cookbook: Added basic mouse scroll recipe

Added a recipe explaining the basics of mouse scroll events.
2010-08-11 10:34:49 +01:00
parent ed39948ccf
commit ec71866277
2 changed files with 223 additions and 0 deletions
--- a/doc/cookbook/examples/events-mouse-scroll.c
+++ b/doc/cookbook/examples/events-mouse-scroll.c
@ -0,0 +1,108 @@
+/*
+ * Scroll in the y axis by moving an enclosed box (with layout)
+ * up and down inside a "letterbox" in the center of the stage
+ *
+ * gcc -g -O0 -DTESTS_DATA_DIR="\"/home/ell/dev/clutter_src/tests/data\"" -o events-mouse-scroll events-mouse-scroll.c `pkg-config --libs --cflags clutter-1.0 glib-2.0` -lm
+ */
+#include <clutter/clutter.h>
+
+#define STAGE_HEIGHT 400
+#define STAGE_WIDTH STAGE_HEIGHT * 2
+#define SCROLL_AMOUNT STAGE_HEIGHT * 0.2
+
+static const ClutterColor stage_color = { 0x33, 0x33, 0x55, 0xff };
+static const ClutterColor box_color = { 0xaa, 0xaa, 0x55, 0xff };
+
+static gboolean
+_scroll_event_cb (ClutterActor *scroll,
+                  ClutterEvent *event,
+                  gpointer      user_data)
+{
+  ClutterActor *viewport = CLUTTER_ACTOR (user_data);
+
+  gfloat y = clutter_actor_get_y (viewport);
+
+  ClutterScrollDirection direction;
+  direction = clutter_event_get_scroll_direction (event);
+
+  switch (direction)
+    {
+    case CLUTTER_SCROLL_UP:
+      y -= SCROLL_AMOUNT;
+      break;
+    case CLUTTER_SCROLL_DOWN:
+      y += SCROLL_AMOUNT;
+      break;
+    }
+
+  y = CLAMP (y,
+             clutter_actor_get_height (scroll)
+             + clutter_actor_get_y (scroll)
+             - clutter_actor_get_height (viewport),
+             0.0);
+
+  clutter_actor_animate (viewport,
+                         CLUTTER_EASE_OUT_CUBIC,
+                         300,
+                         "y", y,
+                         NULL);
+
+  return TRUE;
+}
+
+int
+main (int argc, char *argv[])
+{
+  ClutterActor *stage;
+  ClutterActor *scroll;
+  ClutterActor *viewport;
+  ClutterActor *texture;
+
+  clutter_init (&argc, &argv);
+
+  stage = clutter_stage_get_default ();
+  clutter_actor_set_size (stage, STAGE_WIDTH, STAGE_HEIGHT);
+  clutter_stage_set_color (CLUTTER_STAGE (stage), &stage_color);
+  g_signal_connect (stage, "destroy", G_CALLBACK (clutter_main_quit), NULL);
+
+  /* the "letterbox" which the viewport is scrolled within */
+  scroll = clutter_group_new ();
+  clutter_actor_set_size (scroll, STAGE_WIDTH, STAGE_HEIGHT * 0.75);
+  clutter_actor_add_constraint (scroll, clutter_align_constraint_new (stage, CLUTTER_BIND_Y, 0.5));
+  clutter_actor_set_reactive (scroll, TRUE);
+
+  /* this clips all actors inside the scroll group to that group's allocation */
+  clutter_actor_set_clip_to_allocation (scroll, TRUE);
+
+  viewport = clutter_box_new (clutter_bin_layout_new (CLUTTER_BIN_ALIGNMENT_CENTER,
+                                                      CLUTTER_BIN_ALIGNMENT_CENTER));
+  clutter_box_set_color (CLUTTER_BOX (viewport), &box_color);
+
+  /* the actor to scroll */
+  texture = clutter_texture_new ();
+  clutter_actor_set_request_mode (texture, CLUTTER_REQUEST_HEIGHT_FOR_WIDTH);
+  clutter_texture_set_keep_aspect_ratio (CLUTTER_TEXTURE (texture),
+                                         TRUE);
+
+  /* the box resizes itself to fit this texture */
+  clutter_actor_set_width (texture, STAGE_WIDTH);
+
+  clutter_texture_set_from_file (CLUTTER_TEXTURE (texture),
+                                 TESTS_DATA_DIR "/redhand.png",
+                                 NULL);
+
+  g_signal_connect (scroll,
+                    "scroll-event",
+                    G_CALLBACK (_scroll_event_cb),
+                    viewport);
+
+  clutter_container_add_actor (CLUTTER_CONTAINER (viewport), texture);
+  clutter_container_add_actor (CLUTTER_CONTAINER (scroll), viewport);
+  clutter_container_add_actor (CLUTTER_CONTAINER (stage), scroll);
+
+  clutter_actor_show (stage);
+
+  clutter_main ();
+
+  return 0;
+}