1 /* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*- */
2 /*
3 * st-drawing-area.c: A dynamically-sized Cairo drawing area
4 *
5 * Copyright 2009, 2010 Red Hat, Inc.
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU Lesser General Public License as
9 * published by the Free Software Foundation, either version 2.1 of
10 * the License, or (at your option) any later version.
11 *
12 * This program is distributed in the hope it will be useful, but WITHOUT ANY
13 * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
14 * FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for
15 * more details.
16 *
17 * You should have received a copy of the GNU Lesser General Public License
18 * along with this program. If not, see <http://www.gnu.org/licenses/>.
19 */
20
21 /**
22 * SECTION:st-drawing-area
23 * @short_description: A dynamically-sized Cairo drawing area
24 *
25 * #StDrawingArea allows drawing via Cairo; the primary difference is that
26 * it is dynamically sized. To use, connect to the #StDrawingArea::repaint
27 * signal, and inside the signal handler, call
28 * st_drawing_area_get_context() to get the Cairo context to draw to. The
29 * #StDrawingArea::repaint signal will be emitted by default when the area is
30 * resized or the CSS style changes; you can use the
31 * st_drawing_area_queue_repaint() as well.
32 */
33
34 #include "st-drawing-area.h"
35
36 #include <cairo.h>
37 #include <math.h>
38
39 typedef struct _StDrawingAreaPrivate StDrawingAreaPrivate;
40 struct _StDrawingAreaPrivate {
41 cairo_t *context;
42 guint in_repaint : 1;
43 };
44
45 G_DEFINE_TYPE_WITH_PRIVATE (StDrawingArea, st_drawing_area, ST_TYPE_WIDGET);
46
47 /* Signals */
48 enum
49 {
50 REPAINT,
51 LAST_SIGNAL
52 };
53
54 static guint st_drawing_area_signals [LAST_SIGNAL] = { 0 };
55
56 static gboolean
draw_content(ClutterCanvas * canvas,cairo_t * cr,int width,int height,gpointer user_data)57 draw_content (ClutterCanvas *canvas,
58 cairo_t *cr,
59 int width,
60 int height,
61 gpointer user_data)
62 {
63 StDrawingArea *area = ST_DRAWING_AREA (user_data);
64 StDrawingAreaPrivate *priv = st_drawing_area_get_instance_private (area);
65
66 priv->context = cr;
67 priv->in_repaint = TRUE;
68
69 clutter_cairo_clear (cr);
70 g_signal_emit (area, st_drawing_area_signals[REPAINT], 0);
71
72 priv->context = NULL;
73 priv->in_repaint = FALSE;
74
75 return TRUE;
76 }
77
78 static void
st_drawing_area_allocate(ClutterActor * self,const ClutterActorBox * box)79 st_drawing_area_allocate (ClutterActor *self,
80 const ClutterActorBox *box)
81 {
82 StThemeNode *theme_node = st_widget_get_theme_node (ST_WIDGET (self));
83 ClutterContent *content = clutter_actor_get_content (self);
84 ClutterActorBox content_box;
85 int width, height;
86 float resource_scale;
87
88 resource_scale = clutter_actor_get_resource_scale (self);
89
90 clutter_actor_set_allocation (self, box);
91 st_theme_node_get_content_box (theme_node, box, &content_box);
92
93 width = (int)(0.5 + content_box.x2 - content_box.x1);
94 height = (int)(0.5 + content_box.y2 - content_box.y1);
95
96 clutter_canvas_set_scale_factor (CLUTTER_CANVAS (content), resource_scale);
97 clutter_canvas_set_size (CLUTTER_CANVAS (content), width, height);
98 }
99
100 static void
st_drawing_area_style_changed(StWidget * self)101 st_drawing_area_style_changed (StWidget *self)
102 {
103 (ST_WIDGET_CLASS (st_drawing_area_parent_class))->style_changed (self);
104
105 st_drawing_area_queue_repaint (ST_DRAWING_AREA (self));
106 }
107
108 static void
st_drawing_area_resource_scale_changed(ClutterActor * self)109 st_drawing_area_resource_scale_changed (ClutterActor *self)
110 {
111 float resource_scale;
112 ClutterContent *content = clutter_actor_get_content (self);
113
114 resource_scale = clutter_actor_get_resource_scale (self);
115 clutter_canvas_set_scale_factor (CLUTTER_CANVAS (content), resource_scale);
116
117 if (CLUTTER_ACTOR_CLASS (st_drawing_area_parent_class)->resource_scale_changed)
118 CLUTTER_ACTOR_CLASS (st_drawing_area_parent_class)->resource_scale_changed (self);
119 }
120
121 static void
