTransformation(text, this); } // Get the text view's paint object TextPaint textPaint = getPaint(); // Store the current text size float oldTextSize = textPaint.getTextSize(); // If there is a max text size set, use the lesser of that and the default text size float targetTextSize = mMaxTextSize > 0 ? Math.min(mTextSize, mMaxTextSize) : mTextSize; // Get the required text height int textHeight = getTextHeight(text, textPaint, width, targetTextSize); // Until we either fit within our text view or we had reached our min text size, incrementally try smaller sizes while (textHeight > height && targetTextSize > mMinTextSize) { targetTextSize = Math.max(targetTextSize - 2, mMinTextSize); textHeight = getTextHeight(text, textPaint, width, targetTextSize); } // If we had reached our minimum text size and still don't fit, append an ellipsis if (mAddEllipsis && targetTextSize == mMinTextSize && textHeight > height) { // Draw using a static layout // modified: use a copy of TextPaint for measuring TextPaint paint = new TextPaint(textPaint); // Draw using a static layout StaticLayout layout = new StaticLayout(text, paint, width, Alignment.ALIGN_NORMAL, mSpacingMult, mSpacingAdd, false); // Check that we have a least one line of rendered text if (layout.getLineCount() > 0) { // Since the line at the specific vertical position would be cut off, // we must trim up to the previous line int lastLine = layout.getLineForVertical(height) - 1; // If the text would not even fit on a single line, clear it if (lastLine < 0) { setText(""); } // Otherwise, trim to the previous line and add an ellipsis else { int start = layout.getLineStart(lastLine); int end = layout.getLineEnd(lastLine); float lineWidth = layout.getLineWidth(lastLine); float ellipseWidth = textPaint.measureText(mEllipsis); // Trim characters off until we have enough room to draw the ellipsis while (width < lineWidth + ellipseWidth) { lineWidth = textPaint.measureText(text.subSequence(start, --end + 1).toString()); } setText(text.subSequence(0, end) + mEllipsis); } } } // Some devices try to auto adjust line spacing, so force default line spacing // and invalidate the layout as a side effect setTextSize(TypedValue.COMPLEX_UNIT_PX, targetTextSize); setLineSpacing(mSpacingAdd, mSpacingMult); // Notify the listener if registered if (mTextResizeListener != null) { mTextResizeListener.onTextResize(this, oldTextSize, targetTextSize); } // Reset force resize flag mNeedsResize = false; } // Set the text size of the text paint object and use a static layout to render text off screen before measuring private int getTextHeight(CharSequence source, TextPaint paint, int width, float textSize) { // modified: make a copy of the original TextPaint object for measuring // (apparently the object gets modified while measuring, see also the // docs for TextView.getPaint() (which states to access it read-only) TextPaint paintCopy = new TextPaint(paint); // Update the text paint object paintCopy.setTextSize(textSize); // Measure using a static layout StaticLayout layout = new StaticLayout(source, paintCopy, width, Alignment.ALIGN_NORMAL, mSpacingMult, mSpacingAdd, true); return layout.getHeight(); } } 

警告。 有一个重要的固定错误影响Android 3.1 – 4.04导致所有AutoResizingTextView小部件不能工作。 请阅读： https ： //stackoverflow.com/a/21851157/2075875

Answer 3

更新：下面的代码也满足了一个理想的 AutoScaleTextView的要求，如下所述： 自动适应Android的TextView ，并被标记为胜利者。

更新2：添加maxlines的支持，现在在API级别16之前工作正常。

更新3：支持android:drawableLeft ， android:drawableRight ， android:drawableTop和android:drawableBottom标签，感谢MartinH 在这里的简单修复。

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我的要求有点不同。 我需要一个有效的方式来resize，因为我是从一个整数的animation，在2秒内TextView中可能是0到4000，我想相应地resize。 我的解决scheme有点不同。 以下是最终结果：

和产生它的代码：

 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="wrap_content" android:layout_height="wrap_content" android:orientation="vertical" android:padding="16dp" > <com.vj.widgets.AutoResizeTextView android:layout_width="match_parent" android:layout_height="100dp" android:ellipsize="none" android:maxLines="2" android:text="Auto Resized Text, max 2 lines" android:textSize="100sp" /> <!-- maximum size --> <com.vj.widgets.AutoResizeTextView android:layout_width="match_parent" android:layout_height="100dp" android:ellipsize="none" android:gravity="center" android:maxLines="1" android:text="Auto Resized Text, max 1 line" android:textSize="100sp" /> <!-- maximum size --> <com.vj.widgets.AutoResizeTextView android:layout_width="match_parent" android:layout_height="wrap_content" android:text="Auto Resized Text" android:textSize="500sp" /> <!-- maximum size --> </LinearLayout> 

最后是java代码：

 import android.annotation.TargetApi; import android.content.Context; import android.content.res.Resources; import android.graphics.RectF; import android.os.Build; import android.text.Layout.Alignment; import android.text.StaticLayout; import android.text.TextPaint; import android.util.AttributeSet; import android.util.SparseIntArray; import android.util.TypedValue; import android.widget.TextView; public class AutoResizeTextView extends TextView { private interface SizeTester { /** * * @param suggestedSize * Size of text to be tested * @param availableSpace * available space in which text must fit * @return an integer < 0 if after applying {@code suggestedSize} to * text, it takes less space than {@code availableSpace}, > 0 * otherwise */ public int onTestSize(int suggestedSize, RectF availableSpace); } private RectF mTextRect = new RectF(); private RectF mAvailableSpaceRect; private SparseIntArray mTextCachedSizes; private TextPaint mPaint; private float mMaxTextSize; private float mSpacingMult = 1.0f; private float mSpacingAdd = 0.0f; private float mMinTextSize = 20; private int mWidthLimit; private static final int NO_LINE_LIMIT = -1; private int mMaxLines; private boolean mEnableSizeCache = true; private boolean mInitiallized; public AutoResizeTextView(Context context) { super(context); initialize(); } public AutoResizeTextView(Context context, AttributeSet attrs) { super(context, attrs); initialize(); } public AutoResizeTextView(Context context, AttributeSet attrs, int defStyle) { super(context, attrs, defStyle); initialize(); } private void initialize() { mPaint = new TextPaint(getPaint()); mMaxTextSize = getTextSize(); mAvailableSpaceRect = new RectF(); mTextCachedSizes = new SparseIntArray(); if (mMaxLines == 0) { // no value was assigned during construction mMaxLines = NO_LINE_LIMIT; } mInitiallized = true; } @Override public void setText(final CharSequence text, BufferType type) { super.setText(text, type); adjustTextSize(text.toString()); } @Override public void setTextSize(float size) { mMaxTextSize = size; mTextCachedSizes.clear(); adjustTextSize(getText().toString()); } @Override public void setMaxLines(int maxlines) { super.setMaxLines(maxlines); mMaxLines = maxlines; reAdjust(); } public int getMaxLines() { return mMaxLines; } @Override public void setSingleLine() { super.setSingleLine(); mMaxLines = 1; reAdjust(); } @Override public void setSingleLine(boolean singleLine) { super.setSingleLine(singleLine); if (singleLine) { mMaxLines = 1; } else { mMaxLines = NO_LINE_LIMIT; } reAdjust(); } @Override public void setLines(int lines) { super.setLines(lines); mMaxLines = lines; reAdjust(); } @Override public void setTextSize(int unit, float size) { Context c = getContext(); Resources r; if (c == null) r = Resources.getSystem(); else r = c.getResources(); mMaxTextSize = TypedValue.applyDimension(unit, size, r.getDisplayMetrics()); mTextCachedSizes.clear(); adjustTextSize(getText().toString()); } @Override public void setLineSpacing(float add, float mult) { super.setLineSpacing(add, mult); mSpacingMult = mult; mSpacingAdd = add; } /** * Set the lower text size limit and invalidate the view * * @param minTextSize */ public void setMinTextSize(float minTextSize) { mMinTextSize = minTextSize; reAdjust(); } private void reAdjust() { adjustTextSize(getText().toString()); } private void adjustTextSize(String string) { if (!mInitiallized) { return; } int startSize = (int) mMinTextSize; int heightLimit = getMeasuredHeight() - getCompoundPaddingBottom() - getCompoundPaddingTop(); mWidthLimit = getMeasuredWidth() - getCompoundPaddingLeft() - getCompoundPaddingRight(); mAvailableSpaceRect.right = mWidthLimit; mAvailableSpaceRect.bottom = heightLimit; super.setTextSize( TypedValue.COMPLEX_UNIT_PX, efficientTextSizeSearch(startSize, (int) mMaxTextSize, mSizeTester, mAvailableSpaceRect)); } private final SizeTester mSizeTester = new SizeTester() { @TargetApi(Build.VERSION_CODES.JELLY_BEAN) @Override public int onTestSize(int suggestedSize, RectF availableSPace) { mPaint.setTextSize(suggestedSize); String text = getText().toString(); boolean singleline = getMaxLines() == 1; if (singleline) { mTextRect.bottom = mPaint.getFontSpacing(); mTextRect.right = mPaint.measureText(text); } else { StaticLayout layout = new StaticLayout(text, mPaint, mWidthLimit, Alignment.ALIGN_NORMAL, mSpacingMult, mSpacingAdd, true); // return early if we have more lines if (getMaxLines() != NO_LINE_LIMIT && layout.getLineCount() > getMaxLines()) { return 1; } mTextRect.bottom = layout.getHeight(); int maxWidth = -1; for (int i = 0; i < layout.getLineCount(); i++) { if (maxWidth < layout.getLineWidth(i)) { maxWidth = (int) layout.getLineWidth(i); } } mTextRect.right = maxWidth; } mTextRect.offsetTo(0, 0); if (availableSPace.contains(mTextRect)) { // may be too small, don't worry we will find the best match return -1; } else { // too big return 1; } } }; /** * Enables or disables size caching, enabling it will improve performance * where you are animating a value inside TextView. This stores the font * size against getText().length() Be careful though while enabling it as 0 * takes more space than 1 on some fonts and so on. * * @param enable * enable font size caching */ public void enableSizeCache(boolean enable) { mEnableSizeCache = enable; mTextCachedSizes.clear(); adjustTextSize(getText().toString()); } private int efficientTextSizeSearch(int start, int end, SizeTester sizeTester, RectF availableSpace) { if (!mEnableSizeCache) { return binarySearch(start, end, sizeTester, availableSpace); } String text = getText().toString(); int key = text == null ? 0 : text.length(); int size = mTextCachedSizes.get(key); if (size != 0) { return size; } size = binarySearch(start, end, sizeTester, availableSpace); mTextCachedSizes.put(key, size); return size; } private static int binarySearch(int start, int end, SizeTester sizeTester, RectF availableSpace) { int lastBest = start; int lo = start; int hi = end - 1; int mid = 0; while (lo <= hi) { mid = (lo + hi) >>> 1; int midValCmp = sizeTester.onTestSize(mid, availableSpace); if (midValCmp < 0) { lastBest = lo; lo = mid + 1; } else if (midValCmp > 0) { hi = mid - 1; lastBest = hi; } else { return mid; } } // make sure to return last best // this is what should always be returned return lastBest; } @Override protected void onTextChanged(final CharSequence text, final int start, final int before, final int after) { super.onTextChanged(text, start, before, after); reAdjust(); } @Override protected void onSizeChanged(int width, int height, int oldwidth, int oldheight) { mTextCachedSizes.clear(); super.onSizeChanged(width, height, oldwidth, oldheight); if (width != oldwidth || height != oldheight) { reAdjust(); } } } 

