|Portability||portable (depends on GHC)|
A widget for custom user interface elements
DrawingArea widget is used for creating custom user interface
elements. It's essentially a blank widget; you can draw on
Drawable returned by
After creating a drawing area, the application may want to connect to:
- Mouse and button press signals to respond to input from the user.
realizesignal to take any necessary actions when the widget is instantiated on a particular display. (Create GDK resources in response to this signal.)
configureEventsignal to take any necessary actions when the widget changes size.
exposeEventsignal to handle redrawing the contents of the widget.
Expose events are normally delivered when a drawing area first comes
onscreen, or when it's covered by another window and then uncovered
(exposed). You can also force an expose event by adding to the "damage
region" of the drawing area's window;
windowInvalidateRect are equally good ways to do this. You'll then get an
expose event for the invalid region.
The available routines for drawing are documented on the GDK Drawing Primitives page.
To receive mouse events on a drawing area, you will need to enable them
widgetAddEvents. To receive keyboard events, you will need to set the
widgetCanFocus attribute on the drawing area, and should probably draw some
user-visible indication that the drawing area is focused.