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gecko-dev/other-licenses/libart_lgpl/art_render_gradient.c

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/*
* art_render_gradient.c: Gradient image source for modular rendering.
*
* Libart_LGPL - library of basic graphic primitives
* Copyright (C) 2000 Raph Levien
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public
* License along with this library; if not, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 02111-1307, USA.
*
* Authors: Raph Levien <raph@acm.org>
* Alexander Larsson <alla@lysator.liu.se>
*/
#include "config.h"
#include "art_render_gradient.h"
#include <math.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <assert.h>
/* Hack to find out how to define alloca on different platforms.
* Modified version of glib/galloca.h.
*/
#ifdef __GNUC__
/* GCC does the right thing */
# undef alloca
# define alloca(size) __builtin_alloca (size)
#elif defined (HAVE_ALLOCA_H)
/* a native and working alloca.h is there */
# include <alloca.h>
#else /* !__GNUC__ && !HAVE_ALLOCA_H */
# ifdef _MSC_VER
# include <malloc.h>
# define alloca _alloca
# else /* !_MSC_VER */
# ifdef _AIX
#pragma alloca
# else /* !_AIX */
# ifndef alloca /* predefined by HP cc +Olibcalls */
char *alloca ();
# endif /* !alloca */
# endif /* !_AIX */
# endif /* !_MSC_VER */
#endif /* !__GNUC__ && !HAVE_ALLOCA_H */
#undef DEBUG_SPEW
typedef struct _ArtImageSourceGradLin ArtImageSourceGradLin;
typedef struct _ArtImageSourceGradRad ArtImageSourceGradRad;
struct _ArtImageSourceGradLin {
ArtImageSource super;
const ArtGradientLinear *gradient;
};
struct _ArtImageSourceGradRad {
ArtImageSource super;
const ArtGradientRadial *gradient;
double a;
};
#define EPSILON 1e-6
#ifndef MAX
#define MAX(a, b) (((a) > (b)) ? (a) : (b))
#endif /* MAX */
#ifndef MIN
#define MIN(a, b) (((a) < (b)) ? (a) : (b))
#endif /* MIN */
static void
art_rgba_gradient_run (art_u8 *buf,
art_u8 *color1,
art_u8 *color2,
int len)
{
int i;
int r, g, b, a;
int dr, dg, db, da;
#ifdef DEBUG_SPEW
printf ("gradient run from %3d %3d %3d %3d to %3d %3d %3d %3d in %d pixels\n",
color1[0], color1[1], color1[2], color1[3],
color2[0], color2[1], color2[2], color2[3],
len);
#endif
r = (color1[0] << 16) + 0x8000;
g = (color1[1] << 16) + 0x8000;
b = (color1[2] << 16) + 0x8000;
a = (color1[3] << 16) + 0x8000;
dr = ((color2[0] - color1[0]) << 16) / len;
dg = ((color2[1] - color1[1]) << 16) / len;
db = ((color2[2] - color1[2]) << 16) / len;
da = ((color2[3] - color1[3]) << 16) / len;
for (i = 0; i < len; i++)
{
*buf++ = (r>>16);
*buf++ = (g>>16);
*buf++ = (b>>16);
*buf++ = (a>>16);
r += dr;
g += dg;
b += db;
a += da;
}
}
static void
calc_color_at (ArtGradientStop *stops,
int n_stops,
ArtGradientSpread spread,
double offset,
double offset_fraction,
int favor_start,
int ix,
art_u8 *color)
{
double off0, off1;
int j;
if (spread == ART_GRADIENT_PAD)
{
if (offset < 0.0)
{
color[0] = ART_PIX_8_FROM_MAX (stops[0].color[0]);
color[1] = ART_PIX_8_FROM_MAX (stops[0].color[1]);
color[2] = ART_PIX_8_FROM_MAX (stops[0].color[2]);
