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mutter/src/ui/gradient.c
Florian Müllner 8199699e7c gradient: Port from GdkColor to GdkRGBA 
GdkColor is about to be deprecated, so move to GdkRGBA instead.
It might be worth considering using cairo patterns for the gradients
rather than using custom code to render gradients to a pixbuf which
is then drawn with cairo, but for now this is just a straight port
of the existing code.

https://bugzilla.gnome.org/show_bug.cgi?id=650586
2011-07-08 01:29:54 +02:00

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/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*- */
/* Metacity gradient rendering */
/*
* Copyright (C) 2001 Havoc Pennington, 99% copied from wrlib in
* WindowMaker, Copyright (C) 1997-2000 Dan Pascu and Alfredo Kojima
* Copyright (C) 2005 Elijah Newren
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 2 of the
* License, or (at your option) any later version.
*
* This program 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
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
* 02111-1307, USA. */
#include <meta/gradient.h>
#include <meta/util.h>
#include <string.h>
/* This is all Alfredo's and Dan's usual very nice WindowMaker code,
* slightly GTK-ized
*/
static GdkPixbuf* meta_gradient_create_horizontal (int width,
int height,
const GdkRGBA *from,
const GdkRGBA *to);
static GdkPixbuf* meta_gradient_create_vertical (int width,
int height,
const GdkRGBA *from,
const GdkRGBA *to);
static GdkPixbuf* meta_gradient_create_diagonal (int width,
int height,
const GdkRGBA *from,
const GdkRGBA *to);
static GdkPixbuf* meta_gradient_create_multi_horizontal (int width,
int height,
const GdkRGBA *colors,
int count);
static GdkPixbuf* meta_gradient_create_multi_vertical (int width,
int height,
const GdkRGBA *colors,
int count);
static GdkPixbuf* meta_gradient_create_multi_diagonal (int width,
int height,
const GdkRGBA *colors,
int count);
/* Used as the destroy notification function for gdk_pixbuf_new() */
static void
free_buffer (guchar *pixels, gpointer data)
{
g_free (pixels);
}
static GdkPixbuf*
blank_pixbuf (int width, int height, gboolean no_padding)
{
guchar *buf;
int rowstride;
g_return_val_if_fail (width > 0, NULL);
g_return_val_if_fail (height > 0, NULL);
if (no_padding)
rowstride = width * 3;
else
/* Always align rows to 32-bit boundaries */
rowstride = 4 * ((3 * width + 3) / 4);
buf = g_try_malloc (height * rowstride);
if (!buf)
return NULL;
return gdk_pixbuf_new_from_data (buf, GDK_COLORSPACE_RGB,
FALSE, 8,
width, height, rowstride,
free_buffer, NULL);
}
/**
* meta_gradient_create_simple:
* @width: Width in pixels
* @height: Height in pixels
* @from: Starting color
* @to: Ending color
* @style: Gradient style
*
* Returns: (transfer full): A new linear gradient
*/
GdkPixbuf*
meta_gradient_create_simple (int width,
int height,
const GdkRGBA *from,
const GdkRGBA *to,
MetaGradientType style)
{
switch (style)
{
case META_GRADIENT_HORIZONTAL:
return meta_gradient_create_horizontal (width, height,
from, to);
case META_GRADIENT_VERTICAL:
return meta_gradient_create_vertical (width, height,
from, to);
case META_GRADIENT_DIAGONAL:
return meta_gradient_create_diagonal (width, height,
from, to);
case META_GRADIENT_LAST:
break;
}
g_assert_not_reached ();
return NULL;
}
/**
* meta_gradient_create_multi:
* @width: Width in pixels
* @height: Height in pixels
* @colors: (array length=n_colors): Array of colors
* @n_colors: Number of colors
* @style: Gradient style
*
* Returns: (transfer full): A new multi-step linear gradient
*/
GdkPixbuf*
meta_gradient_create_multi (int width,
int height,
const GdkRGBA *colors,
int n_colors,
MetaGradientType style)
{
if (n_colors > 2)
{
switch (style)
{
case META_GRADIENT_HORIZONTAL:
return meta_gradient_create_multi_horizontal (width, height, colors, n_colors);
case META_GRADIENT_VERTICAL:
return meta_gradient_create_multi_vertical (width, height, colors, n_colors);
case META_GRADIENT_DIAGONAL:
return meta_gradient_create_multi_diagonal (width, height, colors, n_colors);
case META_GRADIENT_LAST:
g_assert_not_reached ();
break;
}
}
else if (n_colors > 1)
{
return meta_gradient_create_simple (width, height, &colors[0], &colors[1],
style);
}
else if (n_colors > 0)
{
return meta_gradient_create_simple (width, height, &colors[0], &colors[0],
style);
}
g_assert_not_reached ();
return NULL;
}
/**
* meta_gradient_create_interwoven: (skip)
*
* Interwoven essentially means we have two vertical gradients,
* cut into horizontal strips of the given thickness, and then the strips
* are alternated. I'm not sure what it's good for, just copied since
* WindowMaker had it.
