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+/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*- */
+/*
+ * st-drawing-area.c: A dynamically-sized Cairo drawing area
+ *
+ * Copyright 2009, 2010 Red Hat, Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as
+ * published by the Free Software Foundation, either version 2.1 of
+ * the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT ANY
+ * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+ * FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/**
+ * SECTION:st-drawing-area
+ * @short_description: A dynamically-sized Cairo drawing area
+ *
+ * #StDrawingArea allows drawing via Cairo; the primary difference is that
+ * it is dynamically sized. To use, connect to the #StDrawingArea::repaint
+ * signal, and inside the signal handler, call
+ * st_drawing_area_get_context() to get the Cairo context to draw to. The
+ * #StDrawingArea::repaint signal will be emitted by default when the area is
+ * resized or the CSS style changes; you can use the
+ * st_drawing_area_queue_repaint() as well.
+ */
+
+#include "st-drawing-area.h"
+
+#include <cairo.h>
+#include <math.h>
+
+typedef struct _StDrawingAreaPrivate StDrawingAreaPrivate;
+struct _StDrawingAreaPrivate {
+ cairo_t *context;
+ guint in_repaint : 1;
+};
+
+G_DEFINE_TYPE_WITH_PRIVATE (StDrawingArea, st_drawing_area, ST_TYPE_WIDGET);
+
+/* Signals */
+enum
+{
+ REPAINT,
+ LAST_SIGNAL
+};
+
+static guint st_drawing_area_signals [LAST_SIGNAL] = { 0 };
+
+static gboolean
+draw_content (ClutterCanvas *canvas,
+ cairo_t *cr,
+ int width,
+ int height,
+ gpointer user_data)
+{
+ StDrawingArea *area = ST_DRAWING_AREA (user_data);
+ StDrawingAreaPrivate *priv = st_drawing_area_get_instance_private (area);
+
+ priv->context = cr;
+ priv->in_repaint = TRUE;
+
+ clutter_cairo_clear (cr);
+ g_signal_emit (area, st_drawing_area_signals[REPAINT], 0);
+
+ priv->context = NULL;
+ priv->in_repaint = FALSE;
+
+ return TRUE;
+}
+
+static void
+st_drawing_area_allocate (ClutterActor *self,
+ const ClutterActorBox *box)
+{
+ StThemeNode *theme_node = st_widget_get_theme_node (ST_WIDGET (self));
+ ClutterContent *content = clutter_actor_get_content (self);
+ ClutterActorBox content_box;
+ int width, height;
+ float resource_scale;
+
+ resource_scale = clutter_actor_get_resource_scale (self);
+
+ clutter_actor_set_allocation (self, box);
+ st_theme_node_get_content_box (theme_node, box, &content_box);
+
+ width = (int)(0.5 + content_box.x2 - content_box.x1);
+ height = (int)(0.5 + content_box.y2 - content_box.y1);
+
+ clutter_canvas_set_scale_factor (CLUTTER_CANVAS (content), resource_scale);
+ clutter_canvas_set_size (CLUTTER_CANVAS (content), width, height);
+}
+
+static void
+st_drawing_area_style_changed (StWidget *self)
+{
+ (ST_WIDGET_CLASS (st_drawing_area_parent_class))->style_changed (self);
+
+ st_drawing_area_queue_repaint (ST_DRAWING_AREA (self));
+}
+
+static void
+st_drawing_area_resource_scale_changed (ClutterActor *self)
+{
+ float resource_scale;
+ ClutterContent *content = clutter_actor_get_content (self);
+
+ resource_scale = clutter_actor_get_resource_scale (self);
+ clutter_canvas_set_scale_factor (CLUTTER_CANVAS (content), resource_scale);
+
+ if (CLUTTER_ACTOR_CLASS (st_drawing_area_parent_class)->resource_scale_changed)
+ CLUTTER_ACTOR_CLASS (st_drawing_area_parent_class)->resource_scale_changed (self);
+}
+
+static void
+st_drawing_area_class_init (StDrawingAreaClass *klass)
+{
+ ClutterActorClass *actor_class = CLUTTER_ACTOR_CLASS (klass);