Answer 4

实际上，Google的DialogTitle类中有一个解决scheme，虽然它不像已经被接受的那样有效，但它更简单，易于适应。

 public class SingleLineTextView extends TextView { public SingleLineTextView(Context context, AttributeSet attrs, int defStyle) { super(context, attrs, defStyle); setSingleLine(); setEllipsize(TruncateAt.END); } public SingleLineTextView(Context context, AttributeSet attrs) { super(context, attrs); setSingleLine(); setEllipsize(TruncateAt.END); } public SingleLineTextView(Context context) { super(context); setSingleLine(); setEllipsize(TruncateAt.END); } @Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { super.onMeasure(widthMeasureSpec, heightMeasureSpec); final Layout layout = getLayout(); if (layout != null) { final int lineCount = layout.getLineCount(); if (lineCount > 0) { final int ellipsisCount = layout.getEllipsisCount(lineCount - 1); if (ellipsisCount > 0) { final float textSize = getTextSize(); // textSize is already expressed in pixels setTextSize(TypedValue.COMPLEX_UNIT_PX, (textSize - 1)); super.onMeasure(widthMeasureSpec, heightMeasureSpec); } } } } } 

Answer 5

我从Chase的解决scheme开始，但是在我的设备（Galaxy Nexus，Android 4.1）上按照预期工作之前，必须适应两件事：

1. 使用TextPaint的副本来测量布局TextView.getPaint（）的文档声明它应该是只读的，所以我在我们使用paint对象进行度量的两个地方都做了一个副本：

    // 1. in resizeText() if (mAddEllipsis && targetTextSize == mMinTextSize && textHeight > height) { // Draw using a static layout // modified: use a copy of TextPaint for measuring TextPaint paint = new TextPaint(textPaint); // 2. in getTextHeight() private int getTextHeight(CharSequence source, TextPaint originalPaint, int width, float textSize) { // modified: make a copy of the original TextPaint object for measuring // (apparently the object gets modified while measuring, see also the // docs for TextView.getPaint() (which states to access it read-only) TextPaint paint = new TextPaint(originalPaint); // Update the text paint object paint.setTextSize(textSize); ... 

2. 添加一个单位来设置文本大小

    // modified: setting text size via this.setTextSize (instead of textPaint.setTextSize(targetTextSize)) setTextSize(TypedValue.COMPLEX_UNIT_PX, targetTextSize); setLineSpacing(mSpacingAdd, mSpacingMult); 

有了这两个修改的解决scheme是完美的为我工作，谢谢蔡斯！ 我不知道这是否是由于Android 4.x，原来的解决scheme无法正常工作。 如果你想看到它的行动或testing它是否真的在你的设备上工作，你可以看看我的闪卡应用程序Flashcards ToGo ，我用这个解决scheme来缩放闪卡的文本。 文本可以有任意长度，并且闪卡会显示在不同的活动中，有时会更小，有时会更大，再加上横向+纵向模式，并且我还没有发现解决scheme无法正常工作的任何angular落案例。

Answer 6

我从Chase的AutoResizeTextView类开始，做了一个小小的改动，使它适合垂直和水平。

我还发现了一个在布局编辑器（在Eclipse中）在一些相当模糊的条件下导致空指针exception的错误。

更改1：垂直和水平放置文本

Chase的原始版本缩小了文字的大小，直到它垂直放置，但允许文字比目标宽。 在我的情况下，我需要的文字，以适应指定的宽度。

此更改将resize，直到文本适合垂直和水平。

在resizeText( int , int )改变：

 // Get the required text height int textHeight = getTextHeight(text, textPaint, width, targetTextSize); // Until we either fit within our text view or we had reached our min text size, incrementally try smaller sizes while(textHeight > height && targetTextSize > mMinTextSize) { targetTextSize = Math.max(targetTextSize - 2, mMinTextSize); textHeight = getTextHeight(text, textPaint, width, targetTextSize); } 

至：

 // Get the required text height int textHeight = getTextHeight(text, textPaint, width, targetTextSize); int textWidth = getTextWidth(text, textPaint, width, targetTextSize); // Until we either fit within our text view or we had reached our min text size, incrementally try smaller sizes while(((textHeight >= height) || (textWidth >= width) ) && targetTextSize > mMinTextSize) { targetTextSize = Math.max(targetTextSize - 2, mMinTextSize); textHeight = getTextHeight(text, textPaint, width, targetTextSize); textWidth = getTextWidth(text, textPaint, width, targetTextSize); } 

然后，在文件末尾附加getTextWidth()例程; 它只是稍微修改了getTextHeight() 。 将它们结合到一个返回高度和宽度的例程可能会更有效率。

 // Set the text size of the text paint object and use a static layout to render text off screen before measuring private int getTextWidth(CharSequence source, TextPaint paint, int width, float textSize) { // Update the text paint object paint.setTextSize(textSize); // Draw using a static layout StaticLayout layout = new StaticLayout(source, paint, width, Alignment.ALIGN_NORMAL, mSpacingMult, mSpacingAdd, true); layout.draw(sTextResizeCanvas); return layout.getWidth(); } 

更改2：修复Eclipse Android布局编辑器中的EmptyStackException

在相当模糊和非常精确的条件下，布局编辑器将无法显示布局的graphics显示; 它会在com.android.ide.eclipse.adt中抛出一个“EmptyStackException：null”exception。

所需条件是：
– 创build一个AutoResizeTextView小部件
– 为该小部件创build一个样式
– 在样式中指定文本项目; 不在小部件定义中

如下所示：

RES /布局/ main.xml中：

 <?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="fill_parent" android:layout_height="fill_parent" android:orientation="vertical" > <com.ajw.DemoCrashInADT.AutoResizeTextView android:id="@+id/resizingText" style="@style/myTextStyle" /> </LinearLayout> 

RES /值/ myStyles.xml：

 <?xml version="1.0" encoding="utf-8"?> <resources> <style name="myTextStyle" parent="@android:style/Widget.TextView"> <item name="android:layout_height">wrap_content</item> <item name="android:layout_width">fill_parent</item> <item name="android:text">some message</item> </style> </resources> 

使用这些文件，在编辑main.xml时selectgraphics布局选项卡将显示：

错误！
EmptyStackException：null
窗口>显示视图>错误日志中loggingexception详细信息

而不是布局的graphics视图。

为了保持一个已经太长的故事，我把它追踪到下面的行（再次在resizeText ）：

 // If there is a max text size set, use the lesser of that and the default text size float targetTextSize = mMaxTextSize > 0 ? Math.min(mTextSize, mMaxTextSize) : mTextSize; 

问题是，在特定的条件下，mTextSize从不初始化; 它的值为0。

有了上面的内容， targetTextSize被设置为零（作为Math.min的结果）。

该零传递给getTextHeight() （和getTextWidth() ）作为textSize参数。 当它到达
layout.draw(sTextResizeCanvas);
我们得到了例外。

在resizeText()的开头testing(mTextSize == 0) resizeText()而不是在getTextHeight()和getTextWidth()testing会更有效率。 早期testing保存所有的干预工作。

有了这些更新，该文件（如我的崩溃演示testing应用程序）现在是：

 // // from: http://stackoverflow.com/questions/5033012/auto-scale-textview-text-to-fit-within-bounds // // package com.ajw.DemoCrashInADT; import android.content.Context; import android.graphics.Canvas; import android.text.Layout.Alignment; import android.text.StaticLayout; import android.text.TextPaint; import android.util.AttributeSet; import android.util.TypedValue; import android.widget.TextView; /** * Text view that auto adjusts text size to fit within the view. If the text * size equals the minimum text size and still does not fit, append with an * ellipsis. * * 2011-10-29 changes by Alan Jay Weiner * * change to fit both vertically and horizontally * * test mTextSize for 0 in resizeText() to fix exception in Layout Editor * * @author Chase Colburn * @since Apr 4, 2011 */ public class AutoResizeTextView extends TextView { // Minimum text size for this text view public static final float MIN_TEXT_SIZE = 20; // Interface for resize notifications public interface OnTextResizeListener { public void onTextResize(TextView textView, float oldSize, float newSize); } // Off screen canvas for text size rendering private static final Canvas sTextResizeCanvas = new Canvas(); // Our ellipse string private static final String mEllipsis = "..."; // Registered resize listener private OnTextResizeListener mTextResizeListener; // Flag for text and/or size changes to force a resize private boolean mNeedsResize = false; // Text size that is set from code. This acts as a starting point for // resizing private float mTextSize; // Temporary upper bounds on the starting text size private float mMaxTextSize = 0; // Lower bounds for text size private float mMinTextSize = MIN_TEXT_SIZE; // Text view line spacing multiplier private float mSpacingMult = 1.0f; // Text view additional line spacing private float mSpacingAdd = 0.0f; // Add ellipsis to text that overflows at the smallest text size private boolean mAddEllipsis = true; // Default constructor override public AutoResizeTextView(Context context) { this(context, null); } // Default constructor when inflating from XML file public AutoResizeTextView(Context context, AttributeSet attrs) { this(context, attrs, 0); } // Default constructor override public AutoResizeTextView(Context context, AttributeSet attrs, int defStyle) { super(context, attrs, defStyle); mTextSize = getTextSize(); } /** * When text changes, set the force resize flag to true and reset the text * size. */ @Override protected void onTextChanged(final CharSequence text, final int start, final int before, final int after) { mNeedsResize = true; // Since this view may be reused, it is good to reset the text size resetTextSize(); } /** * If the text view size changed, set the force resize flag to true */ @Override protected void onSizeChanged(int w, int h, int oldw, int oldh) { if (w != oldw || h != oldh) { mNeedsResize = true; } } /** * Register listener to receive resize notifications * * @param listener */ public void setOnResizeListener(OnTextResizeListener listener) { mTextResizeListener = listener; } /** * Override the set text size to update our internal reference values */ @Override public void setTextSize(float size) { super.setTextSize(size); mTextSize = getTextSize(); } /** * Override the set text size to update our internal reference values */ @Override public void setTextSize(int unit, float size) { super.setTextSize(unit, size); mTextSize = getTextSize(); } /** * Override the set line spacing to update our internal reference values */ @Override public void setLineSpacing(float add, float mult) { super.setLineSpacing(add, mult); mSpacingMult = mult; mSpacingAdd = add; } /** * Set the upper text size limit and invalidate the view * * @param maxTextSize */ public void setMaxTextSize(float maxTextSize) { mMaxTextSize = maxTextSize; requestLayout(); invalidate(); } /** * Return upper text size limit * * @return */ public float getMaxTextSize() { return mMaxTextSize; } /** * Set the lower text size limit and invalidate the view * * @param minTextSize */ public void setMinTextSize(float minTextSize) { mMinTextSize = minTextSize; requestLayout(); invalidate(); } /** * Return lower text size limit * * @return */ public float getMinTextSize() { return mMinTextSize; } /** * Set flag to add ellipsis to text that overflows at the smallest text size * * @param addEllipsis */ public void setAddEllipsis(boolean addEllipsis) { mAddEllipsis = addEllipsis; } /** * Return flag to add ellipsis to text that overflows at the smallest text * size * * @return */ public boolean getAddEllipsis() { return mAddEllipsis; } /** * Reset the text to the original size */ public void resetTextSize() { super.setTextSize(TypedValue.COMPLEX_UNIT_PX, mTextSize); mMaxTextSize = mTextSize; } /** * Resize text after measuring */ @Override protected void onLayout(boolean changed, int left, int top, int right, int bottom) { if (changed || mNeedsResize) { int widthLimit = (right - left) - getCompoundPaddingLeft() - getCompoundPaddingRight(); int heightLimit = (bottom - top) - getCompoundPaddingBottom() - getCompoundPaddingTop(); resizeText(widthLimit, heightLimit); } super.onLayout(changed, left, top, right, bottom); } /** * Resize the text size with default width and height */ public void resizeText() { int heightLimit = getHeight() - getPaddingBottom() - getPaddingTop(); int widthLimit = getWidth() - getPaddingLeft() - getPaddingRight(); resizeText(widthLimit, heightLimit); } /** * Resize the text size with specified width and height * * @param width * @param height */ public void resizeText(int width, int height) { CharSequence text = getText(); // Do not resize if the view does not have dimensions or there is no // text // or if mTextSize has not been initialized if (text == null || text.length() == 0 || height <= 0 || width <= 0 || mTextSize == 0) { return; } // Get the text view's paint object TextPaint textPaint = getPaint(); // Store the current text size float oldTextSize = textPaint.getTextSize(); // If there is a max text size set, use the lesser of that and the // default text size float targetTextSize = mMaxTextSize > 0 ? Math.min(mTextSize, mMaxTextSize) : mTextSize; // Get the required text height int textHeight = getTextHeight(text, textPaint, width, targetTextSize); int textWidth = getTextWidth(text, textPaint, width, targetTextSize); // Until we either fit within our text view or we had reached our min // text size, incrementally try smaller sizes while (((textHeight > height) || (textWidth > width)) && targetTextSize > mMinTextSize) { targetTextSize = Math.max(targetTextSize - 2, mMinTextSize); textHeight = getTextHeight(text, textPaint, width, targetTextSize); textWidth = getTextWidth(text, textPaint, width, targetTextSize); } // If we had reached our minimum text size and still don't fit, append // an ellipsis if (mAddEllipsis && targetTextSize == mMinTextSize && textHeight > height) { // Draw using a static layout StaticLayout layout = new StaticLayout(text, textPaint, width, Alignment.ALIGN_NORMAL, mSpacingMult, mSpacingAdd, false); layout.draw(sTextResizeCanvas); int lastLine = layout.getLineForVertical(height) - 1; int start = layout.getLineStart(lastLine); int end = layout.getLineEnd(lastLine); float lineWidth = layout.getLineWidth(lastLine); float ellipseWidth = textPaint.measureText(mEllipsis); // Trim characters off until we have enough room to draw the // ellipsis while (width < lineWidth + ellipseWidth) { lineWidth = textPaint.measureText(text.subSequence(start, --end + 1) .toString()); } setText(text.subSequence(0, end) + mEllipsis); } // Some devices try to auto adjust line spacing, so force default line // spacing // and invalidate the layout as a side effect textPaint.setTextSize(targetTextSize); setLineSpacing(mSpacingAdd, mSpacingMult); // Notify the listener if registered if (mTextResizeListener != null) { mTextResizeListener.onTextResize(this, oldTextSize, targetTextSize); } // Reset force resize flag mNeedsResize = false; } // Set the text size of the text paint object and use a static layout to // render text off screen before measuring private int getTextHeight(CharSequence source, TextPaint paint, int width, float textSize) { // Update the text paint object paint.setTextSize(textSize); // Draw using a static layout StaticLayout layout = new StaticLayout(source, paint, width, Alignment.ALIGN_NORMAL, mSpacingMult, mSpacingAdd, true); layout.draw(sTextResizeCanvas); return layout.getHeight(); } // Set the text size of the text paint object and use a static layout to // render text off screen before measuring private int getTextWidth(CharSequence source, TextPaint paint, int width, float textSize) { // Update the text paint object paint.setTextSize(textSize); // Draw using a static layout StaticLayout layout = new StaticLayout(source, paint, width, Alignment.ALIGN_NORMAL, mSpacingMult, mSpacingAdd, true); layout.draw(sTextResizeCanvas); return layout.getWidth(); } } 

