mutter/clutter/clutter-base-types.c
Emmanuele Bassi 61f17e345a Add base geometric types
Clutter should provide some more basic geometric types - Point, Size,
Rect - so that we can use them in properties and accessors.
2012-04-27 12:30:46 +01:00

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/*
* Clutter.
*
* An OpenGL based 'interactive canvas' library.
*
* Authored By Matthew Allum <mallum@openedhand.com>
*
* Copyright (C) 2006 OpenedHand
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library. If not, see <http://www.gnu.org/licenses/>.
*/
/**
* SECTION:clutter-base-types
* @Title: Base data types
* @Short_Description: Common data types used by Clutter
*
* Clutter defines a set of data structures that are commonly used across the
* whole API.
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include "clutter-types.h"
#include "clutter-private.h"
#include <math.h>
/*
* ClutterGeometry
*/
static ClutterGeometry*
clutter_geometry_copy (const ClutterGeometry *geometry)
{
return g_slice_dup (ClutterGeometry, geometry);
}
static void
clutter_geometry_free (ClutterGeometry *geometry)
{
if (G_LIKELY (geometry != NULL))
g_slice_free (ClutterGeometry, geometry);
}
/**
* clutter_geometry_union:
* @geometry_a: a #ClutterGeometry
* @geometry_b: another #ClutterGeometry
* @result: (out): location to store the result
*
* Find the union of two rectangles represented as #ClutterGeometry.
*
* Since: 1.4
*/
void
clutter_geometry_union (const ClutterGeometry *geometry_a,
const ClutterGeometry *geometry_b,
ClutterGeometry *result)
{
/* We don't try to handle rectangles that can't be represented
* as a signed integer box */
gint x_1 = MIN (geometry_a->x, geometry_b->x);
gint y_1 = MIN (geometry_a->y, geometry_b->y);
gint x_2 = MAX (geometry_a->x + (gint)geometry_a->width,
geometry_b->x + (gint)geometry_b->width);
gint y_2 = MAX (geometry_a->y + (gint)geometry_a->height,
geometry_b->y + (gint)geometry_b->height);
result->x = x_1;
result->y = y_1;
result->width = x_2 - x_1;
result->height = y_2 - y_1;
}
/**
* clutter_geometry_intersects:
* @geometry0: The first geometry to test
* @geometry1: The second geometry to test
*
* Determines if @geometry0 and geometry1 intersect returning %TRUE if
* they do else %FALSE.
*
* Return value: %TRUE of @geometry0 and geometry1 intersect else
* %FALSE.
*
* Since: 1.4
*/
gboolean
clutter_geometry_intersects (const ClutterGeometry *geometry0,
const ClutterGeometry *geometry1)
{
if (geometry1->x >= (geometry0->x + (gint)geometry0->width) ||
geometry1->y >= (geometry0->y + (gint)geometry0->height) ||
(geometry1->x + (gint)geometry1->width) <= geometry0->x ||
(geometry1->y + (gint)geometry1->height) <= geometry0->y)
return FALSE;
else
return TRUE;
}
static gboolean
clutter_geometry_progress (const GValue *a,
const GValue *b,
gdouble progress,
GValue *retval)
{
const ClutterGeometry *a_geom = g_value_get_boxed (a);
const ClutterGeometry *b_geom = g_value_get_boxed (b);
ClutterGeometry res = { 0, };
gint a_width = a_geom->width;
gint b_width = b_geom->width;
gint a_height = a_geom->height;
gint b_height = b_geom->height;
res.x = a_geom->x + (b_geom->x - a_geom->x) * progress;
res.y = a_geom->y + (b_geom->y - a_geom->y) * progress;
res.width = a_width + (b_width - a_width) * progress;
res.height = a_height + (b_height - a_height) * progress;
g_value_set_boxed (retval, &res);
return TRUE;
}
G_DEFINE_BOXED_TYPE_WITH_CODE (ClutterGeometry, clutter_geometry,
clutter_geometry_copy,
clutter_geometry_free,
CLUTTER_REGISTER_INTERVAL_PROGRESS (clutter_geometry_progress));
/*
* ClutterVertices
*/
/**
* clutter_vertex_new:
* @x: X coordinate
* @y: Y coordinate
* @z: Z coordinate
*
* Creates a new #ClutterVertex for the point in 3D space
* identified by the 3 coordinates @x, @y, @z
*
* Return value: the newly allocate #ClutterVertex. Use
* clutter_vertex_free() to free the resources
*
* Since: 1.0
*/
ClutterVertex *
clutter_vertex_new (gfloat x,
gfloat y,
gfloat z)
{
ClutterVertex *vertex;
vertex = g_slice_new (ClutterVertex);
clutter_vertex_init (vertex, x, y, z);
return vertex;
}
/**
* clutter_vertex_init:
* @vertex: a #ClutterVertex
* @x: X coordinate
* @y: Y coordinate
* @z: Z coordinate
*
* Initializes @vertex with the given coordinates.
