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cookbook: Added walk through of code example for mouse scroll

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Modified the mouse scroll example to fit better with the tutorial
walkthrough.

Added a stepped walkthrough of the scrollable actor code
example.
This commit is contained in:
Elliot Smith
2010-08-11 16:54:28 +01:00
parent 57ba89c8de
commit f568a68ee1
2 changed files with 243 additions and 14 deletions
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33
doc/cookbook/examples/events-mouse-scroll.c
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@ -4,8 +4,6 @@
#define STAGE_WIDTH STAGE_HEIGHT
#define SCROLL_AMOUNT STAGE_HEIGHT * 0.125
static const ClutterColor stage_color = { 0x33, 0x33, 0x55, 0xff };
static gboolean
_scroll_event_cb (ClutterActor *viewport,
ClutterEvent *event,
@ -13,6 +11,13 @@ _scroll_event_cb (ClutterActor *viewport,
{
ClutterActor *scrollable = CLUTTER_ACTOR (user_data);
gfloat viewport_height = clutter_actor_get_height (viewport);
gfloat scrollable_height = clutter_actor_get_height (scrollable);
/* no need to scroll if the scrollable is shorter than the viewport */
if (scrollable_height < viewport_height)
return TRUE;
gfloat y = clutter_actor_get_y (scrollable);
ClutterScrollDirection direction;
@ -26,14 +31,23 @@ _scroll_event_cb (ClutterActor *viewport,
case CLUTTER_SCROLL_DOWN:
y += SCROLL_AMOUNT;
break;
/* we're only interested in up and down */
case CLUTTER_SCROLL_LEFT:
case CLUTTER_SCROLL_RIGHT:
break;
}
/*
* the CLAMP macro returns a value for the first argument
* that falls within the range specified by the second and
* third arguments
*
* we allow the scrollable's y position to be decremented to the point
* where its base is aligned with the base of the viewport
*/
y = CLAMP (y,
clutter_actor_get_height (viewport)
- clutter_actor_get_height (scrollable),
viewport_height - scrollable_height,
0.0);
clutter_actor_animate (scrollable,
@ -48,6 +62,13 @@ _scroll_event_cb (ClutterActor *viewport,
int
main (int argc, char *argv[])
{
gchar *image_file_path = TESTS_DATA_DIR "/redhand.png";
if (argc > 1)
{
image_file_path = argv[1];
}
ClutterActor *stage;
ClutterActor *viewport;
ClutterActor *texture;
@ -56,8 +77,6 @@ main (int argc, char *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 scrollable actor */
texture = clutter_texture_new ();
@ -69,7 +88,7 @@ main (int argc, char *argv[])
clutter_actor_set_height (texture, STAGE_HEIGHT);
clutter_texture_set_from_file (CLUTTER_TEXTURE (texture),
TESTS_DATA_DIR "/redhand.png",
image_file_path,
NULL);
/* the viewport which the box is scrolled within */