A big thank you to Chase for posting the initial code. I enjoyed reading through it to see how it worked, and I'm pleased to be able to add to it.

Answer 7

A workaround for Android 4.x:

I found AutoResizeTextView and it works great on my Android 2.1 emulator. I loved it so much. But unfortunately it failed on my own 4.0.4 cellphone and 4.1 emulator. After trying I found it could be easily resolved by adding following attributes in AutoResizeTextView class in the xml:

android:ellipsize="none"

android:singleLine="true"

With the 2 lines above, now AutoResizeTextView working perfectly on my 2.1 & 4.1 emulators and my own 4.0.4 cellphone now.

希望这可以帮助你。 🙂

Answer 8

Warning, bug in Android Honeycomb and Ice Cream Sandwich

Androids versions: 3.1 – 4.04 have a bug, that setTextSize() inside of TextView works only for the 1st time (1st invocation).

Bug is described here: http://code.google.com/p/android/issues/detail?id=22493 http://code.google.com/p/android/issues/detail?id=17343#c9

workaround is to add new line character to text assigned to TextView before changing size:

 final String DOUBLE_BYTE_SPACE = "\u3000"; textView.append(DOUBLE_BYTE_SPACE); 

I use it in my code as follow:

 final String DOUBLE_BYTE_SPACE = "\u3000"; AutoResizeTextView textView = (AutoResizeTextView) view.findViewById(R.id.aTextView); String fixString = ""; if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.HONEYCOMB_MR1 && android.os.Build.VERSION.SDK_INT <= android.os.Build.VERSION_CODES.ICE_CREAM_SANDWICH_MR1) { fixString = DOUBLE_BYTE_SPACE; } textView.setText(fixString + "The text" + fixString); 

I add this "\u3000" character on left and right of my text, to keep it centered. If you have it aligned to left then append to the right only. Of course it can be also embedded with AutoResizeTextView widget, but I wanted to keep fix code outside.

Answer 9

My need was to resize text in order to perfectly fit view bounds. Chase's solution only reduces text size, this one enlarges also the text if there is enough space.

To make all fast & precise i used a bisection method instead of an iterative while, as you can see in resizeText() method. That's why you have also a MAX_TEXT_SIZE option. I also included onoelle's tips.

Tested on Android 4.4

 /** * DO WHAT YOU WANT TO PUBLIC LICENSE * Version 2, December 2004 * * Copyright (C) 2004 Sam Hocevar <[e-mail]> * * Everyone is permitted to copy and distribute verbatim or modified * copies of this license document, and changing it is allowed as long * as the name is changed. * * DO WHAT YOU WANT TO PUBLIC LICENSE * TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION * * 0. You just DO WHAT YOU WANT TO. */ import android.content.Context; import android.text.Layout.Alignment; import android.text.StaticLayout; import android.text.TextPaint; import android.util.AttributeSet; import android.util.TypedValue; import android.widget.TextView; /** * Text view that auto adjusts text size to fit within the view. * If the text size equals the minimum text size and still does not * fit, append with an ellipsis. * * @author Chase Colburn * @since Apr 4, 2011 */ public class AutoResizeTextView extends TextView { // Minimum text size for this text view public static final float MIN_TEXT_SIZE = 26; // Maximum text size for this text view public static final float MAX_TEXT_SIZE = 128; private static final int BISECTION_LOOP_WATCH_DOG = 30; // Interface for resize notifications public interface OnTextResizeListener { public void onTextResize(TextView textView, float oldSize, float newSize); } // Our ellipse string private static final String mEllipsis = "..."; // Registered resize listener private OnTextResizeListener mTextResizeListener; // Flag for text and/or size changes to force a resize private boolean mNeedsResize = false; // Text size that is set from code. This acts as a starting point for resizing private float mTextSize; // Temporary upper bounds on the starting text size private float mMaxTextSize = MAX_TEXT_SIZE; // Lower bounds for text size private float mMinTextSize = MIN_TEXT_SIZE; // Text view line spacing multiplier private float mSpacingMult = 1.0f; // Text view additional line spacing private float mSpacingAdd = 0.0f; // Add ellipsis to text that overflows at the smallest text size private boolean mAddEllipsis = true; // Default constructor override public AutoResizeTextView(Context context) { this(context, null); } // Default constructor when inflating from XML file public AutoResizeTextView(Context context, AttributeSet attrs) { this(context, attrs, 0); } // Default constructor override public AutoResizeTextView(Context context, AttributeSet attrs, int defStyle) { super(context, attrs, defStyle); mTextSize = getTextSize(); } /** * When text changes, set the force resize flag to true and reset the text size. */ @Override protected void onTextChanged(final CharSequence text, final int start, final int before, final int after) { mNeedsResize = true; // Since this view may be reused, it is good to reset the text size resetTextSize(); } /** * If the text view size changed, set the force resize flag to true */ @Override protected void onSizeChanged(int w, int h, int oldw, int oldh) { if (w != oldw || h != oldh) { mNeedsResize = true; } } /** * Register listener to receive resize notifications * @param listener */ public void setOnResizeListener(OnTextResizeListener listener) { mTextResizeListener = listener; } /** * Override the set text size to update our internal reference values */ @Override public void setTextSize(float size) { super.setTextSize(size); mTextSize = getTextSize(); } /** * Override the set text size to update our internal reference values */ @Override public void setTextSize(int unit, float size) { super.setTextSize(unit, size); mTextSize = getTextSize(); } /** * Override the set line spacing to update our internal reference values */ @Override public void setLineSpacing(float add, float mult) { super.setLineSpacing(add, mult); mSpacingMult = mult; mSpacingAdd = add; } /** * Set the upper text size limit and invalidate the view * @param maxTextSize */ public void setMaxTextSize(float maxTextSize) { mMaxTextSize = maxTextSize; requestLayout(); invalidate(); } /** * Return upper text size limit * @return */ public float getMaxTextSize() { return mMaxTextSize; } /** * Set the lower text size limit and invalidate the view * @param minTextSize */ public void setMinTextSize(float minTextSize) { mMinTextSize = minTextSize; requestLayout(); invalidate(); } /** * Return lower text size limit * @return */ public float getMinTextSize() { return mMinTextSize; } /** * Set flag to add ellipsis to text that overflows at the smallest text size * @param addEllipsis */ public void setAddEllipsis(boolean addEllipsis) { mAddEllipsis = addEllipsis; } /** * Return flag to add ellipsis to text that overflows at the smallest text size * @return */ public boolean getAddEllipsis() { return mAddEllipsis; } /** * Reset the text to the original size */ public void resetTextSize() { if(mTextSize > 0) { super.setTextSize(TypedValue.COMPLEX_UNIT_PX, mTextSize); //mMaxTextSize = mTextSize; } } /** * Resize text after measuring */ @Override protected void onLayout(boolean changed, int left, int top, int right, int bottom) { if(changed || mNeedsResize) { int widthLimit = (right - left) - getCompoundPaddingLeft() - getCompoundPaddingRight(); int heightLimit = (bottom - top) - getCompoundPaddingBottom() - getCompoundPaddingTop(); resizeText(widthLimit, heightLimit); } super.onLayout(changed, left, top, right, bottom); } /** * Resize the text size with default width and height */ public void resizeText() { int heightLimit = getHeight() - getPaddingBottom() - getPaddingTop(); int widthLimit = getWidth() - getPaddingLeft() - getPaddingRight(); resizeText(widthLimit, heightLimit); } /** * Resize the text size with specified width and height * @param width * @param height */ public void resizeText(int width, int height) { CharSequence text = getText(); // Do not resize if the view does not have dimensions or there is no text if(text == null || text.length() == 0 || height <= 0 || width <= 0 || mTextSize == 0) { return; } // Get the text view's paint object TextPaint textPaint = getPaint(); // Store the current text size float oldTextSize = textPaint.getTextSize(); // Bisection method: fast & precise float lower = mMinTextSize; float upper = mMaxTextSize; int loop_counter=1; float targetTextSize = (lower+upper)/2; int textHeight = getTextHeight(text, textPaint, width, targetTextSize); while(loop_counter < BISECTION_LOOP_WATCH_DOG && upper - lower > 1) { targetTextSize = (lower+upper)/2; textHeight = getTextHeight(text, textPaint, width, targetTextSize); if(textHeight > height) upper = targetTextSize; else lower = targetTextSize; loop_counter++; } targetTextSize = lower; textHeight = getTextHeight(text, textPaint, width, targetTextSize); // If we had reached our minimum text size and still don't fit, append an ellipsis if(mAddEllipsis && targetTextSize == mMinTextSize && textHeight > height) { // Draw using a static layout // modified: use a copy of TextPaint for measuring TextPaint paintCopy = new TextPaint(textPaint); paintCopy.setTextSize(targetTextSize); StaticLayout layout = new StaticLayout(text, paintCopy, width, Alignment.ALIGN_NORMAL, mSpacingMult, mSpacingAdd, false); // Check that we have a least one line of rendered text if(layout.getLineCount() > 0) { // Since the line at the specific vertical position would be cut off, // we must trim up to the previous line int lastLine = layout.getLineForVertical(height) - 1; // If the text would not even fit on a single line, clear it if(lastLine < 0) { setText(""); } // Otherwise, trim to the previous line and add an ellipsis else { int start = layout.getLineStart(lastLine); int end = layout.getLineEnd(lastLine); float lineWidth = layout.getLineWidth(lastLine); float ellipseWidth = paintCopy.measureText(mEllipsis); // Trim characters off until we have enough room to draw the ellipsis while(width < lineWidth + ellipseWidth) { lineWidth = paintCopy.measureText(text.subSequence(start, --end + 1).toString()); } setText(text.subSequence(0, end) + mEllipsis); } } } // Some devices try to auto adjust line spacing, so force default line spacing // and invalidate the layout as a side effect setTextSize(TypedValue.COMPLEX_UNIT_PX, targetTextSize); setLineSpacing(mSpacingAdd, mSpacingMult); // Notify the listener if registered if(mTextResizeListener != null) { mTextResizeListener.onTextResize(this, oldTextSize, targetTextSize); } // Reset force resize flag mNeedsResize = false; } // Set the text size of the text paint object and use a static layout to render text off screen before measuring private int getTextHeight(CharSequence source, TextPaint originalPaint, int width, float textSize) { // modified: make a copy of the original TextPaint object for measuring // (apparently the object gets modified while measuring, see also the // docs for TextView.getPaint() (which states to access it read-only) TextPaint paint = new TextPaint(originalPaint); // Update the text paint object paint.setTextSize(textSize); // Measure using a static layout StaticLayout layout = new StaticLayout(source, paint, width, Alignment.ALIGN_NORMAL, mSpacingMult, mSpacingAdd, true); return layout.getHeight(); } } 

