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/* xscreensaver, Copyright (c) 1992, 1995, 1996, 1997, 2006
* Jamie Zawinski <jwz@jwz.org>
*
* 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. No representations are made about the suitability of this
* software for any purpose. It is provided "as is" without express or
* implied warranty.
*/
/* Beauty is only skin deep, unless you've got an alpha channel. */
#include "utils.h"
#include "alpha.h"
#include "visual.h"
#include "hsv.h"
#include "yarandom.h"
#include "resources.h"
#include <X11/Xutil.h>
#ifndef countof
# define countof(x) (sizeof(*(x))/sizeof((x)))
#endif
/* I don't believe this fucking language doesn't have builtin exponentiation.
I further can't believe that the fucking ^ character means fucking XOR!! */
static int
i_exp (int i, int j)
{
int k = 1;
while (j--) k *= i;
return k;
}
static void
merge_colors (int argc, XColor **argv, XColor *into_color, int mask,
Bool additive_p)
{
int j;
*into_color = *argv [0];
into_color->pixel |= mask;
for (j = 1; j < argc; j++)
{
# define SHORT_INC(x,y) (x = ((((x)+(y)) > 0xFFFF) ? 0xFFFF : ((x)+(y))))
# define SHORT_DEC(x,y) (x = ((((x)-(y)) < 0) ? 0 : ((x)-(y))))
if (additive_p)
{
SHORT_INC (into_color->red, argv[j]->red);
SHORT_INC (into_color->green, argv[j]->green);
SHORT_INC (into_color->blue, argv[j]->blue);
}
else
{
SHORT_DEC (into_color->red, argv[j]->red);
SHORT_DEC (into_color->green, argv[j]->green);
SHORT_DEC (into_color->blue, argv[j]->blue);
}
# undef SHORT_INC
# undef SHORT_DEC
}
}
static void
permute_colors (XColor *pcolors, XColor *colors,
int count,
unsigned long *plane_masks,
Bool additive_p)
{
int out = 0;
int max = i_exp (2, count);
if (count > 31) abort ();
for (out = 1; out < max; out++)
{
XColor *argv [32];
int this_mask = 0;
int argc = 0;
int bit;
for (bit = 0; bit < 32; bit++)
if (out & (1<<bit))
{
argv [argc++] = &pcolors [bit];
this_mask |= plane_masks [bit];
}
merge_colors (argc, argv, &colors [out-1], this_mask, additive_p);
}
}
static int
allocate_color_planes (Display *dpy, Colormap cmap,
int nplanes, unsigned long *plane_masks,
unsigned long *base_pixel_ret)
{
while (nplanes > 1 &&
!XAllocColorCells (dpy, cmap, False, plane_masks, nplanes,
base_pixel_ret, 1))
nplanes--;
return nplanes;
}
static void
initialize_transparency_colormap (Display *dpy, Colormap cmap,
int nplanes,
unsigned long base_pixel,
unsigned long *plane_masks,
XColor *colors,
Bool additive_p)
{
int i;
int total_colors = i_exp (2, nplanes);
XColor *all_colors = (XColor *) calloc (total_colors, sizeof (XColor));
for (i = 0; i < nplanes; i++)
colors[i].pixel = base_pixel | plane_masks [i];
permute_colors (colors, all_colors, nplanes, plane_masks, additive_p);
/* clone the default background of the window into our "base" pixel */
all_colors [total_colors - 1].pixel =
get_pixel_resource (dpy, cmap, "background", "Background");
XQueryColor (dpy, cmap, &all_colors [total_colors - 1]);
all_colors [total_colors - 1].pixel = base_pixel;
for (i = 0; i < total_colors; i++)
all_colors[i].flags = DoRed|DoGreen|DoBlue;
XStoreColors (dpy, cmap, all_colors, total_colors);
XFree ((XPointer) all_colors);
}
Bool
allocate_alpha_colors (Screen *screen, Visual *visual, Colormap cmap,
int *nplanesP, Bool additive_p,
unsigned long **plane_masks,
unsigned long *base_pixelP)
{
Display *dpy = DisplayOfScreen (screen);
XColor *colors;
int nplanes = *nplanesP;
int i;
if (!has_writable_cells (screen, visual))
cmap = 0;
if (!cmap) /* A TrueColor visual, or similar. */
{
int depth = visual_depth (screen, visual);
unsigned long masks;
XVisualInfo vi_in, *vi_out;
/* Find out which bits the R, G, and B components actually occupy
on this visual. */
vi_in.screen = screen_number (screen);
vi_in.visualid = XVisualIDFromVisual (visual);
vi_out = XGetVisualInfo (dpy, VisualScreenMask|VisualIDMask,
&vi_in, &i);
if (! vi_out) abort ();
masks = vi_out[0].red_mask | vi_out[0].green_mask | vi_out[0].blue_mask;
XFree ((char *) vi_out);
if (nplanes > depth)
nplanes = depth;
*nplanesP = nplanes;
*base_pixelP = 0;
*plane_masks = (unsigned long *) calloc(sizeof(unsigned long), nplanes);
/* Pick the planar values randomly, but constrain them to fall within
the bit positions of the R, G, and B fields. */
for (i = 0; i < nplanes; i++)
(*plane_masks)[i] = random() & masks;
}
else /* A PseudoColor visual, or similar. */
{
if (nplanes > 31) nplanes = 31;
*plane_masks = (unsigned long *) malloc(sizeof(unsigned long) * nplanes);
nplanes = allocate_color_planes (dpy, cmap, nplanes, *plane_masks,
base_pixelP);
*nplanesP = nplanes;
if (nplanes <= 1)
{
free(*plane_masks);
*plane_masks = 0;
return False;
}
colors = (XColor *) calloc (nplanes, sizeof (XColor));
for (i = 0; i < nplanes; i++)
{
/* pick the base colors. If we are in subtractive mode, pick higher
intensities. */
hsv_to_rgb (random () % 360,
frand (1.0),
frand (0.5) + (additive_p ? 0.2 : 0.5),
&colors[i].red,
&colors[i].green,
&colors[i].blue);
}
initialize_transparency_colormap (dpy, cmap, nplanes,
*base_pixelP, *plane_masks, colors,
additive_p);
XFree ((XPointer) colors);
}
return True;
}
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