*
* Since: 1.10
*/
void
clutter_vertex_init (ClutterVertex *vertex,
gfloat x,
gfloat y,
gfloat z)
{
g_return_if_fail (vertex != NULL);
vertex->x = x;
vertex->y = y;
vertex->z = z;
}
/**
* clutter_vertex_copy:
* @vertex: a #ClutterVertex
*
* Copies @vertex
*
* Return value: a newly allocated copy of #ClutterVertex. Use
* clutter_vertex_free() to free the allocated resources
*
* Since: 1.0
*/
ClutterVertex *
clutter_vertex_copy (const ClutterVertex *vertex)
{
if (G_LIKELY (vertex != NULL))
return g_slice_dup (ClutterVertex, vertex);
return NULL;
}
/**
* clutter_vertex_free:
* @vertex: a #ClutterVertex
*
* Frees a #ClutterVertex allocated using clutter_vertex_copy()
*
* Since: 1.0
*/
void
clutter_vertex_free (ClutterVertex *vertex)
{
if (G_UNLIKELY (vertex != NULL))
g_slice_free (ClutterVertex, vertex);
}
/**
* clutter_vertex_equal:
* @vertex_a: a #ClutterVertex
* @vertex_b: a #ClutterVertex
*
* Compares @vertex_a and @vertex_b for equality
*
* Return value: %TRUE if the passed #ClutterVertex are equal
*
* Since: 1.0
*/
gboolean
clutter_vertex_equal (const ClutterVertex *vertex_a,
const ClutterVertex *vertex_b)
{
g_return_val_if_fail (vertex_a != NULL && vertex_b != NULL, FALSE);
if (vertex_a == vertex_b)
return TRUE;
return vertex_a->x == vertex_b->x &&
vertex_a->y == vertex_b->y &&
vertex_a->z == vertex_b->z;
}
static gboolean
clutter_vertex_progress (const GValue *a,
const GValue *b,
gdouble progress,
GValue *retval)
{
const ClutterVertex *av = g_value_get_boxed (a);
const ClutterVertex *bv = g_value_get_boxed (b);
ClutterVertex res = { 0, };
res.x = av->x + (bv->x - av->x) * progress;
res.y = av->y + (bv->y - av->y) * progress;
res.z = av->z + (bv->z - av->z) * progress;
g_value_set_boxed (retval, &res);
return TRUE;
}
G_DEFINE_BOXED_TYPE_WITH_CODE (ClutterVertex, clutter_vertex,
clutter_vertex_copy,
clutter_vertex_free,
CLUTTER_REGISTER_INTERVAL_PROGRESS (clutter_vertex_progress));
/*
* ClutterMargin
*/
/**
* clutter_margin_new:
*
* Creates a new #ClutterMargin.
*
* Return value: (transfer full): a newly allocated #ClutterMargin. Use
* clutter_margin_free() to free the resources associated with it when
* done.
*
* Since: 1.10
*/
ClutterMargin *
clutter_margin_new (void)
{
return g_slice_new0 (ClutterMargin);
}
/**
* clutter_margin_copy:
* @margin_: a #ClutterMargin
*
* Creates a new #ClutterMargin and copies the contents of @margin_ into
* the newly created structure.
*
* Return value: (transfer full): a copy of the #ClutterMargin.
*
* Since: 1.10
*/
ClutterMargin *
clutter_margin_copy (const ClutterMargin *margin_)
{
if (G_LIKELY (margin_ != NULL))
return g_slice_dup (ClutterMargin, margin_);
return NULL;
}
/**
* clutter_margin_free:
* @margin_: a #ClutterMargin
*
* Frees the resources allocated by clutter_margin_new() and
* clutter_margin_copy().