*/
GdkPixbuf*
meta_gradient_create_interwoven (int width,
int height,
const GdkRGBA colors1[2],
int thickness1,
const GdkRGBA colors2[2],
int thickness2)
{
int i, j, k, l, ll;
long r1, g1, b1, dr1, dg1, db1;
long r2, g2, b2, dr2, dg2, db2;
GdkPixbuf *pixbuf;
unsigned char *ptr;
unsigned char *pixels;
int rowstride;
pixbuf = blank_pixbuf (width, height, FALSE);
if (pixbuf == NULL)
return NULL;
pixels = gdk_pixbuf_get_pixels (pixbuf);
rowstride = gdk_pixbuf_get_rowstride (pixbuf);
r1 = (long)(colors1[0].red*0xffffff);
g1 = (long)(colors1[0].green*0xffffff);
b1 = (long)(colors1[0].blue*0xffffff);
r2 = (long)(colors2[0].red*0xffffff);
g2 = (long)(colors2[0].green*0xffffff);
b2 = (long)(colors2[0].blue*0xffffff);
dr1 = ((colors1[1].red-colors1[0].red)*0xffffff)/(int)height;
dg1 = ((colors1[1].green-colors1[0].green)*0xffffff)/(int)height;
db1 = ((colors1[1].blue-colors1[0].blue)*0xffffff)/(int)height;
dr2 = ((colors2[1].red-colors2[0].red)*0xffffff)/(int)height;
dg2 = ((colors2[1].green-colors2[0].green)*0xffffff)/(int)height;
db2 = ((colors2[1].blue-colors2[0].blue)*0xffffff)/(int)height;
for (i=0,k=0,l=0,ll=thickness1; i<height; i++)
{
ptr = pixels + i * rowstride;
if (k == 0)
{
ptr[0] = (unsigned char) (r1>>16);
ptr[1] = (unsigned char) (g1>>16);
ptr[2] = (unsigned char) (b1>>16);
}
else
{
ptr[0] = (unsigned char) (r2>>16);
ptr[1] = (unsigned char) (g2>>16);
ptr[2] = (unsigned char) (b2>>16);
}
for (j=1; j <= width/2; j *= 2)
memcpy (&(ptr[j*3]), ptr, j*3);
memcpy (&(ptr[j*3]), ptr, (width - j)*3);
if (++l == ll)
{
if (k == 0)
{
k = 1;
ll = thickness2;
}
else
{
k = 0;
ll = thickness1;
}
l = 0;
}
r1+=dr1;
g1+=dg1;
b1+=db1;
r2+=dr2;
g2+=dg2;
b2+=db2;
}
return pixbuf;
}
/*
*----------------------------------------------------------------------
* meta_gradient_create_horizontal--
* Renders a horizontal linear gradient of the specified size in the
* GdkPixbuf format with a border of the specified type.
*
* Returns:
* A 24bit GdkPixbuf with the gradient (no alpha channel).
