ShadowGenerator.java 文件源码

public synchronized Bitmap recreateIcon(Bitmap icon) {
    int[] offset = new int[2];
    Bitmap shadow = icon.extractAlpha(mBlurPaint, offset);
    Bitmap result = Bitmap.createBitmap(mIconSize, mIconSize, Config.ARGB_8888);
    mCanvas.setBitmap(result);

    // Draw ambient shadow
    mDrawPaint.setAlpha(AMBIENT_SHADOW_ALPHA);
    mCanvas.drawBitmap(shadow, offset[0], offset[1], mDrawPaint);

    // Draw key shadow
    mDrawPaint.setAlpha(KEY_SHADOW_ALPHA);
    mCanvas.drawBitmap(shadow, offset[0], offset[1] + KEY_SHADOW_DISTANCE * mIconSize, mDrawPaint);

    // Draw the icon
    mDrawPaint.setAlpha(255);
    mCanvas.drawBitmap(icon, 0, 0, mDrawPaint);

    mCanvas.setBitmap(null);
    return result;
}