gfx/skbitmap_operations.cc

   1 // Copyright (c) 2009 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "gfx/skbitmap_operations.h"
   6
   7 #include <algorithm>
   8 #include <string.h>
   9
  10 #include "base/logging.h"
  11 #include "third_party/skia/include/core/SkBitmap.h"
  12 #include "third_party/skia/include/core/SkCanvas.h"
  13 #include "third_party/skia/include/core/SkColorPriv.h"
  14 #include "third_party/skia/include/core/SkUnPreMultiply.h"
  15
  16 // static
  17 SkBitmap SkBitmapOperations::CreateInvertedBitmap(const SkBitmap& image) {
  18   DCHECK(image.config() == SkBitmap::kARGB_8888_Config);
  19
  20   SkAutoLockPixels lock_image(image);
  21
  22   SkBitmap inverted;
  23   inverted.setConfig(SkBitmap::kARGB_8888_Config, image.width(), image.height(),
  24                      0);
  25   inverted.allocPixels();
  26   inverted.eraseARGB(0, 0, 0, 0);
  27
  28   for (int y = 0; y < image.height(); ++y) {
  29     uint32* image_row = image.getAddr32(0, y);
  30     uint32* dst_row = inverted.getAddr32(0, y);
  31
  32     for (int x = 0; x < image.width(); ++x) {
  33       uint32 image_pixel = image_row[x];
  34       dst_row[x] = (image_pixel & 0xFF000000) |
  35                    (0x00FFFFFF - (image_pixel & 0x00FFFFFF));
  36     }
  37   }
  38
  39   return inverted;
  40 }
  41
  42 // static
  43 SkBitmap SkBitmapOperations::CreateSuperimposedBitmap(const SkBitmap& first,
  44                                                       const SkBitmap& second) {
  45   DCHECK(first.width() == second.width());
  46   DCHECK(first.height() == second.height());
  47   DCHECK(first.bytesPerPixel() == second.bytesPerPixel());
  48   DCHECK(first.config() == SkBitmap::kARGB_8888_Config);
  49
  50   SkAutoLockPixels lock_first(first);
  51   SkAutoLockPixels lock_second(second);
  52
  53   SkBitmap superimposed;
  54   superimposed.setConfig(SkBitmap::kARGB_8888_Config,
  55                          first.width(), first.height());
  56   superimposed.allocPixels();
  57   superimposed.eraseARGB(0, 0, 0, 0);
  58
  59   SkCanvas canvas(superimposed);
  60
  61   SkRect rect;
  62   rect.fLeft = 0;
  63   rect.fTop = 0;
  64   rect.fRight = SkIntToScalar(first.width());
  65   rect.fBottom = SkIntToScalar(first.height());
  66
  67   canvas.drawBitmapRect(first, NULL, rect);
  68   canvas.drawBitmapRect(second, NULL, rect);
  69
  70   return superimposed;
  71 }
  72
  73 // static
  74 SkBitmap SkBitmapOperations::CreateBlendedBitmap(const SkBitmap& first,
  75                                                  const SkBitmap& second,
  76                                                  double alpha) {
  77   DCHECK((alpha >= 0) && (alpha <= 1));
  78   DCHECK(first.width() == second.width());
  79   DCHECK(first.height() == second.height());
  80   DCHECK(first.bytesPerPixel() == second.bytesPerPixel());
  81   DCHECK(first.config() == SkBitmap::kARGB_8888_Config);
  82
  83   // Optimize for case where we won't need to blend anything.
