开发一个Android主屏幕

我正在研究一个有主屏幕的应用程序。 这个主屏幕应该像Android主屏幕一样 ，你可以通过触摸屏幕上的手指在几个视图之间切换。

解决scheme很简单。 我有3个视图实例 ， 右 ， 左和当前视图 。 我从之前初始化的视图中获取这些实例。 因为我有一个HTC G1我的屏幕是320像素的宽度和480像素的高度。

想象一下，当你触摸屏幕时，你捕捉一个行动向下运动事件的下降值。 然后你移动你的手指，屏幕应该以完全相同的方式移动，所以你必须重新计算视图的位置。 它到目前为止，但我面临一个奇怪的问题。 当您触摸右侧视图而不移动手指，但将其保持在屏幕上时，视图消失并显示左侧视图。

这是我的代码：

public class MainActivity extends Activity implements OnTouchListener{ private ViewFlipper vf; private float downXValue; private View view1, view2, view3; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); this.vf = (ViewFlipper) findViewById(R.id.flipper); if(this.vf != null){ this.view1 = vf.getChildAt(0); this.view2 = vf.getChildAt(1); this.view3 = vf.getChildAt(2); vf.setDisplayedChild(0); } LinearLayout layMain = (LinearLayout) findViewById(R.id.layout_main); layMain.setOnTouchListener((OnTouchListener) this); } public boolean onTouch(View v, MotionEvent arg1) { final View currentView = vf.getCurrentView(); final View leftView, rightView; if(currentView == view1){ leftView = view3; rightView = view2; }else if(currentView == view2){ leftView = view1; rightView = view3; }else if(currentView == view3){ leftView = view2; rightView = view1; }else{ leftView = null; rightView = null; } switch (arg1.getAction()){ case MotionEvent.ACTION_DOWN:{ this.downXValue = arg1.getX(); break; } case MotionEvent.ACTION_UP:{ float currentX = arg1.getX(); if ((downXValue < currentX)){ if(currentView != view3){ float t3 = (320-(currentX-downXValue))/320; this.vf.setInAnimation(AnimationHelper.inFromLeftAnimation(t3)); this.vf.setOutAnimation(AnimationHelper.outToRightAnimation(t3)); this.vf.showPrevious(); } } if ((downXValue > currentX)){ if(currentView != view2){ float t = (320-(downXValue-currentX))/320; this.vf.setInAnimation(AnimationHelper.inFromRightAnimation(t)); this.vf.setOutAnimation(AnimationHelper.outToLeftAnimation(t)); this.vf.showNext();} } } break; case MotionEvent.ACTION_MOVE:{ leftView.setVisibility(View.VISIBLE); rightView.setVisibility(View.VISIBLE); float currentX = arg1.getX(); if(downXValue > currentX){ if(currentView != view2){ currentView.layout((int) (currentX - downXValue), currentView.getTop(), (int) (currentX - downXValue) + 320, currentView.getBottom()); } } if(downXValue < currentX){ if(currentView != view3){ currentView.layout((int) (currentX - downXValue), currentView.getTop(), (int) (currentX - downXValue) + 320, currentView.getBottom()); } } leftView.layout(currentView.getLeft()-320, leftView.getTop(), currentView.getLeft(), leftView.getBottom()); rightView.layout(currentView.getRight(), rightView.getTop(), currentView.getRight() + 320, rightView.getBottom()); } } return true; } public static class AnimationHelper { public static Animation inFromRightAnimation(float param) { Animation inFromRight = new TranslateAnimation( Animation.RELATIVE_TO_PARENT, +param, Animation.RELATIVE_TO_PARENT, 0.0f, Animation.RELATIVE_TO_PARENT, 0.0f, Animation.RELATIVE_TO_PARENT, 0.0f); inFromRight.setDuration(250); inFromRight.setInterpolator(new AccelerateInterpolator()); return inFromRight; } public static Animation outToLeftAnimation(float param) { Animation outtoLeft = new TranslateAnimation( Animation.RELATIVE_TO_PARENT, 0.0f, Animation.RELATIVE_TO_PARENT, -param, Animation.RELATIVE_TO_PARENT, 0.0f, Animation.RELATIVE_TO_PARENT, 0.0f); outtoLeft.setDuration(250); outtoLeft.setInterpolator(new AccelerateInterpolator()); return outtoLeft; } // for the next movement public static Animation inFromLeftAnimation(float param) { Animation inFromLeft = new TranslateAnimation( Animation.RELATIVE_TO_PARENT, -param, Animation.RELATIVE_TO_PARENT, 0.0f, Animation.RELATIVE_TO_PARENT, 0.0f, Animation.RELATIVE_TO_PARENT, 0.0f); inFromLeft.setDuration(250); inFromLeft.setInterpolator(new AccelerateInterpolator()); return inFromLeft; } public static Animation outToRightAnimation(float param) { Animation outtoRight = new TranslateAnimation( Animation.RELATIVE_TO_PARENT, 0.0f, Animation.RELATIVE_TO_PARENT, +param, Animation.RELATIVE_TO_PARENT, 0.0f, Animation.RELATIVE_TO_PARENT, 0.0f); outtoRight.setDuration(250); outtoRight.setInterpolator(new AccelerateInterpolator()); return outtoRight; } } } 

