RoundedImageView.java 文件源码

@Override
protected void onDraw(Canvas canvas) {
    Drawable myDrawable = getDrawable();
    if (myDrawable!=null && myDrawable instanceof BitmapDrawable && mCornerRadius > 0) {
        Paint paint = ((BitmapDrawable) myDrawable).getPaint();
        final int color = 0xff000000;
        Rect bitmapBounds = myDrawable.getBounds();
        final RectF rectF = new RectF(bitmapBounds);
        int saveCount = canvas.saveLayer(rectF, null,
                Canvas.MATRIX_SAVE_FLAG |
                        Canvas.CLIP_SAVE_FLAG |
                        Canvas.HAS_ALPHA_LAYER_SAVE_FLAG |
                        Canvas.FULL_COLOR_LAYER_SAVE_FLAG |
                        Canvas.CLIP_TO_LAYER_SAVE_FLAG);
        getImageMatrix().mapRect(rectF);

        paint.setAntiAlias(true);
        canvas.drawARGB(0, 0, 0, 0);
        paint.setColor(color);
        canvas.drawRoundRect(rectF, mCornerRadius, mCornerRadius, paint);

        Xfermode oldMode = paint.getXfermode();
        paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC_IN));
        super.onDraw(canvas);
        paint.setXfermode(oldMode);
        canvas.restoreToCount(saveCount);
    } else {
        super.onDraw(canvas);
    }
}