Fullscreen mode

This guide will give you the code in order to switch between window, borderless and fullscreen modes.

This guide is a follow up to Get started.

Here is some code that can toggle your game’s fullscreen mode with borderless as an option.

bool _isFullscreen = false;
bool _isBorderless = false;
int _width = 0;
int _height = 0;
GraphicsDeviceManager _graphics;
GameWindow _window;

public void ToggleFullscreen() {
    bool oldIsFullscreen = _isFullscreen;

    if (_isBorderless) {
        _isBorderless = false;
    } else {
        _isFullscreen = !_isFullscreen;
    }

    ApplyFullscreenChange(oldIsFullscreen);
}
public void ToggleBorderless() {
    bool oldIsFullscreen = _isFullscreen;

    _isBorderless = !_isBorderless;
    _isFullscreen = _isBorderless;

    ApplyFullscreenChange(oldIsFullscreen);
}

private void ApplyFullscreenChange(bool oldIsFullscreen) {
    if (_isFullscreen) {
        if (oldIsFullscreen) {
            ApplyHardwareMode();
        } else {
            SetFullscreen();
        }
    } else {
        UnsetFullscreen();
    }
}
private void ApplyHardwareMode() {
    _graphics.HardwareModeSwitch = !_isBorderless;
    _graphics.ApplyChanges();
}
private void SetFullscreen() {
    _width = Window.ClientBounds.Width;
    _height = Window.ClientBounds.Height;

    _graphics.PreferredBackBufferWidth = GraphicsAdapter.DefaultAdapter.CurrentDisplayMode.Width;
    _graphics.PreferredBackBufferHeight = GraphicsAdapter.DefaultAdapter.CurrentDisplayMode.Height;
    _graphics.HardwareModeSwitch = !_isBorderless;

    _graphics.IsFullScreen = true;
    _graphics.ApplyChanges();
}
private void UnsetFullscreen() {
    _graphics.PreferredBackBufferWidth = _width;
    _graphics.PreferredBackBufferHeight = _height;
    _graphics.IsFullScreen = false;
    _graphics.ApplyChanges();
}

To use this, call either ToggleFullscreen or ToggleBorderless.

Explanation

Track the current fullscreen state. Initialized to false since the game starts in window mode.

bool _isFullscreen = false;
bool _isBorderless = false;

Window mode happens when both _isFullscreen and _isBorderless are false.

Borderless mode happens when both _isFullscreen and _isBorderless are true.

Fullscreen mode happens when _isFullscreen is true and _isBorderless is false.

Going fullscreen means changing the current window’s width and height. It’s a good idea to save the previous values so that we can restore the window mode. Initialized to 0 but the actual value will be set by SetFullscreen.

int _width = 0;
int _height = 0;

Borderless mode happens when the hardware mode switch is set to false. This method is called when the game is already in fullscreen.

private void ApplyHardwareMode() {
    _graphics.HardwareModeSwitch = !_isBorderless;
    _graphics.ApplyChanges();
}

Going fullscreen we preserve the current window size. Then we apply the size of the monitor that the window is currently in. This method handles the current borderless state.

private void SetFullscreen() {
    _width = Window.ClientBounds.Width;
    _height = Window.ClientBounds.Height;

    _graphics.PreferredBackBufferWidth = GraphicsAdapter.DefaultAdapter.CurrentDisplayMode.Width;
    _graphics.PreferredBackBufferHeight = GraphicsAdapter.DefaultAdapter.CurrentDisplayMode.Height;
    _graphics.HardwareModeSwitch = !_isBorderless;

    _graphics.IsFullScreen = true;
    _graphics.ApplyChanges();
}

To go back to the window mode, we restore the previously saved sizes.

private void UnsetFullscreen() {
    _graphics.PreferredBackBufferWidth = _width;
    _graphics.PreferredBackBufferHeight = _height;
    _graphics.IsFullScreen = false;
    _graphics.ApplyChanges();
}

There are three modes in total: window, borderless, fullscreen. To switch between borderless and fullscreen, it’s just a matter of calling ApplyHardwareMode. To switch between window and the other two, it’s a matter of calling SetFullscreen or UnsetFullscreen.

private void ApplyFullscreenChange(bool oldIsFullscreen) {
    if (_isFullscreen) {
        if (oldIsFullscreen) {
            ApplyHardwareMode();
        } else {
            SetFullscreen();
        }
    } else {
        UnsetFullscreen();
    }
}

Toggling the fullscreen mode is a matter of turning off the borderless mode or toggling the fullscreen state.

public void ToggleFullscreen() {
    bool oldIsFullscreen = _isFullscreen;

    if (_isBorderless) {
        _isBorderless = false;
    } else {
        _isFullscreen = !_isFullscreen;
    }

    ApplyFullscreenChange(oldIsFullscreen);
}

Toggling the borderless mode is a matter of toggling the borderless state and making the fullscreen state be the same.

public void ToggleBorderless() {
    bool oldIsFullscreen = _isFullscreen;

    _isBorderless = !_isBorderless;
    _isFullscreen = _isBorderless;

    ApplyFullscreenChange(oldIsFullscreen);
}

Follow up

Persistent game settings, a follow up tutorial that applies this fullscreen mechanism.

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