gfx/thebes/public/gfxColor.h

   1 /* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 4 -*-
   2  * ***** BEGIN LICENSE BLOCK *****
   3  * Version: MPL 1.1/GPL 2.0/LGPL 2.1
   4  *
   5  * The contents of this file are subject to the Mozilla Public License Version
   6  * 1.1 (the "License"); you may not use this file except in compliance with
   7  * the License. You may obtain a copy of the License at
   8  * http://www.mozilla.org/MPL/
   9  *
  10  * Software distributed under the License is distributed on an "AS IS" basis,
  11  * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
  12  * for the specific language governing rights and limitations under the
  13  * License.
  14  *
  15  * The Original Code is Oracle Corporation code.
  16  *
  17  * The Initial Developer of the Original Code is Oracle Corporation.
  18  * Portions created by the Initial Developer are Copyright (C) 2005
  19  * the Initial Developer. All Rights Reserved.
  20  *
  21  * Contributor(s):
  22  *   Stuart Parmenter <pavlov@pavlov.net>
  23  *
  24  * Alternatively, the contents of this file may be used under the terms of
  25  * either the GNU General Public License Version 2 or later (the "GPL"), or
  26  * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
  27  * in which case the provisions of the GPL or the LGPL are applicable instead
  28  * of those above. If you wish to allow use of your version of this file only
  29  * under the terms of either the GPL or the LGPL, and not to allow others to
  30  * use your version of this file under the terms of the MPL, indicate your
  31  * decision by deleting the provisions above and replace them with the notice
  32  * and other provisions required by the GPL or the LGPL. If you do not delete
  33  * the provisions above, a recipient may use your version of this file under
  34  * the terms of any one of the MPL, the GPL or the LGPL.
  35  *
  36  * ***** END LICENSE BLOCK ***** */
  37
  38 #ifndef GFX_COLOR_H
  39 #define GFX_COLOR_H
  40
  41 #ifdef MOZILLA_INTERNAL_API
  42 #include "nsPrintfCString.h"
  43 #endif
  44
  45 #include "gfxTypes.h"
  46
  47 #include "prbit.h" // for PR_ROTATE_(LEFT,RIGHT)32
  48 #include "prio.h"  // for ntohl
  49
  50 #define GFX_UINT32_FROM_BPTR(pbptr,i) (((PRUint32*)(pbptr))[i])
  51
  52 #if defined(IS_BIG_ENDIAN)
  53   #define GFX_NTOHL(x) (x)
  54   #define GFX_HAVE_CHEAP_NTOHL
  55 #elif defined(_WIN32)
  56   #if (_MSC_VER >= 1300) // also excludes MinGW
  57     #include <stdlib.h>
  58     #pragma intrinsic(_byteswap_ulong)
  59     #define GFX_NTOHL(x) _byteswap_ulong(x)
  60     #define GFX_HAVE_CHEAP_NTOHL
  61   #else
  62     // A reasonably fast generic little-endian implementation.
  63     #define GFX_NTOHL(x) \
  64          ( (PR_ROTATE_RIGHT32((x),8) & 0xFF00FF00) | \
  65            (PR_ROTATE_LEFT32((x),8)  & 0x00FF00FF) )
  66   #endif
  67 #else
  68   #define GFX_NTOHL(x) ntohl(x)
  69   #define GFX_HAVE_CHEAP_NTOHL
  70 #endif
  71
  72 /**
  73  * GFX_0XFF_PPIXEL_FROM_BPTR(x)
  74  *
  75  * Avoid tortured construction of 32-bit ARGB pixel from 3 individual bytes
  76  *   of memory plus constant 0xFF.  RGB bytes are already contiguous!
  77  * Equivalent to: GFX_PACKED_PIXEL(0xff,r,g,b)
  78  *
  79  * Attempt to use fast byte-swapping instruction(s), e.g. bswap on x86, in
  80  *   preference to a sequence of shift/or operations.
  81  */
  82 #if defined(GFX_HAVE_CHEAP_NTOHL)
  83   #define GFX_0XFF_PPIXEL_FROM_UINT32(x) \
  84        ( (GFX_NTOHL(x) >> 8) | (0xFF << 24) )
  85 #else
  86   // A reasonably fast generic little-endian implementation.
