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/* -*- Mode: c; c-basic-offset: 4; indent-tabs-mode: t; tab-width: 8; -*- */
/* cairo - a vector graphics library with display and print output
*
* Copyright © 2004 David Reveman
* Copyright © 2005 Red Hat, Inc.
*
* Permission to use, copy, modify, distribute, and sell this software
* and its documentation for any purpose is hereby granted without
* fee, provided that the above copyright notice appear in all copies
* and that both that copyright notice and this permission notice
* appear in supporting documentation, and that the name of David
* Reveman not be used in advertising or publicity pertaining to
* distribution of the software without specific, written prior
* permission. David Reveman makes no representations about the
* suitability of this software for any purpose. It is provided "as
* is" without express or implied warranty.
*
* DAVID REVEMAN DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS
* SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
* FITNESS, IN NO EVENT SHALL DAVID REVEMAN BE LIABLE FOR ANY SPECIAL,
* INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER
* RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
* OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR
* IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*
* Authors: David Reveman <davidr@novell.com>
* Keith Packard <keithp@keithp.com>
* Carl Worth <cworth@cworth.org>
*/
#include "cairoint.h"
#include "cairo-array-private.h"
#include "cairo-error-private.h"
#include "cairo-freed-pool-private.h"
#include "cairo-image-surface-private.h"
#include "cairo-list-inline.h"
#include "cairo-path-private.h"
#include "cairo-pattern-private.h"
#include "cairo-recording-surface-inline.h"
#include "cairo-surface-snapshot-inline.h"
#include <float.h>
#define PIXMAN_MAX_INT ((pixman_fixed_1 >> 1) - pixman_fixed_e) /* need to ensure deltas also fit */
/**
* SECTION:cairo-pattern
* @Title: cairo_pattern_t
* @Short_Description: Sources for drawing
* @See_Also: #cairo_t, #cairo_surface_t
*
* #cairo_pattern_t is the paint with which cairo draws.
* The primary use of patterns is as the source for all cairo drawing
* operations, although they can also be used as masks, that is, as the
* brush too.
*
* A cairo pattern is created by using one of the many constructors,
* of the form
* <function>cairo_pattern_create_<emphasis>type</emphasis>()</function>
* or implicitly through
* <function>cairo_set_source_<emphasis>type</emphasis>()</function>
* functions.
**/
static freed_pool_t freed_pattern_pool[5];
static const cairo_solid_pattern_t _cairo_pattern_nil = {
{
CAIRO_REFERENCE_COUNT_INVALID, /* ref_count */
CAIRO_STATUS_NO_MEMORY, /* status */
{ 0, 0, 0, NULL }, /* user_data */
{ NULL, NULL }, /* observers */
CAIRO_PATTERN_TYPE_SOLID, /* type */
CAIRO_FILTER_DEFAULT, /* filter */
CAIRO_EXTEND_GRADIENT_DEFAULT, /* extend */
FALSE, /* has component alpha */
{ 1., 0., 0., 1., 0., 0., }, /* matrix */
1.0 /* opacity */
}
};
static const cairo_solid_pattern_t _cairo_pattern_nil_null_pointer = {
{
CAIRO_REFERENCE_COUNT_INVALID, /* ref_count */
CAIRO_STATUS_NULL_POINTER, /* status */
{ 0, 0, 0, NULL }, /* user_data */
{ NULL, NULL }, /* observers */
CAIRO_PATTERN_TYPE_SOLID, /* type */
CAIRO_FILTER_DEFAULT, /* filter */
CAIRO_EXTEND_GRADIENT_DEFAULT, /* extend */
FALSE, /* has component alpha */
{ 1., 0., 0., 1., 0., 0., }, /* matrix */
1.0 /* opacity */
}
};
const cairo_solid_pattern_t _cairo_pattern_black = {
{
CAIRO_REFERENCE_COUNT_INVALID, /* ref_count */
CAIRO_STATUS_SUCCESS, /* status */
{ 0, 0, 0, NULL }, /* user_data */
{ NULL, NULL }, /* observers */
CAIRO_PATTERN_TYPE_SOLID, /* type */
CAIRO_FILTER_NEAREST, /* filter */
CAIRO_EXTEND_REPEAT, /* extend */
FALSE, /* has component alpha */
{ 1., 0., 0., 1., 0., 0., }, /* matrix */
1.0 /* opacity */
},
{ 0., 0., 0., 1., 0, 0, 0, 0xffff },/* color (double rgba, short rgba) */
};
const cairo_solid_pattern_t _cairo_pattern_clear = {
{
CAIRO_REFERENCE_COUNT_INVALID, /* ref_count */
CAIRO_STATUS_SUCCESS, /* status */
{ 0, 0, 0, NULL }, /* user_data */
{ NULL, NULL }, /* observers */
CAIRO_PATTERN_TYPE_SOLID, /* type */
CAIRO_FILTER_NEAREST, /* filter */
CAIRO_EXTEND_REPEAT, /* extend */
FALSE, /* has component alpha */
{ 1., 0., 0., 1., 0., 0., }, /* matrix */
1.0 /* opacity */
},
{ 0., 0., 0., 0., 0, 0, 0, 0 },/* color (double rgba, short rgba) */
};
const cairo_solid_pattern_t _cairo_pattern_white = {
{
CAIRO_REFERENCE_COUNT_INVALID, /* ref_count */
CAIRO_STATUS_SUCCESS, /* status */
{ 0, 0, 0, NULL }, /* user_data */
{ NULL, NULL }, /* observers */
CAIRO_PATTERN_TYPE_SOLID, /* type */
CAIRO_FILTER_NEAREST, /* filter */
CAIRO_EXTEND_REPEAT, /* extend */
FALSE, /* has component alpha */
{ 1., 0., 0., 1., 0., 0., }, /* matrix */
1.0 /* opacity */
},
{ 1., 1., 1., 1., 0xffff, 0xffff, 0xffff, 0xffff },/* color (double rgba, short rgba) */
};
static void
_cairo_pattern_notify_observers (cairo_pattern_t *pattern,
unsigned int flags)
{
cairo_pattern_observer_t *pos;
cairo_list_foreach_entry (pos, cairo_pattern_observer_t, &pattern->observers, link)
pos->notify (pos, pattern, flags);
}
/**
* _cairo_pattern_set_error:
* @pattern: a pattern
* @status: a status value indicating an error
*
* Atomically sets pattern->status to @status and calls _cairo_error;
* Does nothing if status is %CAIRO_STATUS_SUCCESS.
*
* All assignments of an error status to pattern->status should happen
* through _cairo_pattern_set_error(). Note that due to the nature of
* the atomic operation, it is not safe to call this function on the nil
* objects.
*
* The purpose of this function is to allow the user to set a
* breakpoint in _cairo_error() to generate a stack trace for when the
* user causes cairo to detect an error.
**/
static cairo_status_t
_cairo_pattern_set_error (cairo_pattern_t *pattern,
cairo_status_t status)
{
if (status == CAIRO_STATUS_SUCCESS)
return status;
/* Don't overwrite an existing error. This preserves the first
* error, which is the most significant. */
_cairo_status_set_error (&pattern->status, status);
return _cairo_error (status);
}
void
_cairo_pattern_init (cairo_pattern_t *pattern, cairo_pattern_type_t type)
{
#if HAVE_VALGRIND
switch (type) {
case CAIRO_PATTERN_TYPE_SOLID:
VALGRIND_MAKE_MEM_UNDEFINED (pattern, sizeof (cairo_solid_pattern_t));
break;
case CAIRO_PATTERN_TYPE_SURFACE:
VALGRIND_MAKE_MEM_UNDEFINED (pattern, sizeof (cairo_surface_pattern_t));
break;
case CAIRO_PATTERN_TYPE_LINEAR:
VALGRIND_MAKE_MEM_UNDEFINED (pattern, sizeof (cairo_linear_pattern_t));
break;
case CAIRO_PATTERN_TYPE_RADIAL:
VALGRIND_MAKE_MEM_UNDEFINED (pattern, sizeof (cairo_radial_pattern_t));
break;
case CAIRO_PATTERN_TYPE_MESH:
VALGRIND_MAKE_MEM_UNDEFINED (pattern, sizeof (cairo_mesh_pattern_t));
break;
case CAIRO_PATTERN_TYPE_RASTER_SOURCE:
break;
}
#endif
pattern->type = type;
pattern->status = CAIRO_STATUS_SUCCESS;
/* Set the reference count to zero for on-stack patterns.
* Callers needs to explicitly increment the count for heap allocations. */
CAIRO_REFERENCE_COUNT_INIT (&pattern->ref_count, 0);
_cairo_user_data_array_init (&pattern->user_data);
if (type == CAIRO_PATTERN_TYPE_SURFACE ||
type == CAIRO_PATTERN_TYPE_RASTER_SOURCE)
pattern->extend = CAIRO_EXTEND_SURFACE_DEFAULT;
else
pattern->extend = CAIRO_EXTEND_GRADIENT_DEFAULT;
pattern->filter = CAIRO_FILTER_DEFAULT;
pattern->opacity = 1.0;
pattern->has_component_alpha = FALSE;
cairo_matrix_init_identity (&pattern->matrix);
cairo_list_init (&pattern->observers);
}
static cairo_status_t
_cairo_gradient_pattern_init_copy (cairo_gradient_pattern_t *pattern,
const cairo_gradient_pattern_t *other)
{
if (CAIRO_INJECT_FAULT ())
return _cairo_error (CAIRO_STATUS_NO_MEMORY);
if (other->base.type == CAIRO_PATTERN_TYPE_LINEAR)
{
cairo_linear_pattern_t *dst = (cairo_linear_pattern_t *) pattern;
cairo_linear_pattern_t *src = (cairo_linear_pattern_t *) other;
*dst = *src;
}
else
{
cairo_radial_pattern_t *dst = (cairo_radial_pattern_t *) pattern;
cairo_radial_pattern_t *src = (cairo_radial_pattern_t *) other;
*dst = *src;
}
if (other->stops == other->stops_embedded)
pattern->stops = pattern->stops_embedded;
else if (other->stops)
{
pattern->stops = _cairo_malloc_ab (other->stops_size,
sizeof (cairo_gradient_stop_t));
if (unlikely (pattern->stops == NULL)) {
pattern->stops_size = 0;
pattern->n_stops = 0;
return _cairo_pattern_set_error (&pattern->base, CAIRO_STATUS_NO_MEMORY);
}
memcpy (pattern->stops, other->stops,
other->n_stops * sizeof (cairo_gradient_stop_t));
}
return CAIRO_STATUS_SUCCESS;
}
static cairo_status_t
_cairo_mesh_pattern_init_copy (cairo_mesh_pattern_t *pattern,
const cairo_mesh_pattern_t *other)
{
*pattern = *other;
_cairo_array_init (&pattern->patches, sizeof (cairo_mesh_patch_t));
return _cairo_array_append_multiple (&pattern->patches,
_cairo_array_index_const (&other->patches, 0),
_cairo_array_num_elements (&other->patches));
}
cairo_status_t
_cairo_pattern_init_copy (cairo_pattern_t *pattern,
const cairo_pattern_t *other)
{
cairo_status_t status;
if (other->status)
return _cairo_pattern_set_error (pattern, other->status);
switch (other->type) {
case CAIRO_PATTERN_TYPE_SOLID: {
cairo_solid_pattern_t *dst = (cairo_solid_pattern_t *) pattern;
cairo_solid_pattern_t *src = (cairo_solid_pattern_t *) other;
VG (VALGRIND_MAKE_MEM_UNDEFINED (pattern, sizeof (cairo_solid_pattern_t)));
*dst = *src;
} break;
case CAIRO_PATTERN_TYPE_SURFACE: {
cairo_surface_pattern_t *dst = (cairo_surface_pattern_t *) pattern;
cairo_surface_pattern_t *src = (cairo_surface_pattern_t *) other;
VG (VALGRIND_MAKE_MEM_UNDEFINED (pattern, sizeof (cairo_surface_pattern_t)));
*dst = *src;
cairo_surface_reference (dst->surface);
} break;
case CAIRO_PATTERN_TYPE_LINEAR:
case CAIRO_PATTERN_TYPE_RADIAL: {
cairo_gradient_pattern_t *dst = (cairo_gradient_pattern_t *) pattern;
cairo_gradient_pattern_t *src = (cairo_gradient_pattern_t *) other;
if (other->type == CAIRO_PATTERN_TYPE_LINEAR) {
VG (VALGRIND_MAKE_MEM_UNDEFINED (pattern, sizeof (cairo_linear_pattern_t)));
} else {
VG (VALGRIND_MAKE_MEM_UNDEFINED (pattern, sizeof (cairo_radial_pattern_t)));