Answer 10

I hope this helps you

 import android.content.Context; import android.graphics.Rect; import android.text.TextPaint; import android.util.AttributeSet; import android.widget.TextView; /* Based on * from http://stackoverflow.com/questions/2617266/how-to-adjust-text-font-size-to-fit-textview */ public class FontFitTextView extends TextView { private static float MAX_TEXT_SIZE = 20; public FontFitTextView(Context context) { this(context, null); } public FontFitTextView(Context context, AttributeSet attrs) { super(context, attrs); float size = this.getTextSize(); if (size > MAX_TEXT_SIZE) setTextSize(MAX_TEXT_SIZE); } private void refitText(String text, int textWidth) { if (textWidth > 0) { float availableWidth = textWidth - this.getPaddingLeft() - this.getPaddingRight(); TextPaint tp = getPaint(); Rect rect = new Rect(); tp.getTextBounds(text, 0, text.length(), rect); float size = rect.width(); if (size > availableWidth) setTextScaleX(availableWidth / size); } } @Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { super.onMeasure(widthMeasureSpec, heightMeasureSpec); int parentWidth = MeasureSpec.getSize(widthMeasureSpec); int parentHeight = MeasureSpec.getSize(heightMeasureSpec); refitText(this.getText().toString(), parentWidth); this.setMeasuredDimension(parentWidth, parentHeight); } @Override protected void onTextChanged(final CharSequence text, final int start, final int before, final int after) { refitText(text.toString(), this.getWidth()); } @Override protected void onSizeChanged(int w, int h, int oldw, int oldh) { if (w != oldw) { refitText(this.getText().toString(), w); } } } 

NOTE: I use MAX_TEXT_SIZE in case of text size is bigger than 20 because I don't want to allow big fonts applies to my View, if this is not your case, you can just simply remove it.

Answer 11

Since I've been looking for this forever, and I found a solution a while ago which is missing here, I'm gonna write it here, for future reference also.

Note: this code was taken directly from Google Android Lollipop dialer a while back, I don't remember If changes were made at the time. Also, I don't know which license is this under, but I have reason to think it is Apache 2.0 .

Class ResizeTextView , the actual View

 public class ResizeTextView extends TextView { private final int mOriginalTextSize; private final int mMinTextSize; private final static int sMinSize = 20; public ResizeTextView(Context context, AttributeSet attrs) { super(context, attrs); mOriginalTextSize = (int) getTextSize(); mMinTextSize = (int) sMinSize; } @Override protected void onTextChanged(CharSequence text, int start, int lengthBefore, int lengthAfter) { super.onTextChanged(text, start, lengthBefore, lengthAfter); ViewUtil.resizeText(this, mOriginalTextSize, mMinTextSize); } @Override protected void onSizeChanged(int w, int h, int oldw, int oldh) { super.onSizeChanged(w, h, oldw, oldh); ViewUtil.resizeText(this, mOriginalTextSize, mMinTextSize); } 

This ResizeTextView class could extend TextView and all its children as I undestand, so EditText as well.

Class ViewUtil with method resizeText(...)

 /* * Copyright (C) 2012 The Android Open Source Project * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ import android.graphics.Paint; import android.util.TypedValue; import android.widget.TextView; public class ViewUtil { private ViewUtil() {} public static void resizeText(TextView textView, int originalTextSize, int minTextSize) { final Paint paint = textView.getPaint(); final int width = textView.getWidth(); if (width == 0) return; textView.setTextSize(TypedValue.COMPLEX_UNIT_PX, originalTextSize); float ratio = width / paint.measureText(textView.getText().toString()); if (ratio <= 1.0f) { textView.setTextSize(TypedValue.COMPLEX_UNIT_PX, Math.max(minTextSize, originalTextSize * ratio)); } } } 

You should set your view as

 <yourpackage.yourapp.ResizeTextView android:layout_width="match_parent" android:layout_height="64dp" android:gravity="center" android:maxLines="1"/> 

希望它有帮助！

Answer 12

I wrote a blog post about this.

I created a component called ResizableButton based on Kirill Grouchnikov's blog post about custom components used in the new android market app. I placed the src code here .

On the other hand, mosabua read my post and told me he was going to open source his implementation which was faster than mine. I hope he release it soon enough 🙂

Answer 13

AppcompatTextView now supports auto sizing starting from Support Library 26.0. TextView in Android O also works same way. More info can be found here. A simple demo app can be found here .

 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:app="http://schemas.android.com/apk/res-auto" android:layout_width="match_parent" android:layout_height="wrap_content"> <TextView android:layout_width="wrap_content" android:layout_height="wrap_content" app:autoSizeTextType="uniform" app:autoSizeMinTextSize="12sp" app:autoSizeMaxTextSize="100sp" app:autoSizeStepGranularity="2sp" /> </LinearLayout> 

Answer 14

Here's a simple solution that uses TextView itself with a TextChangedListened added to it:

 expressionView = (TextView) findViewById(R.id.expressionView); expressionView.addTextChangedListener(textAutoResizeWatcher(expressionView, 25, 55)); private TextWatcher textAutoResizeWatcher(final TextView view, final int MIN_SP, final int MAX_SP) { return new TextWatcher() { @Override public void beforeTextChanged(CharSequence charSequence, int i, int i1, int i2) {} @Override public void onTextChanged(CharSequence charSequence, int i, int i1, int i2) {} @Override public void afterTextChanged(Editable editable) { final int widthLimitPixels = view.getWidth() - view.getPaddingRight() - view.getPaddingLeft(); Paint paint = new Paint(); float fontSizeSP = pixelsToSp(view.getTextSize()); paint.setTextSize(spToPixels(fontSizeSP)); String viewText = view.getText().toString(); float widthPixels = paint.measureText(viewText); // Increase font size if necessary. if (widthPixels < widthLimitPixels){ while (widthPixels < widthLimitPixels && fontSizeSP <= MAX_SP){ ++fontSizeSP; paint.setTextSize(spToPixels(fontSizeSP)); widthPixels = paint.measureText(viewText); } --fontSizeSP; } // Decrease font size if necessary. else { while (widthPixels > widthLimitPixels || fontSizeSP > MAX_SP) { if (fontSizeSP < MIN_SP) { fontSizeSP = MIN_SP; break; } --fontSizeSP; paint.setTextSize(spToPixels(fontSizeSP)); widthPixels = paint.measureText(viewText); } } view.setTextSize(fontSizeSP); } }; } private float pixelsToSp(float px) { float scaledDensity = getResources().getDisplayMetrics().scaledDensity; return px/scaledDensity; } private float spToPixels(float sp) { float scaledDensity = getResources().getDisplayMetrics().scaledDensity; return sp * scaledDensity; } 

This approach will increase or decrease the font size as needed to fit the text, respecting the MIN_SP and MAX_SP bounds received as parameters.

Answer 15

My implementation is a bit more complex, but comes with the following goodies:

• takes the available width and available height into account
• works with single line and multiline labels
• uses ellipsis in case the minimum font size is hit
• since the internal text representation is changed, remembers the originally set text in a separate variable
• ensures that the canvas is always only as big as it needs to be, while it uses all the available height of the parent

