GTK+ Reference Manual | |||
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#include <gtk/gtk.h> struct GtkDrawingArea; GtkWidget* gtk_drawing_area_new (void); void gtk_drawing_area_size (GtkDrawingArea *darea, gint width, gint height); |
The GtkDrawingArea widget is used for creating custom user interface elements. 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
The "size_allocate" signal to take any necessary actions when the widget changes size.
The "expose_event" signal to handle redrawing the contents of the widget.
The following code portion demonstrates using a drawing area to implement a widget that draws a circle. As this example demonstrates, an expose handler should draw only the pixels within the requested area and should draw or clear all these pixels.
gboolean expose_event (GdkWidget *widget, GdkEventExpose *event, gpointer data) { gdk_window_clear_area (widget->window, event->area.x, event->area.y, event->area.width, event->area.height); gdk_gc_set_clip_rectangle (widget->style->fg_gc[widget->state], &event->area); gdk_draw_arc (widget->window, widget->style->fg_gc[widget->state], TRUE, 0, 0, widget->allocation.width, widget->allocation.height, 0, 64 * 360); gdk_gc_set_clip_rectangle (widget->style->fg_gc[widget->state], NULL); return TRUE; } [...] GtkWidget *drawing_area = gdk_drawing_area_new(); gdk_drawing_area_size (GTK_DRAWING_AREA (drawing_area), 100, 100); gtk_signal_connect (GTK_OBJECT (drawing_area), |
struct GtkDrawingArea; |
The GtkDrawingArea struct contains private data only, and should be accessed using the functions below.
void gtk_drawing_area_size (GtkDrawingArea *darea, gint width, gint height); |
Set the size that the drawing area will request in response to a "size_request" signal. The drawing area may actually be allocated a size larger than this depending on how it is packed within the enclosing containers.
darea : | a GtkDrawingArea. |
width : | the width to request. |
height : | the height to request. |