*
* Side effects:
* None
*----------------------------------------------------------------------
*/
static GdkPixbuf*
meta_gradient_create_horizontal (int width, int height,
const GdkRGBA *from,
const GdkRGBA *to)
{
int i;
long r, g, b, dr, dg, db;
GdkPixbuf *pixbuf;
unsigned char *ptr;
unsigned char *pixels;
int r0, g0, b0;
int rf, gf, bf;
int rowstride;
pixbuf = blank_pixbuf (width, height, FALSE);
if (pixbuf == NULL)
return NULL;
pixels = gdk_pixbuf_get_pixels (pixbuf);
ptr = pixels;
rowstride = gdk_pixbuf_get_rowstride (pixbuf);
r0 = (guchar) (from->red * 0xff);
g0 = (guchar) (from->green * 0xff);
b0 = (guchar) (from->blue * 0xff);
rf = (guchar) (to->red * 0xff);
gf = (guchar) (to->green * 0xff);
bf = (guchar) (to->blue * 0xff);
r = r0 << 16;
g = g0 << 16;
b = b0 << 16;
dr = ((rf-r0)<<16)/(int)width;
dg = ((gf-g0)<<16)/(int)width;
db = ((bf-b0)<<16)/(int)width;
/* render the first line */
for (i=0; i<width; i++)
{
*(ptr++) = (unsigned char)(r>>16);
*(ptr++) = (unsigned char)(g>>16);
*(ptr++) = (unsigned char)(b>>16);
r += dr;
g += dg;
b += db;
}
/* copy the first line to the other lines */
for (i=1; i<height; i++)
{
memcpy (&(pixels[i*rowstride]), pixels, rowstride);
}
return pixbuf;
}
/*
*----------------------------------------------------------------------
* meta_gradient_create_vertical--
* Renders a vertical linear gradient of the specified size in the
* GdkPixbuf format with a border of the specified type.
*
* Returns:
* A 24bit GdkPixbuf with the gradient (no alpha channel).
*
* Side effects:
* None
*----------------------------------------------------------------------
*/
static GdkPixbuf*
meta_gradient_create_vertical (int width, int height,
const GdkRGBA *from,
const GdkRGBA *to)
{
int i, j;
long r, g, b, dr, dg, db;
GdkPixbuf *pixbuf;
unsigned char *ptr;
int r0, g0, b0;
int rf, gf, bf;
int rowstride;
unsigned char *pixels;
pixbuf = blank_pixbuf (width, height, FALSE);
if (pixbuf == NULL)
return NULL;
pixels = gdk_pixbuf_get_pixels (pixbuf);
rowstride = gdk_pixbuf_get_rowstride (pixbuf);
r0 = (guchar) (from->red * 0xff);
g0 = (guchar) (from->green * 0xff);
b0 = (guchar) (from->blue * 0xff);
rf = (guchar) (to->red * 0xff);
gf = (guchar) (to->green * 0xff);
bf = (guchar) (to->blue * 0xff);
r = r0<<16;
g = g0<<16;
b = b0<<16;
dr = ((rf-r0)<<16)/(int)height;
dg = ((gf-g0)<<16)/(int)height;
db = ((bf-b0)<<16)/(int)height;
for (i=0; i<height; i++)
{
ptr = pixels + i * rowstride;
ptr[0] = (unsigned char)(r>>16);
ptr[1] = (unsigned char)(g>>16);
ptr[2] = (unsigned char)(b>>16);
for (j=1; j <= width/2; j *= 2)
memcpy (&(ptr[j*3]), ptr, j*3);
memcpy (&(ptr[j*3]), ptr, (width - j)*3);
r+=dr;
g+=dg;
b+=db;
}
return pixbuf;
}
/*
*----------------------------------------------------------------------
* meta_gradient_create_diagonal--
* Renders a diagonal linear gradient of the specified size in the
* GdkPixbuf format with a border of the specified type.
*
* Returns:
* A 24bit GdkPixbuf with the gradient (no alpha channel).