 /** * Text view that auto adjusts text size to fit within the view. If the text * size equals the minimum text size and still does not fit, append with an * ellipsis. * * Based on the original work from Chase Colburn * &lt;http://stackoverflow.com/a/5535672/305532> * * @author Thomas Keller &lt;[e-mail]> */ public class AutoResizeTextView extends TextView { // in dip private static final int MIN_TEXT_SIZE = 20; private static final boolean SHRINK_TEXT_SIZE = true; private static final char ELLIPSIS = '\u2026'; private static final float LINE_SPACING_MULTIPLIER_MULTILINE = 0.8f; private static final float LINE_SPACING_MULTIPLIER_SINGLELINE = 1f; private static final float LINE_SPACING_EXTRA = 0.0f; private CharSequence mOriginalText; // temporary upper bounds on the starting text size private float mMaxTextSize; // lower bounds for text size private float mMinTextSize; // determines whether we're currently in the process of measuring ourselves, // so we do not enter onMeasure recursively private boolean mInMeasure = false; // if the text size should be shrinked or if the text size should be kept // constant and only characters should be removed to hit the boundaries private boolean mShrinkTextSize; public AutoResizeTextView(Context context) { this(context, null); init(context, null); } public AutoResizeTextView(Context context, AttributeSet attrs) { this(context, attrs, 0); init(context, attrs); } public AutoResizeTextView(Context context, AttributeSet attrs, int defStyle) { super(context, attrs, defStyle); init(context, attrs); } private void init(Context context, AttributeSet attrs) { // the current text size is used as maximum text size we can apply to // our widget mMaxTextSize = getTextSize(); if (attrs != null) { TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.AutoResizeTextView); mMinTextSize = a.getFloat(R.styleable.AutoResizeTextView_minFontSize, MIN_TEXT_SIZE); mShrinkTextSize = a.getBoolean(R.styleable.AutoResizeTextView_shrinkTextSize, SHRINK_TEXT_SIZE); a.recycle(); } } @Override public void setTextSize(float size) { mMaxTextSize = size; super.setTextSize(size); } /** * Returns the original, unmodified text of this widget * * @return */ public CharSequence getOriginalText() { // text has not been resized yet if (mOriginalText == null) { return getText(); } return mOriginalText; } @Override public void setText(CharSequence text, BufferType type) { if (!mInMeasure) { mOriginalText = text.toString(); } super.setText(text, type); } @SuppressLint("DrawAllocation") @Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { mInMeasure = true; try { int availableWidth = MeasureSpec.getSize(widthMeasureSpec) - getCompoundPaddingLeft() - getCompoundPaddingRight(); int availableHeight = MeasureSpec.getSize(heightMeasureSpec) - getCompoundPaddingTop() - getCompoundPaddingBottom(); // Do not resize if the view does not have dimensions or there is no // text if (mOriginalText == null || mOriginalText.length() == 0 || availableWidth <= 0) { return; } TextPaint textPaint = getPaint(); // start with the recorded max text size float targetTextSize = mMaxTextSize; String originalText = mOriginalText.toString(); String finalText = originalText; Rect textSize = getTextSize(originalText, textPaint, targetTextSize); boolean textExceedsBounds = textSize.height() > availableHeight || textSize.width() > availableWidth; if (mShrinkTextSize && textExceedsBounds) { // check whether all lines can be rendered in the available // width / height without violating the bounds of the parent and // without using a text size that is smaller than the minimum // text size float heightMultiplier = availableHeight / (float) textSize.height(); float widthMultiplier = availableWidth / (float) textSize.width(); float multiplier = Math.min(heightMultiplier, widthMultiplier); targetTextSize = Math.max(targetTextSize * multiplier, mMinTextSize); // measure again textSize = getTextSize(finalText, textPaint, targetTextSize); } // we cannot shrink the height further when we hit the available // height, but we can shrink the width by applying an ellipsis on // each line if (textSize.width() > availableWidth) { StringBuilder modifiedText = new StringBuilder(); String lines[] = originalText.split(System.getProperty("line.separator")); for (int i = 0; i < lines.length; i++) { modifiedText.append(resizeLine(textPaint, lines[i], availableWidth)); // add the separator back to all but the last processed line if (i != lines.length - 1) { modifiedText.append(System.getProperty("line.separator")); } } finalText = modifiedText.toString(); // measure again textSize = getTextSize(finalText, textPaint, targetTextSize); } textPaint.setTextSize(targetTextSize); boolean isMultiline = finalText.indexOf('\n') > -1; // do not include extra font padding (for accents, ...) for // multiline texts, this will prevent proper placement with // Gravity.CENTER_VERTICAL if (isMultiline) { setLineSpacing(LINE_SPACING_EXTRA, LINE_SPACING_MULTIPLIER_MULTILINE); setIncludeFontPadding(false); } else { setLineSpacing(LINE_SPACING_EXTRA, LINE_SPACING_MULTIPLIER_SINGLELINE); setIncludeFontPadding(true); } // according to // <http://code.google.com/p/android/issues/detail?id=22493> // we have to add a unicode character to trigger the text centering // in ICS. this particular character is known as "zero-width" and // does no harm. setText(finalText + "\u200B"); int measuredWidth = textSize.width() + getCompoundPaddingLeft() + getCompoundPaddingRight(); int measuredHeight = textSize.height() + getCompoundPaddingTop() + getCompoundPaddingBottom(); // expand the view to the parent's height in case it is smaller or // to the minimum height that has been set // FIXME: honor the vertical measure mode (EXACTLY vs AT_MOST) here // somehow measuredHeight = Math.max(measuredHeight, MeasureSpec.getSize(heightMeasureSpec)); setMeasuredDimension(measuredWidth, measuredHeight); } finally { mInMeasure = false; } } private Rect getTextSize(String text, TextPaint textPaint, float textSize) { textPaint.setTextSize(textSize); // StaticLayout depends on a given width in which it should lay out the // text (and optionally also split into separate lines). // Therefor we calculate the current text width manually and start with // a fake (read: maxmimum) width for the height calculation. // We do _not_ use layout.getLineWidth() here since this returns // slightly smaller numbers and therefor would lead to exceeded text box // drawing. StaticLayout layout = new StaticLayout(text, textPaint, Integer.MAX_VALUE, Alignment.ALIGN_NORMAL, 1f, 0f, true); int textWidth = 0; String lines[] = text.split(System.getProperty("line.separator")); for (int i = 0; i < lines.length; ++i) { textWidth = Math.max(textWidth, measureTextWidth(textPaint, lines[i])); } return new Rect(0, 0, textWidth, layout.getHeight()); } private String resizeLine(TextPaint textPaint, String line, int availableWidth) { checkArgument(line != null && line.length() > 0, "expected non-empty string"); int textWidth = measureTextWidth(textPaint, line); int lastDeletePos = -1; StringBuilder builder = new StringBuilder(line); while (textWidth > availableWidth && builder.length() > 0) { lastDeletePos = builder.length() / 2; builder.deleteCharAt(builder.length() / 2); // don't forget to measure the ellipsis character as well; it // doesn't matter where it is located in the line, it just has to be // there, since there are no (known) ligatures that use this glyph String textToMeasure = builder.toString() + ELLIPSIS; textWidth = measureTextWidth(textPaint, textToMeasure); } if (lastDeletePos > -1) { builder.insert(lastDeletePos, ELLIPSIS); } return builder.toString(); } // there are several methods in Android to determine the text width, namely // getBounds() and measureText(). // The latter works for us the best as it gives us the best / nearest // results without that our text canvas needs to wrap its text later on // again. private int measureTextWidth(TextPaint textPaint, String line) { return Math.round(textPaint.measureText(line)); } } 

[revised on 2012-11-21]

• fixed the placement of the ellipsis (off-by-one error)
• reworked text size calculation; now always the full text including line breaks is measured, to fix problems when the addition of the height of two single measured lines just didn't lead to the same result as the measurement of the height of the text as a whole
• instead of looping to find the smallest available text size, just calculate it after the first measurement

Answer 16

I found the following to work nicely for me. It doesn't loop and accounts for both height and width. Note that it is important to specify the PX unit when calling setTextSize on the view.

 Paint paint = adjustTextSize(getPaint(), numChars, maxWidth, maxHeight); setTextSize(TypedValue.COMPLEX_UNIT_PX,paint.getTextSize()); 

Here is the routine I use, passing in the getPaint() from the view. A 10 character string with a 'wide' character is used to estimate the width independent from the actual string.

 private static final String text10="OOOOOOOOOO"; public static Paint adjustTextSize(Paint paint, int numCharacters, int widthPixels, int heightPixels) { float width = paint.measureText(text10)*numCharacters/text10.length(); float newSize = (int)((widthPixels/width)*paint.getTextSize()); paint.setTextSize(newSize); // remeasure with font size near our desired result width = paint.measureText(text10)*numCharacters/text10.length(); newSize = (int)((widthPixels/width)*paint.getTextSize()); paint.setTextSize(newSize); // Check height constraints FontMetricsInt metrics = paint.getFontMetricsInt(); float textHeight = metrics.descent-metrics.ascent; if (textHeight > heightPixels) { newSize = (int)(newSize * (heightPixels/textHeight)); paint.setTextSize(newSize); } return paint; } 

Answer 17

Here's an enumeration of what else I've found for anyone still searching:

1) Here's a solution that recursively re-paints the textview until it fits. This means literally watching your text shrink into place, but at least it fits when it's done. The code will need some tweaking to implement, but it's mostly there.

2) You can try hacking together a custom solution like this , or dunni's class in this , which is what I did using the getPaint().measureText(str) to search for the right size, but it got a lot messier since I need it to wrap only on whitespace…

3) You can keep searching- I've tried more alternatives than I can count. Ted's advice on StaticLayout hasn't paid off for me but maybe there's something there; I tried using the StaticLayout.getEllipsis(line) to determine if text was going off screen, to no effect. See my (presently un-answered) post about that here .

Answer 18

I needed a specific solution. I have got an edittext and textview in my layout. The textview is fixed height and width. When the user starts to type in the edittext, the text should immediately appear in the textview. The text in the textfield should auto – resize to fit the textview. So I updated Chase's solution to work for me. So when the text changes in the textview, resizing starts. The difference between mine and Chase's soluton: resizing is done even if the user DELETE some chars . I hope it can help someone.

 public class TextFitTextView extends TextView { // Minimum text size for this text view public static final float MIN_TEXT_SIZE = 10; // Maximum text size for this text view - if it is 0, then the text acts // like match_parent public static final float MAX_TEXT_SIZE = 0; // Our ellipse string private static final String mEllipsis = "..."; // Text size that is set from code. This acts as a starting point for // resizing private float mTextSize; // Lower bounds for text size private float mMinTextSize = MIN_TEXT_SIZE; // Max bounds for text size private float mMaxTextSize = MAX_TEXT_SIZE; // Text view line spacing multiplier private float mSpacingMult = 1.0f; // Text view additional line spacing private float mSpacingAdd = 0.0f; // Add ellipsis to text that overflows at the smallest text size private boolean mAddEllipsis = true; // Add ellipsis to text that overflows at the smallest text size private int heightLimit; private int widthLimit; // Default constructor override public TextFitTextView(Context context) { this(context, null); } // Default constructor when inflating from XML file public TextFitTextView(Context context, AttributeSet attrs) { this(context, attrs, 0); } // Default constructor override public TextFitTextView(Context context, AttributeSet attrs, int defStyle) { super(context, attrs, defStyle); mTextSize = getTextSize(); } /** * When text changes resize the text size. */ @Override protected void onTextChanged(final CharSequence text, final int start, final int before, final int after) { // if we are adding new chars to text if (before <= after && after != 1) { resizeText(true); // now we are deleting chars } else { resizeText(false); } } /** * Override the set text size to update our internal reference values */ @Override public void setTextSize(float size) { super.setTextSize(size); mTextSize = getTextSize(); } /** * Override the set text size to update our internal reference values */ @Override public void setTextSize(int unit, float size) { super.setTextSize(unit, size); mTextSize = getTextSize(); } /** * Override the set line spacing to update our internal reference values */ @Override public void setLineSpacing(float add, float mult) { super.setLineSpacing(add, mult); mSpacingMult = mult; mSpacingAdd = add; } /** * Set the lower text size limit and invalidate the view * * @param minTextSize */ public void setMinTextSize(float minTextSize) { mMinTextSize = minTextSize; requestLayout(); invalidate(); } /** * Return lower text size limit * * @return */ public float getMinTextSize() { return mMinTextSize; } /** * Set flag to add ellipsis to text that overflows at the smallest text size * * @param addEllipsis */ public void setAddEllipsis(boolean addEllipsis) { mAddEllipsis = addEllipsis; } /** * Return flag to add ellipsis to text that overflows at the smallest text * size * * @return */ public boolean getAddEllipsis() { return mAddEllipsis; } /** * Get width and height limits */ @Override protected void onLayout(boolean changed, int left, int top, int right, int bottom) { if (widthLimit == 0 && heightLimit == 0) { widthLimit = (right - left) - getCompoundPaddingLeft() - getCompoundPaddingRight(); heightLimit = (bottom - top) - getCompoundPaddingBottom() - getCompoundPaddingTop(); } super.onLayout(changed, left, top, right, bottom); } /** * Resize the text size with specified width and height * * @param width * @param height */ public void resizeText(boolean increase) { CharSequence text = getText(); // Do not resize if the view does not have dimensions or there is no // text if (text == null || text.length() == 0 || heightLimit <= 0 || widthLimit <= 0 || mTextSize == 0) { return; } // Get the text view's paint object TextPaint textPaint = getPaint(); // Get the required text height int textHeight = getTextHeight(text, textPaint, widthLimit, mTextSize); // If the text length is increased // Until we either fit within our text view or we had reached our min // text size, incrementally try smaller sizes if (increase) { while (textHeight > heightLimit && mTextSize > mMinTextSize) { mTextSize = Math.max(mTextSize - 2, mMinTextSize); textHeight = getTextHeight(text, textPaint, widthLimit, mTextSize); } } // text length has been decreased else { // if max test size is set then add it to while condition if (mMaxTextSize != 0) { while (textHeight < heightLimit && mTextSize <= mMaxTextSize) { mTextSize = mTextSize + 2; textHeight = getTextHeight(text, textPaint, widthLimit, mTextSize); } } else { while (textHeight < heightLimit) { mTextSize = mTextSize + 2; textHeight = getTextHeight(text, textPaint, widthLimit, mTextSize); } } mTextSize = textHeight > heightLimit ? mTextSize - 2 : mTextSize; } // If we had reached our minimum text size and still don't fit, append // an ellipsis if (mAddEllipsis && mTextSize == mMinTextSize && textHeight > heightLimit) { // Draw using a static layout TextPaint paint = new TextPaint(textPaint); StaticLayout layout = new StaticLayout(text, paint, widthLimit, Alignment.ALIGN_NORMAL, mSpacingMult, mSpacingAdd, false); // Check that we have a least one line of rendered text if (layout.getLineCount() > 0) { // Since the line at the specific vertical position would be cut // off, // we must trim up to the previous line int lastLine = layout.getLineForVertical(heightLimit) - 1; // If the text would not even fit on a single line, clear it if (lastLine < 0) { setText(""); } // Otherwise, trim to the previous line and add an ellipsis else { int start = layout.getLineStart(lastLine); int end = layout.getLineEnd(lastLine); float lineWidth = layout.getLineWidth(lastLine); float ellipseWidth = paint.measureText(mEllipsis); // Trim characters off until we have enough room to draw the // ellipsis while (widthLimit < lineWidth + ellipseWidth) { lineWidth = paint.measureText(text.subSequence(start, --end + 1).toString()); } setText(text.subSequence(0, end) + mEllipsis); } } } // Some devices try to auto adjust line spacing, so force default line // spacing // and invalidate the layout as a side effect setTextSize(TypedValue.COMPLEX_UNIT_PX, mTextSize); setLineSpacing(mSpacingAdd, mSpacingMult); } // Set the text size of the text paint object and use a static layout to // render text off screen before measuring private int getTextHeight(CharSequence source, TextPaint originalPaint, int width, float textSize) { // Update the text paint object TextPaint paint = new TextPaint(originalPaint); paint.setTextSize(textSize); // Measure using a static layout StaticLayout layout = new StaticLayout(source, paint, width, Alignment.ALIGN_NORMAL, mSpacingMult, mSpacingAdd, true); return layout.getHeight(); } } 

