gfx/src/nsCoord.h

   1 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* This Source Code Form is subject to the terms of the Mozilla Public
   3  * License, v. 2.0. If a copy of the MPL was not distributed with this
   4  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   5
   6 #ifndef NSCOORD_H
   7 #define NSCOORD_H
   8
   9 #include "nsAlgorithm.h"
  10 #include "nscore.h"
  11 #include "nsMathUtils.h"
  12 #include <math.h>
  13 #include <float.h>
  14
  15 #include "nsDebug.h"
  16 #include <algorithm>
  17
  18 /*
  19  * Basic type used for the geometry classes.
  20  *
  21  * Normally all coordinates are maintained in an app unit coordinate
  22  * space. An app unit is 1/60th of a CSS device pixel, which is, in turn
  23  * an integer number of device pixels, such at the CSS DPI is as close to
  24  * 96dpi as possible.
  25  */
  26
  27 // This controls whether we're using integers or floats for coordinates. We
  28 // want to eventually use floats.
  29 //#define NS_COORD_IS_FLOAT
  30
  31 inline float NS_IEEEPositiveInfinity() {
  32   union { uint32_t mPRUint32; float mFloat; } pun;
  33   pun.mPRUint32 = 0x7F800000;
  34   return pun.mFloat;
  35 }
  36 inline bool NS_IEEEIsNan(float aF) {
  37   union { uint32_t mBits; float mFloat; } pun;
  38   pun.mFloat = aF;
  39   return (pun.mBits & 0x7F800000) == 0x7F800000 &&
  40     (pun.mBits & 0x007FFFFF) != 0;
  41 }
  42
  43 #ifdef NS_COORD_IS_FLOAT
  44 typedef float nscoord;
  45 #define nscoord_MAX NS_IEEEPositiveInfinity()
  46 #else
  47 typedef int32_t nscoord;
  48 #define nscoord_MAX nscoord(1 << 30)
  49 #endif
  50
  51 #define nscoord_MIN (-nscoord_MAX)
  52
  53 inline void VERIFY_COORD(nscoord aCoord) {
  54 #ifdef NS_COORD_IS_FLOAT
  55   NS_ASSERTION(floorf(aCoord) == aCoord,
  56                "Coords cannot have fractions");
  57 #endif
  58 }
  59
  60 inline nscoord NSCoordMulDiv(nscoord aMult1, nscoord aMult2, nscoord aDiv) {
  61 #ifdef NS_COORD_IS_FLOAT
  62   return (aMult1 * aMult2 / aDiv);
  63 #else
  64   return (int64_t(aMult1) * int64_t(aMult2) / int64_t(aDiv));
  65 #endif
  66 }
  67
  68 inline nscoord NSToCoordRound(float aValue)
  69 {
  70 #if defined(XP_WIN32) && defined(_M_IX86) && !defined(__GNUC__) && !defined(__clang__)
  71   return NS_lroundup30(aValue);
  72 #else
  73   return nscoord(floorf(aValue + 0.5f));
  74 #endif /* XP_WIN32 && _M_IX86 && !__GNUC__ */
  75 }
  76
  77 inline nscoord NSToCoordRound(double aValue)
  78 {
  79 #if defined(XP_WIN32) && defined(_M_IX86) && !defined(__GNUC__) && !defined(__clang__)
  80   return NS_lroundup30((float)aValue);
  81 #else
  82   return nscoord(floor(aValue + 0.5f));
  83 #endif /* XP_WIN32 && _M_IX86 && !__GNUC__ */
  84 }
  85
  86 inline nscoord NSToCoordRoundWithClamp(float aValue)
  87 {
  88 #ifndef NS_COORD_IS_FLOAT
  89   // Bounds-check before converting out of float, to avoid overflow
  90   if (aValue >= nscoord_MAX) {
  91     return nscoord_MAX;
  92   }
  93   if (aValue <= nscoord_MIN) {
  94     return nscoord_MIN;
  95   }
  96 #endif
  97   return NSToCoordRound(aValue);
  98 }
  99
 100 /**
 101  * Returns aCoord * aScale, capping the product to nscoord_MAX or nscoord_MIN as
 102  * appropriate for the signs of aCoord and aScale.  If requireNotNegative is
 103  * true, this method will enforce that aScale is not negative; use that
 104  * parametrization to get a check of that fact in debug builds.
