android.hardware.Camera入坑之旅

1、相机预览方向适配

可以参考谷歌官方适配方案

 public static void setCameraDisplayOrientation(Activity activity,
         int cameraId, android.hardware.Camera camera) {
     android.hardware.Camera.CameraInfo info =
             new android.hardware.Camera.CameraInfo();
     android.hardware.Camera.getCameraInfo(cameraId, info);
     int rotation = activity.getWindowManager().getDefaultDisplay()
             .getRotation();
     int degrees = 0;
     switch (rotation) {
         case Surface.ROTATION_0: degrees = 0; break;
         case Surface.ROTATION_90: degrees = 90; break;
         case Surface.ROTATION_180: degrees = 180; break;
         case Surface.ROTATION_270: degrees = 270; break;
     }
 
     int result;
     if (info.facing == Camera.CameraInfo.CAMERA_FACING_FRONT) {
         result = (info.orientation + degrees) % 360;
         result = (360 - result) % 360;  // compensate the mirror
     } else {  // back-facing
         result = (info.orientation - degrees + 360) % 360;
     }
     camera.setDisplayOrientation(result);
 }

2、相机对焦时挂掉

相机在非活动时对焦失败，要在mCamera.startPreview()候才可以调用对焦的方法，保险做法是设置一个boolean值isPreviewActive判断是否活动。当mCamera.stopPreview()时isPreviewActive=false;当mCamera.startPreview()时isPreviewActive=true，对焦时先判断这个标志位。
08-08 16:54:59.357   723 25306 E Camera2Client: autoFocus: Camera 0: Call autoFocus when preview is inactive (state = 1).
08-08 16:54:59.358  5205  5205 W System.err: java.lang.RuntimeException: autoFocus failed
08-08 16:54:59.358  5205  5205 W System.err:     at android.hardware.Camera.native_autoFocus(Native Method)
08-08 16:54:59.358  5205  5205 W System.err:     at android.hardware.Camera.autoFocus(Camera.java:1402)

3、自动对焦方式

代码设置了Camera.Parameters.FOCUS_MODE_AUTO，自动对焦效果并不好（相机模糊后并不会自动再次对焦），可以使用

Camera.Parameters.FOCUS_MODE_CONTINUOUS_PICTURE或者Camera.Parameters.FOCUS_MODE_CONTINUOUS_VIDEO来进行自动连续对焦，使用自动连续对焦需要调用mCamera.cancelAutoFocus()停止手动对焦

4、快门声音

 public final void takePicture(ShutterCallback shutter, PictureCallback raw,
            PictureCallback postview, PictureCallback jpeg) 

调用takePicture拍照时，第一个参数为null则拍照无声音，否则有快门声