Graphics.UI.Gtk.Gdk.GC

Graphics contexts - objects to encapsulate drawing properties

Detail

All drawing operations in Gdk take a graphics context (GC) argument. A graphics context encapsulates information about the way things are drawn, such as the foreground color or line width. By using graphics contexts, the number of arguments to each drawing call is greatly reduced, and communication overhead is minimized, since identical arguments do not need to be passed repeatedly.

Most values of a graphics context can be set at creation time by using gcNewWithValues. A few of the values in the GC, such as the dash pattern, can only be set by the latter method.

Graphics Contexts are removed in Gtk3, so this module is empty.

data GC

Instances

Eq GC

Ord GC

GObjectClass GC

GCClass GC

class GObjectClass o => GCClass o

Instances

GCClass GC

castToGC :: GObjectClass obj => obj -> GC

gTypeGC :: GType

gcNew :: DrawableClass d => d -> IO GC

Create an empty graphics context.

data GCValues

Intermediate data structure for GCs.

• If graphicsExposure is set then copying portions into a drawable will generate an "exposure" event, even if the destination area is not currently visible.

Removed in Gtk3.

Constructors

GCValues

Fields

foreground :: Color

background :: Color

function :: Function

fill :: Fill

tile :: Maybe Pixmap

stipple :: Maybe Pixmap

clipMask :: Maybe Pixmap

subwindowMode :: SubwindowMode

tsXOrigin :: Int

tsYOrigin :: Int

clipXOrigin :: Int

clipYOrigin :: Int

graphicsExposure :: Bool

lineWidth :: Int

lineStyle :: LineStyle

capStyle :: CapStyle

joinStyle :: JoinStyle

Instances

Storable GCValues

newGCValues :: GCValues

data Color :: *

Color

• Specifies a color with three integer values for red, green and blue. All values range from 0 (least intense) to 65535 (highest intensity).

Constructors

Color Word16 Word16 Word16

Instances

Eq Color

Show Color

data Function

Determine how bitmap operations are carried out.

Removed in Gtk3.

Constructors

Copy

Invert

Xor

Clear

And

AndReverse

AndInvert

Noop

Or

Equiv

OrReverse

CopyInvert

OrInvert

Nand

Nor

Set

Instances

Enum Function

Eq Function

Show Function

data Fill

How objects are filled.

Removed in Gtk3.

Constructors

Solid

Tiled

Stippled

OpaqueStippled

Instances

Enum Fill

Eq Fill

Show Fill

data SubwindowMode

Determine if child widget may be overdrawn.

Removed in Gtk3.

Constructors

ClipByChildren

IncludeInferiors

Instances

Enum SubwindowMode

visibility of a window

Eq SubwindowMode

Show SubwindowMode

data LineStyle

Determines if a line is solid or dashed.

Removed in Gtk3.

Constructors

LineSolid

LineOnOffDash

LineDoubleDash

Instances

Enum LineStyle

Eq LineStyle

Show LineStyle

data CapStyle

Specify the how the ends of a line is drawn.

Removed in Gtk3.

Constructors

CapNotLast

CapButt

CapRound

CapProjecting

Instances

Enum CapStyle

Eq CapStyle

Show CapStyle

data JoinStyle

Constructors

JoinMiter

JoinRound

JoinBevel

Instances

Enum JoinStyle

Eq JoinStyle

Show JoinStyle

gcNewWithValues :: DrawableClass d => d -> GCValues -> IO GC

Creates a graphics context with specific values.

gcSetValues :: GC -> GCValues -> IO ()

Change some of the values of a graphics context.

gcGetValues :: GC -> IO GCValues

Retrieve the values in a graphics context.

gcSetClipRectangle :: GC -> Rectangle -> IO ()

Set a clipping rectangle.

• All drawing operations are restricted to this rectangle. This rectangle is interpreted relative to the clip origin.

gcSetClipRegion :: GC -> Region -> IO ()

Set a clipping region.

• All drawing operations are restricted to this region. This region is interpreted relative to the clip origin.

gcSetDashes :: GC -> Int -> [(Int, Int)] -> IO ()

Specify the pattern with which lines are drawn.

• Every tuple in the list contains an even and an odd segment. Even segments are drawn normally, whereby the lineStyle member of the graphics context defines if odd segements are drawn or not. A phase argument greater than 0 will drop phase pixels before starting to draw.