color[3] = ART_PIX_8_FROM_MAX (stops[0].color[3]);
return;
}
if (offset >= 1.0)
{
color[0] = ART_PIX_8_FROM_MAX (stops[n_stops-1].color[0]);
color[1] = ART_PIX_8_FROM_MAX (stops[n_stops-1].color[1]);
color[2] = ART_PIX_8_FROM_MAX (stops[n_stops-1].color[2]);
color[3] = ART_PIX_8_FROM_MAX (stops[n_stops-1].color[3]);
return;
}
}
if (ix > 0 && ix < n_stops)
{
off0 = stops[ix - 1].offset;
off1 = stops[ix].offset;
if (fabs (off1 - off0) > EPSILON)
{
double interp;
double o;
o = offset_fraction;
if ((fabs (o) < EPSILON) && (!favor_start))
o = 1.0;
else if ((fabs (o-1.0) < EPSILON) && (favor_start))
o = 0.0;
/*
if (offset_fraction == 0.0 && !favor_start)
offset_fraction = 1.0;
*/
interp = (o - off0) / (off1 - off0);
for (j = 0; j < 4; j++)
{
int z0, z1;
int z;
z0 = stops[ix - 1].color[j];
z1 = stops[ix].color[j];
z = floor (z0 + (z1 - z0) * interp + 0.5);
color[j] = ART_PIX_8_FROM_MAX (z);
}
return;
}
/* If offsets are too close to safely do the division, just
pick the ix color. */
color[0] = ART_PIX_8_FROM_MAX (stops[ix].color[0]);
color[1] = ART_PIX_8_FROM_MAX (stops[ix].color[1]);
color[2] = ART_PIX_8_FROM_MAX (stops[ix].color[2]);
color[3] = ART_PIX_8_FROM_MAX (stops[ix].color[3]);
return;
}
printf ("WARNING! bad ix %d in calc_color_at() [internal error]\n", ix);
assert (0);
}
static void
art_render_gradient_linear_render_8 (ArtRenderCallback *self,
ArtRender *render,
art_u8 *dest, int y)
{
ArtImageSourceGradLin *z = (ArtImageSourceGradLin *)self;
const ArtGradientLinear *gradient = z->gradient;
int i;
int width = render->x1 - render->x0;
int len;
double offset, d_offset;
double offset_fraction;
int next_stop;
int ix;
art_u8 color1[4], color2[4];
int n_stops = gradient->n_stops;
int extra_stops;
ArtGradientStop *stops = gradient->stops;
ArtGradientStop *tmp_stops;
art_u8 *bufp = render->image_buf;
ArtGradientSpread spread = gradient->spread;
#ifdef DEBUG_SPEW
printf ("x1: %d, x2: %d, y: %d\n", render->x0, render->x1, y);
printf ("spread: %d, stops:", gradient->spread);
for (i=0;i<n_stops;i++)
{
printf ("%f, ", gradient->stops[i].offset);
}
printf ("\n");
#endif
offset = render->x0 * gradient->a + y * gradient->b + gradient->c;
d_offset = gradient->a;
/* We need to force the gradient to extend the whole 0..1 segment,
because the rest of the code doesn't handle partial gradients
correctly */
if ((gradient->stops[0].offset != 0.0) ||
(gradient->stops[n_stops-1].offset != 1.0))
{
extra_stops = 0;
tmp_stops = stops = alloca (sizeof (ArtGradientStop) * (n_stops + 2));
if (gradient->stops[0].offset != 0.0)
{
memcpy (tmp_stops, gradient->stops, sizeof (ArtGradientStop));
tmp_stops[0].offset = 0.0;
tmp_stops += 1;
extra_stops++;
}
memcpy (tmp_stops, gradient->stops, sizeof (ArtGradientStop) * n_stops);
if (gradient->stops[n_stops-1].offset != 1.0)
{
tmp_stops += n_stops;
memcpy (tmp_stops, &gradient->stops[n_stops-1], sizeof (ArtGradientStop));
tmp_stops[0].offset = 1.0;
extra_stops++;
}
n_stops += extra_stops;
#ifdef DEBUG_SPEW
printf ("start/stop modified stops:");
for (i=0;i<n_stops;i++)
{
printf ("%f, ", stops[i].offset);
}
printf ("\n");
#endif
