在canvas上绘制图像

如何在canvas上获取图像以便在该图像上绘制？

Answer 1

在canvas上绘制Drawable的好方法不是自己解码，而是将其留给系统来完成：

Drawable d = getResources().getDrawable(R.drawable.foobar); d.setBounds(left, top, right, bottom); d.draw(canvas); 

这将与各种绘图工作，不仅位图。 而且这也意味着只要尺寸发生变化就可以再次使用同样的drawable。

Answer 2

您需要将图像加载为位图：

  Resources res = getResources(); Bitmap bitmap = BitmapFactory.decodeResource(res, R.drawable.your_image); 

然后使位图可变，并创build一个canvas：

 Canvas canvas = new Canvas(bitmap.copy(Bitmap.Config.ARGB_8888, true)); 

然后你可以在canvas上画画。

Answer 3

也可以使用这种方式。 它会改变你的canvas的适合你的canvas：

 Resources res = getResources(); Bitmap bitmap = BitmapFactory.decodeResource(res, yourDrawable); yourCanvas.drawBitmap(bitmap, 0, 0, yourPaint); 

Answer 4

尝试这个

 Bitmap mBitmap = Bitmap.createScaledBitmap(Bitmap src, int dstWidth, int dstHeight, boolean filter); protected void onDraw(Canvas canvas) { canvas.drawColor(0xFFAAAAAA); canvas.drawBitmap(mBitmap, 0, 0, mBitmapPaint); } 

Answer 5

 Drawable d = ContextCompat.getDrawable(context, R.drawable.***) d.setBounds(left, top, right, bottom); d.draw(canvas); 

Answer 6

 package com.android.jigsawtest; import android.content.Context; import android.graphics.Bitmap; import android.graphics.BitmapFactory; import android.graphics.Canvas; import android.graphics.Color; import android.graphics.Paint; import android.view.SurfaceHolder; import android.view.SurfaceView; public class SurafaceClass extends SurfaceView implements SurfaceHolder.Callback { Bitmap mBitmap; Paint paint =new Paint(); public SurafaceClass(Context context) { super(context); mBitmap = BitmapFactory.decodeResource(getResources(), R.drawable.icon); // TODO Auto-generated constructor stub } @Override public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) { // TODO Auto-generated method stub } @Override public void surfaceCreated(SurfaceHolder holder) { // TODO Auto-generated method stub } @Override public void surfaceDestroyed(SurfaceHolder holder) { // TODO Auto-generated method stub } @Override protected void onDraw(Canvas canvas) { canvas.drawColor(Color.BLACK); canvas.drawBitmap(mBitmap, 0, 0, paint); } } 

Answer 7

我不确定是否必须将图像作为位图加载（ http://grepcode.com/file/repository.grepcode.com/java/ext/com.google.android/android/2.1_r2/android /widget/ProgressBar.java#ProgressBar.onDraw%28android.graphics.Canvas％29 ）使用Drawable.draw(Canvas c) 。