Source code Contents Index

Canvas

Description

HTk's canvas widget. A canvas is a drawing pad, that can also contain widgets in embedded windows. A canvas widget contains canvas items.

Synopsis

class (GUIObject w) => HasPostscript w where postscript :: w -> [CreationConfig PostScript] -> IO () data ScrollBar class (Widget w) => HasScroller w where isWfOrientation :: w -> Orientation -> Bool scrollbar :: Orientation -> ScrollBar -> Config w moveto :: Orientation -> w -> Fraction -> IO () scroll :: Orientation -> w -> Int -> ScrollUnit -> IO () view :: Orientation -> w -> IO (Fraction, Fraction) data ScrollUnit data Canvas newCanvas :: (Container par) => par -> [Config Canvas] -> IO Canvas closeEnough :: Double -> Canvas -> IO Canvas getCloseEnough :: Canvas -> IO Double confine :: Bool -> Canvas -> IO Canvas getConfine :: Canvas -> IO Bool screenToCanvasCoord :: Canvas -> Orientation -> Distance -> Maybe Distance -> IO Distance type ScrollRegion = (Position, Position) scrollRegion :: ScrollRegion -> Canvas -> IO Canvas getScrollRegion :: Canvas -> IO ScrollRegion scrollIncrement :: Orientation -> Distance -> Canvas -> IO Canvas

Documentation

class (GUIObject w) => HasPostscript w where

Widgets that support postscript export instantiate the class HasPostscript. Methods postscript :: w -> [CreationConfig PostScript] -> IO () Exports postscript from the given widget. Instances HasPostscript Canvas

data ScrollBar

The ScrollBar datatype.

class (Widget w) => HasScroller w where

Methods isWfOrientation :: w -> Orientation -> Bool True for widgets that are scrollable in the given orientation. scrollbar :: Orientation -> ScrollBar -> Config w Associates a scrollbar with a scrollable widget. moveto :: Orientation -> w -> Fraction -> IO () Positions the scrolled widget so the give Fraction is off-screen to the left. scroll :: Orientation -> w -> Int -> ScrollUnit -> IO () Scrolls the associated widget by n pages or units (depending on the given ScrollUnit). view :: Orientation -> w -> IO (Fraction, Fraction) Returns two fractions between 0 and 1 that describe the amount of the widget off-screen to the left and the amount of the widget visible. Instances HasScroller Canvas HasScroller Editor HasScroller (Entry a) HasScroller (ListBox a) (HasScroller a) => HasScroller (ScrollBox a)

data ScrollUnit

data Canvas

The Canvas datatype.

newCanvas

:: (Container par) => par the parent widget, which has to be a container widget (an instance of class Container). -> [Config Canvas] the list of configuration options for this canvas. -> IO Canvas A canvas widget. Constructs a new canvas widget and returns a handler.

closeEnough :: Double -> Canvas -> IO Canvas

getCloseEnough

:: Canvas the canvas to get this configuration from. -> IO Double The requested distance. Selector for the maximum distance from the mouse to an overlapped object.

confine

:: Bool Bool, see above. -> Canvas the canvas to apply this configuration. -> IO Canvas The concerned canvas. True constraints view to the scroll region.

getConfine

:: Canvas the canvas to get this configuration from. -> IO Bool The confine configuration as a Bool value (see confine). Selector for the confine configuration, constraints view to the scroll region if True.

screenToCanvasCoord

:: Canvas the concerned canvas widget. -> Orientation the orientation (Vertical or Horizontal). -> Distance the input coordinate. -> Maybe Distance an optional grid (the output can be rounded to multiples of this grid if specified). -> IO Distance The requested distance in the specified orientation. Maps from screen X or Y coordinates (orientation parameter) to the corresponding coordinates in canvas space.

type ScrollRegion = (Position, Position)

The ScrollRegion datatype (scrollable region of the canvas widget).

scrollRegion

:: ScrollRegion the scroll region to set. -> Canvas the canvas widget to apply this scrollregion. -> IO Canvas The concerned canvas. Sets the scrollable region for a canvas widget.

getScrollRegion

:: Canvas the canvas widget to get the applied scroll region from. -> IO ScrollRegion The requested scroll region. Gets the applied scroll region from a canvas widget.

scrollIncrement

:: Orientation the orientation (Vertical or Horizontal). -> Distance the distance to set. -> Canvas the canvas widget to apply this scrolling distance. -> IO Canvas The concerned canvas. Sets the distance for one scrolling unit.

Produced by Haddock version 0.3