Android 通过MotionLayot实现点赞动画本篇文章主要介绍，如何使用MotionLayout来实现之前的文章

在之前的文章Android 一种点赞动画的实现中，通过Animation和Animator实现了一种点赞动画效果，有知友评论用MotionLayout是否会比较简单。我之前还没有使用过MotionLayout，刚好通过实现这个点赞动画来学习一下MotionLayout的使用。

MotionLayout

MotionLayout是ConstraintLayout的子类，包含在ConstraintLayout库中，在ConstraintLayout的基础上，增加了管理控件动画的功能。

官方文档

添加库

如果之前没有使用ConstraintLayout，那么需要在app module下的build.gradle中添加代码，如下:

dependencies {
    // 项目中使用AndroidX
    implementation 'androidx.constraintlayout:constraintlayout:2.0.0-beta1'
    
    // 项目中未使用AndroidX
    implementation 'com.android.support.constraint:constraint-layout:2.0.0-beta1'
}

点赞效果的实现

尝试使用MotionLayout来实现之前的点赞动画，最终实现了缩放以及发散效果。

布局中添加MotionLayout

<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:motion="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools">

    <!--根节点改为使用MotionLayout-->
    <!--layoutDescription 配置MotionScene配置文件-->
    <!--showPaths设置是否显示动画的轨迹-->
    <androidx.constraintlayout.motion.widget.MotionLayout
        android:id="@+id/motion_layout"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        motion:layoutDescription="@xml/example_motion_scene"
        tools:showPaths="true">

        <include
            android:id="@+id/include_title"
            layout="@layout/layout_title" />

        <androidx.appcompat.widget.AppCompatImageView
            android:id="@+id/iv_thumb_up"
            android:layout_width="25dp"
            android:layout_height="25dp"
            android:layout_marginTop="2dp"
            android:src="@drawable/icon_thumb_up"
            motion:layout_constraintBottom_toBottomOf="parent"
            motion:layout_constraintEnd_toEndOf="parent"
            motion:layout_constraintStart_toStartOf="parent"
            motion:layout_constraintTop_toTopOf="parent" />

        <androidx.appcompat.widget.AppCompatImageView
            android:id="@+id/iv_thumb_up1"
            android:layout_width="25dp"
            android:layout_height="25dp"
            android:layout_marginTop="2dp"
            android:src="@drawable/icon_thumb_up"
            android:visibility="gone"
            motion:layout_constraintBottom_toBottomOf="parent"
            motion:layout_constraintEnd_toEndOf="parent"
            motion:layout_constraintStart_toStartOf="parent"
            motion:layout_constraintTop_toTopOf="parent" />

        <androidx.appcompat.widget.AppCompatImageView
            android:id="@+id/iv_thumb_up2"
            android:layout_width="25dp"
            android:layout_height="25dp"
            android:layout_marginTop="2dp"
            android:src="@drawable/icon_thumb_up"
            android:visibility="gone"
            motion:layout_constraintBottom_toBottomOf="parent"
            motion:layout_constraintEnd_toEndOf="parent"
            motion:layout_constraintStart_toStartOf="parent"
            motion:layout_constraintTop_toTopOf="parent" />

        <androidx.appcompat.widget.AppCompatImageView
            android:id="@+id/iv_thumb_up3"
            android:layout_width="25dp"
            android:layout_height="25dp"
            android:layout_marginTop="2dp"
            android:src="@drawable/icon_thumb_up"
            android:visibility="gone"
            motion:layout_constraintBottom_toBottomOf="parent"
            motion:layout_constraintEnd_toEndOf="parent"
            motion:layout_constraintStart_toStartOf="parent"
            motion:layout_constraintTop_toTopOf="parent" />

        <androidx.appcompat.widget.AppCompatImageView
            android:id="@+id/iv_thumb_up4"
            android:layout_width="25dp"
            android:layout_height="25dp"
            android:layout_marginTop="2dp"
            android:src="@drawable/icon_thumb_up"
            android:visibility="gone"
            motion:layout_constraintBottom_toBottomOf="parent"
            motion:layout_constraintEnd_toEndOf="parent"
            motion:layout_constraintStart_toStartOf="parent"
            motion:layout_constraintTop_toTopOf="parent" />

