How to make the support Toolbar background transparent?

Question

Is there a way to make the new Android support Toolbar:

android.support.v7.widget.Toolbar

Have a transparent background?

I tried setting the colorPrimary to an ARGB (#00ffffff) but it just gives me a solid gray bar. And Toolbar only allows me to set a background drawable. Is it kosher to set the background drawable to a transparent PNG, or is there a better way to do this?

Ideally I'd be able to do it in code / animate it so certain activities have a transparent bar and some activities don't.

Thanks in advance.

Answer 1

You can either set the background to android's default transparent color, which works just fine. Add this to the layout you want a transparent Toolbar :

android:background="@android:color/transparent"

If you want to change the alpha programmatically, you can do it by modifying the alpha on the Toolbar background itself. Just get an instance of the Drawable and set the alpha there:

mToolbar = findViewById(R.id.my_toolbar);
mToolbar.getBackground().setAlpha(0);

Answer 2

要回答Nicholas Pesa的问题，也许还有其他一些问题，你可以通过使用比率来设置浮点数。

mToolbar.getBackground().setAlpha((int)(myFloatValue) * 255);