/* cairo - a vector graphics library with display and print output
*
* Copyright © 2011 Intel Corporation.
*
* 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.og/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.
*
* Contributor(s):
* Robert Bragg <robert@linux.intel.com>
*/
//#include "cairoint.h"
#include "cairo-cogl-private.h"
#include "cairo-cogl-gradient-private.h"
#include "cairo-image-surface-private.h"
#include <cogl/cogl2-experimental.h>
#include <glib.h>
#define DUMP_GRADIENTS_TO_PNG
static unsigned long
_cairo_cogl_linear_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_cogl_linear_gradient_t *
_cairo_cogl_linear_gradient_lookup (cairo_cogl_device_t *ctx,
unsigned long hash,
unsigned int n_stops,
const cairo_gradient_stop_t *stops)
{
cairo_cogl_linear_gradient_t lookup;
lookup.cache_entry.hash = hash,
lookup.n_stops = n_stops;
lookup.stops = stops;
return _cairo_cache_lookup (&ctx->linear_cache, &lookup.cache_entry);
}
cairo_bool_t
_cairo_cogl_linear_gradient_equal (const void *key_a, const void *key_b)
{
const cairo_cogl_linear_gradient_t *a = key_a;
const cairo_cogl_linear_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_cogl_linear_gradient_t *
_cairo_cogl_linear_gradient_reference (cairo_cogl_linear_gradient_t *gradient)
{
assert (CAIRO_REFERENCE_COUNT_HAS_REFERENCE (&gradient->ref_count));
_cairo_reference_count_inc (&gradient->ref_count);
return gradient;
}
void
_cairo_cogl_linear_gradient_destroy (cairo_cogl_linear_gradient_t *gradient)
{
GList *l;
assert (CAIRO_REFERENCE_COUNT_HAS_REFERENCE (&gradient->ref_count));
if (! _cairo_reference_count_dec_and_test (&gradient->ref_count))
return;
for (l = gradient->textures; l; l = l->next) {
cairo_cogl_linear_texture_entry_t *entry = l->data;
cogl_object_unref (entry->texture);
free (entry);
}
g_list_free (gradient->textures);
free (gradient);
}
static int
_cairo_cogl_util_next_p2 (int a)
{
int rval = 1;
while (rval < a)
rval <<= 1;
return rval;
}
static float
get_max_color_component_range (const cairo_color_stop_t *color0, const cairo_color_stop_t *color1)
{
float range;
float max = 0;
range = fabs (color0->red - color1->red);
max = MAX (range, max);
range = fabs (color0->green - color1->green);
max = MAX (range, max);
range = fabs (color0->blue - color1->blue);
max = MAX (range, max);
range = fabs (color0->alpha - color1->alpha);
max = MAX (range, max);
return max;
}
static int
_cairo_cogl_linear_gradient_width_for_stops (cairo_extend_t extend,
unsigned int n_stops,
const cairo_gradient_stop_t *stops)
{
unsigned int n;
float max_texels_per_unit_offset = 0;
float total_offset_range;
/* Find the stop pair demanding the most precision because we are
* interpolating the largest color-component range.
*
* From that we can define the relative sizes of all the other
* stop pairs within our texture and thus the overall size.
*
* To determine the maximum number of texels for a given gap we
* look at the range of colors we are expected to interpolate (so
* long as the stop offsets are not degenerate) and we simply
* assume we want one texel for each unique color value possible
* for a one byte-per-component representation.
* XXX: maybe this is overkill and just allowing 128 levels
* instead of 256 would be enough and then we'd rely on the
* bilinear filtering to give the full range.
*
* XXX: potentially we could try and map offsets to pixels to come
* up with a more precise mapping, but we are aiming to cache
* the gradients so we can't make assumptions about how it will be
* scaled in the future.
*/
for (n = 1; n < n_stops; n++) {
float color_range;
float offset_range;
float texels;
float texels_per_unit_offset;
/* note: degenerate stops don't need to be represented in the
* texture but we want to be sure that solid gaps get at least
* one texel and all other gaps get at least 2 texels.