*
* Since: 1.10
*/
void
clutter_margin_free (ClutterMargin *margin_)
{
if (G_LIKELY (margin_ != NULL))
g_slice_free (ClutterMargin, margin_);
}
G_DEFINE_BOXED_TYPE (ClutterMargin, clutter_margin,
clutter_margin_copy,
clutter_margin_free)
/*
* ClutterPoint
*/
ClutterPoint *
clutter_point_new (void)
{
return g_slice_new0 (ClutterPoint);
}
ClutterPoint *
clutter_point_init (ClutterPoint *point,
float x,
float y)
{
g_return_val_if_fail (point != NULL, NULL);
point->x = x;
point->y = y;
return point;
}
ClutterPoint *
clutter_point_copy (const ClutterPoint *point)
{
return g_slice_dup (ClutterPoint, point);
}
void
clutter_point_free (ClutterPoint *point)
{
if (point != NULL)
g_slice_free (ClutterPoint, point);
}
gboolean
clutter_point_equals (const ClutterPoint *a,
const ClutterPoint *b)
{
if (a == b)
return TRUE;
if (a == NULL || b == NULL)
return FALSE;
return a->x == b->x && a->y == b->y;
}
static gboolean
clutter_point_progress (const GValue *a,
const GValue *b,
gdouble progress,
GValue *retval)
{
const ClutterPoint *ap = g_value_get_boxed (a);
const ClutterPoint *bp = g_value_get_boxed (b);
ClutterPoint res = CLUTTER_POINT_INIT (0, 0);
res.x = ap->x + (bp->x - ap->x) * progress;
res.y = ap->y + (bp->y - ap->y) * progress;
g_value_set_boxed (retval, &res);
return TRUE;
}
G_DEFINE_BOXED_TYPE_WITH_CODE (ClutterPoint, clutter_point,
clutter_point_copy,
clutter_point_free,
CLUTTER_REGISTER_INTERVAL_PROGRESS (clutter_point_progress))
/*
* ClutterSize
*/
ClutterSize *
clutter_size_new (void)
{
return g_slice_new0 (ClutterSize);
}
ClutterSize *
clutter_size_init (ClutterSize *size,
float width,
float height)
{
g_return_val_if_fail (size != NULL, NULL);
size->width = width;
size->height = height;
return size;
}
ClutterSize *
clutter_size_copy (const ClutterSize *size)
{
return g_slice_dup (ClutterSize, size);
}
void
clutter_size_free (ClutterSize *size)
{
if (size != NULL)
g_slice_free (ClutterSize, size);
}
gboolean
clutter_size_equals (const ClutterSize *a,
const ClutterSize *b)
{
if (a == b)
return TRUE;
if (a == NULL || b == NULL)
return FALSE;
return a->width == b->width && a->height == b->height;
}
static gboolean
clutter_size_progress (const GValue *a,
const GValue *b,
gdouble progress,
GValue *retval)
{
const ClutterSize *as = g_value_get_boxed (a);
const ClutterSize *bs = g_value_get_boxed (b);
ClutterSize res = CLUTTER_SIZE_INIT (0, 0);
res.width = as->width + (bs->width - as->width) * progress;
res.height = as->height + (bs->height - as->height) * progress;
g_value_set_boxed (retval, &res);
return TRUE;
}
G_DEFINE_BOXED_TYPE_WITH_CODE (ClutterSize, clutter_size,
clutter_size_copy,
clutter_size_free,
CLUTTER_REGISTER_INTERVAL_PROGRESS (clutter_size_progress))
/*
* ClutterRect
*/
static gboolean clutter_rect_progress (const GValue *a,
const GValue *b,
gdouble progress,
GValue *res);
G_DEFINE_BOXED_TYPE_WITH_CODE (ClutterRect, clutter_rect,
clutter_rect_copy,
clutter_rect_free,
CLUTTER_REGISTER_INTERVAL_PROGRESS (clutter_rect_progress))
static inline void
clutter_rect_normalize_internal (ClutterRect *rect)
{
if (rect->size.width >= 0.f && rect->size.height >= 0.f)
return;
if (rect->size.width < 0.f)
{
float size = fabsf (rect->size.width);
rect->origin.x -= size;
rect->size.width = size;
}
if (rect->size.height < 0.f)
{
float size = fabsf (rect->size.height);
rect->origin.y -= size;
rect->size.height = size;
}
}
/**
* clutter_rect_new:
*
* Creates a new, empty #ClutterRect.
