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Be careful with Alpha

Source: Romain Guy, Google IO, Romain Guy

In general change the alpha of the content not the view itself:

//not this
textView.setAlpha(alpha);

//but this
int newTextColor = (int) (0xFF * alpha) << 24 | baseTextColor & 0xFFFFFF;
textView.setTextColor(newTextColor);

//not this
imageView.setAlpha(alpha);

//but this
imageView.setImageAlpha((int) (alpha * 255));

//not this
customView.setAlpha(alpha);

//but this
int alpha = (int) (255 * slider.getProgress() / 100.0f);
paint.setAlpha(alpha);
canvas.draw*(..., paint);