试图拍摄视图及其子级的屏幕快照

Question

I have relative layout named rel that dynamically adds an imageview to it like so:

     rel.setBackgroundResource(R.drawable.bg_share_one);

                RelativeLayout.LayoutParams p1 = new RelativeLayout.LayoutParams(921, 691);
                p1.leftMargin = 30;
                p1.topMargin = 30;

                ImageView img = new ImageView(this);
                img.setLayoutParams(p1);
                myBitmap = BitmapFactory.decodeFile(files[0].getAbsolutePath(), option1);
                img.setImageBitmap(myBitmap);

                rel.addView(img);
                saveCompareImage();

i then call this method to take a screen shot that relative layout but the imageview it added is not showing up in the bitmap:

 protected void saveCompareImage() {
    // TODO Auto-generated method stub

    rel.setDrawingCacheEnabled(true);
    try {

        File file = new File("/sdcard/LC/compare.jpg");
        file.createNewFile();
        Bitmap bm = rel.getDrawingCache();
        FileOutputStream ostream = new FileOutputStream(file);
        bm.compress(Bitmap.CompressFormat.JPEG, 80, ostream);
        ostream.close();
    } catch (Exception e) {
        e.printStackTrace();
    }
}

Answer 1

Perhaps you have hardware acceleration enabled? The documentation of setDrawingCacheEnabled() states that in that case rendering is done differently:

When hardware acceleration is turned on, enabling the drawing cache has no effect on rendering because the system uses a different mechanism for acceleration which ignores the flag. If you want to use a Bitmap for the view, even when hardware acceleration is enabled, see setLayerType(int, android.graphics.Paint) for information on how to enable software and hardware layers.

Try setLayerType(LAYER_TYPE_SOFTWARE, null) or something.

Answer 2

problem was not calling measure: this works:

protected void saveCompareImage() {
    // TODO Auto-generated method stub

    rel.setDrawingCacheEnabled(true);

    try {
        File file = new File("/sdcard/LC/compare.jpg");
        file.createNewFile();   
        Bitmap bitmap;
        rel.setDrawingCacheEnabled(true);
        rel.measure(MeasureSpec.makeMeasureSpec(rel.getLayoutParams().width, MeasureSpec.EXACTLY),
                MeasureSpec.makeMeasureSpec(rel.getLayoutParams().height, MeasureSpec.EXACTLY));
        rel.layout(0, 0, rel.getMeasuredWidth(), rel.getMeasuredHeight());

        bitmap = Bitmap.createBitmap(rel.getDrawingCache());


        FileOutputStream ostream = new FileOutputStream(file);
        bitmap.compress(Bitmap.CompressFormat.JPEG, 100, ostream);
        ostream.close();
    } catch (Exception e) {
        Log.v("ERRRO","e:"+e);
    }
}