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Diffstat (limited to 'libXmu/src/CmapAlloc.c')
| -rw-r--r-- | libXmu/src/CmapAlloc.c | 346 |
1 files changed, 346 insertions, 0 deletions
diff --git a/libXmu/src/CmapAlloc.c b/libXmu/src/CmapAlloc.c new file mode 100644 index 000000000..e025ca5e4 --- /dev/null +++ b/libXmu/src/CmapAlloc.c @@ -0,0 +1,346 @@ +/* $Xorg: CmapAlloc.c,v 1.4 2001/02/09 02:03:51 xorgcvs Exp $ */ + +/* + +Copyright 1989, 1994, 1998 The Open Group + +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. + +The above copyright notice and this permission notice shall be included in +all copies or substantial portions of the Software. + +THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR +IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, +FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE +OPEN GROUP BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN +AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN +CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. + +Except as contained in this notice, the name of The Open Group shall not be +used in advertising or otherwise to promote the sale, use or other dealings +in this Software without prior written authorization from The Open Group. + +*/ +/* $XFree86: xc/lib/Xmu/CmapAlloc.c,v 1.6 2001/01/17 19:42:53 dawes Exp $ */ + +/* + * Author: Donna Converse, MIT X Consortium + */ + +#ifdef HAVE_CONFIG_H +#include <config.h> +#endif +#include <X11/Xlib.h> +#include <X11/Xatom.h> +#include <X11/Xutil.h> +#include <X11/Xmu/StdCmap.h> +#include <stdio.h> + +#define lowbit(x) ((x) & (~(x) + 1)) + +/* + * Prototypes + */ +static void best_allocation(XVisualInfo*, unsigned long*, unsigned long*, + unsigned long*); +static int default_allocation(XVisualInfo*, unsigned long*, + unsigned long*, unsigned long*); +static void gray_allocation(int, unsigned long*, unsigned long*, + unsigned long*); +static int icbrt(int); +static int icbrt_with_bits(int, int); +static int icbrt_with_guess(int, int); + +/* To determine the best allocation of reds, greens, and blues in a + * standard colormap, use XmuGetColormapAllocation. + * vinfo specifies visual information for a chosen visual + * property specifies one of the standard colormap property names + * red_max returns maximum red value + * green_max returns maximum green value + * blue_max returns maximum blue value + * + * XmuGetColormapAllocation returns 0 on failure, non-zero on success. + * It is assumed that the visual is appropriate for the colormap property. + */ + +Status +XmuGetColormapAllocation(XVisualInfo *vinfo, Atom property, + unsigned long *red_max, + unsigned long *green_max, + unsigned long *blue_max) +{ + Status status = 1; + + if (vinfo->colormap_size <= 2) + return 0; + + switch (property) + { + case XA_RGB_DEFAULT_MAP: + status = default_allocation(vinfo, red_max, green_max, blue_max); + break; + case XA_RGB_BEST_MAP: + best_allocation(vinfo, red_max, green_max, blue_max); + break; + case XA_RGB_GRAY_MAP: + gray_allocation(vinfo->colormap_size, red_max, green_max, blue_max); + break; + case XA_RGB_RED_MAP: + *red_max = vinfo->colormap_size - 1; + *green_max = *blue_max = 0; + break; + case XA_RGB_GREEN_MAP: + *green_max = vinfo->colormap_size - 1; + *red_max = *blue_max = 0; + break; + case XA_RGB_BLUE_MAP: + *blue_max = vinfo->colormap_size - 1; + *red_max = *green_max = 0; + break; + default: + status = 0; + } + return status; +} + +/****************************************************************************/ +/* Determine the appropriate color allocations of a gray scale. + * + * Keith Packard, MIT X Consortium + */ + +static void +gray_allocation(int n, unsigned long *red_max, unsigned long *green_max, + unsigned long *blue_max) +{ + *red_max = (n * 30) / 100; + *green_max = (n * 59) / 100; + *blue_max = (n * 11) / 100; + *green_max += ((n - 1) - (*red_max + *green_max + *blue_max)); +} + +/****************************************************************************/ +/* Determine an appropriate color allocation for the RGB_DEFAULT_MAP. + * If a map has less than a minimum number of definable entries, we do not + * produce an allocation for an RGB_DEFAULT_MAP. + * + * For 16 planes, the default colormap will have 27 each RGB; for 12 planes, + * 12 each. For 8 planes, let n = the number of colormap entries, which may + * be 256 or 254. Then, maximum red value = floor(cube_root(n - 125)) - 1. + * Maximum green and maximum blue values are identical to maximum red. + * This leaves at least 125 cells which clients can allocate. + * + * Return 0 if an allocation has been determined, non-zero otherwise. + */ + +static int +default_allocation(XVisualInfo *vinfo, unsigned long *red, + unsigned long *green, unsigned long *blue) +{ + int ngrays; /* number of