Java 如何使支持工具栏背景透明？
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How to make the support Toolbar background transparent?
提问by Keith
Is there a way to make the new Android support Toolbar:
有没有办法让新的Android支持工具栏：
android.support.v7.widget.Toolbar
Have a transparent background?
有透明背景吗？
I tried setting the colorPrimaryto an ARGB (#00ffffff) but it just gives me a solid gray bar. And Toolbaronly 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?
我尝试将 设置colorPrimary为 ARGB (#00ffffff)，但它只给了我一个纯灰色条。并且Toolbar只允许我设置背景可绘制。将可绘制的背景设置为透明的 PNG 是否符合犹太教规，还是有更好的方法来做到这一点？
Ideally I'd be able to do it in code / animate it so certain activities have a transparent bar and some activities don't.
理想情况下，我可以用代码/动画来完成它，所以某些活动有一个透明的栏，而有些活动没有。
Thanks in advance.
提前致谢。
采纳答案by ebarrenechea
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:
您可以将背景设置为 android 的默认透明颜色，这很好用。将此添加到您想要透明的布局中Toolbar：
android:background="@android:color/transparent"
android:background="@android:color/transparent"
If you want to change the alpha programmatically, you can do it by modifying the alpha on the Toolbarbackground itself. Just get an instance of the Drawableand set the alpha there:
如果要以编程方式更改 alpha，可以通过修改Toolbar背景本身的 alpha 来实现。只需获取 的实例Drawable并在那里设置 alpha：
mToolbar = findViewById(R.id.my_toolbar);
mToolbar.getBackground().setAlpha(0);
回答by Jraco11
To answer Nicholas Pesa's question and maybe some others in the future you could set the alpha with a float by using a ratio, something like.
要回答 Nicholas Pesa 的问题以及将来可能的其他问题，您可以使用比率设置带有浮点数的 alpha，例如。
mToolbar.getBackground().setAlpha((int)(myFloatValue) * 255);
