Camera预览旋转设置

实现效果如下：

点击4个按钮分别实现4个角度的旋转。

1. 目标版本设置为21，这样不需要动态申请权限。
2. 在清单文件申请CAMERA权限
3. 布局

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

4. 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)
           }
       }
   
   }