}
status = _cairo_gradient_pattern_init_copy (dst, src);
if (unlikely (status))
return status;
} break;
case CAIRO_PATTERN_TYPE_MESH: {
cairo_mesh_pattern_t *dst = (cairo_mesh_pattern_t *) pattern;
cairo_mesh_pattern_t *src = (cairo_mesh_pattern_t *) other;
VG (VALGRIND_MAKE_MEM_UNDEFINED (pattern, sizeof (cairo_mesh_pattern_t)));
status = _cairo_mesh_pattern_init_copy (dst, src);
if (unlikely (status))
return status;
} break;
case CAIRO_PATTERN_TYPE_RASTER_SOURCE: {
status = _cairo_raster_source_pattern_init_copy (pattern, other);
if (unlikely (status))
return status;
} break;
}
/* The reference count and user_data array are unique to the copy. */
CAIRO_REFERENCE_COUNT_INIT (&pattern->ref_count, 0);
_cairo_user_data_array_init (&pattern->user_data);
return CAIRO_STATUS_SUCCESS;
}
void
_cairo_pattern_init_static_copy (cairo_pattern_t *pattern,
const cairo_pattern_t *other)
{
int size;
assert (other->status == CAIRO_STATUS_SUCCESS);
switch (other->type) {
default:
ASSERT_NOT_REACHED;
case CAIRO_PATTERN_TYPE_SOLID:
size = sizeof (cairo_solid_pattern_t);
break;
case CAIRO_PATTERN_TYPE_SURFACE:
size = sizeof (cairo_surface_pattern_t);
break;
case CAIRO_PATTERN_TYPE_LINEAR:
size = sizeof (cairo_linear_pattern_t);
break;
case CAIRO_PATTERN_TYPE_RADIAL:
size = sizeof (cairo_radial_pattern_t);
break;
case CAIRO_PATTERN_TYPE_MESH:
size = sizeof (cairo_mesh_pattern_t);
break;
case CAIRO_PATTERN_TYPE_RASTER_SOURCE:
size = sizeof (cairo_raster_source_pattern_t);
break;
}
memcpy (pattern, other, size);
CAIRO_REFERENCE_COUNT_INIT (&pattern->ref_count, 0);
_cairo_user_data_array_init (&pattern->user_data);
}
cairo_status_t
_cairo_pattern_init_snapshot (cairo_pattern_t *pattern,
const cairo_pattern_t *other)
{
cairo_status_t status;
/* We don't bother doing any fancy copy-on-write implementation
* for the pattern's data. It's generally quite tiny. */
status = _cairo_pattern_init_copy (pattern, other);
if (unlikely (status))
return status;
/* But we do let the surface snapshot stuff be as fancy as it
* would like to be. */
if (pattern->type == CAIRO_PATTERN_TYPE_SURFACE) {
cairo_surface_pattern_t *surface_pattern =
(cairo_surface_pattern_t *) pattern;
cairo_surface_t *surface = surface_pattern->surface;
surface_pattern->surface = _cairo_surface_snapshot (surface);
cairo_surface_destroy (surface);
status = surface_pattern->surface->status;
} else if (pattern->type == CAIRO_PATTERN_TYPE_RASTER_SOURCE)
status = _cairo_raster_source_pattern_snapshot (pattern);
return status;
}
void
_cairo_pattern_fini (cairo_pattern_t *pattern)
{
_cairo_user_data_array_fini (&pattern->user_data);
switch (pattern->type) {
case CAIRO_PATTERN_TYPE_SOLID:
break;
case CAIRO_PATTERN_TYPE_SURFACE: {
cairo_surface_pattern_t *surface_pattern =
(cairo_surface_pattern_t *) pattern;
cairo_surface_destroy (surface_pattern->surface);
} break;
case CAIRO_PATTERN_TYPE_LINEAR:
case CAIRO_PATTERN_TYPE_RADIAL: {
cairo_gradient_pattern_t *gradient =
(cairo_gradient_pattern_t *) pattern;
if (gradient->stops && gradient->stops != gradient->stops_embedded)
free (gradient->stops);
} break;
case CAIRO_PATTERN_TYPE_MESH: {
cairo_mesh_pattern_t *mesh =
(cairo_mesh_pattern_t *) pattern;
_cairo_array_fini (&mesh->patches);
} break;
case CAIRO_PATTERN_TYPE_RASTER_SOURCE:
_cairo_raster_source_pattern_finish (pattern);
break;
}
#if HAVE_VALGRIND
switch (pattern->type) {
case CAIRO_PATTERN_TYPE_SOLID:
VALGRIND_MAKE_MEM_NOACCESS (pattern, sizeof (cairo_solid_pattern_t));
break;
case CAIRO_PATTERN_TYPE_SURFACE:
VALGRIND_MAKE_MEM_NOACCESS (pattern, sizeof (cairo_surface_pattern_t));
break;
case CAIRO_PATTERN_TYPE_LINEAR:
VALGRIND_MAKE_MEM_NOACCESS (pattern, sizeof (cairo_linear_pattern_t));
break;
case CAIRO_PATTERN_TYPE_RADIAL:
VALGRIND_MAKE_MEM_NOACCESS (pattern, sizeof (cairo_radial_pattern_t));
break;
case CAIRO_PATTERN_TYPE_MESH:
VALGRIND_MAKE_MEM_NOACCESS (pattern, sizeof (cairo_mesh_pattern_t));
break;
case CAIRO_PATTERN_TYPE_RASTER_SOURCE:
break;
}
#endif
}
cairo_status_t
_cairo_pattern_create_copy (cairo_pattern_t **pattern_out,
const cairo_pattern_t *other)
{
cairo_pattern_t *pattern;
cairo_status_t status;
if (other->status)
return other->status;
switch (other->type) {
case CAIRO_PATTERN_TYPE_SOLID:
pattern = malloc (sizeof (cairo_solid_pattern_t));
break;
case CAIRO_PATTERN_TYPE_SURFACE:
pattern = malloc (sizeof (cairo_surface_pattern_t));
break;
case CAIRO_PATTERN_TYPE_LINEAR:
pattern = malloc (sizeof (cairo_linear_pattern_t));
break;
case CAIRO_PATTERN_TYPE_RADIAL:
pattern = malloc (sizeof (cairo_radial_pattern_t));
break;
case CAIRO_PATTERN_TYPE_MESH:
pattern = malloc (sizeof (cairo_mesh_pattern_t));
break;
case CAIRO_PATTERN_TYPE_RASTER_SOURCE:
pattern = malloc (sizeof (cairo_raster_source_pattern_t));
break;
default:
ASSERT_NOT_REACHED;
return _cairo_error (CAIRO_STATUS_PATTERN_TYPE_MISMATCH);
}
if (unlikely (pattern == NULL))
return _cairo_error (CAIRO_STATUS_NO_MEMORY);
status = _cairo_pattern_init_copy (pattern, other);
if (unlikely (status)) {
free (pattern);
return status;
}
CAIRO_REFERENCE_COUNT_INIT (&pattern->ref_count, 1);
*pattern_out = pattern;
return CAIRO_STATUS_SUCCESS;
}
void
_cairo_pattern_init_solid (cairo_solid_pattern_t *pattern,
const cairo_color_t *color)
{
_cairo_pattern_init (&pattern->base, CAIRO_PATTERN_TYPE_SOLID);
pattern->color = *color;
}
void
_cairo_pattern_init_for_surface (cairo_surface_pattern_t *pattern,
cairo_surface_t *surface)
{
if (surface->status) {
/* Force to solid to simplify the pattern_fini process. */
_cairo_pattern_init (&pattern->base, CAIRO_PATTERN_TYPE_SOLID);
_cairo_pattern_set_error (&pattern->base, surface->status);
return;
}
_cairo_pattern_init (&pattern->base, CAIRO_PATTERN_TYPE_SURFACE);
pattern->surface = cairo_surface_reference (surface);
}
static void
_cairo_pattern_init_gradient (cairo_gradient_pattern_t *pattern,
cairo_pattern_type_t type)
{
_cairo_pattern_init (&pattern->base, type);
pattern->n_stops = 0;
pattern->stops_size = 0;
pattern->stops = NULL;
}
static void
_cairo_pattern_init_linear (cairo_linear_pattern_t *pattern,
double x0, double y0, double x1, double y1)
{
_cairo_pattern_init_gradient (&pattern->base, CAIRO_PATTERN_TYPE_LINEAR);
pattern->pd1.x = x0;
pattern->pd1.y = y0;
pattern->pd2.x = x1;
pattern->pd2.y = y1;
}
static void
_cairo_pattern_init_radial (cairo_radial_pattern_t *pattern,
double cx0, double cy0, double radius0,
double cx1, double cy1, double radius1)
{
_cairo_pattern_init_gradient (&pattern->base, CAIRO_PATTERN_TYPE_RADIAL);
pattern->cd1.center.x = cx0;
pattern->cd1.center.y = cy0;
pattern->cd1.radius = fabs (radius0);
pattern->cd2.center.x = cx1;
pattern->cd2.center.y = cy1;
pattern->cd2.radius = fabs (radius1);
}
cairo_pattern_t *
_cairo_pattern_create_solid (const cairo_color_t *color)
{
cairo_solid_pattern_t *pattern;
pattern =
_freed_pool_get (&freed_pattern_pool[CAIRO_PATTERN_TYPE_SOLID]);
if (unlikely (pattern == NULL)) {
/* None cached, need to create a new pattern. */
pattern = malloc (sizeof (cairo_solid_pattern_t));
if (unlikely (pattern == NULL)) {
_cairo_error_throw (CAIRO_STATUS_NO_MEMORY);
return (cairo_pattern_t *) &_cairo_pattern_nil;
}
}
_cairo_pattern_init_solid (pattern, color);
CAIRO_REFERENCE_COUNT_INIT (&pattern->base.ref_count, 1);
return &pattern->base;
}
cairo_pattern_t *
_cairo_pattern_create_in_error (cairo_status_t status)
{
cairo_pattern_t *pattern;
if (status == CAIRO_STATUS_NO_MEMORY)
return (cairo_pattern_t *)&_cairo_pattern_nil.base;
CAIRO_MUTEX_INITIALIZE ();
pattern = _cairo_pattern_create_solid (CAIRO_COLOR_BLACK);
if (pattern->status == CAIRO_STATUS_SUCCESS)
status = _cairo_pattern_set_error (pattern, status);
return pattern;
}
/**
* cairo_pattern_create_rgb:
* @red: red component of the color
* @green: green component of the color
* @blue: blue component of the color
*
* Creates a new #cairo_pattern_t corresponding to an opaque color. The
* color components are floating point numbers in the range 0 to 1.
* If the values passed in are outside that range, they will be
* clamped.
*
* Return value: the newly created #cairo_pattern_t if successful, or
* an error pattern in case of no memory. The caller owns the
* returned object and should call cairo_pattern_destroy() when
* finished with it.
*
* This function will always return a valid pointer, but if an error
* occurred the pattern status will be set to an error. To inspect
* the status of a pattern use cairo_pattern_status().
*
* Since: 1.0
**/
cairo_pattern_t *
cairo_pattern_create_rgb (double red, double green, double blue)
{
return cairo_pattern_create_rgba (red, green, blue, 1.0);
}
slim_hidden_def (cairo_pattern_create_rgb);
/**
* cairo_pattern_create_rgba:
* @red: red component of the color
* @green: green component of the color
* @blue: blue component of the color
* @alpha: alpha component of the color
*
* Creates a new #cairo_pattern_t corresponding to a translucent color.
* The color components are floating point numbers in the range 0 to
* 1. If the values passed in are outside that range, they will be
* clamped.
*
* Return value: the newly created #cairo_pattern_t if successful, or
* an error pattern in case of no memory. The caller owns the
* returned object and should call cairo_pattern_destroy() when
* finished with it.
*
* This function will always return a valid pointer, but if an error
* occurred the pattern status will be set to an error. To inspect
* the status of a pattern use cairo_pattern_status().
*
* Since: 1.0
**/
cairo_pattern_t *
cairo_pattern_create_rgba (double red, double green, double blue,
double alpha)
{
cairo_color_t color;
red = _cairo_restrict_value (red, 0.0, 1.0);
green = _cairo_restrict_value (green, 0.0, 1.0);
blue = _cairo_restrict_value (blue, 0.0, 1.0);
alpha = _cairo_restrict_value (alpha, 0.0, 1.0);
_cairo_color_init_rgba (&color, red, green, blue, alpha);
CAIRO_MUTEX_INITIALIZE ();
return _cairo_pattern_create_solid (&color);
}
slim_hidden_def (cairo_pattern_create_rgba);
/**
* cairo_pattern_create_for_surface:
* @surface: the surface
*
* Create a new #cairo_pattern_t for the given surface.
