android - 如何获得相对于设备主体的 Activity 的真实旋转

Question

我的应用程序使用相机。要以正确的方式显示相机的预览，我必须考虑相对于物理设备方向的 Activity 方向。 IE。如果 Activity 方向被锁定并且永远不会改变，我不需要采取任何进一步的步骤 - 随着设备旋转，预览图像将相应地旋转。但是，想象一下我的 Activity 可以改变方向。您旋转设备 - 并预览 - 直到达到纵向模式(假设它最初是横向)，此时 Activity 旋转以适应新方向。但是预览图像随它旋转，现在它与相机和周围的现实不同步。我必须做的是确定 Activity 方向并相应地旋转图像。

Display.getRotation() 似乎可以用于此目的。但显然，它不能:https://groups.google.com/forum/#!topic/android-developers/ij_0QbApKKc

问题是原点不是由 Android API 固定的。一些平板电脑在正常方向(横向、音量按钮向上)返回旋转 0，而其他一些(比如我的 Nexus 7 2013)返回 1。

我该如何解决这个问题？

Answer 1

您可以使用 OrientationEventListener 确定方向就像这样

    mOrientationEventListener = new OrientationEventListener(context, SensorManager.SENSOR_DELAY_NORMAL) {

            @Override
            public void onOrientationChanged(int orientation) {

                // determine our orientation based on sensor response

                Display display = ((WindowManager)getSystemService(WINDOW_SERVICE)).getDefaultDisplay();                                        

                if (display.getOrientation() == Surface.ROTATION_0) {   // landscape oriented devices
                    isLandscapeOriented = true;
                    if (orientation >= 315 || orientation < 45) {
                        if (mOrientation != ORIENTATION_LANDSCAPE_NORMAL) {                         
                            mOrientation = ORIENTATION_LANDSCAPE_NORMAL;
                        }
                    } else if (orientation < 315 && orientation >= 225) {
                        if (mOrientation != ORIENTATION_PORTRAIT_INVERTED) {
                            mOrientation = ORIENTATION_PORTRAIT_INVERTED;
                        }                       
                    } else if (orientation < 225 && orientation >= 135) {
                        if (mOrientation != ORIENTATION_LANDSCAPE_INVERTED) {
                            mOrientation = ORIENTATION_LANDSCAPE_INVERTED;
                        }                       
                    } else if (orientation <135 && orientation > 45) { 
                        if (mOrientation != ORIENTATION_PORTRAIT_NORMAL) {
                            mOrientation = ORIENTATION_PORTRAIT_NORMAL;
                        }                       
                    }                       
                } else {  // portrait oriented devices

                    if (orientation >= 315 || orientation < 45) {
                        if (mOrientation != ORIENTATION_PORTRAIT_NORMAL) {                          
                            mOrientation = ORIENTATION_PORTRAIT_NORMAL;
                        }
                    } else if (orientation < 315 && orientation >= 225) {
                        if (mOrientation != ORIENTATION_LANDSCAPE_NORMAL) {
                            mOrientation = ORIENTATION_LANDSCAPE_NORMAL;
                        }                       
                    } else if (orientation < 225 && orientation >= 135) {
                        if (mOrientation != ORIENTATION_PORTRAIT_INVERTED) {
                            mOrientation = ORIENTATION_PORTRAIT_INVERTED;
                        }                       
                    } else if (orientation <135 && orientation > 45) { 
                        if (mOrientation != ORIENTATION_LANDSCAPE_INVERTED) {
                            mOrientation = ORIENTATION_LANDSCAPE_INVERTED;
                        }                       
                    }
                }


            }
        };
    }
    if (mOrientationEventListener.canDetectOrientation()) {
        mOrientationEventListener.enable();
    }

不要忘记调用 mOrientationEventListener.disable();

编辑:

    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 result;
     if (info.facing == Camera.CameraInfo.CAMERA_FACING_FRONT) {
         result = (info.orientation + degrees) % 360;
         result = (360 - result) % 360;  // compensate the mirror
     } else {  // back-facing
       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;
       }
         result = (info.orientation - degrees + 360) % 360;
     }
     camera.setDisplayOrientation(result);
 }