检查屏幕是否处于锁屏或关闭状态

主要解决的问题是：在屏幕处于锁屏或关闭状态下，无法正常显示MessageDlg

　

procedure WaitUntilScreenIsActive;
begin
  while True do
  begin
    Application.ProcessMessages;
    if isScreenOn and isKeyguardunLock then
     Break;
  end;
end;

function isScreenOn : Boolean;
var
  Native:JObject ;
  PowerManager : JPowerManager;
begin
  Native:=SharedActivityContext.getSystemService(TJContext.JavaClass.POWER_SERVICE);
  if not Assigned(Native) then
  begin
    raise Exception.Create('Could not locate Connectivity Service');
  end;
  PowerManager := TJPowerManager.Wrap((Native as ILocalObject).GetObjectID) ;
  if not Assigned(PowerManager) then
    Result := True
  else
    Result := PowerManager.isScreenOn;
  Native:=SharedActivityContext.getSystemService(TJContext.JavaClass.KEYGUARD_SERVICE);
end;

function isKeyguardunLock : Boolean;
var
  Native:JObject ;
  KeyguardManager : JKeyguardManager;
begin  Native:=SharedActivityContext.getSystemService(TJContext.JavaClass.KEYGUARD_SERVICE);
  if not Assigned(Native) then
  begin
    raise Exception.Create('Could not locate Connectivity Service');
  end;
  KeyguardManager := TJKeyguardManager.Wrap((Native as ILocalObject).GetObjectID) ;
  if not Assigned(KeyguardManager) then
    Result := True
  else
    Result := not KeyguardManager.isKeyguardLocked;

end;