1 /* 2 * Copyright (C) 2003, 2004, 2005, 2006, 2008 Apple Inc. All rights reserved. 3 * 4 * Redistribution and use in source and binary forms, with or without 5 * modification, are permitted provided that the following conditions 6 * are met: 7 * 1. Redistributions of source code must retain the above copyright 8 * notice, this list of conditions and the following disclaimer. 9 * 2. Redistributions in binary form must reproduce the above copyright 10 * notice, this list of conditions and the following disclaimer in the 11 * documentation and/or other materials provided with the distribution. 12 * 13 * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY 14 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 15 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 16 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE COMPUTER, INC. OR 17 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, 18 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, 19 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR 20 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY 21 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 23 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 24 */ 25 26 #include "config.h" 27 #include "platform/graphics/Color.h" 28 29 #include "platform/Decimal.h" 30 #include "wtf/Assertions.h" 31 #include "wtf/HexNumber.h" 32 #include "wtf/MathExtras.h" 33 #include "wtf/dtoa.h" 34 #include "wtf/text/StringBuilder.h" 35 36 using namespace std; 37 38 namespace WebCore { 39 40 #if !COMPILER(MSVC) || COMPILER(CLANG) 41 // FIXME: Use C++11 strong enums to avoid static data member with initializer definition problems. 42 const RGBA32 Color::black; 43 const RGBA32 Color::white; 44 const RGBA32 Color::darkGray; 45 const RGBA32 Color::gray; 46 const RGBA32 Color::lightGray; 47 const RGBA32 Color::transparent; 48 #endif 49 50 static const RGBA32 lightenedBlack = 0xFF545454; 51 static const RGBA32 darkenedWhite = 0xFFABABAB; 52 53 RGBA32 makeRGB(int r, int g, int b) 54 { 55 return 0xFF000000 | max(0, min(r, 255)) << 16 | max(0, min(g, 255)) << 8 | max(0, min(b, 255)); 56 } 57 58 RGBA32 makeRGBA(int r, int g, int b, int a) 59 { 60 return max(0, min(a, 255)) << 24 | max(0, min(r, 255)) << 16 | max(0, min(g, 255)) << 8 | max(0, min(b, 255)); 61 } 62 63 static int colorFloatToRGBAByte(float f) 64 { 65 // We use lroundf and 255 instead of nextafterf(256, 0) to match CG's rounding 66 return max(0, min(static_cast<int>(lroundf(255.0f * f)), 255)); 67 } 68 69 RGBA32 makeRGBA32FromFloats(float r, float g, float b, float a) 70 { 71 return colorFloatToRGBAByte(a) << 24 | colorFloatToRGBAByte(r) << 16 | colorFloatToRGBAByte(g) << 8 | colorFloatToRGBAByte(b); 72 } 73 74 RGBA32 colorWithOverrideAlpha(RGBA32 color, float overrideAlpha) 75 { 76 RGBA32 rgbOnly = color & 0x00FFFFFF; 77 RGBA32 rgba = rgbOnly | colorFloatToRGBAByte(overrideAlpha) << 24; 78 return rgba; 79 } 80 81 static double calcHue(double temp1, double temp2, double hueVal) 82 { 83 if (hueVal < 0.0) 84 hueVal++; 85 else if (hueVal > 1.0) 86 hueVal--; 87 if (hueVal * 6.0 < 1.0) 88 return temp1 + (temp2 - temp1) * hueVal * 6.0; 89 if (hueVal * 2.0 < 1.0) 90 return temp2; 91 if (hueVal * 3.0 < 2.0) 92 return temp1 + (temp2 - temp1) * (2.0 / 3.0 - hueVal) * 6.0; 93 return temp1; 94 } 95 96 // Explanation of this algorithm can be found in the CSS3 Color Module 97 // specification at http://www.w3.org/TR/css3-color/#hsl-color with further 98 // explanation available at http://en.wikipedia.org/wiki/HSL_color_space 99 100 // all values are in the range of 0 to 1.0 101 RGBA32 makeRGBAFromHSLA(double hue, double saturation, double