我认为这样的主屏幕是一个有趣的UI元素。

有任何想法吗？

---

你可以在这里下载工作的eclipse项目： http : //www.megaupload.com/?d=3M3IYGGM

Answer 1

编辑 （2012年7月3日）：

由于似乎还有不less关于这个答案的意见和评论，我想我应该添加一个注释，即使用较新的SDK，现在应该使用ViewPager来具有相同的function。 该类还包含在Android支持库中，因此您也可以使用它在早期的Android设备上运行。

编辑 （2013年3月4日）：

由于还有人来这里，只是想说我把ViewPager放在一起，背景移动速度慢一些，给出了视差效果。 代码在这里 。

如果你真的想手工做这一切，原来的答案在这里下面…

我想你可以在这里find你要找的东西： http : //www.anddev.org/why_do_not_these_codes_work-t4012.html

我在不同的项目中使用它也创build了不同视图的主屏幕。 这是直接从Android启动器，它遵循该线程后，相当不错。

这里是我的代码…第一个源代码

 package com.matthieu.launcher; import android.content.Context; import android.util.Log; import android.content.res.TypedArray; import android.util.AttributeSet; import android.view.MotionEvent; import android.view.VelocityTracker; import android.view.View; import android.view.ViewGroup; import android.view.ViewConfiguration; import android.widget.Scroller; public class DragableSpace extends ViewGroup { private Scroller mScroller; private VelocityTracker mVelocityTracker; private int mScrollX = 0; private int mCurrentScreen = 0; private float mLastMotionX; private static final String LOG_TAG = "DragableSpace"; private static final int SNAP_VELOCITY = 1000; private final static int TOUCH_STATE_REST = 0; private final static int TOUCH_STATE_SCROLLING = 1; private int mTouchState = TOUCH_STATE_REST; private int mTouchSlop = 0; public DragableSpace(Context context) { super(context); mScroller = new Scroller(context); mTouchSlop = ViewConfiguration.get(getContext()).getScaledTouchSlop(); this.setLayoutParams(new ViewGroup.LayoutParams( ViewGroup.LayoutParams.WRAP_CONTENT, ViewGroup.LayoutParams.FILL_PARENT)); } public DragableSpace(Context context, AttributeSet attrs) { super(context, attrs); mScroller = new Scroller(context); mTouchSlop = ViewConfiguration.get(getContext()).getScaledTouchSlop(); this.setLayoutParams(new ViewGroup.LayoutParams( ViewGroup.LayoutParams.WRAP_CONTENT , ViewGroup.LayoutParams.FILL_PARENT)); TypedArray a=getContext().obtainStyledAttributes(attrs,R.styleable.DragableSpace); mCurrentScreen = a.getInteger(R.styleable.DragableSpace_default_screen, 0); } @Override public boolean onInterceptTouchEvent(MotionEvent ev) { /* * This method JUST determines whether we want to intercept the motion. * If we return true, onTouchEvent will be called and we do the actual * scrolling there. */ /* * Shortcut the most recurring case: the user is in the dragging state * and he is moving his finger. We want to intercept this motion. */ final int action = ev.getAction(); if ((action == MotionEvent.ACTION_MOVE) && (mTouchState != TOUCH_STATE_REST)) { return true; } final float x = ev.getX(); switch (action) { case MotionEvent.ACTION_MOVE: /* * mIsBeingDragged == false, otherwise the shortcut would have caught it. Check * whether the user has moved far enough from his original down touch. */ /* * Locally do absolute value. mLastMotionX is set to the y value * of the down event. */ final int xDiff = (int) Math.abs(x - mLastMotionX); boolean xMoved = xDiff > mTouchSlop; if (xMoved) { // Scroll if the user moved far enough along the X axis mTouchState = TOUCH_STATE_SCROLLING; } break; case MotionEvent.ACTION_DOWN: // Remember location of down touch mLastMotionX = x; /* * If being flinged and user touches the screen, initiate drag; * otherwise don't. mScroller.isFinished should be false when * being flinged. */ mTouchState = mScroller.isFinished() ? TOUCH_STATE_REST : TOUCH_STATE_SCROLLING; break; case MotionEvent.ACTION_CANCEL: case MotionEvent.ACTION_UP: // Release the drag mTouchState = TOUCH_STATE_REST; break; } /* * The only time we want to intercept motion events is if we are in the * drag mode. */ return mTouchState != TOUCH_STATE_REST; } @Override public boolean onTouchEvent(MotionEvent event) { if (mVelocityTracker == null) { mVelocityTracker = VelocityTracker.obtain(); } mVelocityTracker.addMovement(event); final