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130 lines
3.6 KiB
C
130 lines
3.6 KiB
C
#include <clutter/clutter.h>
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#define STAGE_HEIGHT 300
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#define STAGE_WIDTH STAGE_HEIGHT
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#define SCROLL_AMOUNT STAGE_HEIGHT * 0.125
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static gboolean
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_scroll_event_cb (ClutterActor *viewport,
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ClutterEvent *event,
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gpointer user_data)
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{
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ClutterActor *scrollable = CLUTTER_ACTOR (user_data);
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gfloat viewport_height = clutter_actor_get_height (viewport);
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gfloat scrollable_height = clutter_actor_get_height (scrollable);
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gfloat y;
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ClutterScrollDirection direction;
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/* no need to scroll if the scrollable is shorter than the viewport */
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if (scrollable_height < viewport_height)
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return TRUE;
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y = clutter_actor_get_y (scrollable);
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direction = clutter_event_get_scroll_direction (event);
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switch (direction)
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{
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case CLUTTER_SCROLL_UP:
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y -= SCROLL_AMOUNT;
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break;
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case CLUTTER_SCROLL_DOWN:
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y += SCROLL_AMOUNT;
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break;
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/* we're only interested in up and down */
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case CLUTTER_SCROLL_LEFT:
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case CLUTTER_SCROLL_RIGHT:
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break;
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}
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/*
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* the CLAMP macro returns a value for the first argument
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* that falls within the range specified by the second and
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* third arguments
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*
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* we allow the scrollable's y position to be decremented to the point
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* where its base is aligned with the base of the viewport
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*/
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y = CLAMP (y,
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viewport_height - scrollable_height,
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0.0);
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/* animate the change to the scrollable's y coordinate */
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clutter_actor_animate (scrollable,
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CLUTTER_EASE_OUT_CUBIC,
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300,
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"y", y,
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NULL);
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return TRUE;
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}
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int
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main (int argc, char *argv[])
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{
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ClutterActor *stage;
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ClutterActor *viewport;
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ClutterActor *texture;
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gchar *image_file_path = TESTS_DATA_DIR "/redhand.png";
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if (argc > 1)
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{
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image_file_path = argv[1];
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}
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if (clutter_init (&argc, &argv) != CLUTTER_INIT_SUCCESS)
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return 1;
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stage = clutter_stage_new ();
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clutter_actor_set_size (stage, STAGE_WIDTH, STAGE_HEIGHT);
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g_signal_connect (stage, "destroy", G_CALLBACK (clutter_main_quit), NULL);
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/* the scrollable actor */
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texture = clutter_texture_new ();
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clutter_texture_set_keep_aspect_ratio (CLUTTER_TEXTURE (texture),
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TRUE);
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/* set the texture's height so it's as tall as the stage */
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clutter_actor_set_request_mode (texture, CLUTTER_REQUEST_WIDTH_FOR_HEIGHT);
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clutter_actor_set_height (texture, STAGE_HEIGHT);
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clutter_texture_set_from_file (CLUTTER_TEXTURE (texture),
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image_file_path,
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NULL);
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/* the viewport which the box is scrolled within */
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viewport = clutter_actor_new ();
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/* viewport is shorter than the stage */
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clutter_actor_set_size (viewport, STAGE_WIDTH, STAGE_HEIGHT * 0.5);
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/* align the viewport to the center of the stage's y axis */
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clutter_actor_add_constraint (viewport, clutter_align_constraint_new (stage, CLUTTER_BIND_Y, 0.5));
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/* viewport needs to respond to scroll events */
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clutter_actor_set_reactive (viewport, TRUE);
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/* clip all actors inside the viewport to that group's allocation */
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clutter_actor_set_clip_to_allocation (viewport, TRUE);
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/* put the texture inside the viewport */
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clutter_actor_add_child (viewport, texture);
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/* add the viewport to the stage */
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clutter_actor_add_child (stage, viewport);
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g_signal_connect (viewport,
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"scroll-event",
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G_CALLBACK (_scroll_event_cb),
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texture);
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clutter_actor_show (stage);
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clutter_main ();
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return 0;
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}
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