*
* Side effects:
* None
*----------------------------------------------------------------------
*/
static GdkPixbuf*
meta_gradient_create_diagonal (int width, int height,
const GdkRGBA *from,
const GdkRGBA *to)
{
GdkPixbuf *pixbuf, *tmp;
int j;
float a, offset;
unsigned char *ptr;
unsigned char *pixels;
int rowstride;
if (width == 1)
return meta_gradient_create_vertical (width, height, from, to);
else if (height == 1)
return meta_gradient_create_horizontal (width, height, from, to);
pixbuf = blank_pixbuf (width, height, FALSE);
if (pixbuf == NULL)
return NULL;
pixels = gdk_pixbuf_get_pixels (pixbuf);
rowstride = gdk_pixbuf_get_rowstride (pixbuf);
tmp = meta_gradient_create_horizontal (2*width-1, 1, from, to);
if (!tmp)
{
g_object_unref (G_OBJECT (pixbuf));
return NULL;
}
ptr = gdk_pixbuf_get_pixels (tmp);
a = ((float)(width - 1))/((float)(height - 1));
width = width * 3;
/* copy the first line to the other lines with corresponding offset */
for (j=0, offset=0.0; j<rowstride*height; j += rowstride)
{
memcpy (&(pixels[j]), &ptr[3*(int)offset], width);
offset += a;
}
g_object_unref (G_OBJECT (tmp));
return pixbuf;
}
static GdkPixbuf*
meta_gradient_create_multi_horizontal (int width, int height,
const GdkRGBA *colors,
int count)
{
int i, j, k;
long r, g, b, dr, dg, db;
GdkPixbuf *pixbuf;
unsigned char *ptr;
unsigned char *pixels;
int width2;
int rowstride;
g_return_val_if_fail (count > 2, NULL);
pixbuf = blank_pixbuf (width, height, FALSE);
if (pixbuf == NULL)
return NULL;
pixels = gdk_pixbuf_get_pixels (pixbuf);
rowstride = gdk_pixbuf_get_rowstride (pixbuf);
ptr = pixels;
if (count > width)
count = width;
if (count > 1)
width2 = width/(count-1);
else
width2 = width;
k = 0;
r = (long)(colors[0].red * 0xffffff);
g = (long)(colors[0].green * 0xffffff);
b = (long)(colors[0].blue * 0xffffff);
/* render the first line */
for (i=1; i<count; i++)
{
dr = (int)((colors[i].red - colors[i-1].red) *0xffffff)/(int)width2;
dg = (int)((colors[i].green - colors[i-1].green)*0xffffff)/(int)width2;
db = (int)((colors[i].blue - colors[i-1].blue) *0xffffff)/(int)width2;
for (j=0; j<width2; j++)
{
*ptr++ = (unsigned char)(r>>16);
*ptr++ = (unsigned char)(g>>16);
*ptr++ = (unsigned char)(b>>16);
r += dr;
g += dg;
b += db;
k++;
}
r = (long)(colors[i].red * 0xffffff);
g = (long)(colors[i].green * 0xffffff);
b = (long)(colors[i].blue * 0xffffff);
}
for (j=k; j<width; j++)
{
*ptr++ = (unsigned char)(r>>16);
*ptr++ = (unsigned char)(g>>16);
*ptr++ = (unsigned char)(b>>16);
}
/* copy the first line to the other lines */
for (i=1; i<height; i++)
{
memcpy (&(pixels[i*rowstride]), pixels, rowstride);
}
return pixbuf;
}
static GdkPixbuf*
meta_gradient_create_multi_vertical (int width, int height,
const GdkRGBA *colors,
int count)
{
int i, j, k;
long r, g, b, dr, dg, db;
GdkPixbuf *pixbuf;
unsigned char *ptr, *tmp, *pixels;
int height2;
int x;
int rowstride;
g_return_val_if_fail (count > 2, NULL);
pixbuf = blank_pixbuf (width, height, FALSE);
if (pixbuf == NULL)
return NULL;
pixels = gdk_pixbuf_get_pixels (pixbuf);
rowstride = gdk_pixbuf_get_rowstride (pixbuf);
ptr = pixels;
if (count > height)
count = height;
if (count > 1)
height2 = height/(count-1);
else
height2 = height;
