如何在 Android 中创建始终处于顶部的全屏覆盖活动 [英] How to create always-top fullscreen overlay activity in Android

问题描述

我希望能够创建一个始终位于 Android 显示屏前面的活动.它不应该接收任何输入，只需将其传递给它下面的任何应用程序.类似 HUD 的东西.

I'd like to be able to create an Activity that is always at the front of display of Android. It should receive no input, just pass it down to whatever application is next below it. Something like a HUD.

我能够研究我需要将基础窗口类型设置为 TYPE_SYSTEM_ALERT 但看起来 Android 忽略了我的代码 - 即使我从清单中删除 android.permission.SYSTEM_ALERT_WINDOW 权限也不会抛出异常.(需要使用这种窗口类型).当我尝试在对话框上使用 ALERT 类型时，它工作正常，但我无法将对话框设为全屏透明实体.这是我的代码，也许缺少一些简单的东西.

I was able to research that I need to set underlying window type to TYPE_SYSTEM_ALERT but it looks like Android is ignoring my code - no exception thrown even if I delete android.permission.SYSTEM_ALERT_WINDOW permission from manifest. (it is required to use this window type). When I tried to use ALERT type on dialog, it worked OK, but I cannot make dialog into full screen transparent entity. Here is my code, maybe there is something simple missing.

public void onCreate(Bundle savedInstanceState) {       
     super.onCreate(savedInstanceState);        

     requestWindowFeature(Window.FEATURE_NO_TITLE);
     getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);
     getWindow().setType(WindowManager.LayoutParams.TYPE_SYSTEM_ALERT);             
     getWindow().setBackgroundDrawableResource(android.R.color.transparent);
     getWindow().setFormat(PixelFormat.TRANSLUCENT);
     setContentView(R.layout.main);
}

半透明设置必须在 xml manifest 中从外部启用，否则它也不起作用.

Translucent setting has to be enabled externally in xml manifest, otherwise it also didn't work.

 <item name="android:windowIsTranslucent">true</item>

推荐答案

final WindowManager.LayoutParams params = new WindowManager.LayoutParams(
WindowManager.LayoutParams.FLAG_FULLSCREEN,
WindowManager.LayoutParams.FLAG_FULLSCREEN,
WindowManager.LayoutParams.TYPE_SYSTEM_ALERT,
WindowManager.LayoutParams.FLAG_LAYOUT_IN_SCREEN,
PixelFormat.TRANSLUCENT);

WindowManager wm = (WindowManager) getApplicationContext()
    .getSystemService(Context.WINDOW_SERVICE);

ViewGroup mTopView = (ViewGroup) App.inflater.inflate(R.layout.main, null);
getWindow().setAttributes(params);
wm.addView(mTopView, params);

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