  87   #define GFX_0XFF_PPIXEL_FROM_UINT32(x) \
  88        ( (PR_ROTATE_LEFT32((x),16) | 0xFF00FF00) & ((x) | 0xFFFF00FF) )
  89 #endif
  90
  91 #define GFX_0XFF_PPIXEL_FROM_BPTR(x) \
  92      ( GFX_0XFF_PPIXEL_FROM_UINT32(GFX_UINT32_FROM_BPTR((x),0)) )
  93
  94 /**
  95  * GFX_BLOCK_RGB_TO_FRGB(from,to)
  96  *   sizeof(*from) == sizeof(char)
  97  *   sizeof(*to)   == sizeof(PRUint32)
  98  *
  99  * Copy 4 pixels at a time, reading blocks of 12 bytes (RGB x4)
 100  *   and writing blocks of 16 bytes (FRGB x4)
 101  */
 102 #define GFX_BLOCK_RGB_TO_FRGB(from,to) \
 103   PR_BEGIN_MACRO \
 104     PRUint32 m0 = GFX_UINT32_FROM_BPTR(from,0), \
 105              m1 = GFX_UINT32_FROM_BPTR(from,1), \
 106              m2 = GFX_UINT32_FROM_BPTR(from,2), \
 107              rgbr = GFX_NTOHL(m0), \
 108              gbrg = GFX_NTOHL(m1), \
 109              brgb = GFX_NTOHL(m2), \
 110              p0, p1, p2, p3; \
 111     p0 = 0xFF000000 | ((rgbr) >>  8); \
 112     p1 = 0xFF000000 | ((rgbr) << 16) | ((gbrg) >> 16); \
 113     p2 = 0xFF000000 | ((gbrg) <<  8) | ((brgb) >> 24); \
 114     p3 = 0xFF000000 | (brgb); \
 115     to[0] = p0; to[1] = p1; to[2] = p2; to[3] = p3; \
 116   PR_END_MACRO
 117
 118 /**
 119  * Fast approximate division by 255. It has the property that
 120  * for all 0 <= n <= 255*255, FAST_DIVIDE_BY_255(n) == n/255.
 121  * But it only uses two adds and two shifts instead of an
 122  * integer division (which is expensive on many processors).
 123  *
 124  * equivalent to ((v)/255)
 125  */
 126 #define GFX_DIVIDE_BY_255(v)  \
 127      (((((unsigned)(v)) << 8) + ((unsigned)(v)) + 255) >> 16)
 128
 129 /**
 130  * Fast premultiply macro
 131  *
 132  * equivalent to (((c)*(a))/255)
 133  */
 134 #define GFX_PREMULTIPLY(c,a) GFX_DIVIDE_BY_255((c)*(a))
 135
 136 /**
 137  * Macro to pack the 4 8-bit channels (A,R,G,B)
 138  * into a 32-bit packed premultiplied pixel.
 139  *
 140  * The checks for 0 alpha or max alpha ensure that the
 141  * compiler selects the quicked calculation when alpha is constant.
 142  */
 143 #define GFX_PACKED_PIXEL(a,r,g,b)                                       \
 144     ((a) == 0x00) ? 0x00000000 :                                        \
 145     ((a) == 0xFF) ? ((0xFF << 24) | ((r) << 16) | ((g) << 8) | (b))     \
 146                   : ((a) << 24) |                                       \
 147                     (GFX_PREMULTIPLY(r,a) << 16) |                      \
 148                     (GFX_PREMULTIPLY(g,a) << 8) |                       \
 149                     (GFX_PREMULTIPLY(b,a))
 150
 151
 152 /**
 153  * A color value, storing red, green, blue and alpha components.
 154  * This class does not use premultiplied alpha.
 155  *
 156  * XXX should this use doubles (instead of gfxFloat), for consistency with
 157  * cairo?
 158  */
 159 struct THEBES_API gfxRGBA {
 160     gfxFloat r, g, b, a;
 161
 162     enum PackedColorType {
 163         PACKED_ABGR,
 164         PACKED_ABGR_PREMULTIPLIED,
 165
 166         PACKED_ARGB,
 167         PACKED_ARGB_PREMULTIPLIED,
 168
 169         PACKED_XBGR,
 170         PACKED_XRGB
 171     };
 172
 173     gfxRGBA() { }
 174     gfxRGBA(const gfxRGBA& c) : r(c.r), g(c.g), b(c.b), a(c.a) {}
 175     /**
 176      * Intialize this color using explicit red, green, blue and alpha
 177      * values.
 178      */
 179     gfxRGBA(gfxFloat _r, gfxFloat _g, gfxFloat _b, gfxFloat _a=1.0) : r(_r), g(_g), b(_b), a(_a) {}
 180
 181     /**
 182      * Initialize this color from a packed 32-bit color.
 183      * The color value is interpreted based on colorType;
 184      * all values use the native platform endianness.