k = 0;
r = (long)(colors[0].red * 0xffffff);
g = (long)(colors[0].green * 0xffffff);
b = (long)(colors[0].blue * 0xffffff);
for (i=1; i<count; i++)
{
dr = (int)((colors[i].red - colors[i-1].red) *0xffffff)/(int)height2;
dg = (int)((colors[i].green - colors[i-1].green)*0xffffff)/(int)height2;
db = (int)((colors[i].blue - colors[i-1].blue) *0xffffff)/(int)height2;
for (j=0; j<height2; j++)
{
ptr[0] = (unsigned char)(r>>16);
ptr[1] = (unsigned char)(g>>16);
ptr[2] = (unsigned char)(b>>16);
for (x=1; x <= width/2; x *= 2)
memcpy (&(ptr[x*3]), ptr, x*3);
memcpy (&(ptr[x*3]), ptr, (width - x)*3);
ptr += rowstride;
r += dr;
g += dg;
b += db;
k++;
}
r = (long)(colors[i].red * 0xffffff);
g = (long)(colors[i].green * 0xffffff);
b = (long)(colors[i].blue * 0xffffff);
}
if (k<height)
{
tmp = ptr;
ptr[0] = (unsigned char) (r>>16);
ptr[1] = (unsigned char) (g>>16);
ptr[2] = (unsigned char) (b>>16);
for (x=1; x <= width/2; x *= 2)
memcpy (&(ptr[x*3]), ptr, x*3);
memcpy (&(ptr[x*3]), ptr, (width - x)*3);
ptr += rowstride;
for (j=k+1; j<height; j++)
{
memcpy (ptr, tmp, rowstride);
ptr += rowstride;
}
}
return pixbuf;
}
static GdkPixbuf*
meta_gradient_create_multi_diagonal (int width, int height,
const GdkRGBA *colors,
int count)
{
GdkPixbuf *pixbuf, *tmp;
float a, offset;
int j;
unsigned char *ptr;
unsigned char *pixels;
int rowstride;
g_return_val_if_fail (count > 2, NULL);
if (width == 1)
return meta_gradient_create_multi_vertical (width, height, colors, count);
else if (height == 1)
return meta_gradient_create_multi_horizontal (width, height, colors, count);
pixbuf = gdk_pixbuf_new (GDK_COLORSPACE_RGB, FALSE, 8,
width, height);
if (pixbuf == NULL)
return NULL;
pixels = gdk_pixbuf_get_pixels (pixbuf);
rowstride = gdk_pixbuf_get_rowstride (pixbuf);
if (count > width)
count = width;
if (count > height)
count = height;
if (count > 2)
tmp = meta_gradient_create_multi_horizontal (2*width-1, 1, colors, count);
else
/* wrlib multiplies these colors by 256 before passing them in, but
* I think it's a bug in wrlib, so changed here. I could be wrong
* though, if we notice two-color multi diagonals not working.
*/
tmp = meta_gradient_create_horizontal (2*width-1, 1,
&colors[0], &colors[1]);
if (!tmp)
{
g_object_unref (G_OBJECT (pixbuf));
return NULL;
}
ptr = gdk_pixbuf_get_pixels (tmp);
a = ((float)(width - 1))/((float)(height - 1));
width = width * 3;
/* copy the first line to the other lines with corresponding offset */
for (j=0, offset=0; j<rowstride*height; j += rowstride)
{
memcpy (&(pixels[j]), &ptr[3*(int)offset], width);
offset += a;
}
g_object_unref (G_OBJECT (tmp));
return pixbuf;
}
static void
simple_multiply_alpha (GdkPixbuf *pixbuf,
guchar alpha)
{
guchar *pixels;
int rowstride;
int height;
int row;
g_return_if_fail (GDK_IS_PIXBUF (pixbuf));
if (alpha == 255)
return;
g_assert (gdk_pixbuf_get_has_alpha (pixbuf));
pixels = gdk_pixbuf_get_pixels (pixbuf);
rowstride = gdk_pixbuf_get_rowstride (pixbuf);
height = gdk_pixbuf_get_height (pixbuf);
row = 0;
while (row < height)
{
guchar *p;
guchar *end;
p = pixels + row * rowstride;
end = p + rowstride;
while (p != end)
{
p += 3; /* skip RGB */
/* multiply the two alpha channels. not sure this is right.