*
* Return value: the newly created #cairo_pattern_t if successful, or
* an error pattern in case of no memory. The caller owns the
* returned object and should call cairo_pattern_destroy() when
* finished with it.
*
* This function will always return a valid pointer, but if an error
* occurred the pattern status will be set to an error. To inspect
* the status of a pattern use cairo_pattern_status().
*
* Since: 1.0
**/
cairo_pattern_t *
cairo_pattern_create_for_surface (cairo_surface_t *surface)
{
cairo_surface_pattern_t *pattern;
if (surface == NULL) {
_cairo_error_throw (CAIRO_STATUS_NULL_POINTER);
return (cairo_pattern_t*) &_cairo_pattern_nil_null_pointer;
}
if (surface->status)
return _cairo_pattern_create_in_error (surface->status);
pattern =
_freed_pool_get (&freed_pattern_pool[CAIRO_PATTERN_TYPE_SURFACE]);
if (unlikely (pattern == NULL)) {
pattern = malloc (sizeof (cairo_surface_pattern_t));
if (unlikely (pattern == NULL)) {
_cairo_error_throw (CAIRO_STATUS_NO_MEMORY);
return (cairo_pattern_t *)&_cairo_pattern_nil.base;
}
}
CAIRO_MUTEX_INITIALIZE ();
_cairo_pattern_init_for_surface (pattern, surface);
CAIRO_REFERENCE_COUNT_INIT (&pattern->base.ref_count, 1);
return &pattern->base;
}
slim_hidden_def (cairo_pattern_create_for_surface);
/**
* cairo_pattern_create_linear:
* @x0: x coordinate of the start point
* @y0: y coordinate of the start point
* @x1: x coordinate of the end point
* @y1: y coordinate of the end point
*
* Create a new linear gradient #cairo_pattern_t along the line defined
* by (x0, y0) and (x1, y1). Before using the gradient pattern, a
* number of color stops should be defined using
* cairo_pattern_add_color_stop_rgb() or
* cairo_pattern_add_color_stop_rgba().
*
* Note: The coordinates here are in pattern space. For a new pattern,
* pattern space is identical to user space, but the relationship
* between the spaces can be changed with cairo_pattern_set_matrix().
*
* Return value: the newly created #cairo_pattern_t if successful, or
* an error pattern in case of no memory. The caller owns the
* returned object and should call cairo_pattern_destroy() when
* finished with it.
*
* This function will always return a valid pointer, but if an error
* occurred the pattern status will be set to an error. To inspect
* the status of a pattern use cairo_pattern_status().
*
* Since: 1.0
**/
cairo_pattern_t *
cairo_pattern_create_linear (double x0, double y0, double x1, double y1)
{
cairo_linear_pattern_t *pattern;
pattern =
_freed_pool_get (&freed_pattern_pool[CAIRO_PATTERN_TYPE_LINEAR]);
if (unlikely (pattern == NULL)) {
pattern = malloc (sizeof (cairo_linear_pattern_t));
if (unlikely (pattern == NULL)) {
_cairo_error_throw (CAIRO_STATUS_NO_MEMORY);
return (cairo_pattern_t *) &_cairo_pattern_nil.base;
}
}
CAIRO_MUTEX_INITIALIZE ();
_cairo_pattern_init_linear (pattern, x0, y0, x1, y1);
CAIRO_REFERENCE_COUNT_INIT (&pattern->base.base.ref_count, 1);
return &pattern->base.base;
}
/**
* cairo_pattern_create_radial:
* @cx0: x coordinate for the center of the start circle
* @cy0: y coordinate for the center of the start circle
* @radius0: radius of the start circle
* @cx1: x coordinate for the center of the end circle
* @cy1: y coordinate for the center of the end circle
* @radius1: radius of the end circle
*
* Creates a new radial gradient #cairo_pattern_t between the two
* circles defined by (cx0, cy0, radius0) and (cx1, cy1, radius1). Before using the
* gradient pattern, a number of color stops should be defined using
* cairo_pattern_add_color_stop_rgb() or
* cairo_pattern_add_color_stop_rgba().
*
* Note: The coordinates here are in pattern space. For a new pattern,
* pattern space is identical to user space, but the relationship
* between the spaces can be changed with cairo_pattern_set_matrix().
*
* Return value: the newly created #cairo_pattern_t if successful, or
* an error pattern in case of no memory. The caller owns the
* returned object and should call cairo_pattern_destroy() when
* finished with it.
*
* This function will always return a valid pointer, but if an error
* occurred the pattern status will be set to an error. To inspect
* the status of a pattern use cairo_pattern_status().
*
* Since: 1.0
**/
cairo_pattern_t *
cairo_pattern_create_radial (double cx0, double cy0, double radius0,
double cx1, double cy1, double radius1)
{
cairo_radial_pattern_t *pattern;
pattern =
_freed_pool_get (&freed_pattern_pool[CAIRO_PATTERN_TYPE_RADIAL]);
if (unlikely (pattern == NULL)) {
pattern = malloc (sizeof (cairo_radial_pattern_t));
if (unlikely (pattern == NULL)) {
_cairo_error_throw (CAIRO_STATUS_NO_MEMORY);
return (cairo_pattern_t *) &_cairo_pattern_nil.base;
}
}
CAIRO_MUTEX_INITIALIZE ();
_cairo_pattern_init_radial (pattern, cx0, cy0, radius0, cx1, cy1, radius1);
CAIRO_REFERENCE_COUNT_INIT (&pattern->base.base.ref_count, 1);
return &pattern->base.base;
}
/* This order is specified in the diagram in the documentation for
* cairo_pattern_create_mesh() */
static const int mesh_path_point_i[12] = { 0, 0, 0, 0, 1, 2, 3, 3, 3, 3, 2, 1 };
static const int mesh_path_point_j[12] = { 0, 1, 2, 3, 3, 3, 3, 2, 1, 0, 0, 0 };
static const int mesh_control_point_i[4] = { 1, 1, 2, 2 };
static const int mesh_control_point_j[4] = { 1, 2, 2, 1 };
/**
* cairo_pattern_create_mesh:
*
* Create a new mesh pattern.
*
* Mesh patterns are tensor-product patch meshes (type 7 shadings in
* PDF). Mesh patterns may also be used to create other types of
* shadings that are special cases of tensor-product patch meshes such
* as Coons patch meshes (type 6 shading in PDF) and Gouraud-shaded
* triangle meshes (type 4 and 5 shadings in PDF).
*
* Mesh patterns consist of one or more tensor-product patches, which
* should be defined before using the mesh pattern. Using a mesh
* pattern with a partially defined patch as source or mask will put
* the context in an error status with a status of
* %CAIRO_STATUS_INVALID_MESH_CONSTRUCTION.
*
* A tensor-product patch is defined by 4 Bézier curves (side 0, 1, 2,
* 3) and by 4 additional control points (P0, P1, P2, P3) that provide
* further control over the patch and complete the definition of the
* tensor-product patch. The corner C0 is the first point of the
* patch.
*
* Degenerate sides are permitted so straight lines may be used. A
* zero length line on one side may be used to create 3 sided patches.
*
* <informalexample><screen>
* C1 Side 1 C2
* +---------------+
* | |
* | P1 P2 |
* | |
* Side 0 | | Side 2
* | |
* | |
* | P0 P3 |
* | |
* +---------------+
* C0 Side 3 C3
* </screen></informalexample>
*
* Each patch is constructed by first calling
* cairo_mesh_pattern_begin_patch(), then cairo_mesh_pattern_move_to()
* to specify the first point in the patch (C0). Then the sides are
* specified with calls to cairo_mesh_pattern_curve_to() and
* cairo_mesh_pattern_line_to().
*
* The four additional control points (P0, P1, P2, P3) in a patch can
* be specified with cairo_mesh_pattern_set_control_point().
*
* At each corner of the patch (C0, C1, C2, C3) a color may be
* specified with cairo_mesh_pattern_set_corner_color_rgb() or
* cairo_mesh_pattern_set_corner_color_rgba(). Any corner whose color
* is not explicitly specified defaults to transparent black.
*
* A Coons patch is a special case of the tensor-product patch where
* the control points are implicitly defined by the sides of the
* patch. The default value for any control point not specified is the
* implicit value for a Coons patch, i.e. if no control points are
* specified the patch is a Coons patch.
*
* A triangle is a special case of the tensor-product patch where the
* control points are implicitly defined by the sides of the patch,
* all the sides are lines and one of them has length 0, i.e. if the
* patch is specified using just 3 lines, it is a triangle. If the
* corners connected by the 0-length side have the same color, the
* patch is a Gouraud-shaded triangle.
*
* Patches may be oriented differently to the above diagram. For
* example the first point could be at the top left. The diagram only
* shows the relationship between the sides, corners and control
* points. Regardless of where the first point is located, when
* specifying colors, corner 0 will always be the first point, corner
* 1 the point between side 0 and side 1 etc.
*
* Calling cairo_mesh_pattern_end_patch() completes the current
* patch. If less than 4 sides have been defined, the first missing
* side is defined as a line from the current point to the first point
* of the patch (C0) and the other sides are degenerate lines from C0
* to C0. The corners between the added sides will all be coincident
* with C0 of the patch and their color will be set to be the same as
* the color of C0.
*
* Additional patches may be added with additional calls to
* cairo_mesh_pattern_begin_patch()/cairo_mesh_pattern_end_patch().
*
* <informalexample><programlisting>
* cairo_pattern_t *pattern = cairo_pattern_create_mesh ();
*
* /&ast; Add a Coons patch &ast;/
* cairo_mesh_pattern_begin_patch (pattern);
* cairo_mesh_pattern_move_to (pattern, 0, 0);
* cairo_mesh_pattern_curve_to (pattern, 30, -30, 60, 30, 100, 0);
* cairo_mesh_pattern_curve_to (pattern, 60, 30, 130, 60, 100, 100);
* cairo_mesh_pattern_curve_to (pattern, 60, 70, 30, 130, 0, 100);
* cairo_mesh_pattern_curve_to (pattern, 30, 70, -30, 30, 0, 0);
* cairo_mesh_pattern_set_corner_color_rgb (pattern, 0, 1, 0, 0);
* cairo_mesh_pattern_set_corner_color_rgb (pattern, 1, 0, 1, 0);
* cairo_mesh_pattern_set_corner_color_rgb (pattern, 2, 0, 0, 1);
* cairo_mesh_pattern_set_corner_color_rgb (pattern, 3, 1, 1, 0);
* cairo_mesh_pattern_end_patch (pattern);
*
* /&ast; Add a Gouraud-shaded triangle &ast;/
* cairo_mesh_pattern_begin_patch (pattern)
* cairo_mesh_pattern_move_to (pattern, 100, 100);
* cairo_mesh_pattern_line_to (pattern, 130, 130);
* cairo_mesh_pattern_line_to (pattern, 130, 70);
* cairo_mesh_pattern_set_corner_color_rgb (pattern, 0, 1, 0, 0);
* cairo_mesh_pattern_set_corner_color_rgb (pattern, 1, 0, 1, 0);
* cairo_mesh_pattern_set_corner_color_rgb (pattern, 2, 0, 0, 1);
* cairo_mesh_pattern_end_patch (pattern)
* </programlisting></informalexample>
*
* When two patches overlap, the last one that has been added is drawn
* over the first one.
*
* When a patch folds over itself, points are sorted depending on
* their parameter coordinates inside the patch. The v coordinate
* ranges from 0 to 1 when moving from side 3 to side 1; the u
* coordinate ranges from 0 to 1 when going from side 0 to side
* 2. Points with higher v coordinate hide points with lower v
* coordinate. When two points have the same v coordinate, the one
* with higher u coordinate is above. This means that points nearer to
* side 1 are above points nearer to side 3; when this is not
* sufficient to decide which point is above (for example when both
* points belong to side 1 or side 3) points nearer to side 2 are
* above points nearer to side 0.
*
* For a complete definition of tensor-product patches, see the PDF
* specification (ISO32000), which describes the parametrization in
* detail.
*
* Note: The coordinates are always in pattern space. For a new
* pattern, pattern space is identical to user space, but the
* relationship between the spaces can be changed with
* cairo_pattern_set_matrix().
*
* Return value: the newly created #cairo_pattern_t if successful, or
* an error pattern in case of no memory. The caller owns the returned
* object and should call cairo_pattern_destroy() when finished with
* it.
*
* This function will always return a valid pointer, but if an error
* occurred the pattern status will be set to an error. To inspect the
* status of a pattern use cairo_pattern_status().