 105  */
 106 inline nscoord _nscoordSaturatingMultiply(nscoord aCoord, float aScale,
 107                                           bool requireNotNegative) {
 108   VERIFY_COORD(aCoord);
 109   if (requireNotNegative) {
 110     NS_ABORT_IF_FALSE(aScale >= 0.0f,
 111                       "negative scaling factors must be handled manually");
 112   }
 113 #ifdef NS_COORD_IS_FLOAT
 114   return floorf(aCoord * aScale);
 115 #else
 116   float product = aCoord * aScale;
 117   if (requireNotNegative ? aCoord > 0 : (aCoord > 0) == (aScale > 0))
 118     return NSToCoordRoundWithClamp(std::min<float>(nscoord_MAX, product));
 119   return NSToCoordRoundWithClamp(std::max<float>(nscoord_MIN, product));
 120 #endif
 121 }
 122
 123 /**
 124  * Returns aCoord * aScale, capping the product to nscoord_MAX or nscoord_MIN as
 125  * appropriate for the sign of aCoord.  This method requires aScale to not be
 126  * negative; use this method when you know that aScale should never be
 127  * negative to get a sanity check of that invariant in debug builds.
 128  */
 129 inline nscoord NSCoordSaturatingNonnegativeMultiply(nscoord aCoord, float aScale) {
 130   return _nscoordSaturatingMultiply(aCoord, aScale, true);
 131 }
 132
 133 /**
 134  * Returns aCoord * aScale, capping the product to nscoord_MAX or nscoord_MIN as
 135  * appropriate for the signs of aCoord and aScale.
 136  */
 137 inline nscoord NSCoordSaturatingMultiply(nscoord aCoord, float aScale) {
 138   return _nscoordSaturatingMultiply(aCoord, aScale, false);
 139 }
 140
 141 /**
 142  * Returns a + b, capping the sum to nscoord_MAX.
 143  *
 144  * This function assumes that neither argument is nscoord_MIN.
 145  *
 146  * Note: If/when we start using floats for nscoords, this function won't be as
 147  * necessary.  Normal float addition correctly handles adding with infinity,
 148  * assuming we aren't adding nscoord_MIN. (-infinity)
 149  */
 150 inline nscoord
 151 NSCoordSaturatingAdd(nscoord a, nscoord b)
 152 {
 153   VERIFY_COORD(a);
 154   VERIFY_COORD(b);
 155
 156 #ifdef NS_COORD_IS_FLOAT
 157   // Float math correctly handles a+b, given that neither is -infinity.
 158   return a + b;
 159 #else
 160   if (a == nscoord_MAX || b == nscoord_MAX) {
 161     // infinity + anything = anything + infinity = infinity
 162     return nscoord_MAX;
 163   } else {
 164     // a + b = a + b
 165     // Cap the result, just in case we're dealing with numbers near nscoord_MAX
 166     return std::min(nscoord_MAX, a + b);
 167   }
 168 #endif
 169 }
 170
 171 /**
 172  * Returns a - b, gracefully handling cases involving nscoord_MAX.
 173  * This function assumes that neither argument is nscoord_MIN.
 174  *
 175  * The behavior is as follows:
 176  *
 177  *  a)  infinity - infinity -> infMinusInfResult
 178  *  b)  N - infinity        -> 0  (unexpected -- triggers NOTREACHED)
 179  *  c)  infinity - N        -> infinity
 180  *  d)  N1 - N2             -> N1 - N2
 181  *
 182  * Note: For float nscoords, cases (c) and (d) are handled by normal float
 183  * math.  We still need to explicitly specify the behavior for cases (a)
 184  * and (b), though.  (Under normal float math, those cases would return NaN
 185  * and -infinity, respectively.)