+ StWidgetClass *widget_class = ST_WIDGET_CLASS (klass);
+
+ actor_class->allocate = st_drawing_area_allocate;
+ widget_class->style_changed = st_drawing_area_style_changed;
+ actor_class->resource_scale_changed = st_drawing_area_resource_scale_changed;
+
+ st_drawing_area_signals[REPAINT] =
+ g_signal_new ("repaint",
+ G_TYPE_FROM_CLASS (klass),
+ G_SIGNAL_RUN_LAST,
+ G_STRUCT_OFFSET (StDrawingAreaClass, repaint),
+ NULL, NULL, NULL,
+ G_TYPE_NONE, 0);
+}
+
+static void
+st_drawing_area_init (StDrawingArea *area)
+{
+ ClutterContent *content = clutter_canvas_new ();
+ g_signal_connect (content, "draw", G_CALLBACK (draw_content), area);
+ clutter_actor_set_content (CLUTTER_ACTOR (area), content);
+ g_object_unref (content);
+}
+
+/**
+ * st_drawing_area_queue_repaint:
+ * @area: the #StDrawingArea
+ *
+ * Will cause the actor to emit a #StDrawingArea::repaint signal before it is
+ * next drawn to the scene. Useful if some parameters for the area being
+ * drawn other than the size or style have changed. Note that
+ * clutter_actor_queue_redraw() will simply result in the same
+ * contents being drawn to the scene again.
+ */
+void
+st_drawing_area_queue_repaint (StDrawingArea *area)
+{
+ g_return_if_fail (ST_IS_DRAWING_AREA (area));
+
+ clutter_content_invalidate (clutter_actor_get_content (CLUTTER_ACTOR (area)));
+}
+
+/**
+ * st_drawing_area_get_context:
+ * @area: the #StDrawingArea
+ *
+ * Gets the Cairo context to paint to. This function must only be called
+ * from a signal handler or virtual function for the #StDrawingArea::repaint
+ * signal.
+ *
+ * JavaScript code must call the special dispose function before returning from
+ * the signal handler or virtual function to avoid leaking memory:
+ *
+ * |[<!-- language="JavaScript" -->
+ * function onRepaint(area) {
+ * let cr = area.get_context();
+ *
+ * // Draw to the context
+ *
+ * cr.$dispose();
+ * }
+ *
+ * let area = new St.DrawingArea();
+ * area.connect('repaint', onRepaint);
+ * ]|
+ *
+ * Returns: (transfer none): the Cairo context for the paint operation
+ */
+cairo_t *
+st_drawing_area_get_context (StDrawingArea *area)
+{
+ StDrawingAreaPrivate *priv;
+
+ g_return_val_if_fail (ST_IS_DRAWING_AREA (area), NULL);
+
+ priv = st_drawing_area_get_instance_private (area);
+ g_return_val_if_fail (priv->in_repaint, NULL);
+
+ return priv->context;
+}
+
+/**
+ * st_drawing_area_get_surface_size:
+ * @area: the #StDrawingArea
+ * @width: (out) (optional): location to store the width of the painted area
+ * @height: (out) (optional): location to store the height of the painted area
+ *
+ * Gets the size of the cairo surface being painted to, which is equal
+ * to the size of the content area of the widget. This function must
+ * only be called from a signal handler for the #StDrawingArea::repaint signal.
+ */
+void
+st_drawing_area_get_surface_size (StDrawingArea *area,
+ guint *width,
+ guint *height)
+{
+ StDrawingAreaPrivate *priv;
+ ClutterContent *content;
+ float w, h, resource_scale;
+
+ g_return_if_fail (ST_IS_DRAWING_AREA (area));
+
+ priv = st_drawing_area_get_instance_private (area);
+ g_return_if_fail (priv->in_repaint);
+
+ content = clutter_actor_get_content (CLUTTER_ACTOR (area));
+ clutter_content_get_preferred_size (content, &w, &h);
+
+ resource_scale = clutter_actor_get_resource_scale (CLUTTER_ACTOR (area));
+
+ w /= resource_scale;
+ h /= resource_scale;
+
+ if (width)
+ *width = ceilf (w);
+ if (height)
+ *height = ceilf (h);
+}