Answer 19

At google IO conference in 2017, google introduced autoSize property of TextView

https://youtu.be/fjUdJ2aVqE4

 <android.support.v7.widget.AppCompatTextView android:layout_width="match_parent" android:layout_height="match_parent" android:text="@string/my_text" app:autoSizeTextType="uniform" app:autoSizeMaxTextSize="10sp" app:autoSizeMinTextSize="6sp" app:autoSizeStepGranularity="1sp"/> 

Answer 20

You can use the android.text.StaticLayout class for this. That's what TextView uses internally.

Answer 21

I just created the following method (based on the ideas of Chase) which might help you if you want to draw text to any canvas:

 private static void drawText(Canvas canvas, int xStart, int yStart, int xWidth, int yHeigth, String textToDisplay, TextPaint paintToUse, float startTextSizeInPixels, float stepSizeForTextSizeSteps) { // Text view line spacing multiplier float mSpacingMult = 1.0f; // Text view additional line spacing float mSpacingAdd = 0.0f; StaticLayout l = null; do { paintToUse.setTextSize(startTextSizeInPixels); startTextSizeInPixels -= stepSizeForTextSizeSteps; l = new StaticLayout(textToDisplay, paintToUse, xWidth, Alignment.ALIGN_NORMAL, mSpacingMult, mSpacingAdd, true); } while (l.getHeight() > yHeigth); int textCenterX = xStart + (xWidth / 2); int textCenterY = (yHeigth - l.getHeight()) / 2; canvas.save(); canvas.translate(textCenterX, textCenterY); l.draw(canvas); canvas.restore(); } 

This could be used eg in any onDraw() method of any custom view.

Answer 22

Here's yet another solution, just for kicks. It's probably not very efficient, but it does cope with both height and width of the text, and with marked-up text.

 @Override protected void onMeasure(final int widthMeasureSpec, final int heightMeasureSpec) { if ((MeasureSpec.getMode(widthMeasureSpec) != MeasureSpec.UNSPECIFIED) && (MeasureSpec.getMode(heightMeasureSpec) != MeasureSpec.UNSPECIFIED)) { final float desiredWidth = MeasureSpec.getSize(widthMeasureSpec); final float desiredHeight = MeasureSpec.getSize(heightMeasureSpec); float textSize = getTextSize(); float lastScale = Float.NEGATIVE_INFINITY; while (textSize > MINIMUM_AUTO_TEXT_SIZE_PX) { // Measure how big the textview would like to be with the current text size. super.onMeasure(MeasureSpec.UNSPECIFIED, MeasureSpec.UNSPECIFIED); // Calculate how much we'd need to scale it to fit the desired size, and // apply that scaling to the text size as an estimate of what we need. final float widthScale = desiredWidth / getMeasuredWidth(); final float heightScale = desiredHeight / getMeasuredHeight(); final float scale = Math.min(widthScale, heightScale); // If we don't need to shrink the text, or we don't seem to be converging, we're done. if ((scale >= 1f) || (scale <= lastScale)) { break; } // Shrink the text size and keep trying. textSize = Math.max((float) Math.floor(scale * textSize), MINIMUM_AUTO_TEXT_SIZE_PX); setTextSize(TypedValue.COMPLEX_UNIT_PX, textSize); lastScale = scale; } } super.onMeasure(widthMeasureSpec, heightMeasureSpec); } 

Answer 23

I combined some of the above suggestions to make one that scales up and down, with bisection method. It also scales within the width.

 /** * DO WHAT YOU WANT TO PUBLIC LICENSE * Version 2, December 2004 * * Copyright (C) 2004 Sam Hocevar <[e-mail]> * * Everyone is permitted to copy and distribute verbatim or modified * copies of this license document, and changing it is allowed as long * as the name is changed. * * DO WHAT YOU WANT TO PUBLIC LICENSE * TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION * * 0. You just DO WHAT YOU WANT TO. */ import android.content.Context; import android.text.Layout.Alignment; import android.text.StaticLayout; import android.text.TextPaint; import android.util.AttributeSet; import android.util.TypedValue; import android.widget.TextView; /** * Text view that auto adjusts text size to fit within the view. If the text * size equals the minimum text size and still does not fit, append with an * ellipsis. * * @author Chase Colburn * @since Apr 4, 2011 */ public class AutoResizeTextView extends TextView { // Minimum text size for this text view public static final float MIN_TEXT_SIZE = 10; // Minimum text size for this text view public static final float MAX_TEXT_SIZE = 128; private static final int BISECTION_LOOP_WATCH_DOG = 30; // Interface for resize notifications public interface OnTextResizeListener { public void onTextResize(TextView textView, float oldSize, float newSize); } // Our ellipse string private static final String mEllipsis = "..."; // Registered resize listener private OnTextResizeListener mTextResizeListener; // Flag for text and/or size changes to force a resize private boolean mNeedsResize = false; // Text size that is set from code. This acts as a starting point for // resizing private float mTextSize; // Temporary upper bounds on the starting text size private float mMaxTextSize = MAX_TEXT_SIZE; // Lower bounds for text size private float mMinTextSize = MIN_TEXT_SIZE; // Text view line spacing multiplier private float mSpacingMult = 1.0f; // Text view additional line spacing private float mSpacingAdd = 0.0f; // Add ellipsis to text that overflows at the smallest text size private boolean mAddEllipsis = true; // Default constructor override public AutoResizeTextView(Context context) { this(context, null); } // Default constructor when inflating from XML file public AutoResizeTextView(Context context, AttributeSet attrs) { this(context, attrs, 0); } // Default constructor override public AutoResizeTextView(Context context, AttributeSet attrs, int defStyle) { super(context, attrs, defStyle); mTextSize = getTextSize(); } /** * When text changes, set the force resize flag to true and reset the text * size. */ @Override protected void onTextChanged(final CharSequence text, final int start, final int before, final int after) { mNeedsResize = true; // Since this view may be reused, it is good to reset the text size resetTextSize(); } /** * If the text view size changed, set the force resize flag to true */ @Override protected void onSizeChanged(int w, int h, int oldw, int oldh) { if (w != oldw || h != oldh) { mNeedsResize = true; } } /** * Register listener to receive resize notifications * * @param listener */ public void setOnResizeListener(OnTextResizeListener listener) { mTextResizeListener = listener; } /** * Override the set text size to update our internal reference values */ @Override public void setTextSize(float size) { super.setTextSize(size); mTextSize = getTextSize(); } /** * Override the set text size to update our internal reference values */ @Override public void setTextSize(int unit, float size) { super.setTextSize(unit, size); mTextSize = getTextSize(); } /** * Override the set line spacing to update our internal reference values */ @Override public void setLineSpacing(float add, float mult) { super.setLineSpacing(add, mult); mSpacingMult = mult; mSpacingAdd = add; } /** * Set the upper text size limit and invalidate the view * * @param maxTextSize */ public void setMaxTextSize(float maxTextSize) { mMaxTextSize = maxTextSize; requestLayout(); invalidate(); } /** * Return upper text size limit * * @return */ public float getMaxTextSize() { return mMaxTextSize; } /** * Set the lower text size limit and invalidate the view * * @param minTextSize */ public void setMinTextSize(float minTextSize) { mMinTextSize = minTextSize; requestLayout(); invalidate(); } /** * Return lower text size limit * * @return */ public float getMinTextSize() { return mMinTextSize; } /** * Set flag to add ellipsis to text that overflows at the smallest text size * * @param addEllipsis */ public void setAddEllipsis(boolean addEllipsis) { mAddEllipsis = addEllipsis; } /** * Return flag to add ellipsis to text that overflows at the smallest text * size * * @return */ public boolean getAddEllipsis() { return mAddEllipsis; } /** * Reset the text to the original size */ public void resetTextSize() { if (mTextSize > 0) { super.setTextSize(TypedValue.COMPLEX_UNIT_PX, mTextSize); // mMaxTextSize = mTextSize; } } /** * Resize text after measuring */ @Override protected void onLayout(boolean changed, int left, int top, int right, int bottom) { if (changed || mNeedsResize) { int widthLimit = (right - left) - getCompoundPaddingLeft() - getCompoundPaddingRight(); int heightLimit = (bottom - top) - getCompoundPaddingBottom() - getCompoundPaddingTop(); resizeText(widthLimit, heightLimit); } super.onLayout(changed, left, top, right, bottom); } /** * Resize the text size with default width and height */ public void resizeText() { // Height and width with a padding as a percentage of height int heightLimit = getHeight() - getPaddingBottom() - getPaddingTop(); int widthLimit = getWidth() - getPaddingLeft() - getPaddingRight(); resizeText(widthLimit, heightLimit); } /** * Resize the text size with specified width and height * * @param width * @param height */ public void resizeText(int width, int height) { CharSequence text = getText(); // Do not resize if the view does not have dimensions or there is no // text if (text == null || text.length() == 0 || height <= 0 || width <= 0 || mTextSize == 0) { return; } // Get the text view's paint object TextPaint textPaint = getPaint(); // Store the current text size float oldTextSize = textPaint.getTextSize(); // Bisection method: fast & precise float lower = mMinTextSize; float upper = mMaxTextSize; int loop_counter = 1; float targetTextSize = (lower + upper) / 2; int textHeight = getTextHeight(text, textPaint, width, targetTextSize); int textWidth = getTextWidth(text, textPaint, width, targetTextSize); while (loop_counter < BISECTION_LOOP_WATCH_DOG && upper - lower > 1) { targetTextSize = (lower + upper) / 2; textHeight = getTextHeight(text, textPaint, width, targetTextSize); textWidth = getTextWidth(text, textPaint, width, targetTextSize); if (textHeight > (height) || textWidth > (width)) upper = targetTextSize; else lower = targetTextSize; loop_counter++; } targetTextSize = lower; textHeight = getTextHeight(text, textPaint, width, targetTextSize); // If we had reached our minimum text size and still don't fit, append // an ellipsis if (mAddEllipsis && targetTextSize == mMinTextSize && textHeight > height) { // Draw using a static layout // modified: use a copy of TextPaint for measuring TextPaint paintCopy = new TextPaint(textPaint); paintCopy.setTextSize(targetTextSize); StaticLayout layout = new StaticLayout(text, paintCopy, width, Alignment.ALIGN_NORMAL, mSpacingMult, mSpacingAdd, false); // Check that we have a least one line of rendered text if (layout.getLineCount() > 0) { // Since the line at the specific vertical position would be cut // off, // we must trim up to the previous line int lastLine = layout.getLineForVertical(height) - 1; // If the text would not even fit on a single line, clear it if (lastLine < 0) { setText(""); } // Otherwise, trim to the previous line and add an ellipsis else { int start = layout.getLineStart(lastLine); int end = layout.getLineEnd(lastLine); float lineWidth = layout.getLineWidth(lastLine); float ellipseWidth = paintCopy.measureText(mEllipsis); // Trim characters off until we have enough room to draw the // ellipsis while (width < lineWidth + ellipseWidth) { lineWidth = paintCopy.measureText(text.subSequence( start, --end + 1).toString()); } setText(text.subSequence(0, end) + mEllipsis); } } } // Some devices try to auto adjust line spacing, so force default line // spacing // and invalidate the layout as a side effect setTextSize(TypedValue.COMPLEX_UNIT_PX, targetTextSize); setLineSpacing(mSpacingAdd, mSpacingMult); // Notify the listener if registered if (mTextResizeListener != null) { mTextResizeListener.onTextResize(this, oldTextSize, targetTextSize); } // Reset force resize flag mNeedsResize = false; } // Set the text size of the text paint object and use a static layout to // render text off screen before measuring private int getTextHeight(CharSequence source, TextPaint originalPaint, int width, float textSize) { // modified: make a copy of the original TextPaint object for measuring // (apparently the object gets modified while measuring, see also the // docs for TextView.getPaint() (which states to access it read-only) TextPaint paint = new TextPaint(originalPaint); // Update the text paint object paint.setTextSize(textSize); // Measure using a static layout StaticLayout layout = new StaticLayout(source, paint, width, Alignment.ALIGN_NORMAL, mSpacingMult, mSpacingAdd, true); return layout.getHeight(); } // Set the text size of the text paint object and use a static layout to // render text off screen before measuring private int getTextWidth(CharSequence source, TextPaint originalPaint, int width, float textSize) { // Update the text paint object TextPaint paint = new TextPaint(originalPaint); // Draw using a static layout paint.setTextSize(textSize); StaticLayout layout = new StaticLayout(source, paint, width, Alignment.ALIGN_NORMAL, mSpacingMult, mSpacingAdd, true); return (int) layout.getLineWidth(0); } } 