  84   static const double alpha_min = 1.0 / 255;
  85   static const double alpha_max = 254.0 / 255;
  86   if (alpha < alpha_min)
  87     return first;
  88   else if (alpha > alpha_max)
  89     return second;
  90
  91   SkAutoLockPixels lock_first(first);
  92   SkAutoLockPixels lock_second(second);
  93
  94   SkBitmap blended;
  95   blended.setConfig(SkBitmap::kARGB_8888_Config, first.width(), first.height(),
  96                     0);
  97   blended.allocPixels();
  98   blended.eraseARGB(0, 0, 0, 0);
  99
 100   double first_alpha = 1 - alpha;
 101
 102   for (int y = 0; y < first.height(); ++y) {
 103     uint32* first_row = first.getAddr32(0, y);
 104     uint32* second_row = second.getAddr32(0, y);
 105     uint32* dst_row = blended.getAddr32(0, y);
 106
 107     for (int x = 0; x < first.width(); ++x) {
 108       uint32 first_pixel = first_row[x];
 109       uint32 second_pixel = second_row[x];
 110
 111       int a = static_cast<int>((SkColorGetA(first_pixel) * first_alpha) +
 112                                (SkColorGetA(second_pixel) * alpha));
 113       int r = static_cast<int>((SkColorGetR(first_pixel) * first_alpha) +
 114                                (SkColorGetR(second_pixel) * alpha));
 115       int g = static_cast<int>((SkColorGetG(first_pixel) * first_alpha) +
 116                                (SkColorGetG(second_pixel) * alpha));
 117       int b = static_cast<int>((SkColorGetB(first_pixel) * first_alpha) +
 118                                (SkColorGetB(second_pixel) * alpha));
 119
 120       dst_row[x] = SkColorSetARGB(a, r, g, b);
 121     }
 122   }
 123
 124   return blended;
 125 }
 126
 127 // static
 128 SkBitmap SkBitmapOperations::CreateMaskedBitmap(const SkBitmap& rgb,
 129                                                 const SkBitmap& alpha) {
 130   DCHECK(rgb.width() == alpha.width());
 131   DCHECK(rgb.height() == alpha.height());
 132   DCHECK(rgb.bytesPerPixel() == alpha.bytesPerPixel());
 133   DCHECK(rgb.config() == SkBitmap::kARGB_8888_Config);
 134   DCHECK(alpha.config() == SkBitmap::kARGB_8888_Config);
 135
 136   SkBitmap masked;
 137   masked.setConfig(SkBitmap::kARGB_8888_Config, rgb.width(), rgb.height(), 0);
 138   masked.allocPixels();
 139   masked.eraseARGB(0, 0, 0, 0);
 140
 141   SkAutoLockPixels lock_rgb(rgb);
 142   SkAutoLockPixels lock_alpha(alpha);
 143   SkAutoLockPixels lock_masked(masked);
 144
 145   for (int y = 0; y < masked.height(); ++y) {
 146     uint32* rgb_row = rgb.getAddr32(0, y);
 147     uint32* alpha_row = alpha.getAddr32(0, y);
 148     uint32* dst_row = masked.getAddr32(0, y);
 149
 150     for (int x = 0; x < masked.width(); ++x) {
 151       SkColor rgb_pixel = SkUnPreMultiply::PMColorToColor(rgb_row[x]);
 152       int alpha = SkAlphaMul(SkColorGetA(rgb_pixel), SkColorGetA(alpha_row[x]));
 153       dst_row[x] = SkColorSetARGB(alpha,
 154                                   SkAlphaMul(SkColorGetR(rgb_pixel), alpha),
 155                                   SkAlphaMul(SkColorGetG(rgb_pixel), alpha),
 156                                   SkAlphaMul(SkColorGetB(rgb_pixel), alpha));
 157     }
 158   }
 159
 160   return masked;
 161 }
 162
 163 // static
 164 SkBitmap SkBitmapOperations::CreateButtonBackground(SkColor color,
 165                                                     const SkBitmap& image,
 166                                                     const SkBitmap& mask) {
 167   DCHECK(image.config() == SkBitmap::kARGB_8888_Config);
 168   DCHECK(mask.config() == SkBitmap::kARGB_8888_Config);
 169
 170   SkBitmap background;
 171   background.setConfig(
 172       SkBitmap::kARGB_8888_Config, mask.width(), mask.height(), 0);
 173   background.allocPixels();
 174
 175   double bg_a = SkColorGetA(color);
 176   double bg_r = SkColorGetR(color);
 177   double bg_g = SkColorGetG(color);
 178   double bg_b = SkColorGetB(color);
 179
 180   SkAutoLockPixels lock_mask(mask);
 181   SkAutoLockPixels lock_image(image);
 182   SkAutoLockPixels lock_background(background);
 183
 184   for (int y = 0; y < mask.height(); ++y) {
 185     uint32* dst_row = background.getAddr32(0, y);
 186     uint32* image_row = image.getAddr32(0, y % image.height());
 187     uint32* mask_row = mask.getAddr32(0, y);
 188
 189     for (int x = 0; x < mask.width(); ++x) {
 190       uint32 image_pixel = image_row[x % image.width()];
 191
 192       double img_a = SkColorGetA(image_pixel);
 193       double img_r = SkColorGetR(image_pixel);
 194       double img_g = SkColorGetG(image_pixel);
 195       double img_b = SkColorGetB(image_pixel);
 196
 197       double img_alpha = static_cast<double>(img_a) / 255.0;
 198       double img_inv = 1 - img_alpha;
 199
 200       double mask_a = static_cast<double>(SkColorGetA(mask_row[x])) / 255.0;
 201
 202       dst_row[x] = SkColorSetARGB(
 203           static_cast<int>(std::min(255.0, bg_a + img_a) * mask_a),
 204           static_cast<int>(((bg_r * img_inv) + (img_r * img_alpha)) * mask_a),
 205           static_cast<int>(((bg_g * img_inv) + (img_g * img_alpha)) * mask_a),
 206           static_cast<int>(((bg_b * img_inv) + (img_b * img_alpha)) * mask_a));
 207     }
 208   }
 209
 210   return background;
 211 }
 212
 213 namespace {
 214 namespace HSLShift {
 215
 216 // TODO(viettrungluu): Some things have yet to be optimized at all.
