FloatingActionButton控件学习

1. 导入库

implementation 'com.android.support:design:27.1.1'

2. 在xml中引用

<android.support.design.widget.FloatingActionButton
 android:id="@+id/fab_plus"
 android:layout_width="wrap_content"
 android:layout_height="wrap_content"
 android:layout_gravity="bottom|end"
 android:layout_marginBottom="16dp"
 android:layout_marginEnd="16dp"
 android:elevation="6dp"
 app:pressedTranslationZ="12dp"
 app:srcCompat="@drawable/ic_add"></android.support.design.widget.FloatingActionButton>

3. 添加动画

<?xml version="1.0" encoding="utf-8"?>
<set xmlns:android="http://schemas.android.com/apk/res/android"
 android:fillAfter="true">
 <!--尺寸动画-->
 <scale
 android:duration="300"
 android:fromXScale="0.8"
 android:fromYScale="0.8"
 android:interpolator="@android:anim/linear_interpolator"
 android:pivotX="50%"
 android:pivotY="50%"
 android:toXScale="0.0"
 android:toYScale="0.0" />
 <!--透明度渐变-->
 <alpha
 android:duration="300"
 android:fromAlpha="1.0"
 android:interpolator="@android:anim/accelerate_interpolator"
 android:toAlpha="0.0" />
</set>

<?xml version="1.0" encoding="utf-8"?>
<set xmlns:android="http://schemas.android.com/apk/res/android"
 android:fillAfter="true">
 <!--尺寸动画-->
 <scale
 android:duration="300"
 android:fromXScale="0.0"
 android:fromYScale="0.0"
 android:interpolator="@android:anim/linear_interpolator"
 android:pivotX="50%"
 android:pivotY="50%"
 android:toXScale="0.8"
 android:toYScale="0.8" />
 <!--透明度渐变-->
 <alpha
 android:duration="300"
 android:fromAlpha="0.0"
 android:interpolator="@android:anim/accelerate_interpolator"
 android:toAlpha="1.0" />
</set>

<?xml version="1.0" encoding="utf-8"?>
<set xmlns:android="http://schemas.android.com/apk/res/android"
 android:fillAfter="true">
 <rotate
 android:duration="300"
 android:fromDegrees="0"
 android:toDegrees="45"
 android:pivotX="50%"
 android:interpolator="@android:anim/linear_interpolator"
 android:pivotY="50%"/>
</set>

<?xml version="1.0" encoding="utf-8"?>
<set xmlns:android="http://schemas.android.com/apk/res/android"
 android:fillAfter="true">
 <rotate
 android:duration="300"
 android:fromDegrees="45"
 android:interpolator="@android:anim/linear_interpolator"
 android:pivotX="50%"
 android:pivotY="50%"
 android:toDegrees="0" />
</set>