AppCompatButton backgroundTint API < 21

问题

I want to use ripple effects on Buttons. AppCompat v22.1 added AppCompatButton and new functionalities to AppCompat tinting.

My Layout:

<android.support.v7.widget.AppCompatButton
        android:id="@+id/add_remove_button"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:backgroundTint="@color/primary"
        android:textColor="@android:color/white"
        android:text="Remove" />

On my API 22 test device the ripple effect works perfectly, but i'm coding for API 11 and unfortunately backgroundTint needs API >= 21. How can i set the ripple effect to Buttons on older API versions?

回答1:

Just use app:backgroundTint instead of android:backgroundTint, the tint will take effect below Lollipop. The reason is AppCompatActivity AppCompatDelegateImplV7 use AppCompatViewInflater to auto change Button or TextView to AppCompatButton or AppCompatTextView, then app:backgroundTint take effect.

回答2:

Ripples are not available as a build in functionality on Android <21. This is due to performance issues: devices with the new API can use the RenderThread which is not available to older devices. See also: http://android-developers.blogspot.de/2014/10/appcompat-v21-material-design-for-pre.html

Why are there no ripples on pre-Lollipop? A lot of what allows RippleDrawable to run smoothly is Android 5.0’s new RenderThread. To optimize for performance on previous versions of Android, we've left RippleDrawable out for now.

回答3:

To support ripple functionality below API 21 you may have to add a drawable in the background of your button:

<android.support.v7.widget.AppCompatButton
    android:id="@+id/add_remove_button"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@drawable/button_ripple"
    android:backgroundTint="@color/primary"
    android:textColor="@android:color/white"
    android:text="Remove" />

Then you have to add your xmls with the same name in both drawable and drawable-v21 directories (if you don't have them you may create and they will be automatically linked).

/res/drawable-v21/button_ripple.xml

<?xml version="1.0" encoding="utf-8"?>
<ripple xmlns:android="http://schemas.android.com/apk/res/android"
    android:color="@color/white">
    <item>
        <shape>
            <solid android:color="@color/white" />
        </shape>
    </item>
</ripple>

/res/drawable/button_ripple.xml

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item>
        <shape>
            <solid android:color="@color/white" />
        </shape>
    </item>
</selector>

来源：https://stackoverflow.com/questions/29890654/appcompatbutton-backgroundtint-api-21