*
* Since: 1.12
**/
cairo_pattern_t *
cairo_pattern_create_mesh (void)
{
cairo_mesh_pattern_t *pattern;
pattern =
_freed_pool_get (&freed_pattern_pool[CAIRO_PATTERN_TYPE_MESH]);
if (unlikely (pattern == NULL)) {
pattern = malloc (sizeof (cairo_mesh_pattern_t));
if (unlikely (pattern == NULL)) {
_cairo_error_throw (CAIRO_STATUS_NO_MEMORY);
return (cairo_pattern_t *) &_cairo_pattern_nil.base;
}
}
CAIRO_MUTEX_INITIALIZE ();
_cairo_pattern_init (&pattern->base, CAIRO_PATTERN_TYPE_MESH);
_cairo_array_init (&pattern->patches, sizeof (cairo_mesh_patch_t));
pattern->current_patch = NULL;
CAIRO_REFERENCE_COUNT_INIT (&pattern->base.ref_count, 1);
return &pattern->base;
}
/**
* cairo_pattern_reference:
* @pattern: a #cairo_pattern_t
*
* Increases the reference count on @pattern by one. This prevents
* @pattern from being destroyed until a matching call to
* cairo_pattern_destroy() is made.
*
* The number of references to a #cairo_pattern_t can be get using
* cairo_pattern_get_reference_count().
*
* Return value: the referenced #cairo_pattern_t.
*
* Since: 1.0
**/
cairo_pattern_t *
cairo_pattern_reference (cairo_pattern_t *pattern)
{
if (pattern == NULL ||
CAIRO_REFERENCE_COUNT_IS_INVALID (&pattern->ref_count))
return pattern;
assert (CAIRO_REFERENCE_COUNT_HAS_REFERENCE (&pattern->ref_count));
_cairo_reference_count_inc (&pattern->ref_count);
return pattern;
}
slim_hidden_def (cairo_pattern_reference);
/**
* cairo_pattern_get_type:
* @pattern: a #cairo_pattern_t
*
* This function returns the type a pattern.
* See #cairo_pattern_type_t for available types.
*
* Return value: The type of @pattern.
*
* Since: 1.2
**/
cairo_pattern_type_t
cairo_pattern_get_type (cairo_pattern_t *pattern)
{
return pattern->type;
}
/**
* cairo_pattern_status:
* @pattern: a #cairo_pattern_t
*
* Checks whether an error has previously occurred for this
* pattern.
*
* Return value: %CAIRO_STATUS_SUCCESS, %CAIRO_STATUS_NO_MEMORY,
* %CAIRO_STATUS_INVALID_MATRIX, %CAIRO_STATUS_PATTERN_TYPE_MISMATCH,
* or %CAIRO_STATUS_INVALID_MESH_CONSTRUCTION.
*
* Since: 1.0
**/
cairo_status_t
cairo_pattern_status (cairo_pattern_t *pattern)
{
return pattern->status;
}
/**
* cairo_pattern_destroy:
* @pattern: a #cairo_pattern_t
*
* Decreases the reference count on @pattern by one. If the result is
* zero, then @pattern and all associated resources are freed. See
* cairo_pattern_reference().
*
* Since: 1.0
**/
void
cairo_pattern_destroy (cairo_pattern_t *pattern)
{
cairo_pattern_type_t type;
if (pattern == NULL ||
CAIRO_REFERENCE_COUNT_IS_INVALID (&pattern->ref_count))
return;
assert (CAIRO_REFERENCE_COUNT_HAS_REFERENCE (&pattern->ref_count));
if (! _cairo_reference_count_dec_and_test (&pattern->ref_count))
return;
type = pattern->type;
_cairo_pattern_fini (pattern);
/* maintain a small cache of freed patterns */
if (type < ARRAY_LENGTH (freed_pattern_pool))
_freed_pool_put (&freed_pattern_pool[type], pattern);
else
free (pattern);
}
slim_hidden_def (cairo_pattern_destroy);
/**
* cairo_pattern_get_reference_count:
* @pattern: a #cairo_pattern_t
*
* Returns the current reference count of @pattern.
*
* Return value: the current reference count of @pattern. If the
* object is a nil object, 0 will be returned.
*
* Since: 1.4
**/
unsigned int
cairo_pattern_get_reference_count (cairo_pattern_t *pattern)
{
if (pattern == NULL ||
CAIRO_REFERENCE_COUNT_IS_INVALID (&pattern->ref_count))
return 0;
return CAIRO_REFERENCE_COUNT_GET_VALUE (&pattern->ref_count);
}
/**
* cairo_pattern_get_user_data:
* @pattern: a #cairo_pattern_t
* @key: the address of the #cairo_user_data_key_t the user data was
* attached to
*
* Return user data previously attached to @pattern using the
* specified key. If no user data has been attached with the given
* key this function returns %NULL.
*
* Return value: the user data previously attached or %NULL.
*
* Since: 1.4
**/
void *
cairo_pattern_get_user_data (cairo_pattern_t *pattern,
const cairo_user_data_key_t *key)
{
return _cairo_user_data_array_get_data (&pattern->user_data,
key);
}
/**
* cairo_pattern_set_user_data:
* @pattern: a #cairo_pattern_t
* @key: the address of a #cairo_user_data_key_t to attach the user data to
* @user_data: the user data to attach to the #cairo_pattern_t
* @destroy: a #cairo_destroy_func_t which will be called when the
* #cairo_t is destroyed or when new user data is attached using the
* same key.
*
* Attach user data to @pattern. To remove user data from a surface,
* call this function with the key that was used to set it and %NULL
* for @data.
*
* Return value: %CAIRO_STATUS_SUCCESS or %CAIRO_STATUS_NO_MEMORY if a
* slot could not be allocated for the user data.
*
* Since: 1.4
**/
cairo_status_t
cairo_pattern_set_user_data (cairo_pattern_t *pattern,
const cairo_user_data_key_t *key,
void *user_data,
cairo_destroy_func_t destroy)
{
if (CAIRO_REFERENCE_COUNT_IS_INVALID (&pattern->ref_count))
return pattern->status;
return _cairo_user_data_array_set_data (&pattern->user_data,
key, user_data, destroy);
}
/**
* cairo_mesh_pattern_begin_patch:
* @pattern: a #cairo_pattern_t
*
* Begin a patch in a mesh pattern.
*
* After calling this function, the patch shape should be defined with
* cairo_mesh_pattern_move_to(), cairo_mesh_pattern_line_to() and
* cairo_mesh_pattern_curve_to().
*
* After defining the patch, cairo_mesh_pattern_end_patch() must be
* called before using @pattern as a source or mask.
*
* Note: If @pattern is not a mesh pattern then @pattern will be put
* into an error status with a status of
* %CAIRO_STATUS_PATTERN_TYPE_MISMATCH. If @pattern already has a
* current patch, it will be put into an error status with a status of
* %CAIRO_STATUS_INVALID_MESH_CONSTRUCTION.
*
* Since: 1.12
**/
void
cairo_mesh_pattern_begin_patch (cairo_pattern_t *pattern)
{
cairo_mesh_pattern_t *mesh;
cairo_status_t status;
cairo_mesh_patch_t *current_patch;
int i;
if (unlikely (pattern->status))
return;
if (unlikely (pattern->type != CAIRO_PATTERN_TYPE_MESH)) {
_cairo_pattern_set_error (pattern, CAIRO_STATUS_PATTERN_TYPE_MISMATCH);
return;
}
mesh = (cairo_mesh_pattern_t *) pattern;
if (unlikely (mesh->current_patch)) {
_cairo_pattern_set_error (pattern, CAIRO_STATUS_INVALID_MESH_CONSTRUCTION);
return;
}
status = _cairo_array_allocate (&mesh->patches, 1, (void **) &current_patch);
if (unlikely (status)) {
_cairo_pattern_set_error (pattern, status);
return;
}
mesh->current_patch = current_patch;
mesh->current_side = -2; /* no current point */
for (i = 0; i < 4; i++)
mesh->has_control_point[i] = FALSE;
for (i = 0; i < 4; i++)
mesh->has_color[i] = FALSE;
}
static void
_calc_control_point (cairo_mesh_patch_t *patch, int control_point)
{
/* The Coons patch is a special case of the Tensor Product patch
* where the four control points are:
*
* P11 = S(1/3, 1/3)
* P12 = S(1/3, 2/3)
* P21 = S(2/3, 1/3)
* P22 = S(2/3, 2/3)
*
* where S is the gradient surface.
*
* When one or more control points has not been specified
* calculated the Coons patch control points are substituted. If
* no control points are specified the gradient will be a Coons
* patch.
*
* The equations below are defined in the ISO32000 standard.
*/
cairo_point_double_t *p[3][3];
int cp_i, cp_j, i, j;
cp_i = mesh_control_point_i[control_point];
cp_j = mesh_control_point_j[control_point];
for (i = 0; i < 3; i++)
for (j = 0; j < 3; j++)
p[i][j] = &patch->points[cp_i ^ i][cp_j ^ j];
p[0][0]->x = (- 4 * p[1][1]->x
+ 6 * (p[1][0]->x + p[0][1]->x)
- 2 * (p[1][2]->x + p[2][1]->x)
+ 3 * (p[2][0]->x + p[0][2]->x)
- 1 * p[2][2]->x) * (1. / 9);
p[0][0]->y = (- 4 * p[1][1]->y
+ 6 * (p[1][0]->y + p[0][1]->y)
- 2 * (p[1][2]->y + p[2][1]->y)
+ 3 * (p[2][0]->y + p[0][2]->y)
- 1 * p[2][2]->y) * (1. / 9);
}
/**
* cairo_mesh_pattern_end_patch:
* @pattern: a #cairo_pattern_t
*
* Indicates the end of the current patch in a mesh pattern.
*
* If the current patch has less than 4 sides, it is closed with a
* straight line from the current point to the first point of the
* patch as if cairo_mesh_pattern_line_to() was used.
*
* Note: If @pattern is not a mesh pattern then @pattern will be put
* into an error status with a status of
* %CAIRO_STATUS_PATTERN_TYPE_MISMATCH. If @pattern has no current
* patch or the current patch has no current point, @pattern will be
* put into an error status with a status of
* %CAIRO_STATUS_INVALID_MESH_CONSTRUCTION.
*
* Since: 1.12
**/
void
cairo_mesh_pattern_end_patch (cairo_pattern_t *pattern)
{
cairo_mesh_pattern_t *mesh;
cairo_mesh_patch_t *current_patch;
int i;
if (unlikely (pattern->status))
return;
if (unlikely (pattern->type != CAIRO_PATTERN_TYPE_MESH)) {
_cairo_pattern_set_error (pattern, CAIRO_STATUS_PATTERN_TYPE_MISMATCH);
return;
}
mesh = (cairo_mesh_pattern_t *) pattern;
current_patch = mesh->current_patch;
if (unlikely (!current_patch)) {
_cairo_pattern_set_error (pattern, CAIRO_STATUS_INVALID_MESH_CONSTRUCTION);
return;
}
if (unlikely (mesh->current_side == -2)) {
_cairo_pattern_set_error (pattern, CAIRO_STATUS_INVALID_MESH_CONSTRUCTION);
return;
}
while (mesh->current_side < 3) {
int corner_num;
cairo_mesh_pattern_line_to (pattern,
current_patch->points[0][0].x,
current_patch->points[0][0].y);
corner_num = mesh->current_side + 1;
if (corner_num < 4 && ! mesh->has_color[corner_num]) {
current_patch->colors[corner_num] = current_patch->colors[0];
mesh->has_color[corner_num] = TRUE;
}
}
for (i = 0; i < 4; i++) {
if (! mesh->has_control_point[i])
_calc_control_point (current_patch, i);
}
for (i = 0; i < 4; i++) {
if (! mesh->has_color[i])
current_patch->colors[i] = *CAIRO_COLOR_TRANSPARENT;
}
mesh->current_patch = NULL;
}
/**
* cairo_mesh_pattern_curve_to:
* @pattern: a #cairo_pattern_t
* @x1: the X coordinate of the first control point
* @y1: the Y coordinate of the first control point
* @x2: the X coordinate of the second control point
* @y2: the Y coordinate of the second control point
* @x3: the X coordinate of the end of the curve
* @y3: the Y coordinate of the end of the curve
*
* Adds a cubic Bézier spline to the current patch from the current
* point to position (@x3, @y3) in pattern-space coordinates, using
* (@x1, @y1) and (@x2, @y2) as the control points.
