GdkScreen: GDK 3 Reference Manual

## GdkScreen GdkScreen — Object representing a physical screen |

## Functions

GdkScreen * | gdk_screen_get_default ()
GdkVisual * | gdk_screen_get_system_visual ()
GdkVisual * | gdk_screen_get_rgba_visual ()
gboolean | gdk_screen_is_composited ()
GdkWindow * | gdk_screen_get_root_window ()
GdkDisplay * | gdk_screen_get_display ()
gint | gdk_screen_get_number ()
gint | gdk_screen_get_width ()
gint | gdk_screen_get_height ()
gint | gdk_screen_get_width_mm ()
gint | gdk_screen_get_height_mm ()
GList * | gdk_screen_list_visuals ()
GList * | gdk_screen_get_toplevel_windows ()
gchar * | gdk_screen_make_display_name ()
gint | gdk_screen_get_n_monitors ()
gint | gdk_screen_get_primary_monitor ()
void | gdk_screen_get_monitor_geometry ()
void | gdk_screen_get_monitor_workarea ()
gint | gdk_screen_get_monitor_at_point ()
gint | gdk_screen_get_monitor_at_window ()
gint | gdk_screen_get_monitor_height_mm ()
gint | gdk_screen_get_monitor_width_mm ()
gchar * | gdk_screen_get_monitor_plug_name ()
gint | gdk_screen_get_monitor_scale_factor ()
gboolean | gdk_screen_get_setting ()
const cairo_font_options_t * | gdk_screen_get_font_options ()
void | gdk_screen_set_font_options ()
gdouble | gdk_screen_get_resolution ()
void | gdk_screen_set_resolution ()
GdkWindow * | gdk_screen_get_active_window ()
GList * | gdk_screen_get_window_stack ()

## Properties

gpointer | font-options | Read / Write
gdouble | resolution | Read / Write

## Signals

void | composited-changed | Run Last
void | monitors-changed | Run Last
void | size-changed | Run Last

## Types and Values

| GdkScreen

## Object Hierarchy

        GObject
        ╰── GdkScreen

## Includes

    #include <gdk/gdk.h>

## Description

GdkScreen objects are the GDK representation of the screen on which windows can be displayed and on which the pointer moves. X originally identified screens with physical screens, but nowadays it is more common to have a single GdkScreen which combines several physical monitors (see `gdk_screen_get_n_monitors()`).

GdkScreen is used throughout GDK and GTK+ to specify which screen the top level windows are to be displayed on. it is also used to query the screen specification and default settings such as the default visual (`gdk_screen_get_system_visual()`), the dimensions of the physical monitors (`gdk_screen_get_monitor_geometry()`), etc.

## Functions

### gdk_screen_get_default ()

    GdkScreen *
    gdk_screen_get_default (void);

Gets the default screen for the default display. (See `gdk_display_get_default()`).

#### Returns

a GdkScreen, or `NULL` if there is no default display.

[nullable][transfer none]

Since: 2.2

### gdk_screen_get_system_visual ()

    GdkVisual *
    gdk_screen_get_system_visual (GdkScreen *screen);

Get the system’s default visual for `screen` . This is the visual for the root window of the display. The return value should not be freed.

#### Parameters

screen | a GdkScreen. |

#### Returns

the system visual.

[transfer none]

Since: 2.2

### gdk_screen_get_rgba_visual ()

    GdkVisual *
    gdk_screen_get_rgba_visual (GdkScreen *screen);

Gets a visual to use for creating windows with an alpha channel. The windowing system on which GTK+ is running may not support this capability, in which case `NULL` will be returned. Even if a non-`NULL` value is returned, its possible that the window’s alpha channel won’t be honored when displaying the window on the screen: in particular, for X an appropriate windowing manager and compositing manager must be running to provide appropriate display.

This functionality is not implemented in the Windows backend.

For setting an overall opacity for a top-level window, see `gdk_window_set_opacity()`.