lightness, double alpha) 102 { 103 const double scaleFactor = nextafter(256.0, 0.0); 104 105 if (!saturation) { 106 int greyValue = static_cast<int>(lightness * scaleFactor); 107 return makeRGBA(greyValue, greyValue, greyValue, static_cast<int>(alpha * scaleFactor)); 108 } 109 110 double temp2 = lightness < 0.5 ? lightness * (1.0 + saturation) : lightness + saturation - lightness * saturation; 111 double temp1 = 2.0 * lightness - temp2; 112 113 return makeRGBA(static_cast<int>(calcHue(temp1, temp2, hue + 1.0 / 3.0) * scaleFactor), 114 static_cast<int>(calcHue(temp1, temp2, hue) * scaleFactor), 115 static_cast<int>(calcHue(temp1, temp2, hue - 1.0 / 3.0) * scaleFactor), 116 static_cast<int>(alpha * scaleFactor)); 117 } 118 119 RGBA32 makeRGBAFromCMYKA(float c, float m, float y, float k, float a) 120 { 121 double colors = 1 - k; 122 int r = static_cast<int>(nextafter(256, 0) * (colors * (1 - c))); 123 int g = static_cast<int>(nextafter(256, 0) * (colors * (1 - m))); 124 int b = static_cast<int>(nextafter(256, 0) * (colors * (1 - y))); 125 return makeRGBA(r, g, b, static_cast<float>(nextafter(256, 0) * a)); 126 } 127 128 // originally moved here from the CSS parser 129 template <typename CharacterType> 130 static inline bool parseHexColorInternal(const CharacterType* name, unsigned length, RGBA32& rgb) 131 { 132 if (length != 3 && length != 6) 133 return false; 134 unsigned value = 0; 135 for (unsigned i = 0; i < length; ++i) { 136 if (!isASCIIHexDigit(name[i])) 137 return false; 138 value <<= 4; 139 value |= toASCIIHexValue(name[i]); 140 } 141 if (length == 6) { 142 rgb = 0xFF000000 | value; 143 return true; 144 } 145 // #abc converts to #aabbcc 146 rgb = 0xFF000000 147 | (value & 0xF00) << 12 | (value & 0xF00) << 8 148 | (value & 0xF0) << 8 | (value & 0xF0) << 4 149 | (value & 0xF) << 4 | (value & 0xF); 150 return true; 151 } 152 153 bool Color::parseHexColor(const LChar* name, unsigned length, RGBA32& rgb) 154 { 155 return parseHexColorInternal(name, length, rgb); 156 } 157 158 bool Color::parseHexColor(const UChar* name, unsigned length, RGBA32& rgb) 159 { 160 return parseHexColorInternal(name, length, rgb); 161 } 162 163 bool Color::parseHexColor(const String& name, RGBA32& rgb) 164 { 165 unsigned length = name.length(); 166 167 if (!length) 168 return false; 169 if (name.is8Bit()) 170 return parseHexColor(name.characters8(), name.length(), rgb); 171 return parseHexColor(name.characters16(), name.length(), rgb); 172 } 173 174 int differenceSquared(const Color& c1, const Color& c2) 175 { 176 int dR = c1.red() - c2.red(); 177 int dG = c1.green() - c2.green(); 178 int dB = c1.blue() - c2.blue(); 179 return dR * dR + dG * dG + dB * dB; 180 } 181 182 bool Color::setFromString(const String& name) 183 { 184 if (name[0] != '#') 185 return setNamedColor(name); 186 if (name.is8Bit()) 187 return parseHexColor(name.characters8() + 1, name.length() - 1, m_color); 188 return parseHexColor(name.characters16() + 1, name.length() - 1, m_color); 189 } 190 191 String Color::serializedAsCSSComponentValue() const 192 { 193 StringBuilder result; 194 result.reserveCapacity(32); 195 bool colorHasAlpha = hasAlpha(); 196 if (colorHasAlpha) 197 result.append("rgba(", 5); 198 else 199 result.append("rgb(", 4); 200 201 result.appendNumber(static_cast<unsigned char>(red())); 202 result.append(", ", 2); 203 204 result.appendNumber(static_cast<unsigned char>(green())); 205 result.append(", ", 2); 206 207 result.appendNumber(static_cast<unsigned char>(blue())); 208 if (colorHasAlpha) { 209 result.append(", ", 2); 210 211 NumberToStringBuffer buffer; 212 const char* alphaString = numberToFixedPrecisionString(alpha() / 