ee9a4d02bb
Added a simple application for scaling a texture while keeping the mouse pointer over the same coordinates on its surface.
155 lines
4.4 KiB
C
155 lines
4.4 KiB
C
/*
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* Load an image into a texture, which can then be zoomed in/out
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* (double click on button 1, double click on button 3 respectively);
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* also resets the texture to the stage center when a key is pressed
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* (better would be to prevent drags taking the actor off-stage,
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* but the implementation is much more complicated)
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*/
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#include <stdlib.h>
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#include <clutter/clutter.h>
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#define STAGE_SIDE 400.0
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static const ClutterColor stage_color = { 0x33, 0x33, 0x55, 0xff };
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/* on key press, center the actor on the stage;
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* useful if you drag it off-stage accidentally
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*/
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static gboolean
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key_press_cb (ClutterActor *actor,
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ClutterEvent *event,
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gpointer user_data)
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{
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gfloat width, height;
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clutter_actor_get_size (actor, &width, &height);
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clutter_actor_set_anchor_point (actor, width / 2, height / 2);
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clutter_actor_set_position (actor,
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STAGE_SIDE / 2,
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STAGE_SIDE / 2);
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return TRUE;
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}
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/* on double click, zoom in on the clicked point;
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* also keeps scale in the range 0.1 to 20
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*/
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static gboolean
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clicked_cb (ClutterActor *actor,
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ClutterEvent *event,
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gpointer user_data)
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{
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gdouble scale;
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gfloat click_x, click_y;
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gfloat click_target_x, click_target_y;
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guint32 button;
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/* don't do anything unless there was a double click */
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if (clutter_event_get_click_count (event) < 2)
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return TRUE;
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/* work out new scale */
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button = clutter_event_get_button (event);
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clutter_actor_get_scale (actor, &scale, NULL);
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if (button == 1)
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scale *= 1.2;
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else if (button == 3)
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scale /= 1.2;
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/* don't do anything if scale is outside bounds */
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if (scale < 0.1 || scale > 20.0)
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return TRUE;
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/* get the location of the click on the scaled actor */
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clutter_event_get_coords (event, &click_x, &click_y);
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clutter_actor_transform_stage_point (actor,
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click_x, click_y,
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&click_target_x, &click_target_y);
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/* anchor the actor on the clicked point on its surface */
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clutter_actor_set_anchor_point (actor, click_target_x, click_target_y);
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/* set the actor's position to the click coords: it won't move,
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* because the anchor point is already there; but
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* the scale will now be centered on these coords (as the
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* scale center defaults to the anchor point); so the anchor point
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* on the actor won't move from under the pointer
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*/
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clutter_actor_set_position (actor, click_x, click_y);
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clutter_actor_animate (actor, CLUTTER_LINEAR, 500,
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"scale-x", scale,
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"scale-y", scale,
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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,
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char *argv[])
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{
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ClutterActor *stage;
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ClutterActor *texture;
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gchar *image_path;
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GError *error = NULL;
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if (argc < 2)
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{
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g_print ("Usage: %s <path to image file>\n", argv[0]);
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exit (EXIT_FAILURE);
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}
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image_path = argv[1];
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clutter_init (&argc, &argv);
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stage = clutter_stage_get_default ();
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clutter_actor_set_size (stage, STAGE_SIDE, STAGE_SIDE);
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clutter_stage_set_color (CLUTTER_STAGE (stage), &stage_color);
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g_signal_connect (stage, "destroy", G_CALLBACK (clutter_main_quit), NULL);
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texture = clutter_texture_new ();
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clutter_actor_set_reactive (texture, TRUE);
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clutter_actor_set_width (texture, STAGE_SIDE);
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clutter_texture_set_keep_aspect_ratio (CLUTTER_TEXTURE (texture), TRUE);
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clutter_actor_add_action (texture, clutter_drag_action_new ());
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g_object_set (G_OBJECT (texture),
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"scale-gravity", CLUTTER_GRAVITY_NORTH_WEST,
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NULL);
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clutter_texture_set_from_file (CLUTTER_TEXTURE (texture), image_path, &error);
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if (error != NULL)
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{
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g_warning ("Error loading %s\n%s", image_path, error->message);
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g_error_free (error);
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exit (EXIT_FAILURE);
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}
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clutter_actor_set_y (texture, (STAGE_SIDE - clutter_actor_get_height (texture)) * 0.5);
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g_signal_connect (texture,
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"button-release-event",
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G_CALLBACK (clicked_cb),
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NULL);
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g_signal_connect_swapped (stage,
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"key-press-event",
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G_CALLBACK (key_press_cb),
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texture);
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clutter_container_add_actor (CLUTTER_CONTAINER (stage), texture);
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clutter_actor_show (stage);
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clutter_main ();
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return EXIT_SUCCESS;
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}
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