#### Parameters

screen | a GdkScreen |

#### Returns

a visual to use for windows with an alpha channel or `NULL` if the capability is not available.

[nullable][transfer none]

Since: 2.8

### gdk_screen_is_composited ()

    gboolean
    gdk_screen_is_composited (GdkScreen *screen);

Returns whether windows with an RGBA visual can reasonably be expected to have their alpha channel drawn correctly on the screen.

On X11 this function returns whether a compositing manager is compositing `screen` .

#### Parameters

screen | a GdkScreen |

#### Returns

Whether windows with RGBA visuals can reasonably be expected to have their alpha channels drawn correctly on the screen.

Since: 2.10

### gdk_screen_get_root_window ()

    GdkWindow *
    gdk_screen_get_root_window (GdkScreen *screen);

Gets the root window of `screen` .

#### Parameters

screen | a GdkScreen |

#### Returns

the root window.

[transfer none]

Since: 2.2

### gdk_screen_get_display ()

    GdkDisplay *
    gdk_screen_get_display (GdkScreen *screen);

Gets the display to which the `screen` belongs.

#### Parameters

screen | a GdkScreen |

#### Returns

the display to which `screen` belongs.

[transfer none]

Since: 2.2

### gdk_screen_get_number ()

    gint
    gdk_screen_get_number (GdkScreen *screen);

Gets the index of `screen` among the screens in the display to which it belongs. (See `gdk_screen_get_display()`)

#### Parameters

screen | a GdkScreen |

#### Returns

the index

Since: 2.2

### gdk_screen_get_width ()

    gint
    gdk_screen_get_width (GdkScreen *screen);

Gets the width of `screen` in pixels. The returned size is in ”application pixels”, not in ”device pixels” (see `gdk_screen_get_monitor_scale_factor()`).

#### Parameters

screen | a GdkScreen |

#### Returns

the width of `screen` in pixels.

Since: 2.2

### gdk_screen_get_height ()

    gint
    gdk_screen_get_height (GdkScreen *screen);

Gets the height of `screen` in pixels. The returned size is in ”application pixels”, not in ”device pixels” (see `gdk_screen_get_monitor_scale_factor()`).

#### Parameters

screen | a GdkScreen |

#### Returns

the height of `screen` in pixels.

Since: 2.2

### gdk_screen_get_width_mm ()

    gint
    gdk_screen_get_width_mm (GdkScreen *screen);

Gets the width of `screen` in millimeters.

Note that this value is somewhat ill-defined when the screen has multiple monitors of different resolution. It is recommended to use the monitor dimensions instead.

#### Parameters

screen | a GdkScreen |

#### Returns

the width of `screen` in millimeters.

Since: 2.2

### gdk_screen_get_height_mm ()

    gint
    gdk_screen_get_height_mm (GdkScreen *screen);

Returns the height of `screen` in millimeters.

Note that this value is somewhat ill-defined when the screen has multiple monitors of different resolution. It is recommended to use the monitor dimensions instead.

#### Parameters

screen | a GdkScreen |

#### Returns

the heigth of `screen` in millimeters.

Since: 2.2

### gdk_screen_list_visuals ()

    GList *
    gdk_screen_list_visuals (GdkScreen *screen);

Lists the available visuals for the specified `screen` . A visual describes a hardware image data format. For example, a visual might support 24-bit color, or 8-bit color, and might expect pixels to be in a certain format.

Call `g_list_free()` on the return value when you’re finished with it.

#### Parameters

screen | the relevant GdkScreen. |

#### Returns

a list of visuals; the list must be freed, but not its contents.

[transfer container][element-type GdkVisual]

Since: 2.2

### gdk_screen_get_toplevel_windows ()

    GList *
    gdk_screen_get_toplevel_windows (GdkScreen *screen);

Obtains a list of all toplevel windows known to GDK on the screen `screen` . A toplevel window is a child of the root window (see `gdk_get_default_root_window()`).

