Android 在PreviewView上绘制画布

我正在使用新的

camerax

库使用

PreviewView

组件显示相机预览。我有一个

画布

对象，我想在相机预览中显示它。我该怎么做

这是XML文件

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

    <data>

    </data>

    <androidx.constraintlayout.widget.ConstraintLayout
        android:id="@+id/constraint_layout"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:background="@android:color/black"
        tools:context=".MainActivity">

        <androidx.camera.view.PreviewView
            android:id="@+id/view_finder"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toTopOf="parent" />
    </androidx.constraintlayout.widget.ConstraintLayout>
</layout>

有一种在相机预览上绘制画布的方法，但它仅适用于

SurfaceView

而不适用于

PreviewView

surfaceHolder = surfaceView!!.holder
val canvas: Canvas = surfaceHolder!!.lockCanvas()

paint.apply {
    color = Color.RED
    textSize = 80.0f
    strokeWidth = 8.0f
}

canvas.drawLine(0f,0f,50f,50f,paint)
surfaceHolder!!.unlockCanvasAndPost(canvas)

问题是

SurfaceView

仅适用于

camera2

库，我无法将其用于

camerax

。如果解决方案是使用

SurfaceView

，如何使用

camerax

surfaceHolder = surfaceView!!.holder
val canvas: Canvas = surfaceHolder!!.lockCanvas()

paint.apply {
    color = Color.RED
    textSize = 80.0f
    strokeWidth = 8.0f
}

canvas.drawLine(0f,0f,50f,50f,paint)
surfaceHolder!!.unlockCanvasAndPost(canvas)