Answer 24

I have use code from chase and M-WaJeEh and I found some advantage & disadvantage here

from chase

优点：

• it's perfect for 1 line TextView

Disadvantage:

• if it's more than 1 line with custom font some of text will disappear

• if it's enable ellipse, it didn't prepare space for ellipse

• if it's custom font (typeface), it didn't support

from M-WaJeEh

优点：

• it's perfect for multi-line

Disadvantage:

• if set height as wrap-content, this code will start from minimum size and it will reduce to smallest as it can, not from the setSize and reduce by the limited width

• if it's custom font (typeface), it didn't support

Answer 25

If anyone needs it, here is the same code snippet but for Xamarin.Android.

 /** * DO WHAT YOU WANT TO PUBLIC LICENSE * Version 1, December 2017 * * Copyright (C) 2017 Nathan Westfall * * Everyone is permitted to copy and distribute verbatim or modified * copies of this license document, and changing it is allowed as long * as the name is changed. * * DO WHAT YOU WANT TO PUBLIC LICENSE * TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION * * 0. You just DO WHAT YOU WANT TO. */ using Android.Content; using Android.Runtime; using Android.Widget; using Android.Util; using Android.Text; using Java.Lang; namespace My.Text { public class AutoResizeTextView : TextView { public const float MIN_TEXT_SIZE = 20; public interface OnTextResizeListener { void OnTextResize(TextView textView, float oldSize, float newSize); } private const string mEllipsis = "..."; private OnTextResizeListener mTextResizeListener; private bool mNeedsResize = false; private float mTextSize; private float mMaxTextSize = 0; private float mMinTextSize = MIN_TEXT_SIZE; private float mSpacingMult = 1.0f; private float mSpacingAdd = 0.0f; public bool AddEllipsis { get; set; } = true; public AutoResizeTextView(Context context) : this(context, null) { } public AutoResizeTextView(Context context, IAttributeSet attrs) : this(context, attrs, 0) { } public AutoResizeTextView(Context context, IAttributeSet attrs, int defStyle): base(context, attrs, defStyle) { mTextSize = TextSize; } protected override void OnTextChanged(ICharSequence text, int start, int lengthBefore, int lengthAfter) { base.OnTextChanged(text, start, lengthBefore, lengthAfter); mNeedsResize = true; ResetTextSize(); } protected override void OnSizeChanged(int w, int h, int oldw, int oldh) { base.OnSizeChanged(w, h, oldw, oldh); if (w != oldw || h != oldh) mNeedsResize = true; } public void SetOnResizeListener(OnTextResizeListener listener) { mTextResizeListener = listener; } public override void SetTextSize([GeneratedEnum] ComplexUnitType unit, float size) { base.SetTextSize(unit, size); mTextSize = TextSize; } public override void SetLineSpacing(float add, float mult) { base.SetLineSpacing(add, mult); mSpacingMult = mult; mSpacingAdd = add; } public void SetMaxTextSize(float maxTextSize) { mMaxTextSize = maxTextSize; RequestLayout(); Invalidate(); } public float GetMaxTextSize() { return mMaxTextSize; } public void SetMinTextSize(float minTextSize) { mMinTextSize = minTextSize; RequestLayout(); Invalidate(); } public float GetMinTextSize() { return mMinTextSize; } public void ResetTextSize() { if(mTextSize > 0) { base.SetTextSize(ComplexUnitType.Px, mTextSize); mMaxTextSize = mTextSize; } } protected override void OnLayout(bool changed, int left, int top, int right, int bottom) { if(changed || mNeedsResize) { int widthLimit = (right - left) - CompoundPaddingLeft - CompoundPaddingRight; int heightLimit = (bottom - top) - CompoundPaddingBottom - CompoundPaddingTop; ResizeText(widthLimit, heightLimit); } base.OnLayout(changed, left, top, right, bottom); base.OnLayout(changed, left, top, right, bottom); } public void ResizeText() { int heightLimit = Height - PaddingBottom - PaddingTop; int widthLimit = Width - PaddingLeft - PaddingRight; ResizeText(widthLimit, heightLimit); } public void ResizeText(int width, int height) { var text = TextFormatted; if (text == null || text.Length() == 0 || height <= 0 || width <= 0 || mTextSize == 0) return; if (TransformationMethod != null) text = TransformationMethod.GetTransformationFormatted(TextFormatted, this); TextPaint textPaint = Paint; float oldTextSize = textPaint.TextSize; float targetTextSize = mMaxTextSize > 0 ? System.Math.Min(mTextSize, mMaxTextSize) : mTextSize; int textHeight = GetTextHeight(text, textPaint, width, targetTextSize); while(textHeight > height && targetTextSize > mMinTextSize) { targetTextSize = System.Math.Max(targetTextSize - 2, mMinTextSize); textHeight = GetTextHeight(text, textPaint, width, targetTextSize); } if(AddEllipsis && targetTextSize == mMinTextSize && textHeight > height) { TextPaint paint = new TextPaint(textPaint); StaticLayout layout = new StaticLayout(text, paint, width, Layout.Alignment.AlignNormal, mSpacingMult, mSpacingAdd, false); if(layout.LineCount > 0) { int lastLine = layout.GetLineForVertical(height) - 1; if (lastLine < 0) SetText("", BufferType.Normal); else { int start = layout.GetLineStart(lastLine); int end = layout.GetLineEnd(lastLine); float lineWidth = layout.GetLineWidth(lastLine); float ellipseWidth = textPaint.MeasureText(mEllipsis); while (width < lineWidth + ellipseWidth) lineWidth = textPaint.MeasureText(text.SubSequence(start, --end + 1).ToString()); SetText(text.SubSequence(0, end) + mEllipsis, BufferType.Normal); } } } SetTextSize(ComplexUnitType.Px, targetTextSize); SetLineSpacing(mSpacingAdd, mSpacingMult); mTextResizeListener?.OnTextResize(this, oldTextSize, targetTextSize); mNeedsResize = false; } private int GetTextHeight(ICharSequence source, TextPaint paint, int width, float textSize) { TextPaint paintCopy = new TextPaint(paint); paintCopy.TextSize = textSize; StaticLayout layout = new StaticLayout(source, paintCopy, width, Layout.Alignment.AlignNormal, mSpacingMult, mSpacingAdd, false); return layout.Height; } } } 

Answer 26

This solutions works for us:

 public class CustomFontButtonTextFit extends CustomFontButton { private final float DECREMENT_FACTOR = .1f; public CustomFontButtonTextFit(Context context) { super(context); } public CustomFontButtonTextFit(Context context, AttributeSet attrs) { super(context, attrs); } public CustomFontButtonTextFit(Context context, AttributeSet attrs, int defStyle) { super(context, attrs, defStyle); } private synchronized void refitText(String text, int textWidth) { if (textWidth > 0) { float availableWidth = textWidth - this.getPaddingLeft() - this.getPaddingRight(); TextPaint tp = getPaint(); Rect rect = new Rect(); tp.getTextBounds(text, 0, text.length(), rect); float size = rect.width(); while(size > availableWidth) { setTextSize( getTextSize() - DECREMENT_FACTOR ); tp = getPaint(); tp.getTextBounds(text, 0, text.length(), rect); size = rect.width(); } } } @Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { super.onMeasure(widthMeasureSpec, heightMeasureSpec); int parentWidth = MeasureSpec.getSize(widthMeasureSpec); int parentHeight = MeasureSpec.getSize(heightMeasureSpec); refitText(this.getText().toString(), parentWidth); if(parentWidth < getSuggestedMinimumWidth()) parentWidth = getSuggestedMinimumWidth(); if(parentHeight < getSuggestedMinimumHeight()) parentHeight = getSuggestedMinimumHeight(); this.setMeasuredDimension(parentWidth, parentHeight); } @Override protected void onTextChanged(final CharSequence text, final int start, final int before, final int after) { super.onTextChanged(text, start, before, after); refitText(text.toString(), this.getWidth()); } @Override protected void onSizeChanged(int w, int h, int oldw, int oldh) { super.onSizeChanged(w, h, oldw, oldh); if (w != oldw) refitText(this.getText().toString(), w); } } 

Answer 27

Thanks to Chase and onoelle, for the lazy programmers, let me post here a working version of their fantastic merged code, adapted on a Button, instead of a TextView.

