android - OrientationEventListener 与 Display.getRotation

Question

OrientationEventListener.onOrientationChanged报告的学位之间有什么关系？和 WindowManager().getDefaultDisplay().getRotation 报告的显示旋转.

这两个都以度数返回设备的方向。这些值(value)观之间有什么关系，应该如何解读它们？

Answer 1

所以我做了一些挖掘并编写了一个辅助类，如下所示，它可以是 Activity 中的嵌套类。 OrientationEventListener 监听 changes in the Accelerometer data .如果您以自然方向(纵向/垂直)握持手机，则方向为 0。顺时针方向旋转手机时方向逐渐增加。所以当左侧在上面(横向)时，方向是 90。当手机倒置时，它是 180。当右侧向上时，它是 270。

虽然 getRotation() 是屏幕从其“自然”方向的旋转。根据文档，角度是屏幕上绘制图形的旋转，与设备的物理旋转方向相反。因此，当手机处于纵向模式/自然方向时，旋转和方向均为 0。如果左侧在顶部，则方向为 90，但旋转为 270，因为绘制的图形与方向相反设备旋转。同样，如果右侧在顶部，则方向为 270，旋转为 90。有趣的情况:手机倒置 - 方向为 180，但旋转仍然为 0。如果在电话时不重绘图形旋转，则 Display.getRotation() 保持不变。从下面的代码也可以验证这一点。我只在发生变化时打印旋转和方向，并且方向已量化为 0、90、180、270 的 4 个值。

static final class CustomOrientationListener extends OrientationEventListener {
    private static final String TAG = CustomOrientationListener.class.getSimpleName();
    private int savedOrientation = Integer.MIN_VALUE;
    private int savedRotation = Integer.MIN_VALUE;
    AppCompatActivity activity;
    public CustomOrientationListener(AppCompatActivity a) {
        super(a);
        activity = a;
    }

    /**
     * Called when the orientation of the device has changed.
     * orientation parameter is in degrees, ranging from 0 to 359.
     * orientation is 0 degrees when the device is oriented in its natural position,
     * 90 degrees when its left side is at the top, 180 degrees when it is upside down,
     * and 270 degrees when its right side is to the top.
     */
    @Override
    public void onOrientationChanged(int orientation) {
        orientation = normalizeOrientation(orientation);
        if (savedOrientation != orientation) {
            Log.i(TAG, "orientation: " + orientation);
            savedOrientation = orientation;
        }
        int rotation = getRotationInDegrees(activity.getWindowManager().getDefaultDisplay().getRotation());
        if (rotation != savedRotation) {
            Log.i(TAG, "rotation: " + rotation);
            savedRotation = rotation;
        }
    }

    /**
     * getRotation() Returns the rotation of the screen from its "natural" orientation. The returned value may be
     * Surface.ROTATION_0 (no rotation), Surface.ROTATION_90, Surface.ROTATION_180, or Surface.ROTATION_270.
     * For example, if a device has a naturally tall screen, and the user has turned it on its side to go into a
     * landscape orientation, the value returned here may be either Surface.ROTATION_90 or Surface.ROTATION_270
     * depending on the direction it was turned. The angle is the rotation of the drawn graphics on the screen,
     * which is the opposite direction of the physical rotation of the device. For example, if the device is rotated
     * 90 degrees counter-clockwise, to compensate rendering will be rotated by 90 degrees clockwise and thus the
     * returned value here will be Surface.ROTATION_90.
     */
    private static int getRotationInDegrees(int rotation) {
        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;
        }
        return degrees;
    }


    private static int normalizeOrientation(int degrees) {
        if (degrees > 315 || degrees <= 45) {
            return 0;
        }

        if (degrees > 45 && degrees <= 135) {
            return 90;
        }

        if (degrees > 135 && degrees <= 225) {
            return 180;
        }

        if (degrees > 225 && degrees <= 315) {
            return 270;
        }

        throw new RuntimeException("The physics as we know them are no more. Watch out for anomalies.");
    }
}