Android Canvas背景透明

Question

I draw on a bitmap an icon with a stroke color. That origin bitmap has a white background. On that with canvas I draw a second bitmap with a stroke (circle).

What happens is, that the resulting bitmap has on Nexus 7 or Galaxy S2 (both hdpi) a transparent backround. On other devices is all fine (its still white).

That bitmap is used as a marker for gmaps.

public Bitmap getMarkerBitmap(){
    Bitmap clusterBackground = backgroundImage.copy(Bitmap.Config.ARGB_8888, true);
    final Canvas canvas = new Canvas(clusterBackground);
    int xAnchor = (clusterBackground.getWidth() / 2)-(newIcon.getWidth() / 2);
    int yAnchor = (clusterBackground.getHeight()/2)-(newIcon.getHeight() / 2);
    final Point center = new Point(xAnchor,yAnchor);
    canvas.drawBitmap(newIcon, center.x, center.y,paint);
    return drawCircle(canvas,clusterBackground);
}

private Bitmap drawCircle(Canvas canvas, Bitmap bitmap){
    paint.setColor(color);
    paint.setStyle(Paint.Style.STROKE);
    paint.setStrokeWidth(strokeWidthInPx);
    int centerX = bitmap.getWidth() / 2;
    int centerY = bitmap.getHeight() / 2;
    canvas.drawCircle(centerX,centerY,centerY-strokeWidthInPx/2,paint);

    return bitmap;
}

When I set the background to white per Paint object, then it works, but then the whole Rect is white, my icon is rounded !

Answer 1

You code looks correct, make sure your backgroundImage is not transparent from the beginning. As you outlined, there are different resource folders for different screen resolutions, so different files can lead to different results on different devices.