*/
if (stops[n].offset == stops[n-1].offset)
continue;
color_range = get_max_color_component_range (&stops[n].color, &stops[n-1].color);
if (color_range == 0)
texels = 1;
else
texels = MAX (2, 256.0f * color_range);
/* So how many texels would we need to map over the full [0,1]
* gradient range so this gap would have enough texels? ... */
offset_range = stops[n].offset - stops[n - 1].offset;
texels_per_unit_offset = texels / offset_range;
if (texels_per_unit_offset > max_texels_per_unit_offset)
max_texels_per_unit_offset = texels_per_unit_offset;
}
total_offset_range = fabs (stops[n_stops - 1].offset - stops[0].offset);
return max_texels_per_unit_offset * total_offset_range;
}
/* Aim to create gradient textures without an alpha component so we can avoid
* needing to use blending... */
static CoglPixelFormat
_cairo_cogl_linear_gradient_format_for_stops (cairo_extend_t extend,
unsigned int n_stops,
const cairo_gradient_stop_t *stops)
{
unsigned int n;
/* We have to add extra transparent texels to the end of the gradient to
* handle CAIRO_EXTEND_NONE... */
if (extend == CAIRO_EXTEND_NONE)
return COGL_PIXEL_FORMAT_BGRA_8888_PRE;
for (n = 1; n < n_stops; n++) {
if (stops[n].color.alpha != 1.0)
return COGL_PIXEL_FORMAT_BGRA_8888_PRE;
}
return COGL_PIXEL_FORMAT_BGR_888;
}
static cairo_cogl_gradient_compatibility_t
_cairo_cogl_compatibility_from_extend_mode (cairo_extend_t extend_mode)
{
switch (extend_mode)
{
case CAIRO_EXTEND_NONE:
return CAIRO_COGL_GRADIENT_CAN_EXTEND_NONE;
case CAIRO_EXTEND_PAD:
return CAIRO_COGL_GRADIENT_CAN_EXTEND_PAD;
case CAIRO_EXTEND_REPEAT:
return CAIRO_COGL_GRADIENT_CAN_EXTEND_REPEAT;
case CAIRO_EXTEND_REFLECT:
return CAIRO_COGL_GRADIENT_CAN_EXTEND_REFLECT;
}
assert (0); /* not reached */
return CAIRO_EXTEND_NONE;
}
cairo_cogl_linear_texture_entry_t *
_cairo_cogl_linear_gradient_texture_for_extend (cairo_cogl_linear_gradient_t *gradient,
cairo_extend_t extend_mode)
{
GList *l;
cairo_cogl_gradient_compatibility_t compatibility =
_cairo_cogl_compatibility_from_extend_mode (extend_mode);
for (l = gradient->textures; l; l = l->next) {
cairo_cogl_linear_texture_entry_t *entry = l->data;
if (entry->compatibility & compatibility)
return entry;
}
return NULL;
}
static void
color_stop_lerp (const cairo_color_stop_t *c0,
const cairo_color_stop_t *c1,
float factor,
cairo_color_stop_t *dest)
{
/* NB: we always ignore the short members in this file so we don't need to
* worry about initializing them here. */
dest->red = c0->red * (1.0f-factor) + c1->red * factor;
dest->green = c0->green * (1.0f-factor) + c1->green * factor;
dest->blue = c0->blue * (1.0f-factor) + c1->blue * factor;
dest->alpha = c0->alpha * (1.0f-factor) + c1->alpha * factor;
}
static size_t
_cairo_cogl_linear_gradient_size (cairo_cogl_linear_gradient_t *gradient)
{
GList *l;
size_t size = 0;
for (l = gradient->textures; l; l = l->next) {
cairo_cogl_linear_texture_entry_t *entry = l->data;
size += cogl_texture_get_width (entry->texture) * 4;
}
return size;
}
static void
emit_stop (CoglVertexP2C4 **position,
float left,
float right,
const cairo_color_stop_t *left_color,
const cairo_color_stop_t *right_color)
{
CoglVertexP2C4 *p = *position;
guint8 lr = left_color->red * 255;
guint8 lg = left_color->green * 255;
guint8 lb = left_color->blue * 255;
guint8 la = left_color->alpha * 255;
guint8 rr = right_color->red * 255;
guint8 rg = right_color->green * 255;
guint8 rb = right_color->blue * 255;
guint8 ra = right_color->alpha * 255;
