How do I know if the screen is in "Extend" mode?

Question

How do I know if the screen is in "Extend" mode?

Asked 7 years, 1 month ago

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4

I want to make a if to know if the screen is in "Extend".

Example: (Win + P)

How can I do this in C#:

if (?) // só pode entrar no if, se a tela está no modo "Estender".
{
    SegundaTela formulario = new SegundaTela();
    Screen[] telas = Screen.AllScreens;
    Rectangle bounds = telas[1].Bounds; // pode ser outro índice.
    formulario.SetBounds(bounds.X, bounds.Y, bounds.Width, bounds.Height);
    formulario.StartPosition = FormStartPosition.Manual;
    formulario.Show();
}

There is no way to do this just with . NET, you will need to call the Windows C++ API. But what is your goal with that? Maybe detecting screen mode is unnecessary, if all you want is something like projecting on a specific screen.

– Oralista de Sistemas

2017/10/19 at 20:40
@Renan, I asked a question here: https://answall.com/questions/245514/como-projetar-uma-imagem-no-tel%C3%A3o of how to project the screen. That’s why I asked the question here to know if PC is in "Extend" mode, because if user does not choose the extend option, the second screen (form) will not show on the screen, for example.

– Matheus Miranda

2017/10/19 at 20:43
Somehow I need to show a warning to activate in "Extend".

– Matheus Miranda

2017/10/19 at 20:48
I think you can see the screen size, if it is extended, the second screen will not have x=0

– Rovann Linhalis

2017/10/19 at 20:53
It’s just a hunch... I’ll take a test

– Rovann Linhalis

2017/10/19 at 20:54
It would serve to force the "extend"?

– vinibrsl

2017/10/19 at 21:05
Yes, it could be @vnbrs

– Matheus Miranda

2017/10/19 at 21:05

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2 answers

6

Just check if there’s more than one Screen:

if (Screen.AllScreens.Length > 1)
{
 //Estendido
}
else
{
 //Duplicado, ou apenas 1 tela
}

You didn’t specify, but this code is for winforms because the Screen class derives from System.Windows.Forms

Does that really work? I swore that the screen count was the same regardless of the mode, because even with screen replication, each one can have different resolution, area and bit depth.

– Oralista de Sistemas

2017/10/19 at 21:17
1

I just tested it here, it surprised me because even though it’s in duplicate mode, the screen count becomes just one.

– Rovann Linhalis

2017/10/19 at 21:17
1

In this case +1, that’s genius.

– Oralista de Sistemas

2017/10/19 at 21:18
3

WPF projects can use System.Windows.Forms without problems

– vinibrsl

2017/10/19 at 21:23
1

It really works, LOOOOL

– Matheus Miranda

2017/10/19 at 21:29

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by vinibrsl • **19,711** points · Answer 1 · 2017-10-19T21:07:54+00:00

I don’t know anything about . NET to use Windows "Extend". Maybe you can do it with Windows API.

Under Windows 7, Windows 8 and 10 you can use the system Displayswitch.exe with the argument /extend. For other versions of the system you will have to test. I do not know if the Win + P was already shortcut in Vista.

var processo = new Process { StartInfo = { FileName = "DisplaySwitch.exe", Arguments = "/extend" } };
processo.Start();

Beyond the /extend, there are other forms of presentation. You can use them with the arguments:

/external: only the second screen;
/internal: only the computer screen;
/clone: duplicate the screens.