1 /* GTK - The GIMP Toolkit
2 * Copyright (C) 1995-1997 Peter Mattis, Spencer Kimball and Josh MacDonald
4 * This library is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU Lesser General Public
6 * License as published by the Free Software Foundation; either
7 * version 2 of the License, or (at your option) any later version.
9 * This library is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 * Lesser General Public License for more details.
14 * You should have received a copy of the GNU Lesser General Public
15 * License along with this library; if not, write to the
16 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
17 * Boston, MA 02111-1307, USA.
21 * Modified by the GTK+ Team and others 1997-2000. See the AUTHORS
22 * file for a list of people on the GTK+ Team. See the ChangeLog
23 * files for a list of changes. These files are distributed with
24 * GTK+ at ftp://ftp.gtk.org/pub/gtk/.
28 #include "gtkdrawingarea.h"
33 * SECTION:gtkdrawingarea
34 * @Short_description: A widget for custom user interface elements
35 * @Title: GtkDrawingArea
36 * @See_also: #GtkImage
38 * The #GtkDrawingArea widget is used for creating custom user interface
39 * elements. It's essentially a blank widget; you can draw on it. After
40 * creating a drawing area, the application may want to connect to:
45 * Mouse and button press signals to respond to input from
46 * the user. (Use gtk_widget_add_events() to enable events
47 * you wish to receive.)
52 * The #GtkWidget::realize signal to take any necessary actions
53 * when the widget is instantiated on a particular display.
54 * (Create GDK resources in response to this signal.)
59 * The #GtkWidget::configure-event signal to take any necessary
60 * actions when the widget changes size.
65 * The #GtkWidget::draw signal to handle redrawing the
66 * contents of the widget.
71 * The following code portion demonstrates using a drawing
72 * area to display a circle in the normal widget foreground
75 * Note that GDK automatically clears the exposed area to the
76 * background color before sending the expose event, and that
77 * drawing is implicitly clipped to the exposed area.
80 * <title>Simple GtkDrawingArea usage</title>
83 * draw_callback (GtkWidget *widget, cairo_t *cr, gpointer data)
85 * guint width, height;
88 * width = gtk_widget_get_allocated_width (widget);
89 * height = gtk_widget_get_allocated_height (widget);
91 * width / 2.0, height / 2.0,
92 * MIN (width, height) / 2.0,
95 * gtk_style_context_get_color (gtk_widget_get_style_context (widget),
98 * gdk_cairo_set_source_rgba (cr, &color);
105 * GtkWidget *drawing_area = gtk_drawing_area_new (<!-- -->);
106 * gtk_widget_set_size_request (drawing_area, 100, 100);
107 * g_signal_connect (G_OBJECT (drawing_area), "draw",
108 * G_CALLBACK (draw_callback), NULL);
112 * Draw signals are normally delivered when a drawing area first comes
113 * onscreen, or when it's covered by another window and then uncovered.
114 * You can also force an expose event by adding to the "damage region"
115 * of the drawing area's window; gtk_widget_queue_draw_area() and
116 * gdk_window_invalidate_rect() are equally good ways to do this.
117 * You'll then get a draw signal for the invalid region.
119 * The available routines for drawing are documented on the <link
120 * linkend="gdk3-Cairo-Interaction">GDK Drawing Primitives</link> page
121 * and the cairo documentation.
123 * To receive mouse events on a drawing area, you will need to enable
124 * them with gtk_widget_add_events(). To receive keyboard events, you
125 * will need to set the #GTK_CAN_FOCUS flag on the drawing area, and
126 * should probably draw some user-visible indication that the drawing
127 * area is focused. Use the GTK_HAS_FOCUS() macro in your expose event
128 * handler to decide whether to draw the focus indicator. See
129 * gtk_paint_focus() for one way to draw focus.
132 static void gtk_drawing_area_realize (GtkWidget *widget);
133 static void gtk_drawing_area_size_allocate (GtkWidget *widget,
134 GtkAllocation *allocation);
135 static void gtk_drawing_area_send_configure (GtkDrawingArea *darea);
137 G_DEFINE_TYPE (GtkDrawingArea, gtk_drawing_area, GTK_TYPE_WIDGET)
140 gtk_drawing_area_class_init (GtkDrawingAreaClass *class)
142 GtkWidgetClass *widget_class = GTK_WIDGET_CLASS (class);
144 widget_class->realize = gtk_drawing_area_realize;
145 widget_class->size_allocate = gtk_drawing_area_size_allocate;
149 gtk_drawing_area_init (GtkDrawingArea *darea)
154 * gtk_drawing_area_new:
156 * Creates a new drawing area.
158 * Returns: a new #GtkDrawingArea
161 gtk_drawing_area_new (void)
163 return g_object_new (GTK_TYPE_DRAWING_AREA, NULL);
167 gtk_drawing_area_realize (GtkWidget *widget)
169 GtkDrawingArea *darea = GTK_DRAWING_AREA (widget);
170 GtkAllocation allocation;
172 GdkWindowAttr attributes;
173 gint attributes_mask;
175 if (!gtk_widget_get_has_window (widget))
177 GTK_WIDGET_CLASS (gtk_drawing_area_parent_class)->realize (widget);
181 gtk_widget_set_realized (widget, TRUE);
183 gtk_widget_get_allocation (widget, &allocation);
185 attributes.window_type = GDK_WINDOW_CHILD;
186 attributes.x = allocation.x;
187 attributes.y = allocation.y;
188 attributes.width = allocation.width;
189 attributes.height = allocation.height;
190 attributes.wclass = GDK_INPUT_OUTPUT;
191 attributes.visual = gtk_widget_get_visual (widget);
192 attributes.event_mask = gtk_widget_get_events (widget) | GDK_EXPOSURE_MASK;
194 attributes_mask = GDK_WA_X | GDK_WA_Y | GDK_WA_VISUAL;
196 window = gdk_window_new (gtk_widget_get_parent_window (widget),
197 &attributes, attributes_mask);
198 gdk_window_set_user_data (window, darea);
199 gtk_widget_set_window (widget, window);
201 gtk_style_context_set_background (gtk_widget_get_style_context (widget),
205 gtk_drawing_area_send_configure (GTK_DRAWING_AREA (widget));
209 gtk_drawing_area_size_allocate (GtkWidget *widget,
210 GtkAllocation *allocation)
212 g_return_if_fail (GTK_IS_DRAWING_AREA (widget));
213 g_return_if_fail (allocation != NULL);
215 gtk_widget_set_allocation (widget, allocation);
217 if (gtk_widget_get_realized (widget))
219 if (gtk_widget_get_has_window (widget))
220 gdk_window_move_resize (gtk_widget_get_window (widget),
221 allocation->x, allocation->y,
222 allocation->width, allocation->height);
224 gtk_drawing_area_send_configure (GTK_DRAWING_AREA (widget));
229 gtk_drawing_area_send_configure (GtkDrawingArea *darea)
231 GtkAllocation allocation;
233 GdkEvent *event = gdk_event_new (GDK_CONFIGURE);
235 widget = GTK_WIDGET (darea);
236 gtk_widget_get_allocation (widget, &allocation);
238 event->configure.window = g_object_ref (gtk_widget_get_window (widget));
239 event->configure.send_event = TRUE;
240 event->configure.x = allocation.x;
241 event->configure.y = allocation.y;
242 event->configure.width = allocation.width;
243 event->configure.height = allocation.height;
245 gtk_widget_event (widget, event);
246 gdk_event_free (event);