Substitute all your Buttons (not ImageButtons) with AutoResizeTextButtons and the same boring problem is fixed for them too.

这是代码。 I just removed the imports.

 /** * DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE * Version 2, December 2004 * * Copyright (C) 2004 Sam Hocevar <[e-mail]> * * Everyone is permitted to copy and distribute verbatim or modified * copies of this license document, and changing it is allowed as long * as the name is changed. * * DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE * TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION * * 0. You just DO WHAT THE FUCK YOU WANT TO. * made better by onoelle * adapted for button by beppi */ /** * Text Button that auto adjusts text size to fit within the view. * If the text size equals the minimum text size and still does not * fit, append with an ellipsis. * * @author Chase Colburn * @since Apr 4, 2011 */ public class AutoResizeTextButton extends Button { // Minimum text size for this text view public static final float MIN_TEXT_SIZE = 20; // Interface for resize notifications public interface OnTextResizeListener { public void onTextResize(Button textView, float oldSize, float newSize); } // Our ellipse string private static final String mEllipsis = "..."; // Registered resize listener private OnTextResizeListener mTextResizeListener; // Flag for text and/or size changes to force a resize private boolean mNeedsResize = false; // Text size that is set from code. This acts as a starting point for resizing private float mTextSize; // Temporary upper bounds on the starting text size private float mMaxTextSize = 0; // Lower bounds for text size private float mMinTextSize = MIN_TEXT_SIZE; // Text view line spacing multiplier private float mSpacingMult = 1.0f; // Text view additional line spacing private float mSpacingAdd = 0.0f; // Add ellipsis to text that overflows at the smallest text size private boolean mAddEllipsis = true; // Default constructor override public AutoResizeTextButton(Context context) { this(context, null); } // Default constructor when inflating from XML file public AutoResizeTextButton(Context context, AttributeSet attrs) { this(context, attrs, 0); } // Default constructor override public AutoResizeTextButton(Context context, AttributeSet attrs, int defStyle) { super(context, attrs, defStyle); mTextSize = getTextSize(); } /** * When text changes, set the force resize flag to true and reset the text size. */ @Override protected void onTextChanged(final CharSequence text, final int start, final int before, final int after) { mNeedsResize = true; // Since this view may be reused, it is good to reset the text size resetTextSize(); } /** * If the text view size changed, set the force resize flag to true */ @Override protected void onSizeChanged(int w, int h, int oldw, int oldh) { if (w != oldw || h != oldh) { mNeedsResize = true; } } /** * Register listener to receive resize notifications * @param listener */ public void setOnResizeListener(OnTextResizeListener listener) { mTextResizeListener = listener; } /** * Override the set text size to update our internal reference values */ @Override public void setTextSize(float size) { super.setTextSize(size); mTextSize = getTextSize(); } /** * Override the set text size to update our internal reference values */ @Override public void setTextSize(int unit, float size) { super.setTextSize(unit, size); mTextSize = getTextSize(); } /** * Override the set line spacing to update our internal reference values */ @Override public void setLineSpacing(float add, float mult) { super.setLineSpacing(add, mult); mSpacingMult = mult; mSpacingAdd = add; } /** * Set the upper text size limit and invalidate the view * @param maxTextSize */ public void setMaxTextSize(float maxTextSize) { mMaxTextSize = maxTextSize; requestLayout(); invalidate(); } /** * Return upper text size limit * @return */ public float getMaxTextSize() { return mMaxTextSize; } /** * Set the lower text size limit and invalidate the view * @param minTextSize */ public void setMinTextSize(float minTextSize) { mMinTextSize = minTextSize; requestLayout(); invalidate(); } /** * Return lower text size limit * @return */ public float getMinTextSize() { return mMinTextSize; } /** * Set flag to add ellipsis to text that overflows at the smallest text size * @param addEllipsis */ public void setAddEllipsis(boolean addEllipsis) { mAddEllipsis = addEllipsis; } /** * Return flag to add ellipsis to text that overflows at the smallest text size * @return */ public boolean getAddEllipsis() { return mAddEllipsis; } /** * Reset the text to the original size */ public void resetTextSize() { if(mTextSize > 0) { super.setTextSize(TypedValue.COMPLEX_UNIT_PX, mTextSize); mMaxTextSize = mTextSize; } } /** * Resize text after measuring */ @Override protected void onLayout(boolean changed, int left, int top, int right, int bottom) { if(changed || mNeedsResize) { int widthLimit = (right - left) - getCompoundPaddingLeft() - getCompoundPaddingRight(); int heightLimit = (bottom - top) - getCompoundPaddingBottom() - getCompoundPaddingTop(); resizeText(widthLimit, heightLimit); } super.onLayout(changed, left, top, right, bottom); } /** * Resize the text size with default width and height */ public void resizeText() { int heightLimit = getHeight() - getPaddingBottom() - getPaddingTop(); int widthLimit = getWidth() - getPaddingLeft() - getPaddingRight(); resizeText(widthLimit, heightLimit); } /** * Resize the text size with specified width and height * @param width * @param height */ public void resizeText(int width, int height) { CharSequence text = getText(); // Do not resize if the view does not have dimensions or there is no text if(text == null || text.length() == 0 || height <= 0 || width <= 0 || mTextSize == 0) { return; } // Get the text view's paint object TextPaint textPaint = getPaint(); // Store the current text size float oldTextSize = textPaint.getTextSize(); // If there is a max text size set, use the lesser of that and the default text size float targetTextSize = mMaxTextSize > 0 ? Math.min(mTextSize, mMaxTextSize) : mTextSize; // Get the required text height int textHeight = getTextHeight(text, textPaint, width, targetTextSize); // Until we either fit within our text view or we had reached our min text size, incrementally try smaller sizes while(textHeight > height && targetTextSize > mMinTextSize) { targetTextSize = Math.max(targetTextSize - 2, mMinTextSize); textHeight = getTextHeight(text, textPaint, width, targetTextSize); } // If we had reached our minimum text size and still don't fit, append an ellipsis if(mAddEllipsis && targetTextSize == mMinTextSize && textHeight > height) { // Draw using a static layout // modified: use a copy of TextPaint for measuring TextPaint paint = new TextPaint(textPaint); StaticLayout layout = new StaticLayout(text, paint, width, Alignment.ALIGN_NORMAL, mSpacingMult, mSpacingAdd, false); // Check that we have a least one line of rendered text if(layout.getLineCount() > 0) { // Since the line at the specific vertical position would be cut off, // we must trim up to the previous line int lastLine = layout.getLineForVertical(height) - 1; // If the text would not even fit on a single line, clear it if(lastLine < 0) { setText(""); } // Otherwise, trim to the previous line and add an ellipsis else { int start = layout.getLineStart(lastLine); int end = layout.getLineEnd(lastLine); float lineWidth = layout.getLineWidth(lastLine); float ellipseWidth = textPaint.measureText(mEllipsis); // Trim characters off until we have enough room to draw the ellipsis while(width < lineWidth + ellipseWidth) { lineWidth = textPaint.measureText(text.subSequence(start, --end + 1).toString()); } setText(text.subSequence(0, end) + mEllipsis); } } } // Some devices try to auto adjust line spacing, so force default line spacing // and invalidate the layout as a side effect // textPaint.setTextSize(targetTextSize); // modified: setting text size via this.setTextSize (instead of textPaint.setTextSize(targetTextSize)) setTextSize(TypedValue.COMPLEX_UNIT_PX, targetTextSize); setLineSpacing(mSpacingAdd, mSpacingMult); // Notify the listener if registered if(mTextResizeListener != null) { mTextResizeListener.onTextResize(this, oldTextSize, targetTextSize); } // Reset force resize flag mNeedsResize = false; } // Set the text size of the text paint object and use a static layout to render text off screen before measuring private int getTextHeight(CharSequence source, TextPaint originalPaint, int width, float textSize) { // modified: make a copy of the original TextPaint object for measuring // (apparently the object gets modified while measuring, see also the // docs for TextView.getPaint() (which states to access it read-only) // Update the text paint object TextPaint paint = new TextPaint(originalPaint); paint.setTextSize(textSize); // Measure using a static layout StaticLayout layout = new StaticLayout(source, paint, width, Alignment.ALIGN_NORMAL, mSpacingMult, mSpacingAdd, true); return layout.getHeight(); } } 

用法：

put a AutoResizeTextButton inside your xml in replace of a normal Button, without changing anything else. Inside the onCreate() put (for example):

  myButton = (AutoResizeTextButton)getView().findViewById(id.myButton); myButton.setMinTextSize(8f); myButton.resizeText(); 

Answer 28

Here is the approach I take. 这很简单。 It uses successive approximation to zero in on the fontsize and can generally have it figured out in less than 10 iterations. Just replace "activityWidth" with the width of whatever view you are using to display the text in. In my example, it's set as a private field to the screen's width. The inital fontsize of 198 is only set in the event the method generates an exception (which really should never happen):

  private float GetFontSizeForScreenWidth(String text) { float fontsize = 198; try { Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG); paint.setColor(Color.RED); Typeface typeface = Typeface.create("Helvetica", Typeface.BOLD); paint.setTypeface(typeface); paint.setTextAlign(Align.CENTER); int lowVal = 0; int highVal = 2000; int currentVal = highVal; /* * Successively approximate the screen size until it is * within 2 pixels of the maximum screen width. Generally * this will get you to the closest font size within about 10 * iterations. */ do { paint.setTextSize(currentVal); float textWidth = paint.measureText(text); float diff = activityWidth - textWidth; if ((diff >= 0) && (diff <= 2)) { fontsize = paint.getTextSize(); return fontsize; } if (textWidth > activityWidth) highVal = currentVal; else if (textWidth < activityWidth) lowVal = currentVal; else { fontsize = paint.getTextSize(); return fontsize; } currentVal = (highVal - lowVal) / 2 + lowVal; } while (true); } catch (Exception ex) { return fontsize; } } 

Answer 29

Extend TextView and override onDraw with the code below. It will keep text aspect ratio but size it to fill the space. You could easily modify code to stretch if necessary.

  @Override protected void onDraw(@NonNull Canvas canvas) { TextPaint textPaint = getPaint(); textPaint.setColor(getCurrentTextColor()); textPaint.setTextAlign(Paint.Align.CENTER); textPaint.drawableState = getDrawableState(); String text = getText().toString(); float desiredWidth = getMeasuredWidth() - getPaddingLeft() - getPaddingRight() - 2; float desiredHeight = getMeasuredHeight() - getPaddingTop() - getPaddingBottom() - 2; float textSize = textPaint.getTextSize(); for (int i = 0; i < 10; i++) { textPaint.getTextBounds(text, 0, text.length(), rect); float width = rect.width(); float height = rect.height(); float deltaWidth = width - desiredWidth; float deltaHeight = height - desiredHeight; boolean fitsWidth = deltaWidth <= 0; boolean fitsHeight = deltaHeight <= 0; if ((fitsWidth && Math.abs(deltaHeight) < 1.0) || (fitsHeight && Math.abs(deltaWidth) < 1.0)) { // close enough break; } float adjustX = desiredWidth / width; float adjustY = desiredHeight / height; textSize = textSize * (adjustY < adjustX ? adjustY : adjustX); // adjust text size textPaint.setTextSize(textSize); } float x = desiredWidth / 2f; float y = desiredHeight / 2f - rect.top - rect.height() / 2f; canvas.drawText(text, x, y, textPaint); } 

Answer 30

Refer to the ScalableTextView.java here Auto-fit TextView for Android . I have added the code to shrink and expand the TextView based on the text length