gtk-0.11.0: Binding to the Gtk+ graphical user interface library.ContentsIndex
Graphics.UI.Gtk.Gdk.GC
Portabilityportable (depends on GHC)
Stabilityprovisional
Maintainergtk2hs-users@lists.sourceforge.net
Contents
Detail
Description
Graphics contexts - objects to encapsulate drawing properties
Synopsis
data GC
class GObjectClass o => GCClass o
castToGC :: GObjectClass obj => obj -> GC
gTypeGC :: GType
gcNew :: DrawableClass d => d -> IO GC
data GCValues = GCValues {
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
}
newGCValues :: GCValues
Color (Color)
data Function
= Copy
| Invert
| Xor
| Clear
| And
| AndReverse
| AndInvert
| Noop
| Or
| Equiv
| OrReverse
| CopyInvert
| OrInvert
| Nand
| Nor
| Set
data Fill
= Solid
| Tiled
| Stippled
| OpaqueStippled
data SubwindowMode
= ClipByChildren
| IncludeInferiors
data LineStyle
= LineSolid
| LineOnOffDash
| LineDoubleDash
data CapStyle
= CapNotLast
| CapButt
| CapRound
| CapProjecting
data JoinStyle
= JoinMiter
| JoinRound
| JoinBevel
gcNewWithValues :: DrawableClass d => d -> GCValues -> IO GC
gcSetValues :: GC -> GCValues -> IO ()
gcGetValues :: GC -> IO GCValues
gcSetClipRectangle :: GC -> Rectangle -> IO ()
gcSetClipRegion :: GC -> Region -> IO ()
gcSetDashes :: GC -> Int -> [(Int, Int)] -> IO ()
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.

data GC
show/hide Instances
class GObjectClass o => GCClass o
show/hide Instances
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.
Constructors
GCValues
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
show/hide Instances
newGCValues :: GCValues
Color (Color)
data Function
Determine how bitmap operations are carried out.
Constructors
Copy
Invert
Xor
Clear
And
AndReverse
AndInvert
Noop
Or
Equiv
OrReverse
CopyInvert
OrInvert
Nand
Nor
Set
show/hide Instances
data Fill
How objects are filled.
Constructors
Solid
Tiled
Stippled
OpaqueStippled
show/hide Instances
data SubwindowMode
Constructors
ClipByChildren
IncludeInferiors
show/hide Instances
data LineStyle
Determines if a line is solid or dashed.
Constructors
LineSolid
LineOnOffDash
LineDoubleDash
show/hide Instances
data CapStyle
Specify the how the ends of a line is drawn.
Constructors
CapNotLast
CapButt
CapRound
CapProjecting
show/hide Instances
data JoinStyle
Constructors
JoinMiter
JoinRound
JoinBevel
show/hide Instances
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.
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