p[0].x = left;
p[0].y = 0;
p[0].r = lr; p[0].g = lg; p[0].b = lb; p[0].a = la;
p[1].x = left;
p[1].y = 1;
p[1].r = lr; p[1].g = lg; p[1].b = lb; p[1].a = la;
p[2].x = right;
p[2].y = 1;
p[2].r = rr; p[2].g = rg; p[2].b = rb; p[2].a = ra;
p[3].x = left;
p[3].y = 0;
p[3].r = lr; p[3].g = lg; p[3].b = lb; p[3].a = la;
p[4].x = right;
p[4].y = 1;
p[4].r = rr; p[4].g = rg; p[4].b = rb; p[4].a = ra;
p[5].x = right;
p[5].y = 0;
p[5].r = rr; p[5].g = rg; p[5].b = rb; p[5].a = ra;
*position = &p[6];
}
#ifdef DUMP_GRADIENTS_TO_PNG
static void
dump_gradient_to_png (CoglTexture *texture)
{
cairo_image_surface_t *image = (cairo_image_surface_t *)
cairo_image_surface_create (CAIRO_FORMAT_ARGB32,
cogl_texture_get_width (texture),
cogl_texture_get_height (texture));
CoglPixelFormat format;
static int gradient_id = 0;
char *gradient_name;
if (image->base.status)
return;
#if G_BYTE_ORDER == G_LITTLE_ENDIAN
format = COGL_PIXEL_FORMAT_BGRA_8888_PRE;
#else
format = COGL_PIXEL_FORMAT_ARGB_8888_PRE;
#endif
cogl_texture_get_data (texture,
format,
0,
image->data);
gradient_name = g_strdup_printf ("./gradient%d.png", gradient_id++);
g_print ("writing gradient: %s\n", gradient_name);
cairo_surface_write_to_png ((cairo_surface_t *)image, gradient_name);
g_free (gradient_name);
}
#endif
cairo_int_status_t
_cairo_cogl_get_linear_gradient (cairo_cogl_device_t *device,
cairo_extend_t extend_mode,
int n_stops,
const cairo_gradient_stop_t *stops,
cairo_cogl_linear_gradient_t **gradient_out)
{
unsigned long hash;
cairo_cogl_linear_gradient_t *gradient;
cairo_cogl_linear_texture_entry_t *entry;
cairo_gradient_stop_t *internal_stops;
int stop_offset;
int n_internal_stops;
int n;
cairo_cogl_gradient_compatibility_t compatibilities;
int width;
int left_padding = 0;
cairo_color_stop_t left_padding_color;
int right_padding = 0;
cairo_color_stop_t right_padding_color;
CoglPixelFormat format;
CoglTexture2D *tex;
GError *error = NULL;
int un_padded_width;
CoglHandle offscreen;
cairo_int_status_t status;
int n_quads;
int n_vertices;
float prev;
float right;
CoglVertexP2C4 *vertices;
CoglVertexP2C4 *p;
CoglPrimitive *prim;
hash = _cairo_cogl_linear_gradient_hash (n_stops, stops);
gradient = _cairo_cogl_linear_gradient_lookup (device, hash, n_stops, stops);
if (gradient) {
cairo_cogl_linear_texture_entry_t *entry =
_cairo_cogl_linear_gradient_texture_for_extend (gradient, extend_mode);
if (entry) {
*gradient_out = _cairo_cogl_linear_gradient_reference (gradient);
return CAIRO_INT_STATUS_SUCCESS;
}
}
if (!gradient) {
gradient = malloc (sizeof (cairo_cogl_linear_gradient_t) +
sizeof (cairo_gradient_stop_t) * (n_stops - 1));
if (!gradient)
return CAIRO_INT_STATUS_NO_MEMORY;
CAIRO_REFERENCE_COUNT_INIT (&gradient->ref_count, 1);
/* NB: we update the cache_entry size at the end before
* [re]adding it to the cache. */
gradient->cache_entry.hash = hash;
gradient->textures = NULL;
gradient->n_stops = n_stops;
gradient->stops = gradient->stops_embedded;
memcpy (gradient->stops_embedded, stops, sizeof (cairo_gradient_stop_t) * n_stops);
} else
_cairo_cogl_linear_gradient_reference (gradient);
entry = malloc (sizeof (cairo_cogl_linear_texture_entry_t));
if (!entry) {
status = CAIRO_INT_STATUS_NO_MEMORY;
goto BAIL;
}
compatibilities = _cairo_cogl_compatibility_from_extend_mode (extend_mode);
n_internal_stops = n_stops;
stop_offset = 0;
/* We really need stops covering the full [0,1] range for repeat/reflect
* if we want to use sampler REPEAT/MIRROR wrap modes so we may need
