GtkDrawingArea {RGtk2} | R Documentation |
A widget for custom user interface elements
gtkDrawingAreaNew(show = TRUE)
gtkDrawingAreaSize(object, width, height)
gtkDrawingArea(show = TRUE)
GObject +----GInitiallyUnowned +----GtkObject +----GtkWidget +----GtkDrawingArea +----GtkCurve
GtkDrawingArea implements
GtkBuildable
and AtkImplementorIface.
The GtkDrawingArea
widget is used for creating custom user interface
elements. It's essentially a blank widget; you can draw on
widget->window
. After creating a drawing area,
the application may want to connect to:
gtkWidgetAddEvents
to enable events
you wish to receive.)
The following code portion demonstrates using a drawing area to display a circle in the normal widget foreground color. Note that GDK automatically clears the exposed area to the background color before sending the expose event, and that drawing is implicitly clipped to the exposed area.
expose_event_callback <- function(widget, event, data) { gdkDrawArc(widget[["window"]], widget[["style"]][["fgGc"]][[widget[["state"]]+1]], TRUE, 0, 0, widget[["allocation"]]$width, widget[["allocation"]]$height, 0, 64 * 360) return(TRUE) } [...] drawing_area = gtkDrawingArea(); drawing_area$setSizeRequest(100, 100) gSignalConnect(drawing_area, "expose_event", expose_event_callback)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;
gtkWidgetQueueDrawArea
and
gdkWindowInvalidateRect
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.
See also gdkDrawPixbuf
for drawing a GdkPixbuf
.
To receive mouse events on a drawing area, you will need to enable
them with gtkWidgetAddEvents
. To receive keyboard events, you
will need to set the GTK_CAN_FOCUS
flag on the drawing area, and
should probably draw some user-visible indication that the drawing
area is focused. Use the gtkHasFocus()
function in your expose event
handler to decide whether to draw the focus indicator. See
gtkPaintFocus
for one way to draw focus.
GtkDrawingArea
GtkDrawingArea
struct contains private data only, and
should be accessed using the functions below.
gtkDrawingArea
is the equivalent of gtkDrawingAreaNew
.
Derived by RGtkGen from GTK+ documentation
http://developer.gnome.org/doc/API/2.0/gtk/GtkDrawingArea.html
GtkImage
GdkPixmap
GtkImage
GdkPixmap
GtkImage