IconCache.java 文件源码

/**
 * Generates a new low-res icon given a high-res icon.
 */
private Bitmap generateLowResIcon(Bitmap icon, int lowResBackgroundColor) {
    if (lowResBackgroundColor == Color.TRANSPARENT) {
        return Bitmap.createScaledBitmap(icon,
                        icon.getWidth() / LOW_RES_SCALE_FACTOR,
                        icon.getHeight() / LOW_RES_SCALE_FACTOR, true);
    } else {
        Bitmap lowResIcon = Bitmap.createBitmap(icon.getWidth() / LOW_RES_SCALE_FACTOR,
                icon.getHeight() / LOW_RES_SCALE_FACTOR, Bitmap.Config.RGB_565);
        synchronized (this) {
            mLowResCanvas.setBitmap(lowResIcon);
            mLowResCanvas.drawColor(lowResBackgroundColor);
            mLowResCanvas.drawBitmap(icon, new Rect(0, 0, icon.getWidth(), icon.getHeight()),
                    new Rect(0, 0, lowResIcon.getWidth(), lowResIcon.getHeight()),
                    mLowResPaint);
            mLowResCanvas.setBitmap(null);
        }
        return lowResIcon;
    }
}