gray cells */ + + switch (vinfo->class) { + case PseudoColor: + + if (vinfo->colormap_size > 65000) + /* intended for displays with 16 planes */ + *red = *green = *blue = (unsigned long) 27; + else if (vinfo->colormap_size > 4000) + /* intended for displays with 12 planes */ + *red = *green = *blue = (unsigned long) 12; + else if (vinfo->colormap_size < 250) + return 0; + else + /* intended for displays with 8 planes */ + *red = *green = *blue = (unsigned long) + (icbrt(vinfo->colormap_size - 125) - 1); + break; + + case DirectColor: + + if (vinfo->colormap_size < 10) + return 0; + *red = *green = *blue = vinfo->colormap_size / 2 - 1; + break; + + case TrueColor: + + *red = vinfo->red_mask / lowbit(vinfo->red_mask); + *green = vinfo->green_mask / lowbit(vinfo->green_mask); + *blue = vinfo->blue_mask / lowbit(vinfo->blue_mask); + break; + + case GrayScale: + + if (vinfo->colormap_size > 65000) + ngrays = 4096; + else if (vinfo->colormap_size > 4000) + ngrays = 512; + else if (vinfo->colormap_size < 250) + return 0; + else + ngrays = 12; + gray_allocation(ngrays, red, green, blue); + break; + + default: + return 0; + } + return 1; +} + +/****************************************************************************/ +/* Determine an appropriate color allocation for the RGB_BEST_MAP. + * + * For a DirectColor or TrueColor visual, the allocation is determined + * by the red_mask, green_mask, and blue_mask members of the visual info. + * + * Otherwise, if the colormap size is an integral power of 2, determine + * the allocation according to the number of bits given to each color, + * with green getting more than red, and red more than blue, if there + * are to be inequities in the distribution. If the colormap size is + * not an integral power of 2, let n = the number of colormap entries. + * Then maximum red value = floor(cube_root(n)) - 1; + * maximum blue value = floor(cube_root(n)) - 1; + * maximum green value = n / ((# red values) * (# blue values)) - 1; + * Which, on a GPX, allows for 252 entries in the best map, out of 254 + * defineable colormap entries. + */ + +static void +best_allocation(XVisualInfo *vinfo, unsigned long *red, unsigned long *green, + unsigned long *blue) +{ + + if (vinfo->class == DirectColor || vinfo->class == TrueColor) + { + *red = vinfo->red_mask; + while ((*red & 01) == 0) + *red >>= 1; + *green = vinfo->green_mask; + while ((*green & 01) == 0) + *green >>=1; + *blue = vinfo->blue_mask; + while ((*blue & 01) == 0) + *blue >>= 1; + } + else + { + register int bits, n; + + /* Determine n such that n is the least integral power of 2 which is + * greater than or equal to the number of entries in the colormap. + */ + n = 1; + bits = 0; + while (vinfo->colormap_size > n) + { + n = n << 1; + bits++; + } + + /* If the number of entries in the colormap is a power of 2, determine + * the allocation by "dealing" the bits, first to green, then red, then + * blue. If not, find the maximum integral red, green, and blue values + * which, when multiplied together, do not exceed the number of + + * colormap entries. + */ + if (n == vinfo->colormap_size) + { + register int r, g, b; + b = bits / 3; + g = b + ((bits % 3) ? 1 : 0); + r = b + (((bits % 3) == 2) ? 1 : 0); + *red = 1 << r; + *green = 1 << g; + *blue = 1 << b; + } + else + { + *red = icbrt_with_bits(vinfo->colormap_size, bits); + *blue = *red; + *green = (vinfo->colormap_size / ((*red) * (*blue))); + } + (*red)--; + (*green)--; + (*blue)--; + } + return; +} + +/* + * integer cube roots by Newton's method + * + * Stephen Gildea, MIT X Consortium, July 1991 + */ + +static int +icbrt(int a) +{ + register int bits = 0; + register unsigned n = a; + + while (n) + { + bits++; + n >>= 1; + } + return icbrt_with_bits(a, bits); +} + + +static int +icbrt_with_bits(int a, int bits) + /* bits - log 2 of a */ +{ + return icbrt_with_guess(a, a>>2*bits/3); +} + +#ifdef _X_ROOT_STATS +int icbrt_loopcount; +#endif + +/* Newton's Method: x_n+1 = x_n - ( f(x_n) / f'(x_n) ) */ + +/* for cube roots, x^3 - a = 0, x_new = x - 1/3 (x - a/x^2) */ + +/* + * Quick and dirty cube roots. Nothing fancy here, just Newton's method. + * Only works for positive integers (since that's all we need). + * We actually return floor(cbrt(a)) because that's what we need here, too. + */ + +static int +icbrt_with_guess(int a, int guess) +{ + register int delta; + +#ifdef _X_ROOT_STATS + icbrt_loopcount = 0; +#endif + if (a <= 0) + return 0; + if (guess < 1) + guess = 1; + + do { +#ifdef _X_ROOT_STATS + icbrt_loopcount++; +#endif + delta = (guess - a/(guess*guess))/3; +#ifdef _X_ROOT_STATS + printf("pass %d: guess=%d, delta=%d\n", icbrt_loopcount, guess, delta); +#endif + guess -= delta; + } while (delta != 0); + + if (guess*guess*guess > a) + guess--; + + return guess; +} |