 186  */
 187 inline nscoord
 188 NSCoordSaturatingSubtract(nscoord a, nscoord b,
 189                           nscoord infMinusInfResult)
 190 {
 191   VERIFY_COORD(a);
 192   VERIFY_COORD(b);
 193
 194   if (b == nscoord_MAX) {
 195     if (a == nscoord_MAX) {
 196       // case (a)
 197       return infMinusInfResult;
 198     } else {
 199       // case (b)
 200       NS_NOTREACHED("Attempted to subtract [n - nscoord_MAX]");
 201       return 0;
 202     }
 203   } else {
 204 #ifdef NS_COORD_IS_FLOAT
 205     // case (c) and (d) for floats.  (float math handles both)
 206     return a - b;
 207 #else
 208     if (a == nscoord_MAX) {
 209       // case (c) for integers
 210       return nscoord_MAX;
 211     } else {
 212       // case (d) for integers
 213       // Cap the result, in case we're dealing with numbers near nscoord_MAX
 214       return std::min(nscoord_MAX, a - b);
 215     }
 216   }
 217 #endif
 218 }
 219
 220 inline float NSCoordToFloat(nscoord aCoord) {
 221   VERIFY_COORD(aCoord);
 222 #ifdef NS_COORD_IS_FLOAT
 223   NS_ASSERTION(!NS_IEEEIsNan(aCoord), "NaN encountered in float conversion");
 224 #endif
 225   return (float)aCoord;
 226 }
 227
 228 /*
 229  * Coord Rounding Functions
 230  */
 231 inline nscoord NSToCoordFloor(float aValue)
 232 {
 233   return nscoord(floorf(aValue));
 234 }
 235
 236 inline nscoord NSToCoordFloor(double aValue)
 237 {
 238   return nscoord(floor(aValue));
 239 }
 240
 241 inline nscoord NSToCoordFloorClamped(float aValue)
 242 {
 243 #ifndef NS_COORD_IS_FLOAT
 244   // Bounds-check before converting out of float, to avoid overflow
 245   if (aValue >= nscoord_MAX) {
 246     return nscoord_MAX;
 247   }
 248   if (aValue <= nscoord_MIN) {
 249     return nscoord_MIN;
 250   }
 251 #endif
 252   return NSToCoordFloor(aValue);
 253 }
 254
 255 inline nscoord NSToCoordCeil(float aValue)
 256 {
 257   return nscoord(ceilf(aValue));
 258 }
 259
 260 inline nscoord NSToCoordCeil(double aValue)
 261 {
 262   return nscoord(ceil(aValue));
 263 }
 264
 265 inline nscoord NSToCoordCeilClamped(double aValue)
 266 {
 267 #ifndef NS_COORD_IS_FLOAT
 268   // Bounds-check before converting out of double, to avoid overflow
 269   if (aValue >= nscoord_MAX) {
 270     return nscoord_MAX;
 271   }
 272   if (aValue <= nscoord_MIN) {
 273     return nscoord_MIN;
 274   }
 275 #endif
 276   return NSToCoordCeil(aValue);
 277 }
 278
 279 // The NSToCoordTrunc* functions remove the fractional component of
 280 // aValue, and are thus equivalent to NSToCoordFloor* for positive
 281 // values and NSToCoordCeil* for negative values.
 282
 283 inline nscoord NSToCoordTrunc(float aValue)
 284 {
 285   // There's no need to use truncf() since it matches the default
 286   // rules for float to integer conversion.
 287   return nscoord(aValue);
 288 }
 289
 290 inline nscoord NSToCoordTrunc(double aValue)
 291 {
 292   // There's no need to use trunc() since it matches the default
 293   // rules for float to integer conversion.
