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/* cairo - a vector graphics library with display and print output
*
* Copyright © 2009 Eric Anholt
* Copyright © 2009 Chris Wilson
* Copyright © 2005,2010 Red Hat, Inc
*
* This library is free software; you can redistribute it and/or
* modify it either under the terms of the GNU Lesser General Public
* License version 2.1 as published by the Free Software Foundation
* (the "LGPL") or, at your option, under the terms of the Mozilla
* Public License Version 1.1 (the "MPL"). If you do not alter this
* notice, a recipient may use your version of this file under either
* the MPL or the LGPL.
*
* You should have received a copy of the LGPL along with this library
* in the file COPYING-LGPL-2.1; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Suite 500, Boston, MA 02110-1335, USA
* You should have received a copy of the MPL along with this library
* in the file COPYING-MPL-1.1
*
* The contents of this file are subject to the Mozilla Public License
* Version 1.1 (the "License"); you may not use this file except in
* compliance with the License. You may obtain a copy of the License at
* http://www.mozilla.org/MPL/
*
* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY
* OF ANY KIND, either express or implied. See the LGPL or the MPL for
* the specific language governing rights and limitations.
*
* The Original Code is the cairo graphics library.
*
* The Initial Developer of the Original Code is Red Hat, Inc.
*
* Contributor(s):
* Benjamin Otte <otte@gnome.org>
* Carl Worth <cworth@cworth.org>
* Chris Wilson <chris@chris-wilson.co.uk>
* Eric Anholt <eric@anholt.net>
*/
#include "cairoint.h"
#include "cairo-error-private.h"
#include "cairo-gl-gradient-private.h"
#include "cairo-gl-private.h"
static int
_cairo_gl_gradient_sample_width (unsigned int n_stops,
const cairo_gradient_stop_t *stops)
{
unsigned int n;
int width;
width = 8;
for (n = 1; n < n_stops; n++) {
double dx = stops[n].offset - stops[n-1].offset;
double delta, max;
int ramp;
if (dx == 0)
return 1024; /* we need to emulate an infinitely sharp step */
max = fabs (stops[n].color.red - stops[n-1].color.red);
delta = fabs (stops[n].color.green - stops[n-1].color.green);
if (delta > max)
max = delta;
delta = fabs (stops[n].color.blue - stops[n-1].color.blue);
if (delta > max)
max = delta;
delta = fabs (stops[n].color.alpha - stops[n-1].color.alpha);
if (delta > max)
max = delta;
ramp = 128 * max / dx;
if (ramp > width)
width = ramp;
}
return (width + 7) & -8;
}
static uint8_t premultiply(double c, double a)
{
int v = c * a * 256;
return v - (v >> 8);
}
static uint32_t color_stop_to_pixel(const cairo_gradient_stop_t *stop)
{
uint8_t a, r, g, b;
a = stop->color.alpha_short >> 8;
r = premultiply(stop->color.red, stop->color.alpha);
g = premultiply(stop->color.green, stop->color.alpha);
b = premultiply(stop->color.blue, stop->color.alpha);
if (_cairo_is_little_endian ())
return a << 24 | r << 16 | g << 8 | b << 0;
else
return a << 0 | r << 8 | g << 16 | b << 24;
}
static cairo_status_t
_cairo_gl_gradient_render (const cairo_gl_context_t *ctx,
unsigned int n_stops,
const cairo_gradient_stop_t *stops,
void *bytes,
int width)
{
pixman_image_t *gradient, *image;
pixman_gradient_stop_t pixman_stops_stack[32];
pixman_gradient_stop_t *pixman_stops;
pixman_point_fixed_t p1, p2;
unsigned int i;
pixman_format_code_t gradient_pixman_format;
/*
* Ensure that the order of the gradient's components in memory is BGRA.
* This is done so that the gradient's pixel data is always suitable for
* texture upload using format=GL_BGRA and type=GL_UNSIGNED_BYTE.
