gnome-shell/src/st/st-shadow.c
Florian Müllner e942444630 [StShadow] Add reference counting
If a shadow property is inherited from a parent, multiple StThemeNodes
share a common StShadow. It would be possible to use st_shadow_copy()
for this purpose, but proper reference counting is nicer.

https://bugzilla.gnome.org/show_bug.cgi?id=624384
2010-09-02 21:49:59 +02:00

157 lines
4.1 KiB
C

/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*- */
#include "config.h"
#include "st-shadow.h"
/**
* SECTION: st-shadow
* @short_description: Boxed type for -st-shadow attributes
*
* #StShadow is a boxed type for storing attributes of the -st-shadow
* property, modelled liberally after the CSS3 box-shadow property.
* See http://www.css3.info/preview/box-shadow/
*
*/
/**
* st_shadow_new:
* @color: shadow's color
* @xoffset: horizontal offset
* @yoffset: vertical offset
* @blur: blur radius
* @spread: spread radius
*
* Creates a new #StShadow
*
* Returns: the newly allocated shadow. Use st_shadow_free() when done
*/
StShadow *
st_shadow_new (ClutterColor *color,
gdouble xoffset,
gdouble yoffset,
gdouble blur,
gdouble spread)
{
StShadow *shadow;
shadow = g_slice_new (StShadow);
shadow->color = *color;
shadow->xoffset = xoffset;
shadow->yoffset = yoffset;
shadow->blur = blur;
shadow->spread = spread;
shadow->ref_count = 1;
return shadow;
}
/**
* st_shadow_ref:
* @shadow: a #StShadow
*
* Atomically increments the reference count of @shadow by one.
*
* Returns: the passed in #StShadow.
*/
StShadow *
st_shadow_ref (StShadow *shadow)
{
g_return_val_if_fail (shadow != NULL, NULL);
g_return_val_if_fail (shadow->ref_count > 0, shadow);
g_atomic_int_add (&shadow->ref_count, 1);
return shadow;
}
/**
* st_shadow_unref:
* @shadow: a #StShadow
*
* Atomically decrements the reference count of @shadow by one.
* If the reference count drops to 0, all memory allocated by the
* #StShadow is released.
*/
void
st_shadow_unref (StShadow *shadow)
{
g_return_if_fail (shadow != NULL);
g_return_if_fail (shadow->ref_count > 0);
if (g_atomic_int_exchange_and_add (&shadow->ref_count, -1) - 1 == 0)
g_slice_free (StShadow, shadow);
}
/**
* st_shadow_equal:
* @shadow: a #StShadow
* @other: a different #StShadow
*
* Check if two shadow objects are identical. Note that two shadows may
* compare non-identically if they differ only by floating point rounding
* errors.
*
* Return value: %TRUE if the two shadows are identical
*/
gboolean
st_shadow_equal (StShadow *shadow,
StShadow *other)
{
g_return_val_if_fail (shadow != NULL, FALSE);
g_return_val_if_fail (other != NULL, FALSE);
/* We use strict equality to compare double quantities; this means
* that, for example, a shadow offset of 0.25in does not necessarily
* compare equal to a shadow offset of 18pt in this test. Assume
* that a few false negatives are mostly harmless.
*/
return (clutter_color_equal (&shadow->color, &other->color) &&
shadow->xoffset == other->xoffset &&
shadow->yoffset == other->yoffset &&
shadow->blur == other->blur &&
shadow->spread == other->spread);
}
/**
* st_shadow_get_box:
* @shadow: a #StShadow
* @actor_box: the box allocated to a #ClutterAlctor
* @shadow_box: computed box occupied by @shadow
*
* Gets the box used to paint @shadow, which will be partly
* outside of @actor_box
*/
void
st_shadow_get_box (StShadow *shadow,
const ClutterActorBox *actor_box,
ClutterActorBox *shadow_box)
{
g_return_if_fail (shadow != NULL);
g_return_if_fail (actor_box != NULL);
g_return_if_fail (shadow_box != NULL);
shadow_box->x1 = actor_box->x1 + shadow->xoffset
- shadow->blur - shadow->spread;
shadow_box->x2 = actor_box->x2 + shadow->xoffset
+ shadow->blur + shadow->spread;
shadow_box->y1 = actor_box->y1 + shadow->yoffset
- shadow->blur - shadow->spread;
shadow_box->y2 = actor_box->y2 + shadow->yoffset
+ shadow->blur + shadow->spread;
}
GType
st_shadow_get_type (void)
{
static GType _st_shadow_type = 0;
if (G_UNLIKELY (_st_shadow_type == 0))
_st_shadow_type =
g_boxed_type_register_static ("StShadow",
(GBoxedCopyFunc) st_shadow_ref,
(GBoxedFreeFunc) st_shadow_unref);
return _st_shadow_type;
}