* but some end cases are that if the pixbuf contains 255,
* then it should be modified to contain "alpha"; if the
* pixbuf contains 0, it should remain 0.
*/
/* ((*p / 255.0) * (alpha / 255.0)) * 255; */
*p = (guchar) (((int) *p * (int) alpha) / (int) 255);
++p; /* skip A */
}
++row;
}
}
static void
meta_gradient_add_alpha_horizontal (GdkPixbuf *pixbuf,
const unsigned char *alphas,
int n_alphas)
{
int i, j;
long a, da;
unsigned char *p;
unsigned char *pixels;
int width2;
int rowstride;
int width, height;
unsigned char *gradient;
unsigned char *gradient_p;
unsigned char *gradient_end;
g_return_if_fail (n_alphas > 0);
if (n_alphas == 1)
{
/* Optimize this */
simple_multiply_alpha (pixbuf, alphas[0]);
return;
}
width = gdk_pixbuf_get_width (pixbuf);
height = gdk_pixbuf_get_height (pixbuf);
gradient = g_new (unsigned char, width);
gradient_end = gradient + width;
if (n_alphas > width)
n_alphas = width;
if (n_alphas > 1)
width2 = width / (n_alphas - 1);
else
width2 = width;
a = alphas[0] << 8;
gradient_p = gradient;
/* render the gradient into an array */
for (i = 1; i < n_alphas; i++)
{
da = (((int)(alphas[i] - (int) alphas[i-1])) << 8) / (int) width2;
for (j = 0; j < width2; j++)
{
*gradient_p++ = (a >> 8);
a += da;
}
a = alphas[i] << 8;
}
/* get leftover pixels */
while (gradient_p != gradient_end)
{
*gradient_p++ = a >> 8;
}
/* Now for each line of the pixbuf, fill in with the gradient */
pixels = gdk_pixbuf_get_pixels (pixbuf);
rowstride = gdk_pixbuf_get_rowstride (pixbuf);
p = pixels;
i = 0;
while (i < height)
{
unsigned char *row_end = p + rowstride;
gradient_p = gradient;
p += 3;
while (gradient_p != gradient_end)
{
/* multiply the two alpha channels. not sure this is right.
* but some end cases are that if the pixbuf contains 255,
* then it should be modified to contain "alpha"; if the
* pixbuf contains 0, it should remain 0.
*/
/* ((*p / 255.0) * (alpha / 255.0)) * 255; */
*p = (guchar) (((int) *p * (int) *gradient_p) / (int) 255);
p += 4;
++gradient_p;
}
p = row_end;
++i;
}
g_free (gradient);
}
void
meta_gradient_add_alpha (GdkPixbuf *pixbuf,
const guchar *alphas,
int n_alphas,
MetaGradientType type)
{
g_return_if_fail (GDK_IS_PIXBUF (pixbuf));
g_return_if_fail (gdk_pixbuf_get_has_alpha (pixbuf));
g_return_if_fail (n_alphas > 0);
switch (type)
{
case META_GRADIENT_HORIZONTAL:
meta_gradient_add_alpha_horizontal (pixbuf, alphas, n_alphas);
break;
case META_GRADIENT_VERTICAL:
g_printerr ("metacity: vertical alpha channel gradient not implemented yet\n");
break;
case META_GRADIENT_DIAGONAL:
g_printerr ("metacity: diagonal alpha channel gradient not implemented yet\n");
break;
case META_GRADIENT_LAST:
g_assert_not_reached ();
break;
}
}
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