The returned list should be freed with `g_list_free()`, but its elements need not be freed.

#### Parameters

screen | The GdkScreen where the toplevels are located. |

#### Returns

list of toplevel windows, free with `g_list_free()`.

[transfer container][element-type GdkWindow]

Since: 2.2

### gdk_screen_make_display_name ()

    gchar *
    gdk_screen_make_display_name (GdkScreen *screen);

Determines the name to pass to `gdk_display_open()` to get a GdkDisplay with this screen as the default screen.

#### Parameters

screen | a GdkScreen |

#### Returns

a newly allocated string, free with `g_free()`

Since: 2.2

### gdk_screen_get_n_monitors ()

    gint
    gdk_screen_get_n_monitors (GdkScreen *screen);

Returns the number of monitors which `screen` consists of.

#### Parameters

screen | a GdkScreen |

#### Returns

number of monitors which `screen` consists of

Since: 2.2

### gdk_screen_get_primary_monitor ()

    gint
    gdk_screen_get_primary_monitor (GdkScreen *screen);

Gets the primary monitor for `screen` . The primary monitor is considered the monitor where the “main desktop” lives. While normal application windows typically allow the window manager to place the windows, specialized desktop applications such as panels should place themselves on the primary monitor.

If no primary monitor is configured by the user, the return value will be 0, defaulting to the first monitor.

#### Parameters

screen | a GdkScreen. |

#### Returns

An integer index for the primary monitor, or 0 if none is configured.

Since: 2.20

### gdk_screen_get_monitor_geometry ()

    void
    gdk_screen_get_monitor_geometry (GdkScreen *screen,
                                     gint monitor_num,
                                     GdkRectangle *dest);

Retrieves the GdkRectangle representing the size and position of the individual monitor within the entire screen area. The returned geometry is in ”application pixels”, not in ”device pixels” (see `gdk_screen_get_monitor_scale_factor()`).

Monitor numbers start at 0. To obtain the number of monitors of `screen` , use `gdk_screen_get_n_monitors()`.

Note that the size of the entire screen area can be retrieved via `gdk_screen_get_width()` and `gdk_screen_get_height()`.

#### Parameters

screen | a GdkScreen |
monitor_num | the monitor number |
dest | a GdkRectangle to be filled with the monitor geometry. | [out][allow-none]

Since: 2.2

### gdk_screen_get_monitor_workarea ()

    void
    gdk_screen_get_monitor_workarea (GdkScreen *screen,
                                     gint monitor_num,
                                     GdkRectangle *dest);

Retrieves the GdkRectangle representing the size and position of the “work area” on a monitor within the entire screen area. The returned geometry is in ”application pixels”, not in ”device pixels” (see `gdk_screen_get_monitor_scale_factor()`).

The work area should be considered when positioning menus and similar popups, to avoid placing them below panels, docks or other desktop components.

Note that not all backends may have a concept of workarea. This function will return the monitor geometry if a workarea is not available, or does not apply.

Monitor numbers start at 0. To obtain the number of monitors of `screen` , use `gdk_screen_get_n_monitors()`.

#### Parameters

screen | a GdkScreen |
monitor_num | the monitor number |
dest | a GdkRectangle to be filled with the monitor workarea. | [out][allow-none]

Since: 3.4

### gdk_screen_get_monitor_at_point ()

    gint
    gdk_screen_get_monitor_at_point (GdkScreen *screen,
                                     gint x,
                                     gint y);

Returns the monitor number in which the point (`x` ,`y` ) is located.

#### Parameters

screen | a GdkScreen. |
x | the x coordinate in the virtual screen. |
y | the y coordinate in the virtual screen. |

#### Returns

the monitor number in which the point (`x` ,`y` ) lies, or a monitor close to (`x` ,`y` ) if the point is not in any monitor.