 217
 218 // Notes on and conventions used in the following code
 219 //
 220 // Conventions:
 221 //  - R, G, B, A = obvious; as variables: |r|, |g|, |b|, |a| (see also below)
 222 //  - H, S, L = obvious; as variables: |h|, |s|, |l| (see also below)
 223 //  - variables derived from S, L shift parameters: |sdec| and |sinc| for S
 224 //    increase and decrease factors, |ldec| and |linc| for L (see also below)
 225 //
 226 // To try to optimize HSL shifts, we do several things:
 227 //  - Avoid unpremultiplying (then processing) then premultiplying. This means
 228 //    that R, G, B values (and also L, but not H and S) should be treated as
 229 //    having a range of 0..A (where A is alpha).
 230 //  - Do things in integer/fixed-point. This avoids costly conversions between
 231 //    floating-point and integer, though I should study the tradeoff more
 232 //    carefully (presumably, at some point of processing complexity, converting
 233 //    and processing using simpler floating-point code will begin to win in
 234 //    performance). Also to be studied is the speed/type of floating point
 235 //    conversions; see, e.g., <http://www.stereopsis.com/sree/fpu2006.html>.
 236 //
 237 // Conventions for fixed-point arithmetic
 238 //  - Each function has a constant denominator (called |den|, which should be a
 239 //    power of 2), appropriate for the computations done in that function.
 240 //  - A value |x| is then typically represented by a numerator, named |x_num|,
 241 //    so that its actual value is |x_num / den| (casting to floating-point
 242 //    before division).
 243 //  - To obtain |x_num| from |x|, simply multiply by |den|, i.e., |x_num = x *
 244 //    den| (casting appropriately).
 245 //  - When necessary, a value |x| may also be represented as a numerator over
 246 //    the denominator squared (set |den2 = den * den|). In such a case, the
 247 //    corresponding variable is called |x_num2| (so that its actual value is
 248 //    |x_num^2 / den2|.
 249 //  - The representation of the product of |x| and |y| is be called |x_y_num| if
 250 //    |x * y == x_y_num / den|, and |xy_num2| if |x * y == x_y_num2 / den2|. In
 251 //    the latter case, notice that one can calculate |x_y_num2 = x_num * y_num|.
 252
 253 // Routine used to process a line; typically specialized for specific kinds of
 254 // HSL shifts (to optimize).
 255 typedef void (*LineProcessor)(color_utils::HSL,
 256                               const SkPMColor*,
 257                               SkPMColor*,
 258                               int width);
 259
 260 enum OperationOnH { kOpHNone = 0, kOpHShift, kNumHOps };
 261 enum OperationOnS { kOpSNone = 0, kOpSDec, kOpSInc, kNumSOps };
 262 enum OperationOnL { kOpLNone = 0, kOpLDec, kOpLInc, kNumLOps };
 263
 264 // Epsilon used to judge when shift values are close enough to various critical
 265 // values (typically 0.5, which yields a no-op for S and L shifts. 1/256 should
 266 // be small enough, but let's play it safe>
 267 const double epsilon = 0.0005;
 268
 269 // Line processor: default/universal (i.e., old-school).
 270 void LineProcDefault(color_utils::HSL hsl_shift, const SkPMColor* in,
 271                      SkPMColor* out, int width) {
 272   for (int x = 0; x < width; x++) {
 273     out[x] = SkPreMultiplyColor(color_utils::HSLShift(
 274         SkUnPreMultiply::PMColorToColor(in[x]), hsl_shift));
 275   }
 276 }
 277
 278 // Line processor: no-op (i.e., copy).
