cookbook: Add example of scaling a texture

Added a simple application for scaling a
texture while keeping the mouse pointer over
the same coordinates on its surface.
This commit is contained in:
Elliot Smith 2010-11-24 12:22:12 +00:00
parent c8f112876e
commit ee9a4d02bb
2 changed files with 157 additions and 0 deletions

View File

@ -13,6 +13,7 @@ noinst_PROGRAMS = \
animations-reuse \
animations-rotating \
animations-scaling \
animations-scaling-zoom \
text-shadow \
textures-reflection \
textures-split-go \
@ -68,6 +69,7 @@ animations_moving_state_SOURCES = animations-moving-state.c
animations_reuse_SOURCES = animations-reuse.c
animations_rotating_SOURCES = animations-rotating.c
animations_scaling_SOURCES = animations-scaling.c
animations_scaling_zoom_SOURCES = animations-scaling-zoom.c
text_shadow_SOURCES = text-shadow.c
textures_reflection_SOURCES = textures-reflection.c
textures_split_go_SOURCES = textures-split-go.c

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