1 /* GTK - The GIMP Toolkit
2 * Copyright (C) 1995-1997 Peter Mattis, Spencer Kimball and Josh MacDonald
3 *
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.
8 *
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.
13 *
14 * You should have received a copy of the GNU Lesser General Public
15 * License along with this library. If not, see <http://www.gnu.org/licenses/>.
16 */
17
18 /*
19 * Modified by the GTK+ Team and others 1997-2000. See the AUTHORS
20 * file for a list of people on the GTK+ Team. See the ChangeLog
21 * files for a list of changes. These files are distributed with
22 * GTK+ at ftp://ftp.gtk.org/pub/gtk/.
23 */
24
25 #include "config.h"
26 #include "gtkdrawingarea.h"
27 #include "gtkintl.h"
28 #include "gtkstylecontext.h"
29
30
31 /**
32 * SECTION:gtkdrawingarea
33 * @Short_description: A widget for custom user interface elements
34 * @Title: GtkDrawingArea
35 * @See_also: #GtkImage
36 *
37 * The #GtkDrawingArea widget is used for creating custom user interface
38 * elements. It’s essentially a blank widget; you can draw on it. After
39 * creating a drawing area, the application may want to connect to:
40 *
41 * - Mouse and button press signals to respond to input from
42 * the user. (Use gtk_widget_add_events() to enable events
43 * you wish to receive.)
44 *
45 * - The #GtkWidget::realize signal to take any necessary actions
46 * when the widget is instantiated on a particular display.
47 * (Create GDK resources in response to this signal.)
48 *
49 * - The #GtkWidget::size-allocate signal to take any necessary
50 * actions when the widget changes size.
51 *
52 * - The #GtkWidget::draw signal to handle redrawing the
53 * contents of the widget.
54 *
55 * The following code portion demonstrates using a drawing
56 * area to display a circle in the normal widget foreground
57 * color.
58 *
59 * Note that GDK automatically clears the exposed area before sending
60 * the expose event, and that drawing is implicitly clipped to the exposed
61 * area. If you want to have a theme-provided background, you need
62 * to call gtk_render_background() in your ::draw method.
63 *
64 * ## Simple GtkDrawingArea usage
65 *
66 * |[<!-- language="C" -->
67 * gboolean
68 * draw_callback (GtkWidget *widget, cairo_t *cr, gpointer data)
69 * {
70 * guint width, height;
71 * GdkRGBA color;
72 * GtkStyleContext *context;
73 *
74 * context = gtk_widget_get_style_context (widget);
75 *
76 * width = gtk_widget_get_allocated_width (widget);
77 * height = gtk_widget_get_allocated_height (widget);
78 *
79 * gtk_render_background (context, cr, 0, 0, width, height);
80 *
81 * cairo_arc (cr,
82 * width / 2.0, height / 2.0,
83 * MIN (width, height) / 2.0,
84 * 0, 2 * G_PI);
85 *
86 * gtk_style_context_get_color (context,
87 * gtk_style_context_get_state (context),
88 * &color);
89 * gdk_cairo_set_source_rgba (cr, &color);
90 *
91 * cairo_fill (cr);
92 *
93 * return FALSE;
94 * }
95 * [...]
96 * GtkWidget *drawing_area = gtk_drawing_area_new ();
97 * gtk_widget_set_size_request (drawing_area, 100, 100);
98 * g_signal_connect (G_OBJECT (drawing_area), "draw",
99 * G_CALLBACK (draw_callback), NULL);
100 * ]|
101 *
102 * Draw signals are normally delivered when a drawing area first comes
103 * onscreen, or when it’s covered by another window and then uncovered.
104 * You can also force an expose event by adding to the “damage region”
105 * of the drawing area’s window; gtk_widget_queue_draw_area() and
106 * gdk_window_invalidate_rect() are equally good ways to do this.
107 * You’ll then get a draw signal for the invalid region.
108 *
109 * The available routines for drawing are documented on the
110 * [GDK Drawing Primitives][gdk3-Cairo-Interaction] page
111 * and the cairo documentation.
112 *
113 * To receive mouse events on a drawing area, you will need to enable
114 * them with gtk_widget_add_events(). To receive keyboard events, you
115 * will need to set the “can-focus” property on the drawing area, and you
116 * should probably draw some user-visible indication that the drawing
117 * area is focused. Use gtk_widget_has_focus() in your expose event
118 * handler to decide whether to draw the focus indicator. See
119 * gtk_render_focus() for one way to draw focus.
120 */
121
122 static void gtk_drawing_area_realize (GtkWidget *widget);
123 static void gtk_drawing_area_style_updated (GtkWidget *widget);
124 static void gtk_drawing_area_size_allocate (GtkWidget *widget,
125 GtkAllocation *allocation);
126 static void gtk_drawing_area_send_configure (GtkDrawingArea *darea);
127
G_DEFINE_TYPE(GtkDrawingArea,gtk_drawing_area,GTK_TYPE_WIDGET)128 G_DEFINE_TYPE (GtkDrawingArea, gtk_drawing_area, GTK_TYPE_WIDGET)
129
130 static void
131 gtk_drawing_area_class_init (GtkDrawingAreaClass *class)
132 {
133 GtkWidgetClass *widget_class = GTK_WIDGET_CLASS (class);
134
135 widget_class->realize = gtk_drawing_area_realize;
136 widget_class->size_allocate = gtk_drawing_area_size_allocate;
137 widget_class->style_updated = gtk_drawing_area_style_updated;
138
139 gtk_widget_class_set_accessible_role (widget_class, ATK_ROLE_DRAWING_AREA);
140 }
141
142 static void
gtk_drawing_area_init(GtkDrawingArea * darea)143 gtk_drawing_area_init (GtkDrawingArea *darea)
144 {
145 }
146
147 /**
148 * gtk_drawing_area_new:
149 *
150 * Creates a new drawing area.