 279 void LineProcCopy(color_utils::HSL hsl_shift, const SkPMColor* in,
 280                   SkPMColor* out, int width) {
 281   DCHECK(hsl_shift.h < 0);
 282   DCHECK(hsl_shift.s < 0 || fabs(hsl_shift.s - 0.5) < HSLShift::epsilon);
 283   DCHECK(hsl_shift.l < 0 || fabs(hsl_shift.l - 0.5) < HSLShift::epsilon);
 284   memcpy(out, in, static_cast<size_t>(width) * sizeof(out[0]));
 285 }
 286
 287 // Line processor: H no-op, S no-op, L decrease.
 288 void LineProcHnopSnopLdec(color_utils::HSL hsl_shift, const SkPMColor* in,
 289                           SkPMColor* out, int width) {
 290   const uint32_t den = 65536;
 291
 292   DCHECK(hsl_shift.h < 0);
 293   DCHECK(hsl_shift.s < 0 || fabs(hsl_shift.s - 0.5) < HSLShift::epsilon);
 294   DCHECK(hsl_shift.l <= 0.5 - HSLShift::epsilon && hsl_shift.l >= 0);
 295
 296   uint32_t ldec_num = static_cast<uint32_t>(hsl_shift.l * 2 * den);
 297   for (int x = 0; x < width; x++) {
 298     uint32_t a = SkGetPackedA32(in[x]);
 299     uint32_t r = SkGetPackedR32(in[x]);
 300     uint32_t g = SkGetPackedG32(in[x]);
 301     uint32_t b = SkGetPackedB32(in[x]);
 302     r = r * ldec_num / den;
 303     g = g * ldec_num / den;
 304     b = b * ldec_num / den;
 305     out[x] = SkPackARGB32(a, r, g, b);
 306   }
 307 }
 308
 309 // Line processor: H no-op, S no-op, L increase.
 310 void LineProcHnopSnopLinc(color_utils::HSL hsl_shift, const SkPMColor* in,
 311                           SkPMColor* out, int width) {
 312   const uint32_t den = 65536;
 313
 314   DCHECK(hsl_shift.h < 0);
 315   DCHECK(hsl_shift.s < 0 || fabs(hsl_shift.s - 0.5) < HSLShift::epsilon);
 316   DCHECK(hsl_shift.l >= 0.5 + HSLShift::epsilon && hsl_shift.l <= 1);
 317
 318   uint32_t linc_num = static_cast<uint32_t>((hsl_shift.l - 0.5) * 2 * den);
 319   for (int x = 0; x < width; x++) {
 320     uint32_t a = SkGetPackedA32(in[x]);
 321     uint32_t r = SkGetPackedR32(in[x]);
 322     uint32_t g = SkGetPackedG32(in[x]);
 323     uint32_t b = SkGetPackedB32(in[x]);
 324     r += (a - r) * linc_num / den;
 325     g += (a - g) * linc_num / den;
 326     b += (a - b) * linc_num / den;
 327     out[x] = SkPackARGB32(a, r, g, b);
 328   }
 329 }
 330
 331 // Saturation changes modifications in RGB
 332 //
 333 // (Note that as a further complication, the values we deal in are
 334 // premultiplied, so R/G/B values must be in the range 0..A. For mathematical
 335 // purposes, one may as well use r=R/A, g=G/A, b=B/A. Without loss of
 336 // generality, assume that R/G/B values are in the range 0..1.)
 337 //
 338 // Let Max = max(R,G,B), Min = min(R,G,B), and Med be the median value. Then L =
 339 // (Max+Min)/2. If L is to remain constant, Max+Min must also remain constant.
 340 //
 341 // For H to remain constant, first, the (numerical) order of R/G/B (from
 342 // smallest to largest) must remain the same. Second, all the ratios
 343 // (R-G)/(Max-Min), (R-B)/(Max-Min), (G-B)/(Max-Min) must remain constant (of
 344 // course, if Max = Min, then S = 0 and no saturation change is well-defined,
 345 // since H is not well-defined).
 346 //
 347 // Let C_max be a colour with value Max, C_min be one with value Min, and C_med
 348 // the remaining colour. Increasing saturation (to the maximum) is accomplished
 349 // by increasing the value of C_max while simultaneously decreasing C_min and
 350 // changing C_med so that the ratios are maintained; for the latter, it suffices
 351 // to keep (C_med-C_min)/(C_max-C_min) constant (and equal to
 352 // (Med-Min)/(Max-Min)).
 353
 354 // Line processor: H no-op, S decrease, L no-op.