}
if (spread == ART_GRADIENT_REFLECT)
{
tmp_stops = stops;
stops = alloca (sizeof (ArtGradientStop) * n_stops * 2);
memcpy (stops, tmp_stops, sizeof (ArtGradientStop) * n_stops);
for (i = 0; i< n_stops; i++)
{
stops[n_stops * 2 - 1 - i].offset = (1.0 - stops[i].offset / 2.0);
memcpy (stops[n_stops * 2 - 1 - i].color, stops[i].color, sizeof (stops[i].color));
stops[i].offset = stops[i].offset / 2.0;
}
spread = ART_GRADIENT_REPEAT;
offset = offset / 2.0;
d_offset = d_offset / 2.0;
n_stops = 2 * n_stops;
#ifdef DEBUG_SPEW
printf ("reflect modified stops:");
for (i=0;i<n_stops;i++)
{
printf ("%f, ", stops[i].offset);
}
printf ("\n");
#endif
}
offset_fraction = offset - floor (offset);
#ifdef DEBUG_SPEW
printf ("inital offset: %f, fraction: %f d_offset: %f\n", offset, offset_fraction, d_offset);
#endif
/* ix is selected so that offset_fraction is
stops[ix-1] <= offset_fraction <= stops[x1]
If offset_fraction is equal to one of the edges, ix
is selected so the the section of the line extending
in the same direction as d_offset is between ix-1 and ix.
*/
for (ix = 0; ix < n_stops; ix++)
if (stops[ix].offset > offset_fraction ||
(d_offset < 0.0 && stops[ix].offset == offset_fraction))
break;
if (ix == 0)
ix = n_stops - 1;
#ifdef DEBUG_SPEW
printf ("Initial ix: %d\n", ix);
#endif
assert (ix > 0);
assert (ix < n_stops);
assert ((stops[ix-1].offset <= offset_fraction) ||
((stops[ix].offset == 1.0) && (offset_fraction == 0.0)));
assert (offset_fraction <= stops[ix].offset);
assert ((offset_fraction != stops[ix-1].offset) ||
(d_offset >= 0.0));
assert ((offset_fraction != stops[ix].offset) ||
(d_offset <= 0.0));
while (width > 0)
{
#ifdef DEBUG_SPEW
printf ("ix: %d\n", ix);
printf ("start offset: %f\n", offset);
#endif
calc_color_at (stops, n_stops,
spread,
offset,
offset_fraction,
(d_offset > 0.0),
ix,
color1);
if (d_offset > 0)
next_stop = ix;
else
next_stop = ix-1;
#ifdef DEBUG_SPEW
printf ("next_stop: %d\n", next_stop);
#endif
if (fabs (d_offset) > EPSILON)
{
double o;
o = offset_fraction;
if ((fabs (o) <= EPSILON) && (ix == n_stops - 1))
o = 1.0;
else if ((fabs (o-1.0) <= EPSILON) && (ix == 1))
o = 0.0;
#ifdef DEBUG_SPEW
printf ("o: %f\n", o);
#endif
len = (int)floor (fabs ((stops[next_stop].offset - o) / d_offset)) + 1;
len = MAX (len, 0);
len = MIN (len, width);
}
else
{
len = width;
}
#ifdef DEBUG_SPEW
printf ("len: %d\n", len);
#endif
if (len > 0)
{
offset = offset + (len-1) * d_offset;
offset_fraction = offset - floor (offset);
#ifdef DEBUG_SPEW
printf ("end offset: %f, fraction: %f\n", offset, offset_fraction);
#endif
calc_color_at (stops, n_stops,
spread,
offset,
offset_fraction,
(d_offset < 0.0),
ix,
color2);
art_rgba_gradient_run (bufp,
color1,
color2,
len);
offset += d_offset;
offset_fraction = offset - floor (offset);
}
if (d_offset > 0)
{
do
{
ix++;
if (ix == n_stops)
ix = 1;
/* Note: offset_fraction can actually be one here on x86 machines that
does calculations with extanded precision, but later rounds to 64bit.
This happens if the 80bit offset_fraction is larger than the
largest 64bit double that is less than one.