        <androidx.appcompat.widget.AppCompatImageView
            android:id="@+id/iv_thumb_up5"
            android:layout_width="25dp"
            android:layout_height="25dp"
            android:layout_marginTop="2dp"
            android:src="@drawable/icon_thumb_up"
            android:visibility="gone"
            motion:layout_constraintBottom_toBottomOf="parent"
            motion:layout_constraintEnd_toEndOf="parent"
            motion:layout_constraintStart_toStartOf="parent"
            motion:layout_constraintTop_toTopOf="parent" />
    </androidx.constraintlayout.motion.widget.MotionLayout>
</layout>

创建`MotionScene`配置文件

<?xml version="1.0" encoding="utf-8"?>
<MotionScene xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:motion="http://schemas.android.com/apk/res-auto">

    <!--配置动画的属性-->
    <!--duration 配置动画的持续时间-->
    <!--constraintSetStart 配置动画开始时，控件集的状态-->
    <!--constraintSetEnd 配置动画结束时，控件集的状态-->
    <!--motionInterpolator 配置动画的插值器，-->
    <Transition
        android:id="@+id/transition_thumb"
        android:duration="1500"
        motion:constraintSetEnd="@id/thumb_end"
        motion:constraintSetStart="@id/thumb_start"
        motion:motionInterpolator="linear">

        <!--点击时触发动画-->
        <!--targetId 配置触发事件的控件id-->
        <!--clickAction 配置点击触发的效果-->
        <!--clickAction toggle 当前控件集为开始状态，则播放动画切换至结束状态，反之亦然-->
        <!--clickAction transitionToEnd 播放控件集开始到结束的动画-->
        <!--clickAction transitionToStart 播放控件集结束到开始的动画-->
        <!--clickAction jumpToEnd 不播放动画，控件集直接切换至结束状态-->
        <!--clickAction jumpToStart 不播放动画，控件集直接切换至开始状态-->
        <OnClick
            motion:clickAction="transitionToEnd"
            motion:targetId="@id/iv_thumb_up" />

        <!--关键帧集合，用于实现缩放效果-->
        <KeyFrameSet>

            <!--修改属性-->
            <!--framePosition 取值范围为0-100-->
            <!--motionTarget 设置修改的对象-->
            <!--scaleX 设置x轴缩放大小-->
            <!--scaleY 设置y轴缩放大小-->
            <KeyAttribute
                android:scaleX="1.6"
                android:scaleY="1.6"
                motion:framePosition="25"
                motion:motionTarget="@id/iv_thumb_up" />

            <KeyAttribute
                android:scaleX="1"
                android:scaleY="1"
                motion:framePosition="50"
                motion:motionTarget="@id/iv_thumb_up" />
        </KeyFrameSet>
    </Transition>

    <!--控件集 动画开始时的状态-->
    <ConstraintSet android:id="@+id/thumb_start">

        <!--与layout文件中的控件对应-->
        <!--visibilityMode 如果需要改变控件的可见性，需要将此字段配置为ignore-->
        <Constraint
            android:id="@+id/iv_thumb_up"
            android:layout_width="25dp"
            android:layout_height="25dp"
            android:layout_marginTop="2dp"
            motion:layout_constraintBottom_toBottomOf="parent"
            motion:layout_constraintEnd_toEndOf="parent"
            motion:layout_constraintStart_toStartOf="parent"
            motion:layout_constraintTop_toTopOf="parent"
            motion:visibilityMode="ignore" />

        <Constraint
            android:id="@+id/iv_thumb_up1"
            android:layout_width="25dp"
            android:layout_height="25dp"
            android:layout_marginTop="2dp"
            motion:layout_constraintBottom_toBottomOf="parent"
            motion:layout_constraintEnd_toEndOf="parent"
            motion:layout_constraintStart_toStartOf="parent"
            motion:layout_constraintTop_toTopOf="parent"
            motion:visibilityMode="ignore">