 355 void LineProcHnopSdecLnop(color_utils::HSL hsl_shift, const SkPMColor* in,
 356                           SkPMColor* out, int width) {
 357   DCHECK(hsl_shift.h < 0);
 358   DCHECK(hsl_shift.s >= 0 && hsl_shift.s <= 0.5 - HSLShift::epsilon);
 359   DCHECK(hsl_shift.l < 0 || fabs(hsl_shift.l - 0.5) < HSLShift::epsilon);
 360
 361   const int32_t denom = 65536;
 362   int32_t s_numer = static_cast<int32_t>(hsl_shift.s * 2 * denom);
 363   for (int x = 0; x < width; x++) {
 364     int32_t a = static_cast<int32_t>(SkGetPackedA32(in[x]));
 365     int32_t r = static_cast<int32_t>(SkGetPackedR32(in[x]));
 366     int32_t g = static_cast<int32_t>(SkGetPackedG32(in[x]));
 367     int32_t b = static_cast<int32_t>(SkGetPackedB32(in[x]));
 368
 369     int32_t vmax, vmin;
 370     if (r > g) {  // This uses 3 compares rather than 4.
 371       vmax = std::max(r, b);
 372       vmin = std::min(g, b);
 373     } else {
 374       vmax = std::max(g, b);
 375       vmin = std::min(r, b);
 376     }
 377
 378     // Use denom * L to avoid rounding.
 379     int32_t denom_l = (vmax + vmin) * (denom / 2);
 380     int32_t s_numer_l = (vmax + vmin) * s_numer / 2;
 381
 382     r = (denom_l + r * s_numer - s_numer_l) / denom;
 383     g = (denom_l + g * s_numer - s_numer_l) / denom;
 384     b = (denom_l + b * s_numer - s_numer_l) / denom;
 385     out[x] = SkPackARGB32(a, r, g, b);
 386   }
 387 }
 388
 389 // Line processor: H no-op, S decrease, L decrease.
 390 void LineProcHnopSdecLdec(color_utils::HSL hsl_shift, const SkPMColor* in,
 391                           SkPMColor* out, int width) {
 392   DCHECK(hsl_shift.h < 0);
 393   DCHECK(hsl_shift.s >= 0 && hsl_shift.s <= 0.5 - HSLShift::epsilon);
 394   DCHECK(hsl_shift.l >= 0 && hsl_shift.l <= 0.5 - HSLShift::epsilon);
 395
 396   // Can't be too big since we need room for denom*denom and a bit for sign.
 397   const int32_t denom = 1024;
 398   int32_t l_numer = static_cast<int32_t>(hsl_shift.l * 2 * denom);
 399   int32_t s_numer = static_cast<int32_t>(hsl_shift.s * 2 * denom);
 400   for (int x = 0; x < width; x++) {
 401     int32_t a = static_cast<int32_t>(SkGetPackedA32(in[x]));
 402     int32_t r = static_cast<int32_t>(SkGetPackedR32(in[x]));
 403     int32_t g = static_cast<int32_t>(SkGetPackedG32(in[x]));
 404     int32_t b = static_cast<int32_t>(SkGetPackedB32(in[x]));
 405
 406     int32_t vmax, vmin;
 407     if (r > g) {  // This uses 3 compares rather than 4.
 408       vmax = std::max(r, b);
 409       vmin = std::min(g, b);
 410     } else {
 411       vmax = std::max(g, b);
 412       vmin = std::min(r, b);
 413     }
 414
 415     // Use denom * L to avoid rounding.
 416     int32_t denom_l = (vmax + vmin) * (denom / 2);
 417     int32_t s_numer_l = (vmax + vmin) * s_numer / 2;
 418
 419     r = (denom_l + r * s_numer - s_numer_l) * l_numer / (denom * denom);
 420     g = (denom_l + g * s_numer - s_numer_l) * l_numer / (denom * denom);
 421     b = (denom_l + b * s_numer - s_numer_l) * l_numer / (denom * denom);
 422     out[x] = SkPackARGB32(a, r, g, b);
 423   }
 424 }
 425
 426 // Line processor: H no-op, S decrease, L increase.
 427 void LineProcHnopSdecLinc(color_utils::HSL hsl_shift, const SkPMColor* in,
 428                           SkPMColor* out, int width) {
 429   DCHECK(hsl_shift.h < 0);
 430   DCHECK(hsl_shift.s >= 0 && hsl_shift.s <= 0.5 - HSLShift::epsilon);
 431   DCHECK(hsl_shift.l >= 0.5 + HSLShift::epsilon && hsl_shift.l <= 1);
 432
 433   // Can't be too big since we need room for denom*denom and a bit for sign.