*/
}
while (!((stops[ix-1].offset <= offset_fraction &&
offset_fraction < stops[ix].offset) ||
(ix == 1 && offset_fraction == 1.0)));
}
else
{
do
{
ix--;
if (ix == 0)
ix = n_stops - 1;
}
while (!((stops[ix-1].offset < offset_fraction &&
offset_fraction <= stops[ix].offset) ||
(ix == n_stops - 1 && offset_fraction == 0.0)));
}
bufp += 4*len;
width -= len;
}
}
/**
* art_render_gradient_setpix: Set a gradient pixel.
* @render: The render object.
* @dst: Pointer to destination (where to store pixel).
* @n_stops: Number of stops in @stops.
* @stops: The stops for the gradient.
* @offset: The offset.
*
* @n_stops must be > 0.
*
* Sets a gradient pixel, storing it at @dst.
**/
static void
art_render_gradient_setpix (ArtRender *render,
art_u8 *dst,
int n_stops, ArtGradientStop *stops,
double offset)
{
int ix;
int j;
double off0, off1;
int n_ch = render->n_chan + 1;
for (ix = 0; ix < n_stops; ix++)
if (stops[ix].offset > offset)
break;
/* stops[ix - 1].offset < offset < stops[ix].offset */
if (ix > 0 && ix < n_stops)
{
off0 = stops[ix - 1].offset;
off1 = stops[ix].offset;
if (fabs (off1 - off0) > EPSILON)
{
double interp;
interp = (offset - off0) / (off1 - off0);
for (j = 0; j < n_ch; j++)
{
int z0, z1;
int z;
z0 = stops[ix - 1].color[j];
z1 = stops[ix].color[j];
z = floor (z0 + (z1 - z0) * interp + 0.5);
if (render->buf_depth == 8)
dst[j] = ART_PIX_8_FROM_MAX (z);
else /* (render->buf_depth == 16) */
((art_u16 *)dst)[j] = z;
}
return;
}
}
else if (ix == n_stops)
ix--;
for (j = 0; j < n_ch; j++)
{
int z;
z = stops[ix].color[j];
if (render->buf_depth == 8)
dst[j] = ART_PIX_8_FROM_MAX (z);
else /* (render->buf_depth == 16) */
((art_u16 *)dst)[j] = z;
}
}
static void
art_render_gradient_linear_done (ArtRenderCallback *self, ArtRender *render)
{
art_free (self);
}
static void
art_render_gradient_linear_render (ArtRenderCallback *self, ArtRender *render,
art_u8 *dest, int y)
{
ArtImageSourceGradLin *z = (ArtImageSourceGradLin *)self;
const ArtGradientLinear *gradient = z->gradient;
int pixstride = (render->n_chan + 1) * (render->depth >> 3);
int x;
int width = render->x1 - render->x0;
double offset, d_offset;
double actual_offset;
int n_stops = gradient->n_stops;
ArtGradientStop *stops = gradient->stops;
art_u8 *bufp = render->image_buf;
ArtGradientSpread spread = gradient->spread;
offset = render->x0 * gradient->a + y * gradient->b + gradient->c;
d_offset = gradient->a;
for (x = 0; x < width; x++)
{
if (spread == ART_GRADIENT_PAD)
actual_offset = offset;
else if (spread == ART_GRADIENT_REPEAT)
actual_offset = offset - floor (offset);
else /* (spread == ART_GRADIENT_REFLECT) */
{
double tmp;
tmp = offset - 2 * floor (0.5 * offset);
actual_offset = tmp > 1 ? 2 - tmp : tmp;
}
art_render_gradient_setpix (render, bufp, n_stops, stops, actual_offset);
offset += d_offset;
bufp += pixstride;
}
}
static void
art_render_gradient_linear_negotiate (ArtImageSource *self, ArtRender *render,
ArtImageSourceFlags *p_flags,
int *p_buf_depth, ArtAlphaType *p_alpha)
{
if (render->depth == 8 &&
render->n_chan == 3)
{
self->super.render = art_render_gradient_linear_render_8;
*p_flags = 0;
*p_buf_depth = 8;
*p_alpha = ART_ALPHA_PREMUL;
return;
}
self->super.render = art_render_gradient_linear_render;
*p_flags = 0;
*p_buf_depth = render->depth;
*p_alpha = ART_ALPHA_PREMUL;
}
/**
* art_render_gradient_linear: Add a linear gradient image source.
