在小视频app源码中实现Camera预览旋转设置

在小视频app源码中实现Camera预览旋转设置的相关代码
目标版本设置为21，这样不需要动态申请权限，在清单文件申请CAMERA权限

布局

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/andrzoid"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">

<FrameLayout
android:id="@+id/fl_container"
android:layout_width="match_parent"
android:layout_height="match_parent" />

<LinearLayout
android:layout_width="match_parent"
android:orientation="horizontal"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true">

<View
android:layout_width="6dp"
android:layout_height="0dp"/>

<Button
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_weight="1"
android:id="@+id/btn_0"
android:onClick="onClick"
android:text="0"/>

<View
android:layout_width="6dp"
android:layout_height="0dp"/>

<Button
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_weight="1"
android:id="@+id/btn_90"
android:onClick="onClick"
android:text="90"/>

<View
android:layout_width="6dp"
android:layout_height="0dp"/>

<Button
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_weight="1"
android:onClick="onClick"
android:id="@+id/btn_180"
android:text="180"/>

<View
android:layout_width="6dp"
android:layout_height="0dp"/>

<Button
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_weight="1"
android:onClick="onClick"
android:id="@+id/btn_270"
android:text="270"/>

<View
android:layout_width="6dp"
android:layout_height="0dp"/>

</LinearLayout>

</RelativeLayout>

代码

class MainActivity : AppCompatActivity() {

private var cameraView: FrameLayout? = null
private var camera: Camera? = null
private lateinit var cameraContainer: ViewGroup

override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
cameraContainer = findViewById(R.id.fl_container)
}

override fun onResume() {
super.onResume()
startPreview()
}

override fun onPause() {
super.onPause()
stopPreview()
}

private fun startPreview() {
val surfaceView = SurfaceView(this)
surfaceView.holder.addCallback(object : SurfaceHolder.Callback {
override fun surfaceCreated(holder: SurfaceHolder) {
camera = Camera.open()
camera?.setPreviewDisplay(holder)
camera?.setDisplayOrientation(0)
camera?.startPreview()
}

override fun surfaceDestroyed(holder: SurfaceHolder) {

}

override fun surfaceChanged(holder: SurfaceHolder, format: Int, width: Int, height: Int) {}
})
cameraView = FrameLayout(this).apply { addView(surfaceView) }
cameraContainer.addView(cameraView)
}

private fun stopPreview() {
camera?.stopPreview()
camera?.release()
camera = null

cameraView?.removeAllViews()
(cameraView?.parent as? ViewGroup)?.removeAllViews()
cameraView = null
}

fun onClick(view: View) {
when (view.id) {
R.id.btn_0 -> camera?.setDisplayOrientation(0)
R.id.btn_90 -> camera?.setDisplayOrientation(90)
R.id.btn_180 -> camera?.setDisplayOrientation(180)
R.id.btn_270 -> camera?.setDisplayOrientation(270)
}
}

}