Question

我正在开发一款适用于平板电脑的应用，平板电脑将放置在一个可以围绕给定点旋转的支架上。这意味着首次打开应用时平板电脑的移动非常少。应用程序将根据平板电脑在支架中的旋转显示各种内容。我无法找到怎样做，无论我搜索多么难以获得与OrientationEventListener.onOrientationChanged(int orientation)的值相当的度数或弧度的初始方向。我已经配置了OrientationEventListener，我的想法是在默认的活动onCreate方法中，我会手动调用OrientationEventListener并使用更新的值。

演示代码本身不会运行，但说明了这一点：

//No problems at this point in the code, the OrientationManager class
//which extends OrientationEventListener properly receives onOrientationChanged
//notices
OrientationEventListener orientationEventListener;
orientationEventListener = new OrientationManager(
                               this,
                               SensorManager.SENSOR_DELAY_NORMAL
                           );
orientationEventListener.enable();

//Here's where the problem is... need to get the current orientation 
//and "initialize" the OrientationEventListener
float[] coords = new float[3];
float[] rotation = new float[16];
SensorManager.getOrientation(rotation, coords);

//Test for correct coords values (logs "0.0, -0.0, -0.0")
Log.d("DEBUG", Float.toString(coords[0]) + ", " 
               + Float.toString(coords[1]) + ", " 
               + Float.toString(coords[2])
     );

//Goal is to be able to call orientationEventListener.onOrientationChanged(??)
//with the value that would be sent if the event was called naturally

现在，我提交了一个问题已经提出并回答了吗？我看了很多SO帖子，但没有到任何地方。

Answer 1

查看来自getOrientationUsingGetRotationMatrix()的{{1}}方法：Link：

DeviceOrientationService

检查private void getOrientationUsingGetRotationMatrix() { if (mGravityVector == null || mMagneticFieldVector == null) { return; } // Get the rotation matrix. // The rotation matrix that transforms from the body frame to the earth frame. float[] deviceRotationMatrix = new float[9]; if (!SensorManager.getRotationMatrix( deviceRotationMatrix, null, mGravityVector, mMagneticFieldVector)) { return; } // Convert rotation matrix to rotation angles. // Assuming that the rotations are appied in the order listed at // http://developer.android.com/reference/android/hardware/SensorEvent.html#values // the rotations are applied about the same axes and in the same order as required by the // API. The only conversions are sign changes as follows. // The angles are in radians float[] rotationAngles = new float[3]; SensorManager.getOrientation(deviceRotationMatrix, rotationAngles); double alpha = Math.toDegrees(-rotationAngles[0]); while (alpha < 0.0) { alpha += 360.0; } // [0, 360) double beta = Math.toDegrees(-rotationAngles[1]); while (beta < -180.0) { beta += 360.0; } // [-180, 180) double gamma = Math.toDegrees(rotationAngles[2]); while (gamma < -90.0) { gamma += 360.0; } // [-90, 90) maybeSendChange(alpha, beta, gamma); }是否确实包含有效值且rotation是否正在返回getRotationMatrix(...)。

事件触发前的Android SensorManager.getOrientation

1 个答案: