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Graphics.UI.Gtk.Gdk.Screen

Portability | portable (depends on GHC)
Stability | provisional
Maintainer | gtk2hs-users@lists.sourceforge.net

Contents

Detail
Class Hierarchy
Types
Methods
Attributes
Signals

Description

Object representing a physical screen

- Module available since Gdk version 2.2

Synopsis

data Screen
class GObjectClass o => ScreenClass o
castToScreen :: GObjectClass obj => obj -> Screen
toScreen :: ScreenClass o => o -> Screen
screenGetDefault :: IO (Maybe Screen)
screenGetSystemColormap :: Screen -> IO Colormap
screenGetRGBColormap :: Screen -> IO Colormap
screenGetRGBAColormap :: Screen -> IO (Maybe Colormap)
screenIsComposited :: Screen -> IO Bool
screenGetRootWindow :: Screen -> IO DrawWindow
screenGetDisplay :: Screen -> IO Display
screenGetNumber :: Screen -> IO Int
screenGetWidth :: Screen -> IO Int
screenGetHeight :: Screen -> IO Int
screenGetWidthMm
screenGetHeightMm
screenGetWidthMM :: Screen -> IO Int
screenGetHeightMM :: Screen -> IO Int
screenMakeDisplayName :: Screen -> IO String
screenGetNMonitors :: Screen -> IO Int
screenGetMonitorAtPoint :: Screen -> Int -> Int -> IO Int
screenGetMonitorAtWindow :: Screen -> DrawWindow -> IO Int
screenGetActiveWindow :: Screen -> IO (Maybe DrawWindow)
screenResolution :: Attr Screen Double
screenDefaultColormap :: Attr Screen Colormap
screenSizeChanged :: ScreenClass self => Signal self (IO ())
screenCompositedChanged :: ScreenClass self => Signal self (IO ())

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

GObjectClass Screen
ScreenClass Screen

class GObjectClass o => ScreenClass o

Instances

ScreenClass Screen

castToScreen :: GObjectClass obj => obj -> Screen
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's default colormap for `screen`

screenGetRGBColormap

:: Screen |
-> IO Colormap | returns the preferred colormap
Gets the preferred colormap for rendering image data on `screen`. Not a very useful function; historically, GDK could only render RGB image data to one colormap and visual, but in the current version it can render to any colormap and visual. So there's no need to call this function.

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

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.

screenMakeDisplayName

:: Screen |
-> IO String | returns a newly allocated string, free with gFree
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.

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.

screenGetActiveWindow

:: Screen |
-> IO (Maybe DrawWindow) | returns the currently active window, or `Nothing`.

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 `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
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 ::composited_changed signal is emitted when the composited status of the screen changes

- Available since Gdk version 2.10

Produced by Haddock version 2.4.2