*
* You can use clutter_rect_init() to initialize the returned rectangle,
* for instance:
*
* |[
* ClutterRect *rect;
*
* rect = clutter_rect_init (clutter_rect_new (), x, y, width, height);
* ]|
*
* Return value: (transfer full): the newly allocated #ClutterRect.
* Use clutter_rect_free() to free its resources
*
* Since: 1.12
*/
ClutterRect *
clutter_rect_new (void)
{
return g_slice_new0 (ClutterRect);
}
/**
* clutter_rect_init:
* @rect: a #ClutterRect
* @x: X coordinate of the origin
* @y: Y coordinate of the origin
* @width: width of the rectangle
* @height: height of the rectangle
*
* Initializes a #ClutterRect with the given origin and size.
*
* Return value: (transfer none): the updated rectangle
*
* Since: 1.12
*/
ClutterRect *
clutter_rect_init (ClutterRect *rect,
float x,
float y,
float width,
float height)
{
g_return_val_if_fail (rect != NULL, NULL);
rect->origin.x = x;
rect->origin.y = y;
rect->size.width = width;
rect->size.height = height;
return rect;
}
/**
* clutter_rect_copy:
* @rect: a #ClutterRect
*
* Copies @rect into a new #ClutterRect instance.
*
* Return value: (transfer full): the newly allocate copy of @rect.
* Use clutter_rect_free() to free the associated resources
*
* Since: 1.12
*/
ClutterRect *
clutter_rect_copy (const ClutterRect *rect)
{
if (rect != NULL)
{
ClutterRect *res;
res = g_slice_dup (ClutterRect, rect);
clutter_rect_normalize_internal (res);
return res;
}
return NULL;
}
/**
* clutter_rect_free:
* @rect: a #ClutterRect
*
* Frees the resources allocated by @rect.
*
* Since: 1.12
*/
void
clutter_rect_free (ClutterRect *rect)
{
if (rect != NULL)
g_slice_free (ClutterRect, rect);
}
/**
* clutter_rect_equals:
* @a: a #ClutterRect
* @b: a #ClutterRect
*
* Checks whether @a and @b are equals.
*
* This function will normalize both @a and @b before comparing
* their origin and size.
*
* Return value: %TRUE if the rectangles match in origin and size.
*
* Since: 1.12
*/
gboolean
clutter_rect_equals (ClutterRect *a,
ClutterRect *b)
{
if (a == b)
return TRUE;
if (a == NULL || b == NULL)
return FALSE;
clutter_rect_normalize_internal (a);
clutter_rect_normalize_internal (b);
return clutter_point_equals (&a->origin, &b->origin) &&
clutter_size_equals (&a->size, &b->size);
}
/**
* clutter_rect_normalize:
* @rect: a #ClutterRect
*
* Normalizes a #ClutterRect.
*
* A #ClutterRect is defined by the area covered by its size; this means
* that a #ClutterRect with #ClutterRect.origin in [ 0, 0 ] and a
* #ClutterRect.size of [ 10, 10 ] is equivalent to a #ClutterRect with
* #ClutterRect.origin in [ 10, 10 ] and a #ClutterRect.size of [ -10, -10 ].
*
* This function is useful to ensure that a rectangle has positive width
* and height; it will modify the passed @rect and normalize its size.
*
* Since: 1.12
*/
ClutterRect *
clutter_rect_normalize (ClutterRect *rect)
{
g_return_val_if_fail (rect != NULL, NULL);
clutter_rect_normalize_internal (rect);
return rect;
}
/**
* clutter_rect_get_center:
* @rect: a #ClutterRect
* @center: (out caller-allocates): a #ClutterPoint
*
* Retrieves the center of @rect, after normalizing the rectangle,
* and updates @center with the correct coordinates.
