沉浸式模式退出问题咨询：附进入沉浸式模式实现代码

Hey there! Let's work through how to properly exit immersive mode based on the code you've shared.

First, let's recap what your current code does: you're using bitwise OR (|=) to add multiple immersive-related SystemUiFlags to your decor view. To exit this mode, we need to reverse that action by removing those exact flags using a bitwise AND NOT (&= ~) operation.

Step-by-Step Solution Code #

Here's the code you can use to exit immersive mode completely:

// Get the current decor view
var decorView = Window.DecorView;
// Capture the current UI visibility state
var currentUiOptions = (int)decorView.SystemUiVisibility;

// Remove all the immersive-related flags you previously set
var newUiOptions = currentUiOptions & ~(int)(
    SystemUiFlags.LowProfile | 
    SystemUiFlags.Fullscreen | 
    SystemUiFlags.HideNavigation | 
    SystemUiFlags.Immersive | 
    SystemUiFlags.ImmersiveSticky
);

// Apply the updated UI visibility state
decorView.SystemUiVisibility = (StatusBarVisibility)newUiOptions;

Key Notes to Keep in Mind #

• Bitwise Operations Explained: The ~ operator flips the bits of the flag combination, and &= keeps only the flags that weren't part of your immersive setup. This effectively undoes the flags you added earlier.
• ImmersiveSticky Behavior: If you used ImmersiveSticky, the system normally hides the status/navigation bars again after user interaction. But to fully exit back to the normal UI state, you must explicitly remove this flag—otherwise, the sticky behavior will persist.
• Main Thread Requirement: Make sure you run this code on the main thread (all UI operations in Android require this). If you're triggering this from a background task, use RunOnUiThread() to wrap the code.
• Triggering the Exit: You can tie this code to user actions like a button click, back press, or any other event where you want to exit immersive mode. For example, overriding OnBackPressed():

  public override void OnBackPressed()
  {
      // Exit immersive mode first
      var decorView = Window.DecorView;
      var currentUiOptions = (int)decorView.SystemUiVisibility;
      var newUiOptions = currentUiOptions & ~(int)(
          SystemUiFlags.LowProfile | 
          SystemUiFlags.Fullscreen | 
          SystemUiFlags.HideNavigation | 
          SystemUiFlags.Immersive | 
          SystemUiFlags.ImmersiveSticky
      );
      decorView.SystemUiVisibility = (StatusBarVisibility)newUiOptions;
  
      // Then proceed with default back press behavior
      base.OnBackPressed();
  }
  

Bonus: Verifying the State #

If you want to check if you're currently in immersive mode before exiting, you can use a bitwise AND to check for the presence of the flags:

var isImmersive = ((int)decorView.SystemUiVisibility & (int)SystemUiFlags.Immersive) != 0;
if (isImmersive) {
    // Run the exit code here
}

内容的提问来源于stack exchange，提问作者Ali