255.0f, 6, buffer, true); 213 result.append(alphaString, strlen(alphaString)); 214 } 215 216 result.append(')'); 217 return result.toString(); 218 } 219 220 String Color::serialized() const 221 { 222 if (!hasAlpha()) { 223 StringBuilder builder; 224 builder.reserveCapacity(7); 225 builder.append('#'); 226 appendByteAsHex(red(), builder, Lowercase); 227 appendByteAsHex(green(), builder, Lowercase); 228 appendByteAsHex(blue(), builder, Lowercase); 229 return builder.toString(); 230 } 231 232 StringBuilder result; 233 result.reserveCapacity(28); 234 const char commaSpace[] = ", "; 235 const char rgbaParen[] = "rgba("; 236 237 result.append(rgbaParen, 5); 238 result.appendNumber(red()); 239 result.append(commaSpace, 2); 240 result.appendNumber(green()); 241 result.append(commaSpace, 2); 242 result.appendNumber(blue()); 243 result.append(commaSpace, 2); 244 245 if (!alpha()) 246 result.append('0'); 247 else { 248 result.append(Decimal::fromDouble(alpha() / 255.0).toString()); 249 } 250 251 result.append(')'); 252 return result.toString(); 253 } 254 255 String Color::nameForRenderTreeAsText() const 256 { 257 if (alpha() < 0xFF) 258 return String::format("#%02X%02X%02X%02X", red(), green(), blue(), alpha()); 259 return String::format("#%02X%02X%02X", red(), green(), blue()); 260 } 261 262 static inline const NamedColor* findNamedColor(const String& name) 263 { 264 char buffer[64]; // easily big enough for the longest color name 265 unsigned length = name.length(); 266 if (length > sizeof(buffer) - 1) 267 return 0; 268 for (unsigned i = 0; i < length; ++i) { 269 UChar c = name[i]; 270 if (!c || c > 0x7F) 271 return 0; 272 buffer[i] = toASCIILower(static_cast<char>(c)); 273 } 274 buffer[length] = '\0'; 275 return findColor(buffer, length); 276 } 277 278 bool Color::setNamedColor(const String& name) 279 { 280 const NamedColor* foundColor = findNamedColor(name); 281 m_color = foundColor ? foundColor->ARGBValue : 0; 282 return foundColor; 283 } 284 285 Color Color::light() const 286 { 287 // Hardcode this common case for speed. 288 if (m_color == black) 289 return lightenedBlack; 290 291 const float scaleFactor = nextafterf(256.0f, 0.0f); 292 293 float r, g, b, a; 294 getRGBA(r, g, b, a); 295 296 float v = max(r, max(g, b)); 297 298 if (v == 0.0f) 299 // Lightened black with alpha. 300 return Color(0x54, 0x54, 0x54, alpha()); 301 302 float multiplier = min(1.0f, v + 0.33f) / v; 303 304 return Color(static_cast<int>(multiplier * r * scaleFactor), 305 static_cast<int>(multiplier * g * scaleFactor), 306 static_cast<int>(multiplier * b * scaleFactor), 307 alpha()); 308 } 309 310 Color Color::dark() const 311 { 312 // Hardcode this common case for speed. 313 if (m_color == white) 314 return darkenedWhite; 315 316 const float scaleFactor = nextafterf(256.0f, 0.0f); 317 318 float r, g, b, a; 319 getRGBA(r, g, b, a); 320 321 float v = max(r, max(g, b)); 322 float multiplier = max(0.0f, (v - 0.33f) / v); 323 324 return Color(static_cast<int>(multiplier * r * scaleFactor), 325 static_cast<int>(multiplier * g * scaleFactor), 326 static_cast<int>(multiplier * b * scaleFactor), 327 alpha()); 328 } 329 330 Color Color::combineWithAlpha(float otherAlpha) const 331 { 332 return colorWithOverrideAlpha(rgb(), (alpha() / 255.f) * otherAlpha); 333 } 334 335 static int blendComponent(int c, int a) 336 { 337 // We use white. 338 float alpha = a / 255.0f; 339 int whiteBlend = 255 - a; 340 c -= whiteBlend; 341 return static_cast<int>(c / alpha); 342 } 343 344 const int cStartAlpha = 153; // 60% 345 const int cEndAlpha = 204; // 80%; 346 const int cAlphaIncrement = 17; // Increments in between. 