Java 通过从左到右填充按钮来更改其背景

我想在按下按钮时改变按钮的背景，从左到右填充颜色，就像水平进度条一样

这是检测按住的代码：

lateinit var buttonView: View
val cdt = object : CountDownTimer(1000, 100) {
            override fun onTick(millisUntilFinished: Long) {

            }

            override fun onFinish() {
                //do something after being press by 1 sec.
            }
        }

        val onTouchListener = View.OnTouchListener { v, event ->
            buttonView = v
            when (event.action) {
                MotionEvent.ACTION_DOWN -> {
                    (v.background as AnimationDrawable).start()
                    cdt.start()
                }
                MotionEvent.ACTION_UP -> {
                    (v.background as AnimationDrawable).stop()
                    cdt.cancel()
                }

            }
            false
        }

这是我用于按钮的背景：

<?xml version="1.0" encoding="utf-8"?>
<animation-list xmlns:android="http://schemas.android.com/apk/res/android">
    ...items with drawables which colors are in different position. Frame by frame....
</animation-list>

（可以用Java来回答）
对于可绘制的，我会选择a作为a中的顶层。这将在视觉上像进度条一样工作

在下面的可绘制中，剪辑可绘制覆盖了一个仅为红色矩形的底层

按钮\u background.xml

<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
    <item>
        <shape android:shape="rectangle">
            <solid android:color="@android:color/holo_red_light" />
        </shape>
    </item>
    <item android:id="@+id/clip_drawable">
        <clip
            android:clipOrientation="horizontal"
            android:gravity="start">
            <shape
                android:shape="rectangle">
                <solid android:color="@android:color/black" />
            </shape>
        </clip>
    </item>
</layer-list>

<android.support.constraint.ConstraintLayout 
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <Button
        android:id="@+id/button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="32dp"
        android:background="@drawable/button_background"
        android:text="Button"
        android:onClick="animateButton"
        android:textColor="@android:color/white"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

</android.support.constraint.ConstraintLayout>

活动\u main.xml

<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
    <item>
        <shape android:shape="rectangle">
            <solid android:color="@android:color/holo_red_light" />
        </shape>
    </item>
    <item android:id="@+id/clip_drawable">
        <clip
            android:clipOrientation="horizontal"
            android:gravity="start">
            <shape
                android:shape="rectangle">
                <solid android:color="@android:color/black" />
            </shape>
        </clip>
    </item>
</layer-list>

<android.support.constraint.ConstraintLayout 
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <Button
        android:id="@+id/button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="32dp"
        android:background="@drawable/button_background"
        android:text="Button"
        android:onClick="animateButton"
        android:textColor="@android:color/white"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

</android.support.constraint.ConstraintLayout>

所以您希望在单击按钮时或在屏幕上显示布局时播放此动画？