Graphics.UI.Gtk.Gdk.Screen

Object representing a physical screen

• Module available since Gdk version 2.2

Detail

Screen objects are the GDK representation of a physical screen. It 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 colormap (screenGetDefaultColormap), the screen width (screenGetWidth), etc.

Note that a screen may consist of multiple monitors which are merged to form a large screen area.

Class Hierarchy

| GObject
| +----Screen

Types

data Screen

Instances

Eq Screen

Ord Screen

GObjectClass Screen

ScreenClass Screen

class GObjectClass o => ScreenClass o

Instances

ScreenClass Screen

castToScreen :: GObjectClass obj => obj -> Screen

gTypeScreen :: GType

toScreen :: ScreenClass o => o -> Screen

Methods

screenGetDefault

Arguments

:: IO (Maybe Screen)

returns a Screen, or Nothing if there is no default display.

Gets the default screen for the default display. (See displayGetDefault).

screenGetSystemVisual

Arguments

:: Screen

-> IO Visual

returns the system visual

Get the system's default visual for screen. This is the visual for the root window of the display.

screenIsComposited

Arguments

:: Screen

-> IO Bool

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

• Available since Gdk version 2.10

screenGetRootWindow

Arguments

:: Screen

-> IO DrawWindow

returns the root window

Gets the root window of screen.

screenGetDisplay

Arguments

:: Screen

-> IO Display

returns the display to which screen belongs

Gets the display to which the screen belongs.

screenGetNumber

Arguments

:: Screen

-> IO Int

returns the index

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

screenGetWidth

Arguments

:: Screen

-> IO Int

returns the width of screen in pixels.

Gets the width of screen in pixels

screenGetHeight

Arguments

:: Screen

-> IO Int

returns the height of screen in pixels.

Gets the height of screen in pixels

screenGetWidthMm :: Screen -> IO Int

screenGetHeightMm :: Screen -> IO Int

screenGetWidthMM

Arguments

:: Screen

-> IO Int

returns the width of screen in millimeters.

Gets the width of screen in millimeters. Note that on some X servers this value will not be correct.

screenGetHeightMM

Arguments

:: Screen

-> IO Int

returns the heigth of screen in millimeters.

Returns the height of screen in millimeters. Note that on some X servers this value will not be correct.

screenListVisuals

Arguments

:: Screen

-> IO [Visual]

returns a list of visuals

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.

screenGetToplevelWindows

Arguments

:: Screen

-> IO [DrawWindow]

returns list of toplevel windows

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 getDefaultRootWindow).

screenMakeDisplayName

Arguments

:: GlibString string

=> Screen

-> IO string

returns a newly allocated string

Determines the name to pass to displayOpen to get a Display with this screen as the default screen.

screenGetNMonitors

Arguments

:: Screen

-> IO Int

returns number of monitors which screen consists of.

Returns the number of monitors which screen consists of.

screenGetMonitorGeometry

Arguments

:: Screen

-> Int

monitorNum - the monitor number.

-> IO Rectangle

Retrieves the Rectangle representing the size and position of the individual monitor within the entire screen area.

Note that the size of the entire screen area can be retrieved via screenGetWidth and screenGetHeight.

screenGetMonitorAtPoint

Arguments

:: Screen

-> Int

x - the x coordinate in the virtual screen.

-> Int

y - the y coordinate in the virtual screen.

-> IO Int

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.

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

screenGetMonitorAtWindow

Arguments

:: Screen

-> DrawWindow

window - a DrawWindow

-> IO Int

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

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

screenGetMonitorHeightMm

Arguments

:: Screen

-> Int

monitorNum - number of the monitor

-> IO Int

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

Gets the height in millimeters of the specified monitor.

• Available since Gdk version 2.14

screenGetMonitorWidthMm

Arguments

:: Screen

-> Int

monitorNum - number of the monitor

-> IO Int

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

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

• Available since Gdk version 2.14

screenGetMonitorPlugName

Arguments

:: GlibString string

=> Screen

-> Int

monitorNum - number of the monitor

-> IO (Maybe string)

returns a newly-allocated string containing the name of the monitor, or Nothing if the name cannot be determined

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

• Available since Gdk version 2.14

screenGetActiveWindow

Arguments

:: Screen

-> IO (Maybe DrawWindow)

returns the currently active window, or Nothing.

Returns the currently active window of this screen.

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 Nothing.

On other platforms, this function may return Nothing, depending on whether it is implementable on that platform.

• Available since Gdk version 2.10

screenGetWindowStack

Arguments

:: Screen

-> IO (Maybe [DrawWindow])

returns a list of DrawWindows for the current window stack, or Nothing.

Returns a list of DrawWindows 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 Nothing.

On other platforms, this function may return Nothing, depending on whether it is implementable on that platform.

• Available since Gdk version 2.10

Attributes

screenFontOptions :: Attr Screen (Maybe FontOptions)

The default font options for the screen.

screenResolution :: Attr Screen Double

The resolution for fonts on the screen.

Default value: -1

Signals

screenSizeChanged :: ScreenClass self => Signal self (IO ())

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

screenCompositedChanged :: ScreenClass self => Signal self (IO ())

The screenCompositedChanged signal is emitted when the composited status of the screen changes

• Available since Gdk version 2.10

screenMonitorsChanged :: ScreenClass self => Signal self (IO ())

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

Only for X for now. Future implementations for Win32 and OS X may be a possibility.

• Available since Gdk version 2.14