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Example code which loads an image into a texture, and resizes the image in response to +/- key presses. The overlay is a transparent rectangle which is bound to the height and width of the texture; on clicking the texture, the overlay is made visible by increasing its opacity. This demonstrates how to use constraints to simplify code for resizing an actor which is "dependent" on another actor.
136 lines
4.3 KiB
C
136 lines
4.3 KiB
C
#include <stdlib.h>
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#include <clutter/clutter.h>
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#define STAGE_SIDE 400
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#define RECTANGLE_SIDE STAGE_SIDE * 0.5
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#define TEXTURE_SIZE_MAX STAGE_SIDE * 0.9
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#define TEXTURE_SIZE_MIN STAGE_SIDE * 0.1
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#define TEXTURE_SIZE_STEP 0.2
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#define OVERLAY_OPACITY_OFF 0
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#define OVERLAY_OPACITY_ON 100
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static const ClutterColor stage_color = { 0x33, 0x33, 0x55, 0xff };
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static const ClutterColor overlay_color = { 0xaa, 0x99, 0x00, 0xff };
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/* change the texture size with +/- */
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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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ClutterActor *texture;
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gfloat texture_width, texture_height;
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guint key_pressed;
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texture = CLUTTER_ACTOR (user_data);
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clutter_actor_get_size (texture, &texture_width, &texture_height);
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key_pressed = clutter_event_get_key_symbol (event);
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if (key_pressed == CLUTTER_KEY_plus)
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{
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texture_width *= 1.0 + TEXTURE_SIZE_STEP;
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texture_height *= 1.0 + TEXTURE_SIZE_STEP;
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}
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else if (key_pressed == CLUTTER_KEY_minus)
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{
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texture_width *= 1.0 - TEXTURE_SIZE_STEP;
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texture_height *= 1.0 - TEXTURE_SIZE_STEP;
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}
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if (texture_width <= TEXTURE_SIZE_MAX && texture_width >= TEXTURE_SIZE_MIN)
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clutter_actor_animate (texture, CLUTTER_EASE_OUT_CUBIC, 500,
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"width", texture_width,
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"height", texture_height,
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NULL);
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return TRUE;
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}
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/* turn overlay opacity on/off */
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static void
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click_cb (ClutterClickAction *action,
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ClutterActor *actor,
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gpointer user_data)
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{
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ClutterActor *overlay = CLUTTER_ACTOR (user_data);
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guint8 opacity = clutter_actor_get_opacity (overlay);
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if (opacity < OVERLAY_OPACITY_ON)
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opacity = OVERLAY_OPACITY_ON;
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else
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opacity = OVERLAY_OPACITY_OFF;
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clutter_actor_set_opacity (overlay, opacity);
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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 *texture;
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ClutterActor *overlay;
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ClutterAction *click;
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GError *error = NULL;
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gchar *filename = TESTS_DATA_DIR "/redhand.png";
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if (argc > 1)
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filename = argv[1];
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clutter_init (&argc, &argv);
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stage = clutter_stage_new ();
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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_texture_set_keep_aspect_ratio (CLUTTER_TEXTURE (texture), TRUE);
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clutter_actor_set_reactive (texture, TRUE);
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clutter_actor_set_size (texture, RECTANGLE_SIDE, RECTANGLE_SIDE);
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clutter_actor_add_constraint (texture, clutter_align_constraint_new (stage, CLUTTER_ALIGN_X_AXIS, 0.5));
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clutter_actor_add_constraint (texture, clutter_align_constraint_new (stage, CLUTTER_ALIGN_Y_AXIS, 0.5));
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clutter_texture_set_from_file (CLUTTER_TEXTURE (texture),
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filename,
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&error);
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if (error != NULL)
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{
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g_warning ("Error loading %s\n%s", filename, 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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/* overlay is 10px wider and taller than the texture, and centered on it;
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* initially, it is transparent; but it is made semi-opaque when the
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* texture is clicked
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*/
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overlay = clutter_rectangle_new_with_color (&overlay_color);
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clutter_actor_set_opacity (overlay, OVERLAY_OPACITY_OFF);
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clutter_actor_add_constraint (overlay, clutter_bind_constraint_new (texture, CLUTTER_BIND_WIDTH, 10));
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clutter_actor_add_constraint (overlay, clutter_bind_constraint_new (texture, CLUTTER_BIND_HEIGHT, 10));
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clutter_actor_add_constraint (overlay, clutter_align_constraint_new (texture, CLUTTER_ALIGN_X_AXIS, 0.5));
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clutter_actor_add_constraint (overlay, clutter_align_constraint_new (texture, CLUTTER_ALIGN_Y_AXIS, 0.5));
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click = clutter_click_action_new ();
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clutter_actor_add_action (texture, click);
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clutter_container_add (CLUTTER_CONTAINER (stage), texture, overlay, NULL);
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clutter_actor_raise_top (overlay);
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g_signal_connect (click, "clicked", G_CALLBACK (click_cb), overlay);
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g_signal_connect (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_actor_show (stage);
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clutter_main ();
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return EXIT_SUCCESS;
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}
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