* to add some extra stops... */
if (extend_mode == CAIRO_EXTEND_REPEAT || extend_mode == CAIRO_EXTEND_REFLECT)
{
/* If we don't need any extra stops then actually the texture
* will be shareable for repeat and reflect... */
compatibilities = (CAIRO_COGL_GRADIENT_CAN_EXTEND_REPEAT |
CAIRO_COGL_GRADIENT_CAN_EXTEND_REFLECT);
if (stops[0].offset != 0) {
n_internal_stops++;
stop_offset++;
}
if (stops[n_stops - 1].offset != 1)
n_internal_stops++;
}
internal_stops = alloca (n_internal_stops * sizeof (cairo_gradient_stop_t));
memcpy (&internal_stops[stop_offset], stops, sizeof (cairo_gradient_stop_t) * n_stops);
/* cairo_color_stop_t values are all unpremultiplied but we need to
* interpolate premultiplied colors so we premultiply all the double
* components now. (skipping any extra stops added for repeat/reflect)
*
* Anothing thing to note is that by premultiplying the colors
* early we'll also reduce the range of colors to interpolate
* which can result in smaller gradient textures.
*/
for (n = stop_offset; n < n_stops; n++) {
cairo_color_stop_t *color = &internal_stops[n].color;
color->red *= color->alpha;
color->green *= color->alpha;
color->blue *= color->alpha;
}
if (n_internal_stops != n_stops)
{
if (extend_mode == CAIRO_EXTEND_REPEAT) {
compatibilities &= ~CAIRO_COGL_GRADIENT_CAN_EXTEND_REFLECT;
if (stops[0].offset != 0) {
/* what's the wrap-around distance between the user's end-stops? */
double dx = (1.0 - stops[n_stops - 1].offset) + stops[0].offset;
internal_stops[0].offset = 0;
color_stop_lerp (&stops[0].color,
&stops[n_stops - 1].color,
stops[0].offset / dx,
&internal_stops[0].color);
}
if (stops[n_stops - 1].offset != 1) {
internal_stops[n_internal_stops - 1].offset = 1;
internal_stops[n_internal_stops - 1].color = internal_stops[0].color;
}
} else if (extend_mode == CAIRO_EXTEND_REFLECT) {
compatibilities &= ~CAIRO_COGL_GRADIENT_CAN_EXTEND_REPEAT;
if (stops[0].offset != 0) {
internal_stops[0].offset = 0;
internal_stops[0].color = stops[n_stops - 1].color;
}
if (stops[n_stops - 1].offset != 1) {
internal_stops[n_internal_stops - 1].offset = 1;
internal_stops[n_internal_stops - 1].color = stops[0].color;
}
}
}
stops = internal_stops;
n_stops = n_internal_stops;
width = _cairo_cogl_linear_gradient_width_for_stops (extend_mode, n_stops, stops);
if (extend_mode == CAIRO_EXTEND_PAD) {
/* Here we need to guarantee that the edge texels of our
* texture correspond to the desired padding color so we
* can use CLAMP_TO_EDGE.
*
* For short stop-gaps and especially for degenerate stops
* it's possible that without special consideration the
* user's end stop colors would not be present in our final
* texture.
*
* To handle this we forcibly add two extra padding texels
* at the edges which extend beyond the [0,1] range of the
* gradient itself and we will later report a translate and
* scale transform to compensate for this.
*/
/* XXX: If we consider generating a mipmap for our 1d texture
* at some point then we also need to consider how much
* padding to add to be sure lower mipmap levels still have
* the desired edge color (as opposed to a linear blend with
* other colors of the gradient).
*/
left_padding = 1;
left_padding_color = stops[0].color;
right_padding = 1;
right_padding_color = stops[n_stops - 1].color;
} else if (extend_mode == CAIRO_EXTEND_NONE) {
/* We handle EXTEND_NONE by adding two extra, transparent, texels at
* the ends of the texture and use CLAMP_TO_EDGE.