* @render: The render object.
* @gradient: The linear gradient.
*
* Adds the linear gradient @gradient as the image source for rendering
* in the render object @render.
**/
void
art_render_gradient_linear (ArtRender *render,
const ArtGradientLinear *gradient,
ArtFilterLevel level)
{
ArtImageSourceGradLin *image_source = art_new (ArtImageSourceGradLin, 1);
image_source->super.super.render = NULL;
image_source->super.super.done = art_render_gradient_linear_done;
image_source->super.negotiate = art_render_gradient_linear_negotiate;
image_source->gradient = gradient;
art_render_add_image_source (render, &image_source->super);
}
static void
art_render_gradient_radial_done (ArtRenderCallback *self, ArtRender *render)
{
art_free (self);
}
static void
art_render_gradient_radial_render (ArtRenderCallback *self, ArtRender *render,
art_u8 *dest, int y)
{
ArtImageSourceGradRad *z = (ArtImageSourceGradRad *)self;
const ArtGradientRadial *gradient = z->gradient;
int pixstride = (render->n_chan + 1) * (render->depth >> 3);
int x;
int x0 = render->x0;
int width = render->x1 - x0;
int n_stops = gradient->n_stops;
ArtGradientStop *stops = gradient->stops;
art_u8 *bufp = render->image_buf;
double fx = gradient->fx;
double fy = gradient->fy;
double dx, dy;
double *affine = gradient->affine;
double aff0 = affine[0];
double aff1 = affine[1];
const double a = z->a;
const double arecip = 1.0 / a;
double b, db;
double c, dc, ddc;
double b_a, db_a;
double rad, drad, ddrad;
dx = x0 * aff0 + y * affine[2] + affine[4] - fx;
dy = x0 * aff1 + y * affine[3] + affine[5] - fy;
b = dx * fx + dy * fy;
db = aff0 * fx + aff1 * fy;
c = dx * dx + dy * dy;
dc = 2 * aff0 * dx + aff0 * aff0 + 2 * aff1 * dy + aff1 * aff1;
ddc = 2 * aff0 * aff0 + 2 * aff1 * aff1;
b_a = b * arecip;
db_a = db * arecip;
rad = b_a * b_a + c * arecip;
drad = 2 * b_a * db_a + db_a * db_a + dc * arecip;
ddrad = 2 * db_a * db_a + ddc * arecip;
for (x = 0; x < width; x++)
{
double z;
if (rad > 0)
z = b_a + sqrt (rad);
else
z = b_a;
art_render_gradient_setpix (render, bufp, n_stops, stops, z);
bufp += pixstride;
b_a += db_a;
rad += drad;
drad += ddrad;
}
}
static void
art_render_gradient_radial_negotiate (ArtImageSource *self, ArtRender *render,
ArtImageSourceFlags *p_flags,
int *p_buf_depth, ArtAlphaType *p_alpha)
{
self->super.render = art_render_gradient_radial_render;
*p_flags = 0;
*p_buf_depth = render->depth;
*p_alpha = ART_ALPHA_PREMUL;
}
/**
* art_render_gradient_radial: Add a radial gradient image source.
* @render: The render object.
* @gradient: The radial gradient.
*
* Adds the radial gradient @gradient as the image source for rendering
* in the render object @render.
**/
void
art_render_gradient_radial (ArtRender *render,
const ArtGradientRadial *gradient,
ArtFilterLevel level)
{
ArtImageSourceGradRad *image_source = art_new (ArtImageSourceGradRad, 1);
double fx = gradient->fx;
double fy = gradient->fy;
image_source->super.super.render = NULL;
image_source->super.super.done = art_render_gradient_radial_done;
image_source->super.negotiate = art_render_gradient_radial_negotiate;
image_source->gradient = gradient;
/* todo: sanitycheck fx, fy? */
image_source->a = 1 - fx * fx - fy * fy;
art_render_add_image_source (render, &image_source->super);
}
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