打开沉浸模式：
/**
* Detects and toggles immersive mode (also known as "hidey bar" mode). */
public void toggleHideyBar() { // BEGIN_INCLUDE (get_current_ui_flags)
// The UI options currently enabled are represented by a bitfield.
// getSystemUiVisibility() gives us that bitfield.
int uiOptions = getActivity().getWindow().getDecorView().getSystemUiVisibility(); int newUiOptions = uiOptions; // END_INCLUDE (get_current_ui_flags)
// BEGIN_INCLUDE (toggle_ui_flags)
boolean isImmersiveModeEnabled =
((uiOptions | View.SYSTEM_UI_FLAG_IMMERSIVE_STICKY) == uiOptions); if (isImmersiveModeEnabled) {
Log.i(TAG, "Turning immersive mode mode off. ");
} else {
Log.i(TAG, "Turning immersive mode mode on.");
} // Navigation bar hiding: Backwards compatible to ICS.
if (Build.VERSION.SDK_INT >= 14) {
newUiOptions ^= View.SYSTEM_UI_FLAG_HIDE_NAVIGATION;
} // Status bar hiding: Backwards compatible to Jellybean
if (Build.VERSION.SDK_INT >= 16) {
newUiOptions ^= View.SYSTEM_UI_FLAG_FULLSCREEN;
} // Immersive mode: Backward compatible to KitKat.
// Note that this flag doesn‘t do anything by itself, it only augments the behavior
// of HIDE_NAVIGATION and FLAG_FULLSCREEN. For the purposes of this sample
// all three flags are being toggled together.
// Note that there are two immersive mode UI flags, one of which is referred to as "sticky".
// Sticky immersive mode differs in that it makes the navigation and status bars
// semi-transparent, and the UI flag does not get cleared when the user interacts with
// the screen.
if (Build.VERSION.SDK_INT >= 18) {
newUiOptions ^= View.SYSTEM_UI_FLAG_IMMERSIVE_STICKY;
}
getActivity().getWindow().getDecorView().setSystemUiVisibility(newUiOptions); //END_INCLUDE (set_ui_flags)
}
而这个状态发生变化可以显示这个监听器：
final View decorView = getActivity().getWindow().getDecorView();
decorView.setOnSystemUiVisibilityChangeListener( new View.OnSystemUiVisibilityChangeListener() { @Override
public void onSystemUiVisibilityChange(int i) { int height = decorView.getHeight();
Log.i(TAG, "Current height: " + height);
}
});
总共有5中Flag作用都不相同
// BEGIN_INCLUDE (get_current_ui_flags)
// The "Decor View" is the parent view of the Activity. It‘s also conveniently the easiest
// one to find from within a fragment, since there‘s a handy helper method to pull it, and
// we don‘t have to bother with picking a view somewhere deeper in the hierarchy and calling
// "findViewById" on it.
View decorView = getActivity().getWindow().getDecorView(); int uiOptions = decorView.getSystemUiVisibility(); int newUiOptions = uiOptions; // END_INCLUDE (get_current_ui_flags)
// BEGIN_INCLUDE (toggle_lowprofile_mode)
// Low profile mode doesn‘t resize the screen at all, but it covers the nav & status bar
// icons with black so they‘re less distracting. Unlike "full screen" and "hide nav bar,"
// this mode doesn‘t interact with immersive mode at all, but it‘s instructive when running
// this sample to observe the differences in behavior.
if (mLowProfileCheckBox.isChecked()) {
newUiOptions |= View.SYSTEM_UI_FLAG_LOW_PROFILE;//低调模式：通知栏和虚拟键变暗
} else {
newUiOptions &= ~View.SYSTEM_UI_FLAG_LOW_PROFILE;
} // END_INCLUDE (toggle_lowprofile_mode)
// BEGIN_INCLUDE (toggle_fullscreen_mode)
// When enabled, this flag hides non-critical UI, such as the status bar,
// which usually shows notification icons, battery life, etc
// on phone-sized devices. The bar reappears when the user swipes it down. When immersive
// mode is also enabled, the app-drawable area expands, and when the status bar is swiped
// down, it appears semi-transparently and slides in over the app, instead of pushing it
// down.
if (mHideStatusBarCheckBox.isChecked()) {//全屏模式：隐藏状态栏，但并不隐藏虚拟键
newUiOptions |= View.SYSTEM_UI_FLAG_FULLSCREEN;
} else {
newUiOptions &= ~View.SYSTEM_UI_FLAG_FULLSCREEN;
} // END_INCLUDE (toggle_fullscreen_mode)
// BEGIN_INCLUDE (toggle_hidenav_mode)
// When enabled, this flag hides the black nav bar along the bottom,
// where the home/back buttons are. The nav bar normally instantly reappears
// when the user touches the screen. When immersive mode is also enabled, the nav bar
// stays hidden until the user swipes it back.
if (mHideNavCheckbox.isChecked()) {//隐藏虚拟键，点击可出现
newUiOptions |= View.SYSTEM_UI_FLAG_HIDE_NAVIGATION;
} else {
newUiOptions &= ~View.SYSTEM_UI_FLAG_HIDE_NAVIGATION;
} // END_INCLUDE (toggle_hidenav_mode)
// BEGIN_INCLUDE (toggle_immersive_mode)
// Immersive mode doesn‘t do anything without at least one of the previous flags
// enabled. When enabled, it allows the user to swipe the status and/or nav bars
// off-screen. When the user swipes the bars back onto the screen, the flags are cleared
// and immersive mode is automatically disabled.
if (mImmersiveModeCheckBox.isChecked()) {
newUiOptions |= View.SYSTEM_UI_FLAG_IMMERSIVE;
} else {
newUiOptions &= ~View.SYSTEM_UI_FLAG_IMMERSIVE;
} // END_INCLUDE (toggle_immersive_mode)
// BEGIN_INCLUDE (toggle_immersive_mode_sticky)
// There‘s actually two forms of immersive mode, normal and "sticky". Sticky immersive mode
// is different in 2 key ways:
//
// * Uses semi-transparent bars for the nav and status bars
// * This UI flag will *not* be cleared when the user interacts with the UI.
// When the user swipes, the bars will temporarily appear for a few seconds and then
// disappear again.
if (mImmersiveModeStickyCheckBox.isChecked()) {
newUiOptions |= View.SYSTEM_UI_FLAG_IMMERSIVE_STICKY;
} else {
newUiOptions &= ~View.SYSTEM_UI_FLAG_IMMERSIVE_STICKY;
} // END_INCLUDE (toggle_immersive_mode_sticky)
// BEGIN_INCLUDE (set_ui_flags)
//Set the new UI flags. decorView.setSystemUiVisibility(newUiOptions);
Log.i(TAG, "Current height: " + decorView.getHeight() + ", width: " + decorView.getWidth()); // END_INCLUDE (set_ui_flags)