 434   const int32_t denom = 1024;
 435   int32_t l_numer = static_cast<int32_t>((hsl_shift.l - 0.5) * 2 * denom);
 436   int32_t s_numer = static_cast<int32_t>(hsl_shift.s * 2 * denom);
 437   for (int x = 0; x < width; x++) {
 438     int32_t a = static_cast<int32_t>(SkGetPackedA32(in[x]));
 439     int32_t r = static_cast<int32_t>(SkGetPackedR32(in[x]));
 440     int32_t g = static_cast<int32_t>(SkGetPackedG32(in[x]));
 441     int32_t b = static_cast<int32_t>(SkGetPackedB32(in[x]));
 442
 443     int32_t vmax, vmin;
 444     if (r > g) {  // This uses 3 compares rather than 4.
 445       vmax = std::max(r, b);
 446       vmin = std::min(g, b);
 447     } else {
 448       vmax = std::max(g, b);
 449       vmin = std::min(r, b);
 450     }
 451
 452     // Use denom * L to avoid rounding.
 453     int32_t denom_l = (vmax + vmin) * (denom / 2);
 454     int32_t s_numer_l = (vmax + vmin) * s_numer / 2;
 455
 456     r = denom_l + r * s_numer - s_numer_l;
 457     g = denom_l + g * s_numer - s_numer_l;
 458     b = denom_l + b * s_numer - s_numer_l;
 459
 460     r = (r * denom + (a * denom - r) * l_numer) / (denom * denom);
 461     g = (g * denom + (a * denom - g) * l_numer) / (denom * denom);
 462     b = (b * denom + (a * denom - b) * l_numer) / (denom * denom);
 463     out[x] = SkPackARGB32(a, r, g, b);
 464   }
 465 }
 466
 467 const LineProcessor kLineProcessors[kNumHOps][kNumSOps][kNumLOps] = {
 468   { // H: kOpHNone
 469     { // S: kOpSNone
 470       LineProcCopy,         // L: kOpLNone
 471       LineProcHnopSnopLdec, // L: kOpLDec
 472       LineProcHnopSnopLinc  // L: kOpLInc
 473     },
 474     { // S: kOpSDec
 475       LineProcHnopSdecLnop, // L: kOpLNone
 476       LineProcHnopSdecLdec, // L: kOpLDec
 477       LineProcHnopSdecLinc  // L: kOpLInc
 478     },
 479     { // S: kOpSInc
 480       LineProcDefault, // L: kOpLNone
 481       LineProcDefault, // L: kOpLDec
 482       LineProcDefault  // L: kOpLInc
 483     }
 484   },
 485   { // H: kOpHShift
 486     { // S: kOpSNone
 487       LineProcDefault, // L: kOpLNone
 488       LineProcDefault, // L: kOpLDec
 489       LineProcDefault  // L: kOpLInc
 490     },
 491     { // S: kOpSDec
 492       LineProcDefault, // L: kOpLNone
 493       LineProcDefault, // L: kOpLDec
 494       LineProcDefault  // L: kOpLInc
 495     },
 496     { // S: kOpSInc
 497       LineProcDefault, // L: kOpLNone
 498       LineProcDefault, // L: kOpLDec
 499       LineProcDefault  // L: kOpLInc
 500     }
 501   }
 502 };
 503
 504 }  // namespace HSLShift
 505 }  // namespace
 506
 507 // static
 508 SkBitmap SkBitmapOperations::CreateHSLShiftedBitmap(
 509     const SkBitmap& bitmap,
 510     color_utils::HSL hsl_shift) {
 511   // Default to NOPs.
 512   HSLShift::OperationOnH H_op = HSLShift::kOpHNone;
 513   HSLShift::OperationOnS S_op = HSLShift::kOpSNone;
 514   HSLShift::OperationOnL L_op = HSLShift::kOpLNone;
 515
 516   if (hsl_shift.h >= 0 && hsl_shift.h <= 1)
 517     H_op = HSLShift::kOpHShift;
 518
 519   // Saturation shift: 0 -> fully desaturate, 0.5 -> NOP, 1 -> fully saturate.