Since: 2.2

### gdk_screen_get_monitor_at_window ()

    gint
    gdk_screen_get_monitor_at_window (GdkScreen *screen,
                                      GdkWindow *window);

Returns the number of the monitor in which the largest area of the bounding rectangle of `window` resides.

#### Parameters

screen | a GdkScreen. |
window | a GdkWindow |

#### Returns

the monitor number in which most of `window` is located, or if `window` does not intersect any monitors, a monitor, close to `window` .

Since: 2.2

### gdk_screen_get_monitor_height_mm ()

    gint
    gdk_screen_get_monitor_height_mm (GdkScreen *screen,
                                      gint monitor_num);

Gets the height in millimeters of the specified monitor.

#### Parameters

screen | a GdkScreen |
monitor_num | number of the monitor, between 0 and gdk_screen_get_n_monitors (screen) |

#### Returns

the height of the monitor, or -1 if not available

Since: 2.14

### gdk_screen_get_monitor_width_mm ()

    gint
    gdk_screen_get_monitor_width_mm (GdkScreen *screen,
                                     gint monitor_num);

Gets the width in millimeters of the specified monitor, if available.

#### Parameters

screen | a GdkScreen |
monitor_num | number of the monitor, between 0 and gdk_screen_get_n_monitors (screen) |

#### Returns

the width of the monitor, or -1 if not available

Since: 2.14

### gdk_screen_get_monitor_plug_name ()

    gchar *
    gdk_screen_get_monitor_plug_name (GdkScreen *screen,
                                      gint monitor_num);

Returns the output name of the specified monitor. Usually something like VGA, DVI, or TV, not the actual product name of the display device.

#### Parameters

screen | a GdkScreen |
monitor_num | number of the monitor, between 0 and gdk_screen_get_n_monitors (screen) |

#### Returns

a newly-allocated string containing the name of the monitor, or `NULL` if the name cannot be determined.

[nullable]

Since: 2.14

### gdk_screen_get_monitor_scale_factor ()

    gint
    gdk_screen_get_monitor_scale_factor (GdkScreen *screen,
                                         gint monitor_num);

Returns the internal scale factor that maps from monitor coordinates to the actual device pixels. On traditional systems this is 1, but on very high density outputs this can be a higher value (often 2).

This can be used if you want to create pixel based data for a particular monitor, but most of the time you’re drawing to a window where it is better to use `gdk_window_get_scale_factor()` instead.

#### Parameters

screen | screen to get scale factor for |
monitor_num | number of the monitor, between 0 and gdk_screen_get_n_monitors (screen) |

#### Returns

the scale factor

Since: 3.10

### gdk_screen_get_setting ()

    gboolean
    gdk_screen_get_setting (GdkScreen *screen,
                            const gchar *name,
                            GValue *value);

Retrieves a desktop-wide setting such as double-click time for the GdkScreen `screen` .

FIXME needs a list of valid settings here, or a link to more information.

#### Parameters

screen | the GdkScreen where the setting is located |
name | the name of the setting |
value | location to store the value of the setting |

#### Returns

`TRUE` if the setting existed and a value was stored in `value` , `FALSE` otherwise.

Since: 2.2

### gdk_screen_get_font_options ()

    const cairo_font_options_t *
    gdk_screen_get_font_options (GdkScreen *screen);

Gets any options previously set with `gdk_screen_set_font_options()`.

#### Parameters

screen | a GdkScreen |

#### Returns

the current font options, or `NULL` if no default font options have been set.

[nullable]

Since: 2.10

### gdk_screen_set_font_options ()

    void
    gdk_screen_set_font_options (GdkScreen *screen,
                                 const cairo_font_options_t *options);

Sets the default font options for the screen. These options will be set on any PangoContext’s newly created with `gdk_pango_context_get_for_screen()`. Changing the default set of font options does not affect contexts that have already been created.

