Gtk2HsContentsIndex
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
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
data Color = Color Word16 Word16 Word16
foreground :: GCValues -> Color
background :: GCValues -> Color
data Function
= Copy
| Invert
| Xor
| Clear
| And
| AndReverse
| AndInvert
| Noop
| Or
| Equiv
| OrReverse
| CopyInvert
| OrInvert
| Nand
| Nor
| Set
function :: GCValues -> Function
data Fill
= Solid
| Tiled
| Stippled
| OpaqueStippled
fill :: GCValues -> Fill
tile :: GCValues -> Maybe Pixmap
stipple :: GCValues -> Maybe Pixmap
clipMask :: GCValues -> Maybe Pixmap
data SubwindowMode
= ClipByChildren
| IncludeInferiors
subwindowMode :: GCValues -> SubwindowMode
tsXOrigin :: GCValues -> Int
tsYOrigin :: GCValues -> Int
clipXOrigin :: GCValues -> Int
clipYOrigin :: GCValues -> Int
graphicsExposure :: GCValues -> Bool
lineWidth :: GCValues -> Int
data LineStyle
= LineSolid
| LineOnOffDash
| LineDoubleDash
lineStyle :: GCValues -> LineStyle
data CapStyle
= CapNotLast
| CapButt
| CapRound
| CapProjecting
capStyle :: GCValues -> CapStyle
data JoinStyle
= JoinMiter
| JoinRound
| JoinBevel
joinStyle :: GCValues -> JoinStyle
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
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
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
show/hide Instances
Storable Color
foreground :: GCValues -> Color
background :: GCValues -> 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
function :: GCValues -> Function
data Fill
How objects are filled.
Constructors
Solid
Tiled
Stippled
OpaqueStippled
show/hide Instances
Enum Fill
fill :: GCValues -> Fill
tile :: GCValues -> Maybe Pixmap
stipple :: GCValues -> Maybe Pixmap
clipMask :: GCValues -> Maybe Pixmap
data SubwindowMode
Determine if child widget may be overdrawn.
Constructors
ClipByChildren
IncludeInferiors
show/hide Instances
subwindowMode :: GCValues -> SubwindowMode
tsXOrigin :: GCValues -> Int
tsYOrigin :: GCValues -> Int
clipXOrigin :: GCValues -> Int
clipYOrigin :: GCValues -> Int
graphicsExposure :: GCValues -> Bool
lineWidth :: GCValues -> Int
data LineStyle
Determines if a line is solid or dashed.
Constructors
LineSolid
LineOnOffDash
LineDoubleDash
show/hide Instances
lineStyle :: GCValues -> LineStyle
data CapStyle
Specify the how the ends of a line is drawn.
Constructors
CapNotLast
CapButt
CapRound
CapProjecting
show/hide Instances
capStyle :: GCValues -> CapStyle
data JoinStyle
Determines how adjacent line ends are drawn.
Constructors
JoinMiter
JoinRound
JoinBevel
show/hide Instances
joinStyle :: GCValues -> 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.
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