*
* Since: 1.12
*/
void
clutter_rect_get_center (ClutterRect *rect,
ClutterPoint *center)
{
g_return_if_fail (rect != NULL);
g_return_if_fail (center != NULL);
clutter_rect_normalize_internal (rect);
center->x = rect->origin.x + (rect->size.width / 2.0f);
center->y = rect->origin.y + (rect->size.height / 2.0f);
}
/**
* clutter_rect_contains_point:
* @rect: a #ClutterRect
* @point: the point to check
*
* Checks whether @point is contained by @rect, after normalizing the
* rectangle.
*
* Return value: %TRUE if the @point is contained by @rect.
*
* Since: 1.12
*/
gboolean
clutter_rect_contains_point (ClutterRect *rect,
ClutterPoint *point)
{
g_return_val_if_fail (rect != NULL, FALSE);
g_return_val_if_fail (point != NULL, FALSE);
clutter_rect_normalize_internal (rect);
return (point->x >= rect->origin.x) &&
(point->y >= rect->origin.y) &&
(point->x <= (rect->origin.x + rect->size.width)) &&
(point->y <= (rect->origin.y + rect->size.height));
}
/**
* clutter_rect_union:
* @a: a #ClutterRect
* @b: a #ClutterRect
* @res: (out caller-allocates): a #ClutterRect
*
* Computes the smallest possible rectangle capable of fully containing
* both @a and @b, and places it into @res.
*
* This function will normalize both @a and @b prior to computing their
* union.
*
* Since: 1.12
*/
void
clutter_rect_union (ClutterRect *a,
ClutterRect *b,
ClutterRect *res)
{
g_return_if_fail (a != NULL);
g_return_if_fail (b != NULL);
g_return_if_fail (res != NULL);
clutter_rect_normalize_internal (a);
clutter_rect_normalize_internal (b);
res->origin.x = MIN (a->origin.x, b->origin.x);
res->origin.y = MIN (a->origin.y, b->origin.y);
res->size.width = MAX (a->size.width, b->size.width);
res->size.height = MAX (a->size.height, b->size.height);
}
/**
* clutter_rect_intersection:
* @a: a #ClutterRect
* @b: a #ClutterRect
* @res: (out caller-allocates) (allow-none): a #ClutterRect, or %NULL
*
* Computes the intersection of @a and @b, and places it in @res, if @res
* is not %NULL.
*
* This function will normalize both @a and @b prior to computing their
* intersection.
*
* This function can be used to simply check if the intersection of @a and @b
* is not empty, by using %NULL for @res.
*
* Return value: %TRUE if the intersection of @a and @b is not empty
*
* Since: 1.12
*/
gboolean
clutter_rect_intersection (ClutterRect *a,
ClutterRect *b,
ClutterRect *res)
{
float x_1, y_1, x_2, y_2;
g_return_val_if_fail (a != NULL, FALSE);
g_return_val_if_fail (b != NULL, FALSE);
clutter_rect_normalize_internal (a);
clutter_rect_normalize_internal (b);
x_1 = MAX (a->origin.x, b->origin.y);
y_1 = MAX (a->origin.y, b->origin.y);
x_2 = MIN (a->origin.x + a->size.width, b->origin.x + b->size.width);
y_2 = MIN (a->origin.y + a->size.height, b->origin.y + b->size.height);
if (x_1 >= x_2 || y_1 >= y_2)
{
if (res != NULL)
clutter_rect_init (res, 0.f, 0.f, 0.f, 0.f);
return FALSE;
}
if (res != NULL)
clutter_rect_init (res, x_1, y_1, x_2 - x_1, y_2 - y_1);
return TRUE;
}
/**
* clutter_rect_offset:
* @rect: a #ClutterRect
* @d_x: the horizontal offset value
* @d_y: the vertical offset value
*
* Offsets the origin of @rect by the given values, after normalizing
* the rectangle.
*
* Since: 1.12
*/
void
clutter_rect_offset (ClutterRect *rect,
float d_x,
float d_y)
{
g_return_if_fail (rect != NULL);
clutter_rect_normalize_internal (rect);
rect->origin.x += d_x;
rect->origin.y += d_y;
}
/**
* clutter_rect_inset:
* @rect: a #ClutterRect
* @d_x: an horizontal value; a positive @d_x will create an inset rectangle,
* and a negative value will create a larger rectangle
* @d_y: a vertical value; a positive @d_x will create an inset rectangle,
* and a negative value will create a larger rectangle
*
* Normalizes the @rect and offsets its origin by the @d_x and @d_y values;
* the size is adjusted by (2 * @d_x, 2 * @d_y).