*
* We add a scale and translate transform so to account for our texels
* extending beyond the [0,1] range. */
left_padding = 1;
left_padding_color.red = 0;
left_padding_color.green = 0;
left_padding_color.blue = 0;
left_padding_color.alpha = 0;
right_padding = 1;
right_padding_color = left_padding_color;
}
/* If we still have stops that don't cover the full [0,1] range
* then we need to define a texture-coordinate scale + translate
* transform to account for that... */
if (stops[n_stops - 1].offset - stops[0].offset < 1) {
float range = stops[n_stops - 1].offset - stops[0].offset;
entry->scale_x = 1.0 / range;
entry->translate_x = -(stops[0].offset * entry->scale_x);
}
width += left_padding + right_padding;
width = _cairo_cogl_util_next_p2 (width);
width = MIN (4096, width); /* lets not go too stupidly big! */
format = _cairo_cogl_linear_gradient_format_for_stops (extend_mode, n_stops, stops);
do {
tex = cogl_texture_2d_new_with_size (device->cogl_context,
width,
1,
format,
&error);
if (!tex)
g_error_free (error);
} while (tex == NULL && width >> 1);
if (!tex) {
status = CAIRO_INT_STATUS_NO_MEMORY;
goto BAIL;
}
entry->texture = COGL_TEXTURE (tex);
entry->compatibility = compatibilities;
un_padded_width = width - left_padding - right_padding;
/* XXX: only when we know the final texture width can we calculate the
* scale and translate factors needed to account for padding... */
if (un_padded_width != width)
entry->scale_x *= (float)un_padded_width / (float)width;
if (left_padding)
entry->translate_x += (entry->scale_x / (float)un_padded_width) * (float)left_padding;
offscreen = cogl_offscreen_new_to_texture (tex);
cogl_push_framebuffer (COGL_FRAMEBUFFER (offscreen));
cogl_ortho (0, width, 1, 0, -1, 100);
cogl_framebuffer_clear4f (COGL_FRAMEBUFFER (offscreen),
COGL_BUFFER_BIT_COLOR,
0, 0, 0, 0);
n_quads = n_stops - 1 + !!left_padding + !!right_padding;
n_vertices = 6 * n_quads;
vertices = alloca (sizeof (CoglVertexP2C4) * n_vertices);
p = vertices;
if (left_padding)
emit_stop (&p, 0, left_padding, &left_padding_color, &left_padding_color);
prev = (float)left_padding;
for (n = 1; n < n_stops; n++) {
right = (float)left_padding + (float)un_padded_width * stops[n].offset;
emit_stop (&p, prev, right, &stops[n-1].color, &stops[n].color);
prev = right;
}
if (right_padding)
emit_stop (&p, prev, width, &right_padding_color, &right_padding_color);
prim = cogl_primitive_new_p2c4 (COGL_VERTICES_MODE_TRIANGLES,
n_vertices,
vertices);
/* Just use this as the simplest way to setup a default pipeline... */
cogl_set_source_color4f (0, 0, 0, 0);
cogl_primitive_draw (prim);
cogl_object_unref (prim);
cogl_pop_framebuffer ();
cogl_object_unref (offscreen);
gradient->textures = g_list_prepend (gradient->textures, entry);
gradient->cache_entry.size = _cairo_cogl_linear_gradient_size (gradient);
#ifdef DUMP_GRADIENTS_TO_PNG
dump_gradient_to_png (COGL_TEXTURE (tex));
#endif
#warning "FIXME:"
/* XXX: it seems the documentation of _cairo_cache_insert isn't true - it
* doesn't handle re-adding the same entry gracefully - the cache will
* just keep on growing and then it will start randomly evicting things
* pointlessly */
/* we ignore errors here and just return an uncached gradient */
if (likely (! _cairo_cache_insert (&device->linear_cache, &gradient->cache_entry)))
_cairo_cogl_linear_gradient_reference (gradient);
*gradient_out = gradient;
return CAIRO_INT_STATUS_SUCCESS;
BAIL:
free (entry);
if (gradient)
_cairo_cogl_linear_gradient_destroy (gradient);
return status;
}