*/
if (_cairo_is_little_endian ())
gradient_pixman_format = PIXMAN_a8r8g8b8;
else
gradient_pixman_format = PIXMAN_b8g8r8a8;
pixman_stops = pixman_stops_stack;
if (unlikely (n_stops > ARRAY_LENGTH (pixman_stops_stack))) {
pixman_stops = _cairo_malloc_ab (n_stops,
sizeof (pixman_gradient_stop_t));
if (unlikely (pixman_stops == NULL))
return _cairo_error (CAIRO_STATUS_NO_MEMORY);
}
for (i = 0; i < n_stops; i++) {
pixman_stops[i].x = _cairo_fixed_16_16_from_double (stops[i].offset);
pixman_stops[i].color.red = stops[i].color.red_short;
pixman_stops[i].color.green = stops[i].color.green_short;
pixman_stops[i].color.blue = stops[i].color.blue_short;
pixman_stops[i].color.alpha = stops[i].color.alpha_short;
}
p1.x = _cairo_fixed_16_16_from_double (0.5);
p1.y = 0;
p2.x = _cairo_fixed_16_16_from_double (width - 0.5);
p2.y = 0;
gradient = pixman_image_create_linear_gradient (&p1, &p2,
pixman_stops,
n_stops);
if (pixman_stops != pixman_stops_stack)
free (pixman_stops);
if (unlikely (gradient == NULL))
return _cairo_error (CAIRO_STATUS_NO_MEMORY);
pixman_image_set_filter (gradient, PIXMAN_FILTER_BILINEAR, NULL, 0);
pixman_image_set_repeat (gradient, PIXMAN_REPEAT_PAD);
image = pixman_image_create_bits (gradient_pixman_format, width, 1,
bytes, sizeof(uint32_t)*width);
if (unlikely (image == NULL)) {
pixman_image_unref (gradient);
return _cairo_error (CAIRO_STATUS_NO_MEMORY);
}
pixman_image_composite32 (PIXMAN_OP_SRC,
gradient, NULL, image,
0, 0,
0, 0,
0, 0,
width, 1);
pixman_image_unref (gradient);
pixman_image_unref (image);
/* We need to fudge pixel 0 to hold the left-most color stop and not
* the neareset stop to the zeroth pixel centre in order to correctly
* populate the border color. For completeness, do both edges.
*/
((uint32_t*)bytes)[0] = color_stop_to_pixel(&stops[0]);
((uint32_t*)bytes)[width-1] = color_stop_to_pixel(&stops[n_stops-1]);
return CAIRO_STATUS_SUCCESS;
}
static unsigned long
_cairo_gl_gradient_hash (unsigned int n_stops,
const cairo_gradient_stop_t *stops)
{
return _cairo_hash_bytes (n_stops,
stops,
sizeof (cairo_gradient_stop_t) * n_stops);
}
static cairo_gl_gradient_t *
_cairo_gl_gradient_lookup (cairo_gl_context_t *ctx,
unsigned long hash,
unsigned int n_stops,
const cairo_gradient_stop_t *stops)
{
cairo_gl_gradient_t lookup;
lookup.cache_entry.hash = hash,
lookup.n_stops = n_stops;
lookup.stops = stops;
return _cairo_cache_lookup (&ctx->gradients, &lookup.cache_entry);
}
cairo_bool_t
_cairo_gl_gradient_equal (const void *key_a, const void *key_b)
{
const cairo_gl_gradient_t *a = key_a;
const cairo_gl_gradient_t *b = key_b;
if (a->n_stops != b->n_stops)
return FALSE;
return memcmp (a->stops, b->stops, a->n_stops * sizeof (cairo_gradient_stop_t)) == 0;
}
cairo_int_status_t
_cairo_gl_gradient_create (cairo_gl_context_t *ctx,
unsigned int n_stops,
const cairo_gradient_stop_t *stops,
cairo_gl_gradient_t **gradient_out)
{
unsigned long hash;
