从多窗口文档：
多窗口模式下禁用的功能
当设备处于多窗口模式时，某些功能会被禁用或忽略，因为它们对于可能与其他活动或应用程序共享设备屏幕的活动没有意义。这些功能包括：
- 某些系统 UI 自定义选项被禁用；例如，如果应用程序未在全屏模式下运行，它们将无法隐藏状态栏。
- 系统会忽略对 android:screenOrientation 属性的更改。
我知道对于大多数应用程序来说，区分纵向和横向模式是没有意义的，但是我正在开发包含相机视图的 SDK，用户可以进行他们希望的任何活动 - 包括支持多窗口模式的活动。问题是相机视图包含显示相机预览的 SurfaceView/TextureView，并且为了在所有活动方向上正确显示预览，需要有关正确活动方向的知识，以便可以正确旋转相机预览。
问题是我的代码通过检查当前配置方向（纵向或横向）和当前屏幕旋转来计算正确的活动方向。问题是在多窗口模式下，当前配置方向并不能反映真实的活动方向。这会导致相机预览旋转 90 度，因为 Android 报告的配置与方向不同。
我目前的解决方法是检查请求的活动方向并将其用作基础，但这有两个问题：
- 请求的活动方向不必反映实际的活动方向（即请求可能仍未得到满足）
- 请求的活动方向可以是“后面”、“传感器”、“用户”等，它不会透露有关当前活动方向的任何信息。
- 根据文档，在多窗口模式下实际上会忽略屏幕方向，因此 1. 和 2. 不起作用
即使在多窗口配置中，是否有任何方法可以稳健地计算正确的活动方向？
这是我目前使用的代码（请参阅有问题的部分的注释）：
protected int calculateHostScreenOrientation() {
int hostScreenOrientation = ActivityInfo.SCREEN_ORIENTATION_UNSPECIFIED;
WindowManager wm = (WindowManager) getContext().getSystemService(Context.WINDOW_SERVICE);
int rotation = getDisplayOrientation(wm);
boolean activityInPortrait;
if ( !isInMultiWindowMode() ) {
activityInPortrait = (mConfigurationOrientation == Configuration.ORIENTATION_PORTRAIT);
} else {
// in multi-window mode configuration orientation can be landscape even if activity is actually in portrait and vice versa
// Try determining from requested orientation (not entirely correct, because the requested orientation does not have to
// be the same as actual orientation (when they differ, this means that OS will soon rotate activity into requested orientation)
// Also not correct because, according to https://developer.android.com/guide/topics/ui/multi-window.html#running this orientation
// is actually ignored.
int requestedOrientation = getHostActivity().getRequestedOrientation();
if ( requestedOrientation == ActivityInfo.SCREEN_ORIENTATION_PORTRAIT ||
requestedOrientation == ActivityInfo.SCREEN_ORIENTATION_REVERSE_PORTRAIT ||
requestedOrientation == ActivityInfo.SCREEN_ORIENTATION_SENSOR_PORTRAIT ||
requestedOrientation == ActivityInfo.SCREEN_ORIENTATION_USER_PORTRAIT ) {
activityInPortrait = true;
} else if ( requestedOrientation == ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE ||
requestedOrientation == ActivityInfo.SCREEN_ORIENTATION_REVERSE_LANDSCAPE ||
requestedOrientation == ActivityInfo.SCREEN_ORIENTATION_SENSOR_LANDSCAPE ||
requestedOrientation == ActivityInfo.SCREEN_ORIENTATION_USER_LANDSCAPE ) {
activityInPortrait = false;
} else {
// what to do when requested orientation is 'behind', 'sensor', 'user', etc. ?!?
activityInPortrait = true; // just guess
}
}
if ( activityInPortrait ) {
Log.d(this, "Activity is in portrait");
if (rotation == Surface.ROTATION_0) {
Log.d(this, "Screen orientation is 0");
hostScreenOrientation = ActivityInfo.SCREEN_ORIENTATION_PORTRAIT;
} else if (rotation == Surface.ROTATION_180) {
Log.d(this, "Screen orientation is 180");
hostScreenOrientation = ActivityInfo.SCREEN_ORIENTATION_REVERSE_PORTRAIT;
} else if (rotation == Surface.ROTATION_270) {
Log.d(this, "Screen orientation is 270");
// natural display rotation is landscape (tablet)
hostScreenOrientation = ActivityInfo.SCREEN_ORIENTATION_PORTRAIT;
} else {
Log.d(this, "Screen orientation is 90");
// natural display rotation is landscape (tablet)
hostScreenOrientation = ActivityInfo.SCREEN_ORIENTATION_REVERSE_PORTRAIT;
}
} else {
Log.d(this, "Activity is in landscape");
if (rotation == Surface.ROTATION_90) {
Log.d(this, "Screen orientation is 90");
hostScreenOrientation = ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE;
} else if (rotation == Surface.ROTATION_270) {
Log.d(this, "Screen orientation is 270");
hostScreenOrientation = ActivityInfo.SCREEN_ORIENTATION_REVERSE_LANDSCAPE;
} else if (rotation == Surface.ROTATION_0) {
Log.d(this, "Screen orientation is 0");
// natural display rotation is landscape (tablet)
hostScreenOrientation = ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE;
} else {
Log.d(this, "Screen orientation is 180");
// natural display rotation is landscape (tablet)
hostScreenOrientation = ActivityInfo.SCREEN_ORIENTATION_REVERSE_LANDSCAPE;
}
}
return hostScreenOrientation;
}
private int getDisplayOrientation(WindowManager wm) {
if (DeviceManager.getSdkVersion() < 8) {
return wm.getDefaultDisplay().getOrientation();
}
return wm.getDefaultDisplay().getRotation();
}
private boolean isInMultiWindowMode() {
return Build.VERSION.SDK_INT >= 24 && getHostActivity().isInMultiWindowMode();
}
protected Activity getHostActivity() {
Context context = getContext();
while (context instanceof ContextWrapper) {
if (context instanceof Activity) {
return (Activity) context;
}
context = ((ContextWrapper) context).getBaseContext();
}
return null;
}
编辑：我也将此报告给Android 问题跟踪器。