How to set a gradient background in a Material Button from Material Components?

问题

I've been trying to set a gradient background in a Material Button from Material Components for Android, but it's not working. So, how to set a gradient background in a Material Button?

回答1:

From the documentation for MaterialButton:

Do not use the android:background attribute. MaterialButton manages its own background drawable, and setting a new background means MaterialButton can no longer guarantee that the new attributes it introduces will function properly. If the default background is changed, MaterialButton cannot guarantee well-defined behavior.

The only supported way to modify the background of the button is to set a color value to the app:backgroundTint attribute. Unfortunately, gradients are not supported here either; you can only use a simple color value or a ColorStateList.

So, there is no supported way to use a gradient background with MaterialButton.

回答2:

Make use of androidx.appcompat.widget.AppCompatButton if you are using Material Theme to be able to apply background gradients, because Material Button doesn't offer support to it yet.

For background gradient, create 3 new resources in drawable folder:

selector_btn.xml

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <!-- disabled state -->
    <item android:drawable="@drawable/btn_gradient_inactive" android:state_enabled="false" />
    <item android:drawable="@drawable/btn_gradient_active" />
</selector>

btn_gradient_inactive.xml

<shape xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="rectangle">
    <gradient
        android:startColor="#01579B"
        android:endColor="#1A237E"
        android:angle="0" />
    <corners android:radius="5dp"/> </shape>

btn_gradient_active.xml

<shape xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="rectangle">
    <gradient
        android:startColor="#2196F3"
        android:endColor="#3F51B5"
        android:angle="0" />
    <corners android:radius="5dp"/>
</shape>

In your styles.xml:

<style name="BtnStyle" parent="Widget.AppCompat.Button.Borderless">
    <item name="android:layout_marginStart">35dp</item>
    <item name="android:layout_marginEnd">35dp</item>
    <item name="android:background">@drawable/selector_btn_gradient</item>
    <item name="android:textColor">@color/selector_text_color</item>
    <item name="android:textAllCaps">false</item>
    <item name="android:textSize">14sp</item>
</style>

In your layout.xml file:

<androidx.appcompat.widget.AppCompatButton
    android:id="@+id/my_btn_id"
    style="@style/BtnStyle"
    android:layout_width="match_parent"
    android:layout_height="wrap_content" />

回答3:

btn_gradient.xml

    <?xml version="1.0" encoding="utf-8"?>
<shape android:shape="rectangle" xmlns:android="http://schemas.android.com/apk/res/android">
    <gradient
        android:startColor="#469FED"
        android:angle="90"
        android:endColor="#2AC88D"/>
    <corners android:radius="4dp"/>
</shape>

and use this instead of a button:

    <RelativeLayout
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_margin="5dp"
                android:clickable="true"
                android:focusable="true"
                android:background="@drawable/btn_gradient">

                <TextView
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"
                    android:gravity="center"
                    android:minHeight="40dp"
                    android:background="?attr/selectableItemBackground"
                    android:padding="5dp"
                    android:text="send" />
 </RelativeLayout>

来源：https://stackoverflow.com/questions/52908045/how-to-set-a-gradient-background-in-a-material-button-from-material-components