cairo_gl_gradient_t *gradient;
cairo_status_t status;
int tex_width;
GLint internal_format;
void *data;
if ((unsigned int) ctx->max_texture_size / 2 <= n_stops)
return CAIRO_INT_STATUS_UNSUPPORTED;
hash = _cairo_gl_gradient_hash (n_stops, stops);
gradient = _cairo_gl_gradient_lookup (ctx, hash, n_stops, stops);
if (gradient) {
*gradient_out = _cairo_gl_gradient_reference (gradient);
return CAIRO_STATUS_SUCCESS;
}
gradient = malloc (sizeof (cairo_gl_gradient_t) + sizeof (cairo_gradient_stop_t) * (n_stops - 1));
if (gradient == NULL)
return _cairo_error (CAIRO_STATUS_NO_MEMORY);
tex_width = _cairo_gl_gradient_sample_width (n_stops, stops);
if (tex_width > ctx->max_texture_size)
tex_width = ctx->max_texture_size;
CAIRO_REFERENCE_COUNT_INIT (&gradient->ref_count, 2);
gradient->cache_entry.hash = hash;
gradient->cache_entry.size = tex_width;
gradient->device = &ctx->base;
gradient->n_stops = n_stops;
gradient->stops = gradient->stops_embedded;
memcpy (gradient->stops_embedded, stops, n_stops * sizeof (cairo_gradient_stop_t));
glGenTextures (1, &gradient->tex);
_cairo_gl_context_activate (ctx, CAIRO_GL_TEX_TEMP);
glBindTexture (ctx->tex_target, gradient->tex);
data = _cairo_malloc_ab (tex_width, sizeof (uint32_t));
if (unlikely (data == NULL)) {
status = _cairo_error (CAIRO_STATUS_NO_MEMORY);
goto cleanup_gradient;
}
status = _cairo_gl_gradient_render (ctx, n_stops, stops, data, tex_width);
if (unlikely (status))
goto cleanup_data;
/*
* In OpenGL ES 2.0 no format conversion is allowed i.e. 'internalFormat'
* must match 'format' in glTexImage2D.
*/
if (_cairo_gl_get_flavor () == CAIRO_GL_FLAVOR_ES)
internal_format = GL_BGRA;
else
internal_format = GL_RGBA;
glTexImage2D (ctx->tex_target, 0, internal_format, tex_width, 1, 0,
GL_BGRA, GL_UNSIGNED_BYTE, data);
free (data);
/* we ignore errors here and just return an uncached gradient */
if (unlikely (_cairo_cache_insert (&ctx->gradients, &gradient->cache_entry)))
CAIRO_REFERENCE_COUNT_INIT (&gradient->ref_count, 1);
*gradient_out = gradient;
return CAIRO_STATUS_SUCCESS;
cleanup_data:
free (data);
cleanup_gradient:
free (gradient);
return status;
}
cairo_gl_gradient_t *
_cairo_gl_gradient_reference (cairo_gl_gradient_t *gradient)
{
assert (CAIRO_REFERENCE_COUNT_HAS_REFERENCE (&gradient->ref_count));
_cairo_reference_count_inc (&gradient->ref_count);
return gradient;
}
void
_cairo_gl_gradient_destroy (cairo_gl_gradient_t *gradient)
{
cairo_gl_context_t *ctx;
cairo_status_t ignore;
assert (CAIRO_REFERENCE_COUNT_HAS_REFERENCE (&gradient->ref_count));
if (! _cairo_reference_count_dec_and_test (&gradient->ref_count))
return;
if (_cairo_gl_context_acquire (gradient->device, &ctx) == CAIRO_STATUS_SUCCESS) {
/* The gradient my still be active in the last operation, so flush */
_cairo_gl_composite_flush (ctx);
glDeleteTextures (1, &gradient->tex);
ignore = _cairo_gl_context_release (ctx, CAIRO_STATUS_SUCCESS);
}
free (gradient);
}