全屏沉浸模式ImmersiveMode

在写播放器的时候，遇到了关于全屏模式的坑。翻阅了网上一些资料和google 官方的demo后，终于把坑填完了。

全屏主要的干扰就是 顶部状态栏stateBar和部分手机的虚拟按键NavigationBar。

这是google demo的源码：

    /**
     * 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)
    }

这个demo比较简单，不做详细的解释。就简单的介绍下Flag等意思。

getActivity().getWindow().getDecorView() //获取当前页面的跟布局。
View.SYSTEM_UI_FLAG_HIDE_NAVIGATION;//控制NavigationBar的隐藏于显示。
View.SYSTEM_UI_FLAG_FULLSCREEN;//控制stateBar的隐藏与显示。

View.SYSTEM_UI_FLAG_IMMERSIVE_STICKY;
这个标签比较有趣。其实这个标签有两个：View.SYSTEM_UI_FLAG_IMMERSIVE_STICKY 和 View.SYSTEM_UI_FLAG_IMMERSIVE。这两个标签都必须和View.SYSTEM_UI_FLAG_HIDE_NAVIGATION、View.SYSTEM_UI_FLAG_FULLSCREEN 一起使用。

下面分为3中情况：

1、只使用View.SYSTEM_UI_FLAG_HIDE_NAVIGATION 和 View.SYSTEM_UI_FLAG_FULLSCREEN 。

这种情况下，在进入全屏模式后，用户有任何操作，SYSTEM_UI_FLAG_HIDE_NAVIGATION和SYSTEM_UI_FLAG_FULLSCREEN 就会被清除。状态栏和虚拟按键会一直可见。除非再次设置SYSTEM_UI_FLAG_HIDE_NAVIGATION和SYSTEM_UI_FLAG_FULLSCREEN。在状态栏和虚拟按键显示变化时会调用View.OnSystemUiVisibilityChangeListener。

2、SYSTEM_UI_FLAG_IMMERSIVE 配合View.SYSTEM_UI_FLAG_HIDE_NAVIGATION 和 View.SYSTEM_UI_FLAG_FULLSCREEN使用。

用户操作不会清除SYSTEM_UI_FLAG_HIDE_NAVIGATION和SYSTEM_UI_FLAG_FULLSCREEN。会一直保持全屏模式。显示切换时也会触发View.OnSystemUiVisibilityChangeListener。还有一个区别就是 ，全屏模式时，从原本状态栏或者虚拟按键的位置 响屏幕内部滑动，会清除SYSTEM_UI_FLAG_HIDE_NAVIGATION和SYSTEM_UI_FLAG_FULLSCREEN，保持可见状态，并且也会触发View.OnSystemUiVisibilityChangeListener监听。

3.SYSTEM_UI_FLAG_IMMERSIVE_STICKY配合View.SYSTEM_UI_FLAG_HIDE_NAVIGATION 和 View.SYSTEM_UI_FLAG_FULLSCREEN使用。

用户操作不会清除SYSTEM_UI_FLAG_HIDE_NAVIGATION和SYSTEM_UI_FLAG_FULLSCREEN。会一直保持全屏模式。显示切换时也会触发View.OnSystemUiVisibilityChangeListener。，全屏模式时，，从原本状态栏或者虚拟按键的位置 响屏幕内部滑动， 状态栏 和 虚拟按键栏会暂时可见，一段时间后自动隐藏。与SYSTEM_UI_FLAG_IMMERSIVE 不同的是，因为是临时的显示，所以不会触发View.OnSystemUiVisibilityChangeListener。


可能说的有点混乱，可以参考下下面的表格。

个人觉得使用toggleHideyBar()来控制有点不顺手，所以拆分成了showBar()和hideBar()。

    public void showBar(){
        int uiOptions = getWindow().getDecorView().getSystemUiVisibility();
        int newUiOptions = uiOptions;
        boolean isImmersiveModeEnabled =
                ((uiOptions | View.SYSTEM_UI_FLAG_IMMERSIVE_STICKY) == uiOptions);
        if (isImmersiveModeEnabled) {
            Log.i(TAG, "Turning immersive mode mode off. ");
            

            //先取 非 后再 与， 把对应位置的1 置成0，原本为0的还是0
            
            if (Build.VERSION.SDK_INT >= 14) {
                newUiOptions &= ~View.SYSTEM_UI_FLAG_HIDE_NAVIGATION;
            }

           
            if (Build.VERSION.SDK_INT >= 16) {
                newUiOptions &= ~View.SYSTEM_UI_FLAG_FULLSCREEN;
            }

        
            if (Build.VERSION.SDK_INT >= 18) {
                newUiOptions &= ~View.SYSTEM_UI_FLAG_IMMERSIVE_STICKY;
            }
            getWindow().getDecorView().setSystemUiVisibility(newUiOptions);
        }
    }


    public void hideBar() {
        // The UI options currently enabled are represented by a bitfield.
        // getSystemUiVisibility() gives us that bitfield.
        int uiOptions = getWindow().getDecorView().getSystemUiVisibility();
        int newUiOptions = uiOptions;
        boolean isImmersiveModeEnabled =
                ((uiOptions | View.SYSTEM_UI_FLAG_IMMERSIVE_STICKY) == uiOptions);
        if (!isImmersiveModeEnabled) {
            Log.i(TAG, "Turning immersive mode mode on. ");

      
            if (Build.VERSION.SDK_INT >= 14) {
                newUiOptions |= View.SYSTEM_UI_FLAG_HIDE_NAVIGATION;
            }

         
            if (Build.VERSION.SDK_INT >= 16) {
                newUiOptions |= View.SYSTEM_UI_FLAG_FULLSCREEN;
            }
            if (Build.VERSION.SDK_INT >= 18) {
                newUiOptions |= View.SYSTEM_UI_FLAG_IMMERSIVE_STICKY;
            }

            getWindow().getDecorView().setSystemUiVisibility(newUiOptions);
        }
    }

暂时就写这么多吧。