Android实现指定区域截屏的实现

View view = activity.getWindow().getDecorView();
view.setDrawingCacheEnabled(true);
view.buildDrawingCache();
bitmap = view.getDrawingCache();

然后我们需呀计算出我们选定区域的坐标点，注意正选和反选的计算方式不同 ，

public boolean onTouch(View v, MotionEvent event) {
     if(event.getAction() == MotionEvent.ACTION_DOWN){
            x = 0;
            y = 0;
            width = 0;
            height = 0;
            x = (int) event.getX();
            y = (int) event.getY();
        }
      if(event.getAction() == MotionEvent.ACTION_MOVE){
            m = (int) event.getX();
            n = (int) event.getY();
            myView.setSeat(x, y, m, n);
            myView.postInvalidate();
        }
      if(event.getAction() == MotionEvent.ACTION_UP){
    if(event.getX()>x){
         width = (int)event.getX()-x;
    }else{
         width = (int)(x-event.getX());
          x = (int) event.getX();
    }
                 if(event.getY()>y){
         height = (int) event.getY()-y;
     }else{
         height = (int)(y-event.getY());
          y = (int) event.getY();
    }
    image2.setImageBitmap(getBitmap(this));
        }
    if(myView.isSign()){
         return false;
    }else{
          return true;
    }
}

然后为我们计算出来的坐标区域添加选中效果

protected void onDraw(Canvas canvas) {
         if(sign){
    paint.setColor(Color.TRANSPARENT);
         }else{
    paint.setColor(Color.RED);
    paint.setAlpha(80);
    canvas.drawRect(new Rect(x, y, m, n), paint);
           }
    super.onDraw(canvas);
}

最后生成我们需要的图片展示出来，顺便保存到SD卡下一张。

Rect frame = new Rect();
      activity.getWindow().getDecorView().getWindowVisibleDisplayFrame(frame);
      int toHeight = frame.top;
      bitmap = Bitmap.createBitmap(bitmap, x, y+2*toHeight, width, height);
      try {
    FileOutputStream fout = new FileOutputStream("mnt/sdcard/test.png");
    bitmap.compress(Bitmap.CompressFormat.PNG, 100, fout);
        } catch (FileNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        view.setDrawingCacheEnabled(false);