Background Drawable没有应用到按钮上

Question

这是登录按钮(login_button_bk)的背景:

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
android:shape="rectangle">
<corners android:radius="27dp" />
<gradient
android:angle="45"
android:centerX="35%"
android:endColor="#79EBFD"
android:startColor="#408bff"
android:type="linear" />
<size
android:width="182dp"
android:height="54dp" />
</shape>

这是我要添加背景的按钮:

<Button
android:id="@+id/btn_login"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center_horizontal"
android:layout_marginTop="@dimen/loginViewsMargin"
android:background="@drawable/login_button_bk"
android:text="Login" />

这是style .xml:

<!-- Base application theme. -->
<style name="AppTheme" parent="Theme.MaterialComponents.Light.NoActionBar">
<!-- Customize your theme here. -->
<item name="colorPrimary">@color/colorPrimary</item>
<item name="colorPrimaryDark">@color/colorPrimaryDark</item>
<item name="colorAccent">@color/colorAccent</item>
</style>

仍然，按钮只是黑色没有绘制应用。如何解决?

Answer 1

要在按钮中获得可绘制的渐变，您必须从button更改属性到androidx.appcompat.widget.AppCompatButton

<androidx.appcompat.widget.AppCompatButton
android:id="@+id/btn_login"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center_horizontal"
android:layout_marginTop="@dimen/loginViewsMargin"
android:background="@drawable/login_button_bk"
android:text="Login" />

同样，使用上面的方法创建一个可绘制的按钮不会在你的按钮中产生涟漪效应，使用这个代码

<?xml version="1.0" encoding="utf-8"?>
<ripple xmlns:android="http://schemas.android.com/apk/res/android"
android:color="@color/white">
<item>
<shape
android:shape="rectangle">
<corners android:radius="27dp" />
<gradient
android:angle="45"
android:centerX="35%"
android:endColor="#79EBFD"
android:startColor="#408bff"
android:type="linear" />
<size
android:width="182dp"
android:height="54dp" />
</shape>
</item>
</ripple>

Answer 2

把你的主题改成下面的

<style name="AppTheme" parent="Theme.AppCompat.Light.DarkActionBar">
<!-- Customize your theme here. -->
<item name="colorPrimary">@color/colorPrimary</item>
<item name="colorPrimaryDark">@color/colorPrimaryDark</item>
<item name="colorAccent">@color/colorAccent</item>
</style>