Question

如何把TextView的背景设置成从黑色到透明渐变

Answer 1

可以TransitionDrawable用这个类来实现
final TransitionDrawable td =
new TransitionDrawable(new Drawable[] {
new ColorDrawable(android.R.color.transparent),
new BitmapDrawable(mResources, bitmap)
});
imageView.setImageDrawable(td);
td.startTransition(400);