Graphics.UI.Gtk.Misc.DrawingArea

A widget for custom user interface elements

Detail

The DrawingArea widget is used for creating custom user interface elements. It's essentially a blank widget; you can draw on the Drawable returned by drawingAreaGetDrawWindow.

After creating a drawing area, the application may want to connect to:

• Mouse and button press signals to respond to input from the user.
• The realize signal to take any necessary actions when the widget is instantiated on a particular display. (Create GDK resources in response to this signal.)
• The configureEvent signal to take any necessary actions when the widget changes size.
• The exposeEvent signal 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; widgetQueueDrawArea and 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 with 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.

Class Hierarchy

| GObject
| +----Object
| +----Widget
| +----DrawingArea

Types

data DrawingArea

Instances

Eq DrawingArea

Ord DrawingArea

GObjectClass DrawingArea

DrawingAreaClass DrawingArea

WidgetClass DrawingArea

class WidgetClass o => DrawingAreaClass o

Instances

DrawingAreaClass Spinner

DrawingAreaClass DrawingArea

castToDrawingArea :: GObjectClass obj => obj -> DrawingArea

gTypeDrawingArea :: GType

toDrawingArea :: DrawingAreaClass o => o -> DrawingArea

Constructors

drawingAreaNew :: IO DrawingArea

Creates a new drawing area.

Methods