Graphics.UI.Gtk.Gdk.Screen

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

class GObjectClass o => ScreenClass o

Instances

ScreenClass Screen

castToScreen :: GObjectClass obj => obj -> Screen

gTypeScreen :: GType

toScreen :: ScreenClass o => o -> Screen

Methods

screenGetDefault

:: IO (Maybe Screen)	returns a `Screen`, or `Nothing` if there is no default display.
Gets the default screen for the default display. (See displayGetDefault).

screenGetSystemColormap

:: Screen
-> IO Colormap	returns the default colormap for `screen`.
Gets the system default colormap for `screen`

screenGetRGBAColormap

:: Screen

-> IO (Maybe Colormap) returns a colormap to use for windows with an alpha channel or Nothing if the capability is not available.

Gets a colormap to use for creating windows or pixmaps with an alpha channel. The windowing system on which Gtk+ is running may not support this capability, in which case Nothing will be returned. Even if a non-Nothing 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.

Available since Gdk version 2.8

screenGetDefaultColormap

:: Screen
-> IO Colormap	returns the default `Colormap`.

screenSetDefaultColormap

:: Screen
-> Colormap	`colormap` - a `Colormap`
-> IO ()

screenIsComposited

:: 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

:: Screen
-> IO DrawWindow	returns the root window
Gets the root window of `screen`.

screenGetDisplay

:: Screen
-> IO Display	returns the display to which `screen` belongs
Gets the display to which the `screen` belongs.

screenGetNumber

:: Screen
-> IO Int	returns the index
Gets the index of `screen` among the screens in the display to which it belongs. (See `screenGetDisplay`)

screenGetWidth

:: Screen
-> IO Int	returns the width of `screen` in pixels.
Gets the width of `screen` in pixels

screenGetHeight

:: Screen
-> IO Int	returns the height of `screen` in pixels.
Gets the height of `screen` in pixels

screenGetWidthMm

screenGetHeightMm

screenGetWidthMM

:: 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

:: 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

:: 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

:: 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

:: 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

:: Screen
-> IO Int	returns number of monitors which `screen` consists of.
Returns the number of monitors which `screen` consists of.

screenGetMonitorGeometry

:: 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

:: 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

:: 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

:: 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

:: 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

:: 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

:: 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

:: 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

screenDefaultColormap :: Attr Screen Colormap

Sets the default colormap for screen.

Gets the default colormap for screen.

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

Produced by Haddock version 2.4.2