int action = event.getAction(); final float x = event.getX(); switch (action) { case MotionEvent.ACTION_DOWN: Log.i(LOG_TAG, "event : down"); /* * If being flinged and user touches, stop the fling. isFinished * will be false if being flinged. */ if (!mScroller.isFinished()) { mScroller.abortAnimation(); } // Remember where the motion event started mLastMotionX = x; break; case MotionEvent.ACTION_MOVE: // Log.i(LOG_TAG,"event : move"); // if (mTouchState == TOUCH_STATE_SCROLLING) { // Scroll to follow the motion event final int deltaX = (int) (mLastMotionX - x); mLastMotionX = x; //Log.i(LOG_TAG, "event : move, deltaX " + deltaX + ", mScrollX " + mScrollX); if (deltaX < 0) { if (mScrollX > 0) { scrollBy(Math.max(-mScrollX, deltaX), 0); } } else if (deltaX > 0) { final int availableToScroll = getChildAt(getChildCount() - 1) .getRight() - mScrollX - getWidth(); if (availableToScroll > 0) { scrollBy(Math.min(availableToScroll, deltaX), 0); } } // } break; case MotionEvent.ACTION_UP: Log.i(LOG_TAG, "event : up"); // if (mTouchState == TOUCH_STATE_SCROLLING) { final VelocityTracker velocityTracker = mVelocityTracker; velocityTracker.computeCurrentVelocity(1000); int velocityX = (int) velocityTracker.getXVelocity(); if (velocityX > SNAP_VELOCITY && mCurrentScreen > 0) { // Fling hard enough to move left snapToScreen(mCurrentScreen - 1); } else if (velocityX < -SNAP_VELOCITY && mCurrentScreen < getChildCount() - 1) { // Fling hard enough to move right snapToScreen(mCurrentScreen + 1); } else { snapToDestination(); } if (mVelocityTracker != null) { mVelocityTracker.recycle(); mVelocityTracker = null; } // } mTouchState = TOUCH_STATE_REST; break; case MotionEvent.ACTION_CANCEL: Log.i(LOG_TAG, "event : cancel"); mTouchState = TOUCH_STATE_REST; } mScrollX = this.getScrollX(); return true; } private void snapToDestination() { final int screenWidth = getWidth(); final int whichScreen = (mScrollX + (screenWidth / 2)) / screenWidth; Log.i(LOG_TAG, "from des"); snapToScreen(whichScreen); } public void snapToScreen(int whichScreen) { Log.i(LOG_TAG, "snap To Screen " + whichScreen); mCurrentScreen = whichScreen; final int newX = whichScreen * getWidth(); final int delta = newX - mScrollX; mScroller.startScroll(mScrollX, 0, delta, 0, Math.abs(delta) * 2); invalidate(); } public void setToScreen(int whichScreen) { Log.i(LOG_TAG, "set To Screen " + whichScreen); mCurrentScreen = whichScreen; final int newX = whichScreen * getWidth(); mScroller.startScroll(newX, 0, 0, 0, 10); invalidate(); } @Override protected void onLayout(boolean changed, int l, int t, int r, int b) { int childLeft = 0; final int count = getChildCount(); for (int i = 0; i < count; i++) { final View child = getChildAt(i); if (child.getVisibility() != View.GONE) { final int childWidth = child.getMeasuredWidth(); child.layout(childLeft, 0, childLeft + childWidth, child .getMeasuredHeight()); childLeft += childWidth; } } } @Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { super.onMeasure(widthMeasureSpec, heightMeasureSpec); final int width = MeasureSpec.getSize(widthMeasureSpec); final int widthMode = MeasureSpec.getMode(widthMeasureSpec); if (widthMode != MeasureSpec.EXACTLY) { throw new IllegalStateException("error mode."); } final int heightMode = MeasureSpec.getMode(heightMeasureSpec); if (heightMode != MeasureSpec.EXACTLY) { throw new IllegalStateException("error mode."); } // The children are given the same width and height as the workspace final int count = getChildCount(); for (int i = 0; i < count; i++) { getChildAt(i).measure(widthMeasureSpec, heightMeasureSpec); } Log.i(LOG_TAG, "moving to screen "+mCurrentScreen); scrollTo(mCurrentScreen * width, 0); } @Override public void computeScroll() { if (mScroller.computeScrollOffset()) { mScrollX = mScroller.getCurrX(); scrollTo(mScrollX, 0); postInvalidate(); } } } 

