cookbook: Example using allocation-changed to sync actor size

An alternative method (not using constraints) to bind
one actor's size and position to another. Used as
an example in the recipe about resizing one actor in
sync with a source actor.

diff --git a/doc/cookbook/examples/Makefile.am b/doc/cookbook/examples/Makefile.am
index f2434f3..b4ca61c 100644 (file)
--- a/doc/cookbook/examples/Makefile.am
+++ b/doc/cookbook/examples/Makefile.am
@@ -10,6 +10,7 @@ noinst_PROGRAMS = \
        textures-reflection     \
        textures-split-go       \
        textures-sub-texture    \
+       layouts-bind-constraint-allocation      \
        layouts-bind-constraint-overlay \
        layouts-bind-constraint-stage   \
        layouts-stacking \
@@ -54,6 +55,7 @@ text_shadow_SOURCES                        = text-shadow.c
 textures_reflection_SOURCES                = textures-reflection.c
 textures_split_go_SOURCES                  = textures-split-go.c
 textures_sub_texture_SOURCES               = textures-sub-texture.c
+layouts_bind_constraint_allocation_SOURCES = layouts-bind-constraint-allocation.c
 layouts_bind_constraint_overlay_SOURCES    = layouts-bind-constraint-overlay.c
 layouts_bind_constraint_stage_SOURCES      = layouts-bind-constraint-stage.c
 layouts_stacking_SOURCES                   = layouts-stacking.c

diff --git a/doc/cookbook/examples/layouts-bind-constraint-allocation.c b/doc/cookbook/examples/layouts-bind-constraint-allocation.c
new file mode 100644 (file)
index 0000000..4369a18
--- /dev/null
+++ b/doc/cookbook/examples/layouts-bind-constraint-allocation.c
@@ -0,0 +1,70 @@
+#include <stdlib.h>
+#include <clutter/clutter.h>
+
+#define OVERLAY_FACTOR 1.1
+
+static const ClutterColor stage_color = { 0x33, 0x33, 0x55, 0xff };
+static const ClutterColor red = { 0xff, 0x00, 0x00, 0xff };
+static const ClutterColor blue = { 0x00, 0x00, 0xff, 0x66 };
+
+void
+allocation_changed_cb (ClutterActor           *actor,
+                       const ClutterActorBox  *allocation,
+                       ClutterAllocationFlags  flags,
+                       gpointer                user_data)
+{
+  ClutterActor *overlay = CLUTTER_ACTOR (user_data);
+
+  gfloat width, height, x, y;
+  clutter_actor_box_get_size (allocation, &width, &height);
+  clutter_actor_box_get_origin (allocation, &x, &y);
+
+  clutter_actor_set_size (overlay,
+                          width * OVERLAY_FACTOR,
+                          height * OVERLAY_FACTOR);
+
+  clutter_actor_set_position (overlay,
+                              x - ((OVERLAY_FACTOR - 1) * width * 0.5),
+                              y - ((OVERLAY_FACTOR - 1) * width * 0.5));
+}
+
+int
+main (int argc, char *argv[])
+{
+  ClutterActor *stage;
+  ClutterActor *actor;
+  ClutterActor *overlay;
+
+  clutter_init (&argc, &argv);
+
+  stage = clutter_stage_get_default ();
+  clutter_actor_set_size (stage, 400, 400);
+  clutter_stage_set_color (CLUTTER_STAGE (stage), &stage_color);
+  g_signal_connect (stage, "destroy", G_CALLBACK (clutter_main_quit), NULL);
+
+  actor = clutter_rectangle_new_with_color (&red);
+  clutter_actor_set_size (actor, 100, 100);
+  clutter_actor_set_position (actor, 150, 150);
+
+  overlay = clutter_rectangle_new_with_color (&blue);
+
+  g_signal_connect (actor,
+                    "allocation-changed",
+                    G_CALLBACK (allocation_changed_cb),
+                    overlay);
+
+  clutter_container_add (CLUTTER_CONTAINER (stage), actor, overlay, NULL);
+
+  clutter_actor_animate (actor, CLUTTER_LINEAR, 2000,
+                         "width", 300.0,
+                         "height", 300.0,
+                         "x", 50.0,
+                         "y", 50.0,
+                         NULL);
+
+  clutter_actor_show (stage);
+
+  clutter_main ();
+
+  return EXIT_SUCCESS;
+}