*
* If the current patch has no current point before the call to
* cairo_mesh_pattern_curve_to(), this function will behave as if
* preceded by a call to cairo_mesh_pattern_move_to(@pattern, @x1,
* @y1).
*
* After this call the current point will be (@x3, @y3).
*
* Note: If @pattern is not a mesh pattern then @pattern will be put
* into an error status with a status of
* %CAIRO_STATUS_PATTERN_TYPE_MISMATCH. If @pattern has no current
* patch or the current patch already has 4 sides, @pattern will be
* put into an error status with a status of
* %CAIRO_STATUS_INVALID_MESH_CONSTRUCTION.
*
* Since: 1.12
**/
void
cairo_mesh_pattern_curve_to (cairo_pattern_t *pattern,
double x1, double y1,
double x2, double y2,
double x3, double y3)
{
cairo_mesh_pattern_t *mesh;
int current_point, i, j;
if (unlikely (pattern->status))
return;
if (unlikely (pattern->type != CAIRO_PATTERN_TYPE_MESH)) {
_cairo_pattern_set_error (pattern, CAIRO_STATUS_PATTERN_TYPE_MISMATCH);
return;
}
mesh = (cairo_mesh_pattern_t *) pattern;
if (unlikely (!mesh->current_patch)) {
_cairo_pattern_set_error (pattern, CAIRO_STATUS_INVALID_MESH_CONSTRUCTION);
return;
}
if (unlikely (mesh->current_side == 3)) {
_cairo_pattern_set_error (pattern, CAIRO_STATUS_INVALID_MESH_CONSTRUCTION);
return;
}
if (mesh->current_side == -2)
cairo_mesh_pattern_move_to (pattern, x1, y1);
assert (mesh->current_side >= -1);
assert (pattern->status == CAIRO_STATUS_SUCCESS);
mesh->current_side++;
current_point = 3 * mesh->current_side;
current_point++;
i = mesh_path_point_i[current_point];
j = mesh_path_point_j[current_point];
mesh->current_patch->points[i][j].x = x1;
mesh->current_patch->points[i][j].y = y1;
current_point++;
i = mesh_path_point_i[current_point];
j = mesh_path_point_j[current_point];
mesh->current_patch->points[i][j].x = x2;
mesh->current_patch->points[i][j].y = y2;
current_point++;
if (current_point < 12) {
i = mesh_path_point_i[current_point];
j = mesh_path_point_j[current_point];
mesh->current_patch->points[i][j].x = x3;
mesh->current_patch->points[i][j].y = y3;
}
}
slim_hidden_def (cairo_mesh_pattern_curve_to);
/**
* cairo_mesh_pattern_line_to:
* @pattern: a #cairo_pattern_t
* @x: the X coordinate of the end of the new line
* @y: the Y coordinate of the end of the new line
*
* Adds a line to the current patch from the current point to position
* (@x, @y) in pattern-space coordinates.
*
* If there is no current point before the call to
* cairo_mesh_pattern_line_to() this function will behave as
* cairo_mesh_pattern_move_to(@pattern, @x, @y).
*
* After this call the current point will be (@x, @y).
*
* Note: If @pattern is not a mesh pattern then @pattern will be put
* into an error status with a status of
* %CAIRO_STATUS_PATTERN_TYPE_MISMATCH. If @pattern has no current
* patch or the current patch already has 4 sides, @pattern will be
* put into an error status with a status of
* %CAIRO_STATUS_INVALID_MESH_CONSTRUCTION.
*
* Since: 1.12
**/
void
cairo_mesh_pattern_line_to (cairo_pattern_t *pattern,
double x, double y)
{
cairo_mesh_pattern_t *mesh;
cairo_point_double_t last_point;
int last_point_idx, i, j;
if (unlikely (pattern->status))
return;
if (unlikely (pattern->type != CAIRO_PATTERN_TYPE_MESH)) {
_cairo_pattern_set_error (pattern, CAIRO_STATUS_PATTERN_TYPE_MISMATCH);
return;
}
mesh = (cairo_mesh_pattern_t *) pattern;
if (unlikely (!mesh->current_patch)) {
_cairo_pattern_set_error (pattern, CAIRO_STATUS_INVALID_MESH_CONSTRUCTION);
return;
}
if (unlikely (mesh->current_side == 3)) {
_cairo_pattern_set_error (pattern, CAIRO_STATUS_INVALID_MESH_CONSTRUCTION);
return;
}
if (mesh->current_side == -2) {
cairo_mesh_pattern_move_to (pattern, x, y);
return;
}
last_point_idx = 3 * (mesh->current_side + 1);
i = mesh_path_point_i[last_point_idx];
j = mesh_path_point_j[last_point_idx];
last_point = mesh->current_patch->points[i][j];
cairo_mesh_pattern_curve_to (pattern,
(2 * last_point.x + x) * (1. / 3),
(2 * last_point.y + y) * (1. / 3),
(last_point.x + 2 * x) * (1. / 3),
(last_point.y + 2 * y) * (1. / 3),
x, y);
}
slim_hidden_def (cairo_mesh_pattern_line_to);
/**
* cairo_mesh_pattern_move_to:
* @pattern: a #cairo_pattern_t
* @x: the X coordinate of the new position
* @y: the Y coordinate of the new position
*
* Define the first point of the current patch in a mesh pattern.
*
* After this call the current point will be (@x, @y).
*
* Note: If @pattern is not a mesh pattern then @pattern will be put
* into an error status with a status of
* %CAIRO_STATUS_PATTERN_TYPE_MISMATCH. If @pattern has no current
* patch or the current patch already has at least one side, @pattern
* will be put into an error status with a status of
* %CAIRO_STATUS_INVALID_MESH_CONSTRUCTION.
*
* Since: 1.12
**/
void
cairo_mesh_pattern_move_to (cairo_pattern_t *pattern,
double x, double y)
{
cairo_mesh_pattern_t *mesh;
if (unlikely (pattern->status))
return;
if (unlikely (pattern->type != CAIRO_PATTERN_TYPE_MESH)) {
_cairo_pattern_set_error (pattern, CAIRO_STATUS_PATTERN_TYPE_MISMATCH);
return;
}
mesh = (cairo_mesh_pattern_t *) pattern;
if (unlikely (!mesh->current_patch)) {
_cairo_pattern_set_error (pattern, CAIRO_STATUS_INVALID_MESH_CONSTRUCTION);
return;
}
if (unlikely (mesh->current_side >= 0)) {
_cairo_pattern_set_error (pattern, CAIRO_STATUS_INVALID_MESH_CONSTRUCTION);
return;
}
mesh->current_side = -1;
mesh->current_patch->points[0][0].x = x;
mesh->current_patch->points[0][0].y = y;
}
slim_hidden_def (cairo_mesh_pattern_move_to);
/**
* cairo_mesh_pattern_set_control_point:
* @pattern: a #cairo_pattern_t
* @point_num: the control point to set the position for
* @x: the X coordinate of the control point
* @y: the Y coordinate of the control point
*
* Set an internal control point of the current patch.
*
* Valid values for @point_num are from 0 to 3 and identify the
* control points as explained in cairo_pattern_create_mesh().
*
* Note: If @pattern is not a mesh pattern then @pattern will be put
* into an error status with a status of
* %CAIRO_STATUS_PATTERN_TYPE_MISMATCH. If @point_num is not valid,
* @pattern will be put into an error status with a status of
* %CAIRO_STATUS_INVALID_INDEX. If @pattern has no current patch,
* @pattern will be put into an error status with a status of
* %CAIRO_STATUS_INVALID_MESH_CONSTRUCTION.
*
* Since: 1.12
**/
void
cairo_mesh_pattern_set_control_point (cairo_pattern_t *pattern,
unsigned int point_num,
double x,
double y)
{
cairo_mesh_pattern_t *mesh;
int i, j;
if (unlikely (pattern->status))
return;
if (unlikely (pattern->type != CAIRO_PATTERN_TYPE_MESH)) {
_cairo_pattern_set_error (pattern, CAIRO_STATUS_PATTERN_TYPE_MISMATCH);
return;
}
if (unlikely (point_num > 3)) {
_cairo_pattern_set_error (pattern, CAIRO_STATUS_INVALID_INDEX);
return;
}
mesh = (cairo_mesh_pattern_t *) pattern;
if (unlikely (!mesh->current_patch)) {
_cairo_pattern_set_error (pattern, CAIRO_STATUS_INVALID_MESH_CONSTRUCTION);
return;
}
i = mesh_control_point_i[point_num];
j = mesh_control_point_j[point_num];
mesh->current_patch->points[i][j].x = x;
mesh->current_patch->points[i][j].y = y;
mesh->has_control_point[point_num] = TRUE;
}
/* make room for at least one more color stop */
static cairo_status_t
_cairo_pattern_gradient_grow (cairo_gradient_pattern_t *pattern)
{
cairo_gradient_stop_t *new_stops;
int old_size = pattern->stops_size;
int embedded_size = ARRAY_LENGTH (pattern->stops_embedded);
int new_size = 2 * MAX (old_size, 4);
/* we have a local buffer at pattern->stops_embedded. try to fulfill the request
* from there. */
if (old_size < embedded_size) {
pattern->stops = pattern->stops_embedded;
pattern->stops_size = embedded_size;
return CAIRO_STATUS_SUCCESS;
}
if (CAIRO_INJECT_FAULT ())
return _cairo_error (CAIRO_STATUS_NO_MEMORY);
assert (pattern->n_stops <= pattern->stops_size);
if (pattern->stops == pattern->stops_embedded) {
new_stops = _cairo_malloc_ab (new_size, sizeof (cairo_gradient_stop_t));
if (new_stops)
memcpy (new_stops, pattern->stops, old_size * sizeof (cairo_gradient_stop_t));
} else {
new_stops = _cairo_realloc_ab (pattern->stops,
new_size,
sizeof (cairo_gradient_stop_t));
}
if (unlikely (new_stops == NULL))
return _cairo_error (CAIRO_STATUS_NO_MEMORY);
pattern->stops = new_stops;
pattern->stops_size = new_size;
return CAIRO_STATUS_SUCCESS;
}
static void
_cairo_mesh_pattern_set_corner_color (cairo_mesh_pattern_t *mesh,
unsigned int corner_num,
double red, double green, double blue,
double alpha)
{
cairo_color_t *color;
assert (mesh->current_patch);
assert (corner_num <= 3);
color = &mesh->current_patch->colors[corner_num];
color->red = red;
color->green = green;
color->blue = blue;
color->alpha = alpha;
color->red_short = _cairo_color_double_to_short (red);
color->green_short = _cairo_color_double_to_short (green);
color->blue_short = _cairo_color_double_to_short (blue);
color->alpha_short = _cairo_color_double_to_short (alpha);
mesh->has_color[corner_num] = TRUE;
}
/**
* cairo_mesh_pattern_set_corner_color_rgb:
* @pattern: a #cairo_pattern_t
* @corner_num: the corner to set the color for
* @red: red component of color
* @green: green component of color
* @blue: blue component of color
*
* Sets the color of a corner of the current patch in a mesh pattern.
*
* The color is specified in the same way as in cairo_set_source_rgb().
*
* Valid values for @corner_num are from 0 to 3 and identify the
* corners as explained in cairo_pattern_create_mesh().
*
* Note: If @pattern is not a mesh pattern then @pattern will be put
* into an error status with a status of
* %CAIRO_STATUS_PATTERN_TYPE_MISMATCH. If @corner_num is not valid,
* @pattern will be put into an error status with a status of
* %CAIRO_STATUS_INVALID_INDEX. If @pattern has no current patch,
* @pattern will be put into an error status with a status of
* %CAIRO_STATUS_INVALID_MESH_CONSTRUCTION.
*
* Since: 1.12
**/
void
cairo_mesh_pattern_set_corner_color_rgb (cairo_pattern_t *pattern,
unsigned int corner_num,
double red, double green, double blue)
{
cairo_mesh_pattern_set_corner_color_rgba (pattern, corner_num, red, green, blue, 1.0);
}
/**
* cairo_mesh_pattern_set_corner_color_rgba:
* @pattern: a #cairo_pattern_t
* @corner_num: the corner to set the color for
* @red: red component of color
* @green: green component of color
* @blue: blue component of color
* @alpha: alpha component of color
*
* Sets the color of a corner of the current patch in a mesh pattern.
*
* The color is specified in the same way as in cairo_set_source_rgba().
*
* Valid values for @corner_num are from 0 to 3 and identify the
* corners as explained in cairo_pattern_create_mesh().