*
* If @d_x and @d_y are positive the size of the rectangle is decreased; if
* the values are negative, the size of the rectangle is increased.
*
* If the resulting rectangle has a negative width or height, the size is
* set to 0.
*
* Since: 1.12
*/
void
clutter_rect_inset (ClutterRect *rect,
float d_x,
float d_y)
{
g_return_if_fail (rect != NULL);
clutter_rect_normalize_internal (rect);
rect->origin.x += d_x;
rect->origin.y += d_y;
if (d_x >= 0.f)
rect->size.width -= (d_x * 2.f);
else
rect->size.width += (d_x * -2.f);
if (d_y >= 0.f)
rect->size.height -= (d_y * 2.f);
else
rect->size.height += (d_y * -2.f);
if (rect->size.width < 0.f)
rect->size.width = 0.f;
if (rect->size.height < 0.f)
rect->size.height = 0.f;
}
/**
* clutter_rect_clamp_to_pixel:
* @rect: a #ClutterRect
*
* Rounds the origin of @rect downwards to the nearest integer, and rounds
* the size of @rect upwards to the nearest integer, so that @rect is
* updated to the smallest rectangle capable of fully containing the
* original, fractional rectangle.
*
* Since: 1.12
*/
void
clutter_rect_clamp_to_pixel (ClutterRect *rect)
{
g_return_if_fail (rect != NULL);
clutter_rect_normalize_internal (rect);
rect->origin.x = floorf (rect->origin.x);
rect->origin.y = floorf (rect->origin.y);
rect->size.width = ceilf (rect->size.width);
rect->size.height = ceilf (rect->size.height);
}
/**
* clutter_rect_get_x:
* @rect: a #ClutterRect
*
* Retrieves the X coordinate of the origin of @rect.
*
* Return value: the X coordinate of the origin of the rectangle
*
* Since: 1.12
*/
float
clutter_rect_get_x (ClutterRect *rect)
{
g_return_val_if_fail (rect != NULL, 0.f);
clutter_rect_normalize_internal (rect);
return rect->origin.x;
}
/**
* clutter_rect_get_y:
* @rect: a #ClutterRect
*
* Retrieves the Y coordinate of the origin of @rect.
*
* Return value: the Y coordinate of the origin of the rectangle
*
* Since: 1.12
*/
float
clutter_rect_get_y (ClutterRect *rect)
{
g_return_val_if_fail (rect != NULL, 0.f);
clutter_rect_normalize_internal (rect);
return rect->origin.y;
}
/**
* clutter_rect_get_width:
* @rect: a #ClutterRect
*
* Retrieves the width of @rect.
*
* Return value: the width of the rectangle
*
* Since: 1.12
*/
float
clutter_rect_get_width (ClutterRect *rect)
{
g_return_val_if_fail (rect != NULL, 0.f);
clutter_rect_normalize_internal (rect);
return rect->size.width;
}
/**
* clutter_rect_get_height:
* @rect: a #ClutterRect
*
* Retrieves the height of @rect.
*
* Return value: the height of the rectangle
*
* Since: 1.12
*/
float
clutter_rect_get_height (ClutterRect *rect)
{
g_return_val_if_fail (rect != NULL, 0.f);
clutter_rect_normalize_internal (rect);
return rect->size.height;
}
static gboolean
clutter_rect_progress (const GValue *a,
const GValue *b,
gdouble progress,
GValue *retval)
{
const ClutterRect *rect_a = g_value_get_boxed (a);
const ClutterRect *rect_b = g_value_get_boxed (b);
ClutterRect res = CLUTTER_RECT_INIT_ZERO;
#define INTERPOLATE(r_a,r_b,member,field,factor) ((r_a)->member.field + (((r_b)->member.field - ((r_b)->member.field)) * (factor)))
res.origin.x = INTERPOLATE (rect_a, rect_b, origin, x, progress);
res.origin.y = INTERPOLATE (rect_a, rect_b, origin, y, progress);
res.size.width = INTERPOLATE (rect_a, rect_b, size, width, progress);
res.size.height = INTERPOLATE (rect_a, rect_b, size, height, progress);
#undef INTERPOLATE
g_value_set_boxed (retval, &res);
return TRUE;
}