截屏 ClipScreen

public class ClipScreen extends Activity{ @Override protected void onCreate(Bundle savedInstanceState) { // TODO Auto-generated method stub super.onCreate(savedInstanceState); this.getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FORCE_NOT_FULLSCREEN); requestWindowFeature(Window.FEATURE_NO_TITLE); setContentView(new ClipScreenView(this)); } } class ClipScreenView extends SurfaceView implements Callback,Runnable{ private SurfaceHolder mSurfaceHolder; private Thread mThread; private Canvas mCanvas; private Canvas mClipCanvas;//The canvas for screenshot. private boolean mFlag; private Paint mPaint; private Bitmap mBmpIcon; private Bitmap mBmpClip; private int mScreenW; private int mScreenH; public ClipScreenView(Context context) { super(context); mSurfaceHolder=this.getHolder(); mSurfaceHolder.addCallback(this); mPaint=new Paint(); mPaint.setColor(Color.WHITE); mPaint.setAntiAlias(true); setFocusable(true); } @Override public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) { mScreenW=this.getWidth(); mScreenH=this.getHeight(); mBmpIcon=BitmapFactory.decodeResource(getResources(), R.drawable.icon); mBmpClip=Bitmap.createBitmap(this.getWidth(), this.getHeight(), Config.ARGB_8888); mClipCanvas=new Canvas(mBmpClip); mClipCanvas.drawColor(Color.WHITE); mClipCanvas.drawBitmap(mBmpIcon, 0, 0, mPaint); mFlag=true; mThread=new Thread(this,"My Thread"); mThread.start(); } @Override public void surfaceCreated(SurfaceHolder holder) { } @Override public void surfaceDestroyed(SurfaceHolder holder) { mFlag=false; } @Override public void run() { while (mFlag) { long start=System.currentTimeMillis(); myDraw(); logic(); long end=System.currentTimeMillis(); if ((end-start)<50) { try { Thread.sleep(50-(end-start)); } catch (InterruptedException e) { // TODO Auto-generated catch block e.printStackTrace(); } } } } private void logic() { // TODO Auto-generated method stub } private void myDraw() { try { mCanvas=mSurfaceHolder.lockCanvas(); if (mCanvas != null) { mCanvas.drawColor(Color.BLACK); mCanvas.drawBitmap(mBmpIcon, 0, 0, mPaint); mCanvas.drawBitmap(mBmpClip, 50, 50, mPaint); } } catch (Exception e) { // TODO: handle exception }finally{ if (mCanvas != null) { mSurfaceHolder.unlockCanvasAndPost(mCanvas); } } } }

问题一：

mBmpIcon=BitmapFactory.decodeResource(getResources(), R.drawable.icon); mBmpClip=Bitmap.createBitmap(this.getWidth(), this.getHeight(), Config.ARGB_8888); mClipCanvas=new Canvas(mBmpClip); mClipCanvas.drawColor(Color.WHITE); mClipCanvas.drawBitmap(mBmpIcon, 0, 0, mPaint);这一段绘制截屏的Bitmap的代码是需要理一下的，刚开始以为截屏就是截取屏幕的高度和宽度截取一张图片就可以了mBmpClip=Bitmap.createBitmap(this.getWidth(), this.getHeight(), Config.ARGB_8888);以为这点代码就可以了，但是这个只是创建了和屏幕一样大小的一个Bitmap上面什么信息也没有，还需要我们根据这个Bitmap创建一个截屏的画布mClipCanvas将在onDraw上面正常的情况下绘制的东西，在这个截屏的画布上重新绘制一遍，那么这个空白的画布上便有了和要截取的画面一样的东西了。

之前程序中有对excel、word、ppt、pdf的页面多点触摸进行放大缩小的程序代码，当进行放大缩小的时候实际上onDraw的时候绘制的也是一张图片，而不是正常情况下绘制的是文字或者图片信息。原理和这个是一样的。