*
* Note: If @pattern is not a mesh pattern then @pattern will be put
* into an error status with a status of
* %CAIRO_STATUS_PATTERN_TYPE_MISMATCH. If @corner_num is not valid,
* @pattern will be put into an error status with a status of
* %CAIRO_STATUS_INVALID_INDEX. If @pattern has no current patch,
* @pattern will be put into an error status with a status of
* %CAIRO_STATUS_INVALID_MESH_CONSTRUCTION.
*
* Since: 1.12
**/
void
cairo_mesh_pattern_set_corner_color_rgba (cairo_pattern_t *pattern,
unsigned int corner_num,
double red, double green, double blue,
double alpha)
{
cairo_mesh_pattern_t *mesh;
if (unlikely (pattern->status))
return;
if (unlikely (pattern->type != CAIRO_PATTERN_TYPE_MESH)) {
_cairo_pattern_set_error (pattern, CAIRO_STATUS_PATTERN_TYPE_MISMATCH);
return;
}
if (unlikely (corner_num > 3)) {
_cairo_pattern_set_error (pattern, CAIRO_STATUS_INVALID_INDEX);
return;
}
mesh = (cairo_mesh_pattern_t *) pattern;
if (unlikely (!mesh->current_patch)) {
_cairo_pattern_set_error (pattern, CAIRO_STATUS_INVALID_MESH_CONSTRUCTION);
return;
}
red = _cairo_restrict_value (red, 0.0, 1.0);
green = _cairo_restrict_value (green, 0.0, 1.0);
blue = _cairo_restrict_value (blue, 0.0, 1.0);
alpha = _cairo_restrict_value (alpha, 0.0, 1.0);
_cairo_mesh_pattern_set_corner_color (mesh, corner_num, red, green, blue, alpha);
}
slim_hidden_def (cairo_mesh_pattern_set_corner_color_rgba);
static void
_cairo_pattern_add_color_stop (cairo_gradient_pattern_t *pattern,
double offset,
double red,
double green,
double blue,
double alpha)
{
cairo_gradient_stop_t *stops;
unsigned int i;
if (pattern->n_stops >= pattern->stops_size) {
cairo_status_t status = _cairo_pattern_gradient_grow (pattern);
if (unlikely (status)) {
status = _cairo_pattern_set_error (&pattern->base, status);
return;
}
}
stops = pattern->stops;
for (i = 0; i < pattern->n_stops; i++)
{
if (offset < stops[i].offset)
{
memmove (&stops[i + 1], &stops[i],
sizeof (cairo_gradient_stop_t) * (pattern->n_stops - i));
break;
}
}
stops[i].offset = offset;
stops[i].color.red = red;
stops[i].color.green = green;
stops[i].color.blue = blue;
stops[i].color.alpha = alpha;
stops[i].color.red_short = _cairo_color_double_to_short (red);
stops[i].color.green_short = _cairo_color_double_to_short (green);
stops[i].color.blue_short = _cairo_color_double_to_short (blue);
stops[i].color.alpha_short = _cairo_color_double_to_short (alpha);
pattern->n_stops++;
}
/**
* cairo_pattern_add_color_stop_rgb:
* @pattern: a #cairo_pattern_t
* @offset: an offset in the range [0.0 .. 1.0]
* @red: red component of color
* @green: green component of color
* @blue: blue component of color
*
* Adds an opaque color stop to a gradient pattern. The offset
* specifies the location along the gradient's control vector. For
* example, a linear gradient's control vector is from (x0,y0) to
* (x1,y1) while a radial gradient's control vector is from any point
* on the start circle to the corresponding point on the end circle.
*
* The color is specified in the same way as in cairo_set_source_rgb().
*
* If two (or more) stops are specified with identical offset values,
* they will be sorted according to the order in which the stops are
* added, (stops added earlier will compare less than stops added
* later). This can be useful for reliably making sharp color
* transitions instead of the typical blend.
*
*
* Note: If the pattern is not a gradient pattern, (eg. a linear or
* radial pattern), then the pattern will be put into an error status
* with a status of %CAIRO_STATUS_PATTERN_TYPE_MISMATCH.
*
* Since: 1.0
**/
void
cairo_pattern_add_color_stop_rgb (cairo_pattern_t *pattern,
double offset,
double red,
double green,
double blue)
{
cairo_pattern_add_color_stop_rgba (pattern, offset, red, green, blue, 1.0);
}
/**
* cairo_pattern_add_color_stop_rgba:
* @pattern: a #cairo_pattern_t
* @offset: an offset in the range [0.0 .. 1.0]
* @red: red component of color
* @green: green component of color
* @blue: blue component of color
* @alpha: alpha component of color
*
* Adds a translucent color stop to a gradient pattern. The offset
* specifies the location along the gradient's control vector. For
* example, a linear gradient's control vector is from (x0,y0) to
* (x1,y1) while a radial gradient's control vector is from any point
* on the start circle to the corresponding point on the end circle.
*
* The color is specified in the same way as in cairo_set_source_rgba().
*
* If two (or more) stops are specified with identical offset values,
* they will be sorted according to the order in which the stops are
* added, (stops added earlier will compare less than stops added
* later). This can be useful for reliably making sharp color
* transitions instead of the typical blend.
*
* Note: If the pattern is not a gradient pattern, (eg. a linear or
* radial pattern), then the pattern will be put into an error status
* with a status of %CAIRO_STATUS_PATTERN_TYPE_MISMATCH.
*
* Since: 1.0
**/
void
cairo_pattern_add_color_stop_rgba (cairo_pattern_t *pattern,
double offset,
double red,
double green,
double blue,
double alpha)
{
if (pattern->status)
return;
if (pattern->type != CAIRO_PATTERN_TYPE_LINEAR &&
pattern->type != CAIRO_PATTERN_TYPE_RADIAL)
{
_cairo_pattern_set_error (pattern, CAIRO_STATUS_PATTERN_TYPE_MISMATCH);
return;
}
offset = _cairo_restrict_value (offset, 0.0, 1.0);
red = _cairo_restrict_value (red, 0.0, 1.0);
green = _cairo_restrict_value (green, 0.0, 1.0);
blue = _cairo_restrict_value (blue, 0.0, 1.0);
alpha = _cairo_restrict_value (alpha, 0.0, 1.0);
_cairo_pattern_add_color_stop ((cairo_gradient_pattern_t *) pattern,
offset, red, green, blue, alpha);
}
slim_hidden_def (cairo_pattern_add_color_stop_rgba);
/**
* cairo_pattern_set_matrix:
* @pattern: a #cairo_pattern_t
* @matrix: a #cairo_matrix_t
*
* Sets the pattern's transformation matrix to @matrix. This matrix is
* a transformation from user space to pattern space.
*
* When a pattern is first created it always has the identity matrix
* for its transformation matrix, which means that pattern space is
* initially identical to user space.
*
* Important: Please note that the direction of this transformation
* matrix is from user space to pattern space. This means that if you
* imagine the flow from a pattern to user space (and on to device
* space), then coordinates in that flow will be transformed by the
* inverse of the pattern matrix.
*
* For example, if you want to make a pattern appear twice as large as
* it does by default the correct code to use is:
*
* <informalexample><programlisting>
* cairo_matrix_init_scale (&amp;matrix, 0.5, 0.5);
* cairo_pattern_set_matrix (pattern, &amp;matrix);
* </programlisting></informalexample>
*
* Meanwhile, using values of 2.0 rather than 0.5 in the code above
* would cause the pattern to appear at half of its default size.
*
* Also, please note the discussion of the user-space locking
* semantics of cairo_set_source().
*
* Since: 1.0
**/
void
cairo_pattern_set_matrix (cairo_pattern_t *pattern,
const cairo_matrix_t *matrix)
{
cairo_matrix_t inverse;
cairo_status_t status;
if (pattern->status)
return;
if (memcmp (&pattern->matrix, matrix, sizeof (cairo_matrix_t)) == 0)
return;
pattern->matrix = *matrix;
_cairo_pattern_notify_observers (pattern, CAIRO_PATTERN_NOTIFY_MATRIX);
inverse = *matrix;
status = cairo_matrix_invert (&inverse);
if (unlikely (status))
status = _cairo_pattern_set_error (pattern, status);
}
slim_hidden_def (cairo_pattern_set_matrix);
/**
* cairo_pattern_get_matrix:
* @pattern: a #cairo_pattern_t
* @matrix: return value for the matrix
*
* Stores the pattern's transformation matrix into @matrix.
*
* Since: 1.0
**/
void
cairo_pattern_get_matrix (cairo_pattern_t *pattern, cairo_matrix_t *matrix)
{
*matrix = pattern->matrix;
}
/**
* cairo_pattern_set_filter:
* @pattern: a #cairo_pattern_t
* @filter: a #cairo_filter_t describing the filter to use for resizing
* the pattern
*
* Sets the filter to be used for resizing when using this pattern.
* See #cairo_filter_t for details on each filter.
*
* * Note that you might want to control filtering even when you do not
* have an explicit #cairo_pattern_t object, (for example when using
* cairo_set_source_surface()). In these cases, it is convenient to
* use cairo_get_source() to get access to the pattern that cairo
* creates implicitly. For example:
*
* <informalexample><programlisting>
* cairo_set_source_surface (cr, image, x, y);
* cairo_pattern_set_filter (cairo_get_source (cr), CAIRO_FILTER_NEAREST);
* </programlisting></informalexample>
*
* Since: 1.0
**/
void
cairo_pattern_set_filter (cairo_pattern_t *pattern, cairo_filter_t filter)
{
if (pattern->status)
return;
pattern->filter = filter;
_cairo_pattern_notify_observers (pattern, CAIRO_PATTERN_NOTIFY_FILTER);
}
/**
* cairo_pattern_get_filter:
* @pattern: a #cairo_pattern_t
*
* Gets the current filter for a pattern. See #cairo_filter_t
* for details on each filter.
*
* Return value: the current filter used for resizing the pattern.
*
* Since: 1.0
**/
cairo_filter_t
cairo_pattern_get_filter (cairo_pattern_t *pattern)
{
return pattern->filter;
}
/**
* cairo_pattern_set_extend:
* @pattern: a #cairo_pattern_t
* @extend: a #cairo_extend_t describing how the area outside of the
* pattern will be drawn
*
* Sets the mode to be used for drawing outside the area of a pattern.
* See #cairo_extend_t for details on the semantics of each extend
* strategy.
*
* The default extend mode is %CAIRO_EXTEND_NONE for surface patterns
* and %CAIRO_EXTEND_PAD for gradient patterns.
*
* Since: 1.0
**/
void
cairo_pattern_set_extend (cairo_pattern_t *pattern, cairo_extend_t extend)
{
if (pattern->status)
return;
pattern->extend = extend;
_cairo_pattern_notify_observers (pattern, CAIRO_PATTERN_NOTIFY_EXTEND);
}
/**
* cairo_pattern_get_extend:
* @pattern: a #cairo_pattern_t
*
* Gets the current extend mode for a pattern. See #cairo_extend_t
* for details on the semantics of each extend strategy.
*
* Return value: the current extend strategy used for drawing the
* pattern.
*
* Since: 1.0
**/
cairo_extend_t
cairo_pattern_get_extend (cairo_pattern_t *pattern)
{
return pattern->extend;
}
slim_hidden_def (cairo_pattern_get_extend);
void
_cairo_pattern_pretransform (cairo_pattern_t *pattern,
const cairo_matrix_t *ctm)
{
if (pattern->status)
return;
cairo_matrix_multiply (&pattern->matrix, &pattern->matrix, ctm);
}
void
_cairo_pattern_transform (cairo_pattern_t *pattern,
const cairo_matrix_t *ctm_inverse)
{
if (pattern->status)
return;
cairo_matrix_multiply (&pattern->matrix, ctm_inverse, &pattern->matrix);
}
static cairo_bool_t
_linear_pattern_is_degenerate (const cairo_linear_pattern_t *linear)
{
return fabs (linear->pd1.x - linear->pd2.x) < DBL_EPSILON &&
fabs (linear->pd1.y - linear->pd2.y) < DBL_EPSILON;
}
static cairo_bool_t
_radial_pattern_is_degenerate (const cairo_radial_pattern_t *radial)
{
/* A radial pattern is considered degenerate if it can be
* represented as a solid or clear pattern. This corresponds to
* one of the two cases:
*
* 1) The radii are both very small:
* |dr| < DBL_EPSILON && min (r0, r1) < DBL_EPSILON
*
* 2) The two circles have about the same radius and are very
* close to each other (approximately a cylinder gradient that
* doesn't move with the parameter):
* |dr| < DBL_EPSILON && max (|dx|, |dy|) < 2 * DBL_EPSILON
*
* These checks are consistent with the assumptions used in
* _cairo_radial_pattern_box_to_parameter ().