st_drawing_area_class_init(StDrawingAreaClass * klass)122 st_drawing_area_class_init (StDrawingAreaClass *klass)
123 {
124 ClutterActorClass *actor_class = CLUTTER_ACTOR_CLASS (klass);
125 StWidgetClass *widget_class = ST_WIDGET_CLASS (klass);
126
127 actor_class->allocate = st_drawing_area_allocate;
128 widget_class->style_changed = st_drawing_area_style_changed;
129 actor_class->resource_scale_changed = st_drawing_area_resource_scale_changed;
130
131 st_drawing_area_signals[REPAINT] =
132 g_signal_new ("repaint",
133 G_TYPE_FROM_CLASS (klass),
134 G_SIGNAL_RUN_LAST,
135 G_STRUCT_OFFSET (StDrawingAreaClass, repaint),
136 NULL, NULL, NULL,
137 G_TYPE_NONE, 0);
138 }
139
140 static void
st_drawing_area_init(StDrawingArea * area)141 st_drawing_area_init (StDrawingArea *area)
142 {
143 ClutterContent *content = clutter_canvas_new ();
144 g_signal_connect (content, "draw", G_CALLBACK (draw_content), area);
145 clutter_actor_set_content (CLUTTER_ACTOR (area), content);
146 g_object_unref (content);
147 }
148
149 /**
150 * st_drawing_area_queue_repaint:
151 * @area: the #StDrawingArea
152 *
153 * Will cause the actor to emit a #StDrawingArea::repaint signal before it is
154 * next drawn to the scene. Useful if some parameters for the area being
155 * drawn other than the size or style have changed. Note that
156 * clutter_actor_queue_redraw() will simply result in the same
157 * contents being drawn to the scene again.
158 */
159 void
st_drawing_area_queue_repaint(StDrawingArea * area)160 st_drawing_area_queue_repaint (StDrawingArea *area)
161 {
162 g_return_if_fail (ST_IS_DRAWING_AREA (area));
163
164 clutter_content_invalidate (clutter_actor_get_content (CLUTTER_ACTOR (area)));
165 }
166
167 /**
168 * st_drawing_area_get_context:
169 * @area: the #StDrawingArea
170 *
171 * Gets the Cairo context to paint to. This function must only be called
172 * from a signal handler or virtual function for the #StDrawingArea::repaint
173 * signal.
174 *
175 * JavaScript code must call the special dispose function before returning from
176 * the signal handler or virtual function to avoid leaking memory:
177 *
178 * |[<!-- language="JavaScript" -->
179 * function onRepaint(area) {
180 * let cr = area.get_context();
181 *
182 * // Draw to the context
183 *
184 * cr.$dispose();
185 * }
186 *
187 * let area = new St.DrawingArea();
188 * area.connect('repaint', onRepaint);
189 * ]|
190 *
191 * Returns: (transfer none): the Cairo context for the paint operation
192 */
193 cairo_t *
st_drawing_area_get_context(StDrawingArea * area)194 st_drawing_area_get_context (StDrawingArea *area)
195 {
196 StDrawingAreaPrivate *priv;
197
198 g_return_val_if_fail (ST_IS_DRAWING_AREA (area), NULL);
199
200 priv = st_drawing_area_get_instance_private (area);
201 g_return_val_if_fail (priv->in_repaint, NULL);
202
203 return priv->context;
204 }
205
206 /**
207 * st_drawing_area_get_surface_size:
208 * @area: the #StDrawingArea
209 * @width: (out) (optional): location to store the width of the painted area
210 * @height: (out) (optional): location to store the height of the painted area
211 *
212 * Gets the size of the cairo surface being painted to, which is equal
213 * to the size of the content area of the widget. This function must
214 * only be called from a signal handler for the #StDrawingArea::repaint signal.
215 */
216 void
st_drawing_area_get_surface_size(StDrawingArea * area,guint * width,guint * height)217 st_drawing_area_get_surface_size (StDrawingArea *area,
218 guint *width,
219 guint *height)
220 {
221 StDrawingAreaPrivate *priv;
222 ClutterContent *content;
223 float w, h, resource_scale;
224
225 g_return_if_fail (ST_IS_DRAWING_AREA (area));
226
227 priv = st_drawing_area_get_instance_private (area);
228 g_return_if_fail (priv->in_repaint);
229
230 content = clutter_actor_get_content (CLUTTER_ACTOR (area));
231 clutter_content_get_preferred_size (content, &w, &h);
232
233 resource_scale = clutter_actor_get_resource_scale (CLUTTER_ACTOR (area));
234
235 w /= resource_scale;
236 h /= resource_scale;
237
238 if (width)
239 *width = ceilf (w);
240 if (height)
241 *height = ceilf (h);
242 }
243