 520   if (hsl_shift.s >= 0 && hsl_shift.s <= (0.5 - HSLShift::epsilon))
 521     S_op = HSLShift::kOpSDec;
 522   else if (hsl_shift.s >= (0.5 + HSLShift::epsilon))
 523     S_op = HSLShift::kOpSInc;
 524
 525   // Lightness shift: 0 -> black, 0.5 -> NOP, 1 -> white.
 526   if (hsl_shift.l >= 0 && hsl_shift.l <= (0.5 - HSLShift::epsilon))
 527     L_op = HSLShift::kOpLDec;
 528   else if (hsl_shift.l >= (0.5 + HSLShift::epsilon))
 529     L_op = HSLShift::kOpLInc;
 530
 531   HSLShift::LineProcessor line_proc =
 532       HSLShift::kLineProcessors[H_op][S_op][L_op];
 533
 534   DCHECK(bitmap.empty() == false);
 535   DCHECK(bitmap.config() == SkBitmap::kARGB_8888_Config);
 536
 537   SkBitmap shifted;
 538   shifted.setConfig(SkBitmap::kARGB_8888_Config, bitmap.width(),
 539                     bitmap.height(), 0);
 540   shifted.allocPixels();
 541   shifted.eraseARGB(0, 0, 0, 0);
 542   shifted.setIsOpaque(false);
 543
 544   SkAutoLockPixels lock_bitmap(bitmap);
 545   SkAutoLockPixels lock_shifted(shifted);
 546
 547   // Loop through the pixels of the original bitmap.
 548   for (int y = 0; y < bitmap.height(); ++y) {
 549     SkPMColor* pixels = bitmap.getAddr32(0, y);
 550     SkPMColor* tinted_pixels = shifted.getAddr32(0, y);
 551
 552     (*line_proc)(hsl_shift, pixels, tinted_pixels, bitmap.width());
 553   }
 554
 555   return shifted;
 556 }
 557
 558 // static
 559 SkBitmap SkBitmapOperations::CreateTiledBitmap(const SkBitmap& source,
 560                                                int src_x, int src_y,
 561                                                int dst_w, int dst_h) {
 562   DCHECK(source.getConfig() == SkBitmap::kARGB_8888_Config);
 563
 564   SkBitmap cropped;
 565   cropped.setConfig(SkBitmap::kARGB_8888_Config, dst_w, dst_h, 0);
 566   cropped.allocPixels();
 567   cropped.eraseARGB(0, 0, 0, 0);
 568
 569   SkAutoLockPixels lock_source(source);
 570   SkAutoLockPixels lock_cropped(cropped);
 571
 572   // Loop through the pixels of the original bitmap.
 573   for (int y = 0; y < dst_h; ++y) {
 574     int y_pix = (src_y + y) % source.height();
 575     while (y_pix < 0)
 576       y_pix += source.height();
 577
 578     uint32* source_row = source.getAddr32(0, y_pix);
 579     uint32* dst_row = cropped.getAddr32(0, y);
 580
 581     for (int x = 0; x < dst_w; ++x) {
 582       int x_pix = (src_x + x) % source.width();
 583       while (x_pix < 0)
 584         x_pix += source.width();
 585
 586       dst_row[x] = source_row[x_pix];
 587     }
 588   }
 589
 590   return cropped;
 591 }
 592
 593 // static
 594 SkBitmap SkBitmapOperations::DownsampleByTwoUntilSize(const SkBitmap& bitmap,
 595                                                       int min_w, int min_h) {
 596   if ((bitmap.width() <= min_w) || (bitmap.height() <= min_h) ||
 597       (min_w < 0) || (min_h < 0))
 598     return bitmap;
 599
 600   // Since bitmaps are refcounted, this copy will be fast.
 601   SkBitmap current = bitmap;
 602   while ((current.width() >= min_w * 2) && (current.height() >= min_h * 2) &&
 603          (current.width() > 1) && (current.height() > 1))
 604     current = DownsampleByTwo(current);
 605   return current;
 606 }
 607
 608 // static
 609 SkBitmap SkBitmapOperations::DownsampleByTwo(const SkBitmap& bitmap) {
 610   // Handle the nop case.
 611   if ((bitmap.width() <= 1) || (bitmap.height() <= 1))
 612     return bitmap;
 613
 614   SkBitmap result;
 615   result.setConfig(SkBitmap::kARGB_8888_Config,
 616                    (bitmap.width() + 1) / 2, (bitmap.height() + 1) / 2);
 617   result.allocPixels();
 618
 619   SkAutoLockPixels lock(bitmap);
 620   for (int dest_y = 0; dest_y < result.height(); ++dest_y) {
 621     for (int dest_x = 0; dest_x < result.width(); ++dest_x) {
 622       // This code is based on downsampleby2_proc32 in SkBitmap.cpp. It is very
 623       // clever in that it does two channels at once: alpha and green ("ag")
 624       // and red and blue ("rb"). Each channel gets averaged across 4 pixels
 625       // to get the result.