*/
return fabs (radial->cd1.radius - radial->cd2.radius) < DBL_EPSILON &&
(MIN (radial->cd1.radius, radial->cd2.radius) < DBL_EPSILON ||
MAX (fabs (radial->cd1.center.x - radial->cd2.center.x),
fabs (radial->cd1.center.y - radial->cd2.center.y)) < 2 * DBL_EPSILON);
}
static void
_cairo_linear_pattern_box_to_parameter (const cairo_linear_pattern_t *linear,
double x0, double y0,
double x1, double y1,
double range[2])
{
double t0, tdx, tdy;
double p1x, p1y, pdx, pdy, invsqnorm;
assert (! _linear_pattern_is_degenerate (linear));
/*
* Linear gradients are othrogonal to the line passing through
* their extremes. Because of convexity, the parameter range can
* be computed as the convex hull (one the real line) of the
* parameter values of the 4 corners of the box.
*
* The parameter value t for a point (x,y) can be computed as:
*
* t = (p2 - p1) . (x,y) / |p2 - p1|^2
*
* t0 is the t value for the top left corner
* tdx is the difference between left and right corners
* tdy is the difference between top and bottom corners
*/
p1x = linear->pd1.x;
p1y = linear->pd1.y;
pdx = linear->pd2.x - p1x;
pdy = linear->pd2.y - p1y;
invsqnorm = 1.0 / (pdx * pdx + pdy * pdy);
pdx *= invsqnorm;
pdy *= invsqnorm;
t0 = (x0 - p1x) * pdx + (y0 - p1y) * pdy;
tdx = (x1 - x0) * pdx;
tdy = (y1 - y0) * pdy;
/*
* Because of the linearity of the t value, tdx can simply be
* added the t0 to move along the top edge. After this, range[0]
* and range[1] represent the parameter range for the top edge, so
* extending it to include the whole box simply requires adding
* tdy to the correct extreme.
*/
range[0] = range[1] = t0;
if (tdx < 0)
range[0] += tdx;
else
range[1] += tdx;
if (tdy < 0)
range[0] += tdy;
else
range[1] += tdy;
}
static cairo_bool_t
_extend_range (double range[2], double value, cairo_bool_t valid)
{
if (!valid)
range[0] = range[1] = value;
else if (value < range[0])
range[0] = value;
else if (value > range[1])
range[1] = value;
return TRUE;
}
/*
* _cairo_radial_pattern_focus_is_inside:
*
* Returns %TRUE if and only if the focus point exists and is
* contained in one of the two extreme circles. This condition is
* equivalent to one of the two extreme circles being completely
* contained in the other one.
*
* Note: if the focus is on the border of one of the two circles (in
* which case the circles are tangent in the focus point), it is not
* considered as contained in the circle, hence this function returns
* %FALSE.
*
*/
cairo_bool_t
_cairo_radial_pattern_focus_is_inside (const cairo_radial_pattern_t *radial)
{
double cx, cy, cr, dx, dy, dr;
cx = radial->cd1.center.x;
cy = radial->cd1.center.y;
cr = radial->cd1.radius;
dx = radial->cd2.center.x - cx;
dy = radial->cd2.center.y - cy;
dr = radial->cd2.radius - cr;
return dx*dx + dy*dy < dr*dr;
}
static void
_cairo_radial_pattern_box_to_parameter (const cairo_radial_pattern_t *radial,
double x0, double y0,
double x1, double y1,
double tolerance,
double range[2])
{
double cx, cy, cr, dx, dy, dr;
double a, x_focus, y_focus;
double mindr, minx, miny, maxx, maxy;
cairo_bool_t valid;
assert (! _radial_pattern_is_degenerate (radial));
assert (x0 < x1);
assert (y0 < y1);
tolerance = MAX (tolerance, DBL_EPSILON);
range[0] = range[1] = 0;
valid = FALSE;
x_focus = y_focus = 0; /* silence gcc */
cx = radial->cd1.center.x;
cy = radial->cd1.center.y;
cr = radial->cd1.radius;
dx = radial->cd2.center.x - cx;
dy = radial->cd2.center.y - cy;
dr = radial->cd2.radius - cr;
/* translate by -(cx, cy) to simplify computations */
x0 -= cx;
y0 -= cy;
x1 -= cx;
y1 -= cy;
/* enlarge boundaries slightly to avoid rounding problems in the
* parameter range computation */
x0 -= DBL_EPSILON;
y0 -= DBL_EPSILON;
x1 += DBL_EPSILON;
y1 += DBL_EPSILON;
/* enlarge boundaries even more to avoid rounding problems when
* testing if a point belongs to the box */
minx = x0 - DBL_EPSILON;
miny = y0 - DBL_EPSILON;
maxx = x1 + DBL_EPSILON;
maxy = y1 + DBL_EPSILON;
/* we dont' allow negative radiuses, so we will be checking that
* t*dr >= mindr to consider t valid */
mindr = -(cr + DBL_EPSILON);
/*
* After the previous transformations, the start circle is
* centered in the origin and has radius cr. A 1-unit change in
* the t parameter corresponds to dx,dy,dr changes in the x,y,r of
* the circle (center coordinates, radius).
*
* To compute the minimum range needed to correctly draw the
* pattern, we start with an empty range and extend it to include
* the circles touching the bounding box or within it.
*/
/*
* Focus, the point where the circle has radius == 0.
*
* r = cr + t * dr = 0
* t = -cr / dr
*
* If the radius is constant (dr == 0) there is no focus (the
* gradient represents a cylinder instead of a cone).
*/
if (fabs (dr) >= DBL_EPSILON) {
double t_focus;
t_focus = -cr / dr;
x_focus = t_focus * dx;
y_focus = t_focus * dy;
if (minx <= x_focus && x_focus <= maxx &&
miny <= y_focus && y_focus <= maxy)
{
valid = _extend_range (range, t_focus, valid);
}
}
/*
* Circles externally tangent to box edges.
*
* All circles have center in (dx, dy) * t
*
* If the circle is tangent to the line defined by the edge of the
* box, then at least one of the following holds true:
*
* (dx*t) + (cr + dr*t) == x0 (left edge)
* (dx*t) - (cr + dr*t) == x1 (right edge)
* (dy*t) + (cr + dr*t) == y0 (top edge)
* (dy*t) - (cr + dr*t) == y1 (bottom edge)
*
* The solution is only valid if the tangent point is actually on
* the edge, i.e. if its y coordinate is in [y0,y1] for left/right
* edges and if its x coordinate is in [x0,x1] for top/bottom
* edges.
*
* For the first equation:
*
* (dx + dr) * t = x0 - cr
* t = (x0 - cr) / (dx + dr)
* y = dy * t
*
* in the code this becomes:
*
* t_edge = (num) / (den)
* v = (delta) * t_edge
*
* If the denominator in t is 0, the pattern is tangent to a line
* parallel to the edge under examination. The corner-case where
* the boundary line is the same as the edge is handled by the
* focus point case and/or by the a==0 case.
*/
#define T_EDGE(num,den,delta,lower,upper) \
if (fabs (den) >= DBL_EPSILON) { \
double t_edge, v; \
\
t_edge = (num) / (den); \
v = t_edge * (delta); \
if (t_edge * dr >= mindr && (lower) <= v && v <= (upper)) \
valid = _extend_range (range, t_edge, valid); \
}
/* circles tangent (externally) to left/right/top/bottom edge */
T_EDGE (x0 - cr, dx + dr, dy, miny, maxy);
T_EDGE (x1 + cr, dx - dr, dy, miny, maxy);
T_EDGE (y0 - cr, dy + dr, dx, minx, maxx);
T_EDGE (y1 + cr, dy - dr, dx, minx, maxx);
#undef T_EDGE
/*
* Circles passing through a corner.
*
* A circle passing through the point (x,y) satisfies:
*
* (x-t*dx)^2 + (y-t*dy)^2 == (cr + t*dr)^2
*
* If we set:
* a = dx^2 + dy^2 - dr^2
* b = x*dx + y*dy + cr*dr
* c = x^2 + y^2 - cr^2
* we have:
* a*t^2 - 2*b*t + c == 0
*/
a = dx * dx + dy * dy - dr * dr;
if (fabs (a) < DBL_EPSILON * DBL_EPSILON) {
double b, maxd2;
/* Ensure that gradients with both a and dr small are
* considered degenerate.
* The floating point version of the degeneracy test implemented
* in _radial_pattern_is_degenerate() is:
*
* 1) The circles are practically the same size:
* |dr| < DBL_EPSILON
* AND
* 2a) The circles are both very small:
* min (r0, r1) < DBL_EPSILON
* OR
* 2b) The circles are very close to each other:
* max (|dx|, |dy|) < 2 * DBL_EPSILON
*
* Assuming that the gradient is not degenerate, we want to
* show that |a| < DBL_EPSILON^2 implies |dr| >= DBL_EPSILON.
*
* If the gradient is not degenerate yet it has |dr| <
* DBL_EPSILON, (2b) is false, thus:
*
* max (|dx|, |dy|) >= 2*DBL_EPSILON
* which implies:
* 4*DBL_EPSILON^2 <= max (|dx|, |dy|)^2 <= dx^2 + dy^2
*
* From the definition of a, we get:
* a = dx^2 + dy^2 - dr^2 < DBL_EPSILON^2
* dx^2 + dy^2 - DBL_EPSILON^2 < dr^2
* 3*DBL_EPSILON^2 < dr^2
*
* which is inconsistent with the hypotheses, thus |dr| <
* DBL_EPSILON is false or the gradient is degenerate.
*/
assert (fabs (dr) >= DBL_EPSILON);
/*
* If a == 0, all the circles are tangent to a line in the
* focus point. If this line is within the box extents, we
* should add the circle with infinite radius, but this would
* make the range unbounded, so we add the smallest circle whose
* distance to the desired (degenerate) circle within the
* bounding box does not exceed tolerance.
*
* The equation of the line is b==0, i.e.:
* x*dx + y*dy + cr*dr == 0
*
* We compute the intersection of the line with the box and
* keep the intersection with maximum square distance (maxd2)
* from the focus point.
*
* In the code the intersection is represented in another
* coordinate system, whose origin is the focus point and
* which has a u,v axes, which are respectively orthogonal and
* parallel to the edge being intersected.
*
* The intersection is valid only if it belongs to the box,
* otherwise it is ignored.
*
* For example:
*
* y = y0
* x*dx + y0*dy + cr*dr == 0
* x = -(y0*dy + cr*dr) / dx
*
* which in (u,v) is:
* u = y0 - y_focus
* v = -(y0*dy + cr*dr) / dx - x_focus
*
* In the code:
* u = (edge) - (u_origin)
* v = -((edge) * (delta) + cr*dr) / (den) - v_focus
*/
#define T_EDGE(edge,delta,den,lower,upper,u_origin,v_origin) \
if (fabs (den) >= DBL_EPSILON) { \
double v; \
\
v = -((edge) * (delta) + cr * dr) / (den); \
if ((lower) <= v && v <= (upper)) { \
double u, d2; \
\
u = (edge) - (u_origin); \
v -= (v_origin); \
d2 = u*u + v*v; \
if (maxd2 < d2) \
maxd2 = d2; \
} \
}
maxd2 = 0;
/* degenerate circles (lines) passing through each edge */
T_EDGE (y0, dy, dx, minx, maxx, y_focus, x_focus);
T_EDGE (y1, dy, dx, minx, maxx, y_focus, x_focus);
T_EDGE (x0, dx, dy, miny, maxy, x_focus, y_focus);
T_EDGE (x1, dx, dy, miny, maxy, x_focus, y_focus);
#undef T_EDGE
/*
* The limit circle can be transformed rigidly to the y=0 line
* and the circles tangent to it in (0,0) are:
*
* x^2 + (y-r)^2 = r^2 <=> x^2 + y^2 - 2*y*r = 0
*
* y is the distance from the line, in our case tolerance;
* x is the distance along the line, i.e. sqrt(maxd2),
* so:
*
* r = cr + dr * t = (maxd2 + tolerance^2) / (2*tolerance)
* t = (r - cr) / dr =
* (maxd2 + tolerance^2 - 2*tolerance*cr) / (2*tolerance*dr)
*/
if (maxd2 > 0) {
double t_limit = maxd2 + tolerance*tolerance - 2*tolerance*cr;
t_limit /= 2 * tolerance * dr;
valid = _extend_range (range, t_limit, valid);
}
/*
* Nondegenerate, nonlimit circles passing through the corners.
*
* a == 0 && a*t^2 - 2*b*t + c == 0
*
* t = c / (2*b)
*
* The b == 0 case has just been handled, so we only have to
* compute this if b != 0.