            <!--改变控件的属性-->
            <!--attributeName 属性名-->
            <!--customFloatValue Float类型属性值-->
            <CustomAttribute
                motion:attributeName="alpha"
                motion:customFloatValue="1" />
        </Constraint>

        <Constraint
            android:id="@+id/iv_thumb_up2"
            android:layout_width="25dp"
            android:layout_height="25dp"
            android:layout_marginTop="2dp"
            motion:layout_constraintBottom_toBottomOf="parent"
            motion:layout_constraintEnd_toEndOf="parent"
            motion:layout_constraintStart_toStartOf="parent"
            motion:layout_constraintTop_toTopOf="parent"
            motion:visibilityMode="ignore">

            <CustomAttribute
                motion:attributeName="alpha"
                motion:customFloatValue="1" />
        </Constraint>

        <Constraint
            android:id="@+id/iv_thumb_up3"
            android:layout_width="25dp"
            android:layout_height="25dp"
            android:layout_marginTop="2dp"
            motion:layout_constraintBottom_toBottomOf="parent"
            motion:layout_constraintEnd_toEndOf="parent"
            motion:layout_constraintStart_toStartOf="parent"
            motion:layout_constraintTop_toTopOf="parent"
            motion:visibilityMode="ignore">

            <CustomAttribute
                motion:attributeName="alpha"
                motion:customFloatValue="1" />
        </Constraint>

        <Constraint
            android:id="@+id/iv_thumb_up4"
            android:layout_width="25dp"
            android:layout_height="25dp"
            android:layout_marginTop="2dp"
            motion:layout_constraintBottom_toBottomOf="parent"
            motion:layout_constraintEnd_toEndOf="parent"
            motion:layout_constraintStart_toStartOf="parent"
            motion:layout_constraintTop_toTopOf="parent"
            motion:visibilityMode="ignore">

            <CustomAttribute
                motion:attributeName="alpha"
                motion:customFloatValue="1" />
        </Constraint>

        <Constraint
            android:id="@+id/iv_thumb_up5"
            android:layout_width="25dp"
            android:layout_height="25dp"
            android:layout_marginTop="2dp"
            motion:layout_constraintBottom_toBottomOf="parent"
            motion:layout_constraintEnd_toEndOf="parent"
            motion:layout_constraintStart_toStartOf="parent"
            motion:layout_constraintTop_toTopOf="parent"
            motion:visibilityMode="ignore">

            <CustomAttribute
                motion:attributeName="alpha"
                motion:customFloatValue="1" />
        </Constraint>
    </ConstraintSet>

    <!--控件集 动画结束时的状态-->
    <ConstraintSet android:id="@+id/thumb_end">

        <Constraint
            android:id="@+id/iv_thumb_up"
            android:layout_width="25dp"
            android:layout_height="25dp"
            android:layout_marginTop="2dp"
            motion:layout_constraintBottom_toBottomOf="parent"
            motion:layout_constraintEnd_toEndOf="parent"
            motion:layout_constraintStart_toStartOf="parent"
            motion:layout_constraintTop_toTopOf="parent"
            motion:visibilityMode="ignore" />

        <Constraint
            android:id="@+id/iv_thumb_up1"
            android:layout_width="25dp"
            android:layout_height="25dp"
            android:layout_marginTop="110dp"
            android:layout_marginEnd="90dp"
            motion:layout_constraintBottom_toBottomOf="parent"
            motion:layout_constraintEnd_toEndOf="parent"
            motion:layout_constraintStart_toStartOf="parent"
            motion:layout_constraintTop_toTopOf="parent"
            motion:visibilityMode="ignore">

            <CustomAttribute
                motion:attributeName="alpha"
                motion:customFloatValue="0.5" />
        </Constraint>

