DrawableFadeDisplayer.java 文件源码

/**
 * @param bitmap
 * @param imageView
 */
public void display(Bitmap bitmap, ImageView imageView) {
    Drawable oldDrawable = imageView.getDrawable();
    Drawable oldBitmapDrawable = null;
    //如果原先的imageView没drawable就创建一个透明的drawable
    if (null == oldDrawable) {
        oldBitmapDrawable = new ColorDrawable(Color.TRANSPARENT);
    }
    //如果原先就是TransitionDrawable,就获得第二张图片
    else if (oldDrawable instanceof TransitionDrawable) {
        oldBitmapDrawable = ((TransitionDrawable) oldDrawable).getDrawable(1);
    } else {
        oldBitmapDrawable = oldDrawable;
    }
    TransitionDrawable td = new TransitionDrawable(new Drawable[]{
            oldBitmapDrawable,
            new BitmapDrawable(Resources.getSystem(), bitmap)
    });
    imageView.setImageDrawable(td);
    td.startTransition(durationMillis);
}