基于Android系统源码解决camera画面预览倒置问题

最新推荐文章于 2024-01-29 09:50:20 发布

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本文介绍如何通过修改Android源码解决相机预览画面倒置的问题，详细解析了Camera.java和android_hardware_Camera.cpp中处理旋转逻辑的代码。

网上有很多关于在应用层开发来解决camera预览画面倒置问题，我这里说一下基于源码解决此问题的方法。

1、frameworks/base/core/java/android/hardware/Camera.java

     public  void setDisplayOrientation(int d) {
         int rotation = SystemProperties.getInt("ro.sf.hwrotation",0);
         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 = 0;
         CameraInfo cameraInfo = new CameraInfo();                                                                                                                                                      
         getCameraInfo(camera_id, cameraInfo);
         if (cameraInfo.facing == CameraInfo.CAMERA_FACING_BACK) {
             result = (cameraInfo.orientation - degrees + 360) % 360; // back-facing
         } else if (cameraInfo.facing == Camera.CameraInfo.CAMERA_FACING_FRONT) {
             result = (cameraInfo.orientation + degrees) % 360;
             result = (360 - result) % 360;  // compensate the mirror
         }
         _setDisplayOrientation(result);
     }
 

     public  native final void _setDisplayOrientation(int degrees);

2、frameworks/base/core/jni/android_hardware_Camera.cpp

 { "_setDisplayOrientation",                                                                                                                                                                          
     "(I)V",
     (void *)android_hardware_Camera_setDisplayOrientation },