 626       int src_x = dest_x << 1;
 627       int src_y = dest_y << 1;
 628       const SkPMColor* cur_src = bitmap.getAddr32(src_x, src_y);
 629       SkPMColor tmp, ag, rb;
 630
 631       // Top left pixel of the 2x2 block.
 632       tmp = *cur_src;
 633       ag = (tmp >> 8) & 0xFF00FF;
 634       rb = tmp & 0xFF00FF;
 635       if (src_x < (bitmap.width() - 1))
 636         ++cur_src;
 637
 638       // Top right pixel of the 2x2 block.
 639       tmp = *cur_src;
 640       ag += (tmp >> 8) & 0xFF00FF;
 641       rb += tmp & 0xFF00FF;
 642       if (src_y < (bitmap.height() - 1))
 643         cur_src = bitmap.getAddr32(src_x, src_y + 1);
 644       else
 645         cur_src = bitmap.getAddr32(src_x, src_y);  // Move back to the first.
 646
 647       // Bottom left pixel of the 2x2 block.
 648       tmp = *cur_src;
 649       ag += (tmp >> 8) & 0xFF00FF;
 650       rb += tmp & 0xFF00FF;
 651       if (src_x < (bitmap.width() - 1))
 652         ++cur_src;
 653
 654       // Bottom right pixel of the 2x2 block.
 655       tmp = *cur_src;
 656       ag += (tmp >> 8) & 0xFF00FF;
 657       rb += tmp & 0xFF00FF;
 658
 659       // Put the channels back together, dividing each by 4 to get the average.
 660       // |ag| has the alpha and green channels shifted right by 8 bits from
 661       // there they should end up, so shifting left by 6 gives them in the
 662       // correct position divided by 4.
 663       *result.getAddr32(dest_x, dest_y) =
 664           ((rb >> 2) & 0xFF00FF) | ((ag << 6) & 0xFF00FF00);
 665     }
 666   }
 667
 668   return result;
 669 }
 670
 671 // static
 672 SkBitmap SkBitmapOperations::UnPreMultiply(const SkBitmap& bitmap) {
 673   if (bitmap.isNull())
 674     return bitmap;
 675   if (bitmap.isOpaque())
 676     return bitmap;
 677
 678   SkBitmap opaque_bitmap;
 679   opaque_bitmap.setConfig(bitmap.config(), bitmap.width(), bitmap.height());
 680   opaque_bitmap.allocPixels();
 681
 682   {
 683     SkAutoLockPixels bitmap_lock(bitmap);
 684     SkAutoLockPixels opaque_bitmap_lock(opaque_bitmap);
 685     for (int y = 0; y < opaque_bitmap.height(); y++) {
 686       for (int x = 0; x < opaque_bitmap.width(); x++) {
 687         uint32 src_pixel = *bitmap.getAddr32(x, y);
 688         uint32* dst_pixel = opaque_bitmap.getAddr32(x, y);
 689         SkColor unmultiplied = SkUnPreMultiply::PMColorToColor(src_pixel);
 690         *dst_pixel = unmultiplied;
 691       }
 692     }
 693   }
 694
 695   opaque_bitmap.setIsOpaque(true);
 696   return opaque_bitmap;
 697 }
 698
 699 // static
 700 SkBitmap SkBitmapOperations::CreateTransposedBtmap(const SkBitmap& image) {
 701   DCHECK(image.config() == SkBitmap::kARGB_8888_Config);
 702
 703   SkAutoLockPixels lock_image(image);
 704
 705   SkBitmap transposed;
 706   transposed.setConfig(
 707       SkBitmap::kARGB_8888_Config, image.height(), image.width(), 0);
 708   transposed.allocPixels();
 709   transposed.eraseARGB(0, 0, 0, 0);
 710
 711   for (int y = 0; y < image.height(); ++y) {
 712     uint32* image_row = image.getAddr32(0, y);
 713     for (int x = 0; x < image.width(); ++x) {
 714       uint32* dst = transposed.getAddr32(y, x);
 715       *dst = image_row[x];
 716     }
 717   }
 718
 719   return transposed;
 720 }
 721