        <Constraint
            android:id="@+id/iv_thumb_up2"
            android:layout_width="25dp"
            android:layout_height="25dp"
            android:layout_marginStart="70dp"
            android:layout_marginTop="95dp"
            motion:layout_constraintBottom_toBottomOf="parent"
            motion:layout_constraintEnd_toEndOf="parent"
            motion:layout_constraintStart_toStartOf="parent"
            motion:layout_constraintTop_toTopOf="parent"
            motion:visibilityMode="ignore">

            <CustomAttribute
                motion:attributeName="alpha"
                motion:customFloatValue="0.4" />
        </Constraint>

        <Constraint
            android:id="@+id/iv_thumb_up3"
            android:layout_width="25dp"
            android:layout_height="25dp"
            android:layout_marginEnd="85dp"
            android:layout_marginBottom="140dp"
            motion:layout_constraintBottom_toBottomOf="parent"
            motion:layout_constraintEnd_toEndOf="parent"
            motion:layout_constraintStart_toStartOf="parent"
            motion:layout_constraintTop_toTopOf="parent"
            motion:visibilityMode="ignore">

            <CustomAttribute
                motion:attributeName="alpha"
                motion:customFloatValue="0.6" />
        </Constraint>

        <Constraint
            android:id="@+id/iv_thumb_up4"
            android:layout_width="25dp"
            android:layout_height="25dp"
            android:layout_marginStart="60dp"
            android:layout_marginBottom="120dp"
            motion:layout_constraintBottom_toBottomOf="parent"
            motion:layout_constraintEnd_toEndOf="parent"
            motion:layout_constraintStart_toStartOf="parent"
            motion:layout_constraintTop_toTopOf="parent"
            motion:visibilityMode="ignore">

            <CustomAttribute
                motion:attributeName="alpha"
                motion:customFloatValue="0.2" />
        </Constraint>

        <Constraint
            android:id="@+id/iv_thumb_up5"
            android:layout_width="25dp"
            android:layout_height="25dp"
            android:layout_marginEnd="20dp"
            android:layout_marginBottom="60dp"
            motion:layout_constraintBottom_toBottomOf="parent"
            motion:layout_constraintEnd_toEndOf="parent"
            motion:layout_constraintStart_toStartOf="parent"
            motion:layout_constraintTop_toTopOf="parent"
            motion:visibilityMode="ignore">

            <CustomAttribute
                motion:attributeName="alpha"
                motion:customFloatValue="0" />
        </Constraint>
    </ConstraintSet>
</MotionScene>

监听动画状态

class MotionLayoutExampleActivity : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        val binding: LayoutMotionLayoutExampleActivityBinding = DataBindingUtil.setContentView(this, R.layout.layout_motion_layout_example_activity)
        binding.motionLayout.setTransitionListener(object : MotionLayout.TransitionListener {
            override fun onTransitionStarted(motionLayout: MotionLayout?, startId: Int, endId: Int) {
                // 动画开始
                // 把发散的按钮显示出来
                binding.ivThumbUp1.visibility = View.VISIBLE
                binding.ivThumbUp2.visibility = View.VISIBLE
                binding.ivThumbUp3.visibility = View.VISIBLE
                binding.ivThumbUp4.visibility = View.VISIBLE
                binding.ivThumbUp5.visibility = View.VISIBLE
            }

            override fun onTransitionChange(motionLayout: MotionLayout?, startId: Int, endId: Int, progress: Float) {
                // 动画进行中
            }

            override fun onTransitionCompleted(motionLayout: MotionLayout?, currentId: Int) {
                // 动画完成
                // 隐藏发散的按钮，将状态还原
                binding.root.postDelayed({
                    binding.ivThumbUp1.visibility = View.GONE
                    binding.ivThumbUp2.visibility = View.GONE
                    binding.ivThumbUp3.visibility = View.GONE
                    binding.ivThumbUp4.visibility = View.GONE
                    binding.ivThumbUp5.visibility = View.GONE
                    binding.motionLayout.progress = 0f
                }, 200)
            }

            override fun onTransitionTrigger(motionLayout: MotionLayout?, triggerId: Int, positive: Boolean, progress: Float) {
                
            }
        })
    }
}