和布局文件：

 <?xml version="1.0" encoding="utf-8"?> <com.matthieu.launcher.DragableSpace xmlns:app="http://schemas.android.com/apk/res/com.matthieu.launcher" xmlns:android="http://schemas.android.com/apk/res/android" android:id="@+id/space" android:layout_width="fill_parent" android:layout_height="fill_parent" app:default_screen="1" > <include android:id="@+id/left" layout="@layout/left_screen" /> <include android:id="@+id/center" layout="@layout/initial_screen" /> <include android:id="@+id/right" layout="@layout/right_screen" /> </com.matthieu.launcher.DragableSpace> 

为了能够在xml文件中拥有额外的属性，你想把它保存在res / values / attrs.xml中

 <?xml version="1.0" encoding="utf-8"?> <resources> <declare-styleable name="DragableSpace"> <attr name="default_screen" format="integer"/> </declare-styleable> </resources> 

Answer 2

您可以查看http://code.google.com/p/andro-views/

Answer 3

Matthieu的代码非常好，但在方向改变后它不能保存状态。 要解决此问题，请将下一个代码添加到DragableSpace类

  /** * Return the parceable instance to be saved */ @Override protected Parcelable onSaveInstanceState() { final SavedState state = new SavedState(super.onSaveInstanceState()); state.currentScreen = mCurrentScreen; return state; } /** * Restore the previous saved current screen */ @Override protected void onRestoreInstanceState(Parcelable state) { SavedState savedState = (SavedState) state; super.onRestoreInstanceState(savedState.getSuperState()); if (savedState.currentScreen != -1) { mCurrentScreen = savedState.currentScreen; } } // ========================= INNER CLASSES ============================== public interface onViewChangedEvent{ void onViewChange (int currentViewIndex); } /** * A SavedState which save and load the current screen */ public static class SavedState extends BaseSavedState { int currentScreen = -1; /** * Internal constructor * * @param superState */ SavedState(Parcelable superState) { super(superState); } /** * Private constructor * * @param in */ private SavedState(Parcel in) { super(in); currentScreen = in.readInt(); } /** * Save the current screen */ @Override public void writeToParcel(Parcel out, int flags) { super.writeToParcel(out, flags); out.writeInt(currentScreen); } /** * Return a Parcelable creator */ public static final Parcelable.Creator<SavedState> CREATOR = new Parcelable.Creator<SavedState>() { public SavedState createFromParcel(Parcel in) { return new SavedState(in); } public SavedState[] newArray(int size) { return new SavedState[size]; } }; } 

我已经从凯文的答案中拿走了。