cookbook: Added scribble example for pointer motion recipe

Simple scribbler application which demonstrates tracking
mouse enter and motion events on a texture, drawing with
COGL and ClutterPath as they occur.

doc/cookbook/examples/Makefile.am

@@ -12,6 +12,7 @@ noinst_PROGRAMS = \
 	layouts-stacking-diff-sized-actors	\
 	events-mouse-scroll \
 	events-pointer-motion-crossing \
+	events-pointer-motion-scribbler \
 	$(NULL)
 
 INCLUDES = \
@@ -42,5 +43,6 @@ layouts_stacking_SOURCES                   = layouts-stacking.c
 layouts_stacking_diff_sized_actors_SOURCES = layouts-stacking-diff-sized-actors.c
 events_mouse_scroll_SOURCES                = events-mouse-scroll.c
 events_pointer_motion_crossing_SOURCES     = events-pointer-motion-crossing.c
+events_pointer_motion_scribbler_SOURCES    = events-pointer-motion-scribbler.c
 
 -include $(top_srcdir)/build/autotools/Makefile.am.gitignore

doc/cookbook/examples/events-pointer-motion-scribbler.c

@@ -0,0 +1,160 @@
+/*
+ * Simple scribble application: move mouse over the dark yellow
+ * rectangle to draw brighter yellow lines
+ */
+#include <clutter/clutter.h>
+
+static const ClutterColor stage_color = { 0x33, 0x33, 0x55, 0xff };
+static const ClutterColor actor_color = { 0xaa, 0x99, 0x00, 0xff };
+
+typedef struct {
+  ClutterPath *path;
+  CoglPath    *cogl_path;
+} Context;
+
+static void
+convert_clutter_path_node_to_cogl_path (const ClutterPathNode *node,
+                                        gpointer               data)
+{
+  g_return_if_fail (node != NULL);
+
+  ClutterKnot knot;
+
+  switch (node->type)
+    {
+    case CLUTTER_PATH_MOVE_TO:
+      knot = node->points[0];
+      cogl_path_move_to (knot.x, knot.y);
+      g_debug ("move to %d, %d", knot.x, knot.y);
+      break;
+    case CLUTTER_PATH_LINE_TO:
+      knot = node->points[0];
+      cogl_path_line_to (knot.x, knot.y);
+      g_debug ("line to %d, %d", knot.x, knot.y);
+      break;
+    default:
+      break;
+    }
+}
+
+static void
+_paint_cb (ClutterActor *actor,
+           gpointer      user_data)
+{
+  Context *context = (Context *)user_data;
+
+  cogl_set_source_color4ub (255, 255, 0, 255);
+
+  cogl_set_path (context->cogl_path);
+
+  clutter_path_foreach (context->path, convert_clutter_path_node_to_cogl_path, NULL);
+
+  cogl_path_stroke_preserve ();
+
+  clutter_path_clear (context->path);
+
+  context->cogl_path = cogl_get_path ();
+
+  g_signal_stop_emission_by_name (actor, "paint");
+}
+
+static gboolean
+_motion_cb (ClutterActor *actor,
+            ClutterEvent *event,
+            gpointer      user_data)
+{
+  ClutterMotionEvent *motion_event = (ClutterMotionEvent *)event;
+  Context *context = (Context *)user_data;
+
+  gfloat x, y;
+  clutter_actor_transform_stage_point (actor, motion_event->x, motion_event->y, &x, &y);
+
+  g_debug ("motion; x %f, y %f", x, y);
+
+  clutter_path_add_line_to (context->path, x, y);
+
+  clutter_actor_queue_redraw (actor);
+
+  return TRUE;
+}
+
+static gboolean
+_enter_cb (ClutterActor *actor,
+           ClutterEvent *event,
+           gpointer      user_data)
+{
+  ClutterCrossingEvent *cross_event = (ClutterCrossingEvent *)event;
+  Context *context = (Context *)user_data;
+
+  gfloat x, y;
+  clutter_actor_transform_stage_point (actor, cross_event->x, cross_event->y, &x, &y);
+
+  g_debug ("enter; x %f, y %f", x, y);
+
+  clutter_path_add_move_to (context->path, x, y);
+
+  clutter_actor_queue_redraw (actor);
+
+  return TRUE;
+}
+
+int
+main (int argc, char *argv[])
+{
+  Context *context = g_new0 (Context, 1);
+
+  ClutterActor *stage;
+  ClutterActor *rect;
+  ClutterActor *canvas;
+
+  clutter_init (&argc, &argv);
+
+  context->path = clutter_path_new ();
+
+  cogl_path_new ();
+  context->cogl_path = cogl_get_path ();
+
+  stage = clutter_stage_get_default ();
+  clutter_actor_set_size (stage, 400, 400);
+  clutter_stage_set_color (CLUTTER_STAGE (stage), &stage_color);
+
+  rect = clutter_rectangle_new_with_color (&actor_color);
+  clutter_actor_set_size (rect, 300, 300);
+  clutter_actor_add_constraint (rect, clutter_align_constraint_new (stage, CLUTTER_ALIGN_X_AXIS, 0.5));
+  clutter_actor_add_constraint (rect, clutter_align_constraint_new (stage, CLUTTER_ALIGN_Y_AXIS, 0.5));
+
+  clutter_container_add_actor (CLUTTER_CONTAINER (stage), rect);
+
+  canvas = clutter_texture_new ();
+  clutter_actor_set_size (canvas, 300, 300);
+  clutter_actor_add_constraint (canvas, clutter_align_constraint_new (rect, CLUTTER_ALIGN_X_AXIS, 0.0));
+  clutter_actor_add_constraint (canvas, clutter_align_constraint_new (rect, CLUTTER_ALIGN_Y_AXIS, 0.0));
+  clutter_actor_set_reactive (canvas, TRUE);
+
+  clutter_container_add_actor (CLUTTER_CONTAINER (stage), canvas);
+  clutter_actor_raise_top (canvas);
+
+  g_signal_connect (canvas,
+                    "motion-event",
+                    G_CALLBACK (_motion_cb),
+                    context);
+
+  g_signal_connect (canvas,
+                    "enter-event",
+                    G_CALLBACK (_enter_cb),
+                    context);
+
+  g_signal_connect (canvas,
+                    "paint",
+                    G_CALLBACK (_paint_cb),
+                    context);
+
+  clutter_actor_show (stage);
+
+  clutter_main ();
+
+  g_object_unref (context->path);
+  g_free (context);
+
+  return 0;
+}