*/
#define T_CORNER(x,y) \
b = (x) * dx + (y) * dy + cr * dr; \
if (fabs (b) >= DBL_EPSILON) { \
double t_corner; \
double x2 = (x) * (x); \
double y2 = (y) * (y); \
double cr2 = (cr) * (cr); \
double c = x2 + y2 - cr2; \
\
t_corner = 0.5 * c / b; \
if (t_corner * dr >= mindr) \
valid = _extend_range (range, t_corner, valid); \
}
/* circles touching each corner */
T_CORNER (x0, y0);
T_CORNER (x0, y1);
T_CORNER (x1, y0);
T_CORNER (x1, y1);
#undef T_CORNER
} else {
double inva, b, c, d;
inva = 1 / a;
/*
* Nondegenerate, nonlimit circles passing through the corners.
*
* a != 0 && a*t^2 - 2*b*t + c == 0
*
* t = (b +- sqrt (b*b - a*c)) / a
*
* If the argument of sqrt() is negative, then no circle
* passes through the corner.
*/
#define T_CORNER(x,y) \
b = (x) * dx + (y) * dy + cr * dr; \
c = (x) * (x) + (y) * (y) - cr * cr; \
d = b * b - a * c; \
if (d >= 0) { \
double t_corner; \
\
d = sqrt (d); \
t_corner = (b + d) * inva; \
if (t_corner * dr >= mindr) \
valid = _extend_range (range, t_corner, valid); \
t_corner = (b - d) * inva; \
if (t_corner * dr >= mindr) \
valid = _extend_range (range, t_corner, valid); \
}
/* circles touching each corner */
T_CORNER (x0, y0);
T_CORNER (x0, y1);
T_CORNER (x1, y0);
T_CORNER (x1, y1);
#undef T_CORNER
}
}
/**
* _cairo_gradient_pattern_box_to_parameter:
*
* Compute a interpolation range sufficient to draw (within the given
* tolerance) the gradient in the given box getting the same result as
* using the (-inf, +inf) range.
*
* Assumes that the pattern is not degenerate. This can be guaranteed
* by simplifying it to a solid clear if _cairo_pattern_is_clear or to
* a solid color if _cairo_gradient_pattern_is_solid.
*
* The range isn't guaranteed to be minimal, but it tries to.
**/
void
_cairo_gradient_pattern_box_to_parameter (const cairo_gradient_pattern_t *gradient,
double x0, double y0,
double x1, double y1,
double tolerance,
double out_range[2])
{
assert (gradient->base.type == CAIRO_PATTERN_TYPE_LINEAR ||
gradient->base.type == CAIRO_PATTERN_TYPE_RADIAL);
if (gradient->base.type == CAIRO_PATTERN_TYPE_LINEAR) {
_cairo_linear_pattern_box_to_parameter ((cairo_linear_pattern_t *) gradient,
x0, y0, x1, y1, out_range);
} else {
_cairo_radial_pattern_box_to_parameter ((cairo_radial_pattern_t *) gradient,
x0, y0, x1, y1, tolerance, out_range);
}
}
/**
* _cairo_gradient_pattern_interpolate:
*
* Interpolate between the start and end objects of linear or radial
* gradients. The interpolated object is stored in out_circle, with
* the radius being zero in the linear gradient case.
**/
void
_cairo_gradient_pattern_interpolate (const cairo_gradient_pattern_t *gradient,
double t,
cairo_circle_double_t *out_circle)
{
assert (gradient->base.type == CAIRO_PATTERN_TYPE_LINEAR ||
gradient->base.type == CAIRO_PATTERN_TYPE_RADIAL);
#define lerp(a,b) (a)*(1-t) + (b)*t
if (gradient->base.type == CAIRO_PATTERN_TYPE_LINEAR) {
cairo_linear_pattern_t *linear = (cairo_linear_pattern_t *) gradient;
out_circle->center.x = lerp (linear->pd1.x, linear->pd2.x);
out_circle->center.y = lerp (linear->pd1.y, linear->pd2.y);
out_circle->radius = 0;
} else {
cairo_radial_pattern_t *radial = (cairo_radial_pattern_t *) gradient;
out_circle->center.x = lerp (radial->cd1.center.x, radial->cd2.center.x);
out_circle->center.y = lerp (radial->cd1.center.y, radial->cd2.center.y);
out_circle->radius = lerp (radial->cd1.radius , radial->cd2.radius);
}
#undef lerp
}
/**
* _cairo_gradient_pattern_fit_to_range:
*
* Scale the extremes of a gradient to guarantee that the coordinates
* and their deltas are within the range (-max_value, max_value). The
* new extremes are stored in out_circle.
*
* The pattern matrix is scaled to guarantee that the aspect of the
* gradient is the same and the result is stored in out_matrix.
*
**/
void
_cairo_gradient_pattern_fit_to_range (const cairo_gradient_pattern_t *gradient,
double max_value,
cairo_matrix_t *out_matrix,
cairo_circle_double_t out_circle[2])
{
double dim;
assert (gradient->base.type == CAIRO_PATTERN_TYPE_LINEAR ||
gradient->base.type == CAIRO_PATTERN_TYPE_RADIAL);
if (gradient->base.type == CAIRO_PATTERN_TYPE_LINEAR) {
cairo_linear_pattern_t *linear = (cairo_linear_pattern_t *) gradient;
out_circle[0].center = linear->pd1;
out_circle[0].radius = 0;
out_circle[1].center = linear->pd2;
out_circle[1].radius = 0;
dim = fabs (linear->pd1.x);
dim = MAX (dim, fabs (linear->pd1.y));
dim = MAX (dim, fabs (linear->pd2.x));
dim = MAX (dim, fabs (linear->pd2.y));
dim = MAX (dim, fabs (linear->pd1.x - linear->pd2.x));
dim = MAX (dim, fabs (linear->pd1.y - linear->pd2.y));
} else {
cairo_radial_pattern_t *radial = (cairo_radial_pattern_t *) gradient;
out_circle[0] = radial->cd1;
out_circle[1] = radial->cd2;
dim = fabs (radial->cd1.center.x);
dim = MAX (dim, fabs (radial->cd1.center.y));
dim = MAX (dim, fabs (radial->cd1.radius));
dim = MAX (dim, fabs (radial->cd2.center.x));
dim = MAX (dim, fabs (radial->cd2.center.y));
dim = MAX (dim, fabs (radial->cd2.radius));
dim = MAX (dim, fabs (radial->cd1.center.x - radial->cd2.center.x));
dim = MAX (dim, fabs (radial->cd1.center.y - radial->cd2.center.y));
dim = MAX (dim, fabs (radial->cd1.radius - radial->cd2.radius));
}
if (unlikely (dim > max_value)) {
cairo_matrix_t scale;
dim = max_value / dim;
out_circle[0].center.x *= dim;
out_circle[0].center.y *= dim;
out_circle[0].radius *= dim;
out_circle[1].center.x *= dim;
out_circle[1].center.y *= dim;
out_circle[1].radius *= dim;
cairo_matrix_init_scale (&scale, dim, dim);
cairo_matrix_multiply (out_matrix, &gradient->base.matrix, &scale);
} else {
*out_matrix = gradient->base.matrix;
}
}
static cairo_bool_t
_gradient_is_clear (const cairo_gradient_pattern_t *gradient,
const cairo_rectangle_int_t *extents)
{
unsigned int i;
assert (gradient->base.type == CAIRO_PATTERN_TYPE_LINEAR ||
gradient->base.type == CAIRO_PATTERN_TYPE_RADIAL);
if (gradient->n_stops == 0 ||
(gradient->base.extend == CAIRO_EXTEND_NONE &&
gradient->stops[0].offset == gradient->stops[gradient->n_stops - 1].offset))
return TRUE;
if (gradient->base.type == CAIRO_PATTERN_TYPE_RADIAL) {
/* degenerate radial gradients are clear */
if (_radial_pattern_is_degenerate ((cairo_radial_pattern_t *) gradient))
return TRUE;
} else if (gradient->base.extend == CAIRO_EXTEND_NONE) {
/* EXTEND_NONE degenerate linear gradients are clear */
if (_linear_pattern_is_degenerate ((cairo_linear_pattern_t *) gradient))
return TRUE;
}
/* Check if the extents intersect the drawn part of the pattern. */
if (extents != NULL &&
(gradient->base.extend == CAIRO_EXTEND_NONE ||
gradient->base.type == CAIRO_PATTERN_TYPE_RADIAL))
{
double t[2];
_cairo_gradient_pattern_box_to_parameter (gradient,
extents->x,
extents->y,
extents->x + extents->width,
extents->y + extents->height,
DBL_EPSILON,
t);
if (gradient->base.extend == CAIRO_EXTEND_NONE &&
(t[0] >= gradient->stops[gradient->n_stops - 1].offset ||
t[1] <= gradient->stops[0].offset))
{
return TRUE;
}
if (t[0] == t[1])
return TRUE;
}
for (i = 0; i < gradient->n_stops; i++)
if (! CAIRO_COLOR_IS_CLEAR (&gradient->stops[i].color))
return FALSE;
return TRUE;
}
static void
_gradient_color_average (const cairo_gradient_pattern_t *gradient,
cairo_color_t *color)
{
double delta0, delta1;
double r, g, b, a;
unsigned int i, start = 1, end;
assert (gradient->n_stops > 0);
assert (gradient->base.extend != CAIRO_EXTEND_NONE);
if (gradient->n_stops == 1) {
_cairo_color_init_rgba (color,
gradient->stops[0].color.red,
gradient->stops[0].color.green,
gradient->stops[0].color.blue,
gradient->stops[0].color.alpha);
return;
}
end = gradient->n_stops - 1;
switch (gradient->base.extend) {
case CAIRO_EXTEND_REPEAT:
/*
* Sa, Sb and Sy, Sz are the first two and last two stops respectively.
* The weight of the first and last stop can be computed as the area of
* the following triangles (taken with height 1, since the whole [0-1]
* will have total weight 1 this way): b*h/2
*
* + +
* / |\ / | \
* / | \ / | \
* / | \ / | \
* ~~~~~+---+---+---+~~~~~~~+-------+---+---+~~~~~
* -1+Sz 0 Sa Sb Sy Sz 1 1+Sa
*
* For the first stop: (Sb-(-1+Sz)/2 = (1+Sb-Sz)/2
* For the last stop: ((1+Sa)-Sy)/2 = (1+Sa-Sy)/2
* Halving the result is done after summing up all the areas.
*/
delta0 = 1.0 + gradient->stops[1].offset - gradient->stops[end].offset;
delta1 = 1.0 + gradient->stops[0].offset - gradient->stops[end-1].offset;
break;
case CAIRO_EXTEND_REFLECT:
/*
* Sa, Sb and Sy, Sz are the first two and last two stops respectively.
* The weight of the first and last stop can be computed as the area of
* the following trapezoids (taken with height 1, since the whole [0-1]
* will have total weight 1 this way): (b+B)*h/2
*
* +-------+ +---+
* | |\ / | |
* | | \ / | |
* | | \ / | |
* +-------+---+~~~~~~~+-------+---+
* 0 Sa Sb Sy Sz 1
*
* For the first stop: (Sa+Sb)/2
* For the last stop: ((1-Sz) + (1-Sy))/2 = (2-Sy-Sz)/2
* Halving the result is done after summing up all the areas.
*/
delta0 = gradient->stops[0].offset + gradient->stops[1].offset;
delta1 = 2.0 - gradient->stops[end-1].offset - gradient->stops[end].offset;
break;
case CAIRO_EXTEND_PAD:
/* PAD is computed as the average of the first and last stop:
* - take both of them with weight 1 (they will be halved
* after the whole sum has been computed).
* - avoid summing any of the inner stops.
*/
delta0 = delta1 = 1.0;
start = end;
break;
case CAIRO_EXTEND_NONE:
default:
ASSERT_NOT_REACHED;
_cairo_color_init_rgba (color, 0, 0, 0, 0);
return;
}
r = delta0 * gradient->stops[0].color.red;
g = delta0 * gradient->stops[0].color.green;
b = delta0 * gradient->stops[0].color.blue;
a = delta0 * gradient->stops[0].color.alpha;
for (i = start; i < end; ++i) {
/* Inner stops weight is the same as the area of the triangle they influence
* (which goes from the stop before to the stop after), again with height 1
* since the whole must sum up to 1: b*h/2
* Halving is done after the whole sum has been computed.
*/
double delta = gradient->stops[i+1].offset - gradient->stops[i-1].offset;
r += delta * gradient->stops[i].color.red;
g += delta * gradient->stops[i].color.green;
b += delta * gradient->stops[i].color.blue;
a += delta * gradient->