151 *
152 * Returns: a new #GtkDrawingArea
153 */
154 GtkWidget*
gtk_drawing_area_new(void)155 gtk_drawing_area_new (void)
156 {
157 return g_object_new (GTK_TYPE_DRAWING_AREA, NULL);
158 }
159
160 static void
set_background(GtkWidget * widget)161 set_background (GtkWidget *widget)
162 {
163 if (gtk_widget_get_realized (widget) &&
164 gtk_widget_get_has_window (widget))
165 {
166 /* We still need to call gtk_style_context_set_background() here for
167 * GtkDrawingArea, since clients expect backgrounds set on it (e.g. through
168 * gtk_widget_override_background_color) to be available even when they
169 * don't chain up from draw().
170 * This should be revisited next time we have a major API break.
171 */
172 G_GNUC_BEGIN_IGNORE_DEPRECATIONS;
173 gtk_style_context_set_background (gtk_widget_get_style_context (widget),
174 gtk_widget_get_window (widget));
175 G_GNUC_END_IGNORE_DEPRECATIONS;
176 }
177 }
178
179 static void
gtk_drawing_area_style_updated(GtkWidget * widget)180 gtk_drawing_area_style_updated (GtkWidget *widget)
181 {
182 GTK_WIDGET_CLASS (gtk_drawing_area_parent_class)->style_updated (widget);
183
184 set_background (widget);
185 }
186
187 static void
gtk_drawing_area_realize(GtkWidget * widget)188 gtk_drawing_area_realize (GtkWidget *widget)
189 {
190 GtkAllocation allocation;
191 GdkWindow *window;
192 GdkWindowAttr attributes;
193 gint attributes_mask;
194
195 if (!gtk_widget_get_has_window (widget))
196 {
197 GTK_WIDGET_CLASS (gtk_drawing_area_parent_class)->realize (widget);
198 }
199 else
200 {
201 gtk_widget_set_realized (widget, TRUE);
202
203 gtk_widget_get_allocation (widget, &allocation);
204
205 attributes.window_type = GDK_WINDOW_CHILD;
206 attributes.x = allocation.x;
207 attributes.y = allocation.y;
208 attributes.width = allocation.width;
209 attributes.height = allocation.height;
210 attributes.wclass = GDK_INPUT_OUTPUT;
211 attributes.visual = gtk_widget_get_visual (widget);
212 attributes.event_mask = gtk_widget_get_events (widget) | GDK_EXPOSURE_MASK;
213
214 attributes_mask = GDK_WA_X | GDK_WA_Y | GDK_WA_VISUAL;
215
216 window = gdk_window_new (gtk_widget_get_parent_window (widget),
217 &attributes, attributes_mask);
218 gtk_widget_register_window (widget, window);
219 gtk_widget_set_window (widget, window);
220
221 set_background (widget);
222 }
223
224 gtk_drawing_area_send_configure (GTK_DRAWING_AREA (widget));
225 }
226
227 static void
gtk_drawing_area_size_allocate(GtkWidget * widget,GtkAllocation * allocation)228 gtk_drawing_area_size_allocate (GtkWidget *widget,
229 GtkAllocation *allocation)
230 {
231 g_return_if_fail (GTK_IS_DRAWING_AREA (widget));
232 g_return_if_fail (allocation != NULL);
233
234 gtk_widget_set_allocation (widget, allocation);
235
236 if (gtk_widget_get_realized (widget))
237 {
238 if (gtk_widget_get_has_window (widget))
239 gdk_window_move_resize (gtk_widget_get_window (widget),
240 allocation->x, allocation->y,
241 allocation->width, allocation->height);
242
243 gtk_drawing_area_send_configure (GTK_DRAWING_AREA (widget));
244 }
245 }
246
247 static void
gtk_drawing_area_send_configure(GtkDrawingArea * darea)248 gtk_drawing_area_send_configure (GtkDrawingArea *darea)
249 {
250 GtkAllocation allocation;
251 GtkWidget *widget;
252 GdkEvent *event = gdk_event_new (GDK_CONFIGURE);
253
254 widget = GTK_WIDGET (darea);
255 gtk_widget_get_allocation (widget, &allocation);
256
257 event->configure.window = g_object_ref (gtk_widget_get_window (widget));
258 event->configure.send_event = TRUE;
259 event->configure.x = allocation.x;
260 event->configure.y = allocation.y;
261 event->configure.width = allocation.width;
262 event->configure.height = allocation.height;
263
264 gtk_widget_event (widget, event);
265 gdk_event_free (event);
266 }
267