 185      *
 186      * @see gfxRGBA::Packed
 187      */
 188     gfxRGBA(PRUint32 c, PackedColorType colorType = PACKED_ABGR) {
 189         if (colorType == PACKED_ABGR ||
 190             colorType == PACKED_XBGR ||
 191             colorType == PACKED_ABGR_PREMULTIPLIED)
 192         {
 193             r = ((c >> 0) & 0xff) / 255.0;
 194             g = ((c >> 8) & 0xff) / 255.0;
 195             b = ((c >> 16) & 0xff) / 255.0;
 196             a = ((c >> 24) & 0xff) / 255.0;
 197         } else if (colorType == PACKED_ARGB ||
 198                    colorType == PACKED_XRGB ||
 199                    colorType == PACKED_ARGB_PREMULTIPLIED)
 200         {
 201             b = ((c >> 0) & 0xff) / 255.0;
 202             g = ((c >> 8) & 0xff) / 255.0;
 203             r = ((c >> 16) & 0xff) / 255.0;
 204             a = ((c >> 24) & 0xff) / 255.0;
 205         }
 206
 207         if (colorType == PACKED_ABGR_PREMULTIPLIED ||
 208             colorType == PACKED_ARGB_PREMULTIPLIED)
 209         {
 210             if (a > 0.0) {
 211                 r /= a;
 212                 g /= a;
 213                 b /= a;
 214             }
 215         } else if (colorType == PACKED_XBGR ||
 216                    colorType == PACKED_XRGB)
 217         {
 218             a = 1.0;
 219         }
 220     }
 221
 222     /**
 223      * Initialize this color by parsing the given string.
 224      * XXX implement me!
 225      */
 226 #if 0
 227     gfxRGBA(const char* str) {
 228         a = 1.0;
 229         // if aString[0] is a #, parse it as hex
 230         // if aString[0] is a letter, parse it as a color name
 231         // if aString[0] is a number, parse it loosely as hex
 232     }
 233 #endif
 234
 235     /**
 236      * Returns this color value as a packed 32-bit integer. This reconstructs
 237      * the int32 based on the given colorType, always in the native byte order.
 238      *
 239      * Note: gcc 4.2.3 on at least Ubuntu (x86) does something strange with
 240      * (PRUint8)(c * 255.0) << x, where the result is different than
 241      * double d = c * 255.0; v = ((PRUint8) d) << x.
 242      */
 243     PRUint32 Packed(PackedColorType colorType = PACKED_ABGR) const {
 244         gfxFloat rb = (r * 255.0);
 245         gfxFloat gb = (g * 255.0);
 246         gfxFloat bb = (b * 255.0);
 247         gfxFloat ab = (a * 255.0);
 248
 249         if (colorType == PACKED_ABGR || colorType == PACKED_XBGR) {
 250             return (PRUint8(ab) << 24) |
 251                    (PRUint8(bb) << 16) |
 252                    (PRUint8(gb) << 8) |
 253                    (PRUint8(rb) << 0);
 254         } else if (colorType == PACKED_ARGB || colorType == PACKED_XRGB) {
 255             return (PRUint8(ab) << 24) |
 256                    (PRUint8(rb) << 16) |
 257                    (PRUint8(gb) << 8) |
 258                    (PRUint8(bb) << 0);
 259         }
 260
 261         rb = (r*a) * 255.0;
 262         gb = (g*a) * 255.0;
 263         bb = (b*a) * 255.0;
 264
 265         if (colorType == PACKED_ABGR_PREMULTIPLIED) {
 266             return (((PRUint8)(ab) << 24) |
 267                     ((PRUint8)(bb) << 16) |
 268                     ((PRUint8)(gb) << 8) |
 269                     ((PRUint8)(rb) << 0));
 270         } else if (colorType == PACKED_ARGB_PREMULTIPLIED) {
 271             return (((PRUint8)(ab) << 24) |
 272                     ((PRUint8)(rb) << 16) |
 273                     ((PRUint8)(gb) << 8) |
 274                     ((PRUint8)(bb) << 0));
 275         }
 276
 277         return 0;
 278     }
 279
 280 #ifdef MOZILLA_INTERNAL_API
 281     /**
 282      * Convert this color to a hex value. For example, for rgb(255,0,0),
 283      * this will return FF0000.
 284      */
 285     // XXX I'd really prefer to just have this return an nsACString
 286     // Does this function even make sense, since we're just ignoring the alpha value?
 287     void Hex(nsACString& result) const {
 288         nsPrintfCString hex(8, "%02x%02x%02x", PRUint8(r*255.0), PRUint8(g*255.0), PRUint8(b*255.0));
 289         result.Assign(hex);
 290     }
 291 #endif
 292
 293 };
 294
 295 #endif /* _GFX_COLOR_H */