347 348 Color Color::blend(const Color& source) const 349 { 350 if (!alpha() || !source.hasAlpha()) 351 return source; 352 353 if (!source.alpha()) 354 return *this; 355 356 int d = 255 * (alpha() + source.alpha()) - alpha() * source.alpha(); 357 int a = d / 255; 358 int r = (red() * alpha() * (255 - source.alpha()) + 255 * source.alpha() * source.red()) / d; 359 int g = (green() * alpha() * (255 - source.alpha()) + 255 * source.alpha() * source.green()) / d; 360 int b = (blue() * alpha() * (255 - source.alpha()) + 255 * source.alpha() * source.blue()) / d; 361 return Color(r, g, b, a); 362 } 363 364 Color Color::blendWithWhite() const 365 { 366 // If the color contains alpha already, we leave it alone. 367 if (hasAlpha()) 368 return *this; 369 370 Color newColor; 371 for (int alpha = cStartAlpha; alpha <= cEndAlpha; alpha += cAlphaIncrement) { 372 // We have a solid color. Convert to an equivalent color that looks the same when blended with white 373 // at the current alpha. Try using less transparency if the numbers end up being negative. 374 int r = blendComponent(red(), alpha); 375 int g = blendComponent(green(), alpha); 376 int b = blendComponent(blue(), alpha); 377 378 newColor = Color(r, g, b, alpha); 379 380 if (r >= 0 && g >= 0 && b >= 0) 381 break; 382 } 383 return newColor; 384 } 385 386 void Color::getRGBA(float& r, float& g, float& b, float& a) const 387 { 388 r = red() / 255.0f; 389 g = green() / 255.0f; 390 b = blue() / 255.0f; 391 a = alpha() / 255.0f; 392 } 393 394 void Color::getRGBA(double& r, double& g, double& b, double& a) const 395 { 396 r = red() / 255.0; 397 g = green() / 255.0; 398 b = blue() / 255.0; 399 a = alpha() / 255.0; 400 } 401 402 void Color::getHSL(double& hue, double& saturation, double& lightness) const 403 { 404 // http://en.wikipedia.org/wiki/HSL_color_space. This is a direct copy of 405 // the algorithm therein, although it's 360^o based and we end up wanting 406 // [0...1) based. It's clearer if we stick to 360^o until the end. 407 double r = static_cast<double>(red()) / 255.0; 408 double g = static_cast<double>(green()) / 255.0; 409 double b = static_cast<double>(blue()) / 255.0; 410 double max = std::max(std::max(r, g), b); 411 double min = std::min(std::min(r, g), b); 412 413 if (max == min) 414 hue = 0.0; 415 else if (max == r) 416 hue = (60.0 * ((g - b) / (max - min))) + 360.0; 417 else if (max == g) 418 hue = (60.0 * ((b - r) / (max - min))) + 120.0; 419 else 420 hue = (60.0 * ((r - g) / (max - min))) + 240.0; 421 422 if (hue >= 360.0) 423 hue -= 360.0; 424 425 // makeRGBAFromHSLA assumes that hue is in [0...1). 426 hue /= 360.0; 427 428 lightness = 0.5 * (max + min); 429 if (max == min) 430 saturation = 0.0; 431 else if (lightness <= 0.5) 432 saturation = ((max - min) / (max + min)); 433 else 434 saturation = ((max - min) / (2.0 - (max + min))); 435 } 436 437 Color colorFromPremultipliedARGB(RGBA32 pixelColor) 438 { 439 int alpha = alphaChannel(pixelColor); 440 if (alpha && alpha < 255) { 441 return Color::createUnchecked( 442 redChannel(pixelColor) * 255 / alpha, 443 greenChannel(pixelColor) * 255 / alpha, 444 blueChannel(pixelColor) * 255 / alpha, 445 alpha); 446 } else 447 return Color(pixelColor); 448 } 449 450 RGBA32 premultipliedARGBFromColor(const Color& color) 451 { 452 unsigned pixelColor; 453 454 unsigned alpha = color.alpha(); 455 if (alpha < 255) { 456 pixelColor = Color::createUnchecked( 457 (color.red() * alpha + 254) / 255, 458 (color.green() * alpha + 254) / 255, 459 (color.blue() * alpha + 254) / 255, 460 alpha).rgb(); 461 } else 462 pixelColor = color.rgb(); 463 464 return pixelColor; 465 } 466 467 } // namespace WebCore 468
