//Code by canyie
javags(SDK_INT,null,"android.os.Build$VERSION","SDK_INT")
s canDraw = false
f(SDK_INT >= 23) 
{
  //6.0及以上，调用Settings.canDrawOverlays
  java(canDraw,null,"android.provider.Settings.canDrawOverlays","Context",activity)
}
else f(SDK_INT < 19)
{
  //4.4以下，不检测
  s canDraw = true
}

f(!canDraw && SDK_INT >= 19) 
{
  //拿AppOpsManager再检测一次
  //一是6.0以下无法使用Settings.canDrawOverlays
  //二是8.0时存在一个bug，更改悬浮窗权限不会立即反映过来
  //所以拿AppOpsManager再试试（听说没用）
  java(appops,activity,"android.app.Activity.getSystemService","String","appops")
  f(appops == null) 
  {
    syso("no AppOpsManager")
    s canDraw = true
    //拿不到AppOpsManager，默认true
  } 
  else
  {
    java(pn,activity,"android.content.Context.getPackageName")
    java(uid,null,"android.os.Process.myUid")
    java(mode,appops,"android.app.AppOpsManager.noteOpNoThrow","int",24,"int",uid,"String",pn)
    f(mode == 0) 
    {
      s canDraw = true
    }
  }
}
tw(canDraw)