#### Parameters

screen | a GdkScreen |
options | a cairo_font_options_t, or `NULL` to unset any previously set default font options. | [allow-none]

Since: 2.10

### gdk_screen_get_resolution ()

    gdouble
    gdk_screen_get_resolution (GdkScreen *screen);

Gets the resolution for font handling on the screen; see `gdk_screen_set_resolution()` for full details.

#### Parameters

screen | a GdkScreen |

#### Returns

the current resolution, or -1 if no resolution has been set.

Since: 2.10

### gdk_screen_set_resolution ()

    void
    gdk_screen_set_resolution (GdkScreen *screen,
                               gdouble dpi);

Sets the resolution for font handling on the screen. This is a scale factor between points specified in a PangoFontDescription and cairo units. The default value is 96, meaning that a 10 point font will be 13 units high. (10 * 96. / 72. = 13.3).

#### Parameters

screen | a GdkScreen |
dpi | the resolution in “dots per inch”. (Physical inches aren’t actually involved; the terminology is conventional.) |

Since: 2.10

### gdk_screen_get_active_window ()

    GdkWindow *
    gdk_screen_get_active_window (GdkScreen *screen);

Returns the screen’s currently active window.

On X11, this is done by inspecting the _NET_ACTIVE_WINDOW property on the root window, as described in the Extended Window Manager Hints. If there is no currently currently active window, or the window manager does not support the _NET_ACTIVE_WINDOW hint, this function returns `NULL`.

On other platforms, this function may return `NULL`, depending on whether it is implementable on that platform.

The returned window should be unrefed using `g_object_unref()` when no longer needed.

#### Parameters

screen | a GdkScreen |

#### Returns

the currently active window, or `NULL`.

[nullable][transfer full]

Since: 2.10

### gdk_screen_get_window_stack ()

    GList *
    gdk_screen_get_window_stack (GdkScreen *screen);

Returns a GList of GdkWindows representing the current window stack.

On X11, this is done by inspecting the _NET_CLIENT_LIST_STACKING property on the root window, as described in the Extended Window Manager Hints. If the window manager does not support the _NET_CLIENT_LIST_STACKING hint, this function returns `NULL`.

On other platforms, this function may return `NULL`, depending on whether it is implementable on that platform.

The returned list is newly allocated and owns references to the windows it contains, so it should be freed using `g_list_free()` and its windows unrefed using `g_object_unref()` when no longer needed.

#### Parameters

screen | a GdkScreen |

#### Returns

a list of GdkWindows for the current window stack, or `NULL`.

[nullable][transfer full][element-type GdkWindow]

Since: 2.10

## Types and Values

### GdkScreen

    typedef struct _GdkScreen GdkScreen;

## Property Details

### The `“font-options”` property

      “font-options”             gpointer

The default font options for the screen.

Flags: Read / Write

### The `“resolution”` property

      “resolution”               gdouble

The resolution for fonts on the screen.

Flags: Read / Write

Allowed values: [-1,10000]

Default value: -1

## Signal Details

### The `“composited-changed”` signal

    void
    user_function (GdkScreen *screen,
                   gpointer   user_data)

The ::composited-changed signal is emitted when the composited status of the screen changes

#### Parameters

screen | the object on which the signal is emitted |
user_data | user data set when the signal handler was connected. |

Flags: Run Last

Since: 2.10

### The `“monitors-changed”` signal

    void
    user_function (GdkScreen *screen,
                   gpointer   user_data)

The ::monitors-changed signal is emitted when the number, size or position of the monitors attached to the screen change.

Only for X11 and OS X for now. A future implementation for Win32 may be a possibility.

#### Parameters

screen | the object on which the signal is emitted |
user_data | user data set when the signal handler was connected. |

Flags: Run Last

Since: 2.14

### The `“size-changed”` signal

    void
    user_function (GdkScreen *screen,
                   gpointer   user_data)

The ::size-changed signal is emitted when the pixel width or height of a screen changes.

#### Parameters

screen | the object on which the signal is emitted |
user_data | user data set when the signal handler was connected. |

Flags: Run Last

Since: 2.2