 294   return nscoord(aValue);
 295 }
 296
 297 inline nscoord NSToCoordTruncClamped(float aValue)
 298 {
 299 #ifndef NS_COORD_IS_FLOAT
 300   // Bounds-check before converting out of float, to avoid overflow
 301   if (aValue >= nscoord_MAX) {
 302     return nscoord_MAX;
 303   }
 304   if (aValue <= nscoord_MIN) {
 305     return nscoord_MIN;
 306   }
 307 #endif
 308   return NSToCoordTrunc(aValue);
 309 }
 310
 311 inline nscoord NSToCoordTruncClamped(double aValue)
 312 {
 313 #ifndef NS_COORD_IS_FLOAT
 314   // Bounds-check before converting out of double, to avoid overflow
 315   if (aValue >= nscoord_MAX) {
 316     return nscoord_MAX;
 317   }
 318   if (aValue <= nscoord_MIN) {
 319     return nscoord_MIN;
 320   }
 321 #endif
 322   return NSToCoordTrunc(aValue);
 323 }
 324
 325 /*
 326  * Int Rounding Functions
 327  */
 328 inline int32_t NSToIntFloor(float aValue)
 329 {
 330   return int32_t(floorf(aValue));
 331 }
 332
 333 inline int32_t NSToIntCeil(float aValue)
 334 {
 335   return int32_t(ceilf(aValue));
 336 }
 337
 338 inline int32_t NSToIntRound(float aValue)
 339 {
 340   return NS_lroundf(aValue);
 341 }
 342
 343 inline int32_t NSToIntRound(double aValue)
 344 {
 345   return NS_lround(aValue);
 346 }
 347
 348 inline int32_t NSToIntRoundUp(double aValue)
 349 {
 350   return int32_t(floor(aValue + 0.5));
 351 }
 352
 353 /*
 354  * App Unit/Pixel conversions
 355  */
 356 inline nscoord NSFloatPixelsToAppUnits(float aPixels, float aAppUnitsPerPixel)
 357 {
 358   return NSToCoordRoundWithClamp(aPixels * aAppUnitsPerPixel);
 359 }
 360
 361 inline nscoord NSIntPixelsToAppUnits(int32_t aPixels, int32_t aAppUnitsPerPixel)
 362 {
 363   // The cast to nscoord makes sure we don't overflow if we ever change
 364   // nscoord to float
 365   nscoord r = aPixels * (nscoord)aAppUnitsPerPixel;
 366   VERIFY_COORD(r);
 367   return r;
 368 }
 369
 370 inline float NSAppUnitsToFloatPixels(nscoord aAppUnits, float aAppUnitsPerPixel)
 371 {
 372   return (float(aAppUnits) / aAppUnitsPerPixel);
 373 }
 374
 375 inline double NSAppUnitsToDoublePixels(nscoord aAppUnits, double aAppUnitsPerPixel)
 376 {
 377   return (double(aAppUnits) / aAppUnitsPerPixel);
 378 }
 379
 380 inline int32_t NSAppUnitsToIntPixels(nscoord aAppUnits, float aAppUnitsPerPixel)
 381 {
 382   return NSToIntRound(float(aAppUnits) / aAppUnitsPerPixel);
 383 }
 384
 385 inline float NSCoordScale(nscoord aCoord, int32_t aFromAPP, int32_t aToAPP)
 386 {
 387   return (NSCoordToFloat(aCoord) * aToAPP) / aFromAPP;
 388 }
 389
 390 /// handy constants
 391 #define TWIPS_PER_POINT_INT           20
 392 #define TWIPS_PER_POINT_FLOAT         20.0f
 393 #define POINTS_PER_INCH_INT           72
 394 #define POINTS_PER_INCH_FLOAT         72.0f
 395 #define CM_PER_INCH_FLOAT             2.54f
 396 #define MM_PER_INCH_FLOAT             25.4f
 397
 398 /*
 399  * Twips/unit conversions
 400  */
 401 inline float NSUnitsToTwips(float aValue, float aPointsPerUnit)
 402 {
 403   return aValue * aPointsPerUnit * TWIPS_PER_POINT_FLOAT;
 404 }
 405
 406 inline float NSTwipsToUnits(float aTwips, float aUnitsPerPoint)
 407 {
 408   return (aTwips * (aUnitsPerPoint / TWIPS_PER_POINT_FLOAT));
 409 }
 410
 411 /// Unit conversion macros
 412 //@{
 413 #define NS_POINTS_TO_TWIPS(x)         NSUnitsToTwips((x), 1.0f)
 414 #define NS_INCHES_TO_TWIPS(x)         NSUnitsToTwips((x), POINTS_PER_INCH_FLOAT)                      // 72 points per inch
 415
 416 #define NS_MILLIMETERS_TO_TWIPS(x)    NSUnitsToTwips((x), (POINTS_PER_INCH_FLOAT * 0.03937f))
 417
 418 #define NS_POINTS_TO_INT_TWIPS(x)     NSToIntRound(NS_POINTS_TO_TWIPS(x))
 419 #define NS_INCHES_TO_INT_TWIPS(x)     NSToIntRound(NS_INCHES_TO_TWIPS(x))
 420
 421 #define NS_TWIPS_TO_INCHES(x)         NSTwipsToUnits((x), 1.0f / POINTS_PER_INCH_FLOAT)
 422
 423 #define NS_TWIPS_TO_MILLIMETERS(x)    NSTwipsToUnits((x), 1.0f / (POINTS_PER_INCH_FLOAT * 0.03937f))
 424 //@}
 425
 426 #endif /* NSCOORD_H */