The Tor Browser: gfx/src/nsCoord.h@97036ab72558 (annotated)

gfx/src/nsCoord.h@97036ab72558 (annotated)

gfx/src/nsCoord.h

Tue, 06 Jan 2015 21:39:09 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Tue, 06 Jan 2015 21:39:09 +0100
branch: TOR_BUG_9701
changeset 8: 97036ab72558
permissions: -rw-r--r--

Conditionally force memory storage according to privacy.thirdparty.isolate;
This solves Tor bug #9701, complying with disk avoidance documented in
https://www.torproject.org/projects/torbrowser/design/#disk-avoidance.

 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 #ifndef NSCOORD_H
 #define NSCOORD_H
 #include "nsAlgorithm.h"
 #include "nscore.h"
 #include "nsMathUtils.h"
 #include <math.h>
 #include <float.h>
 #include "nsDebug.h"
 #include <algorithm>
 /*
  * Basic type used for the geometry classes.
  *
  * Normally all coordinates are maintained in an app unit coordinate
  * space. An app unit is 1/60th of a CSS device pixel, which is, in turn
  * an integer number of device pixels, such at the CSS DPI is as close to
  * 96dpi as possible.
  */
 // This controls whether we're using integers or floats for coordinates. We
 // want to eventually use floats.
 //#define NS_COORD_IS_FLOAT
 inline float NS_IEEEPositiveInfinity() {
   union { uint32_t mPRUint32; float mFloat; } pun;
   pun.mPRUint32 = 0x7F800000;
   return pun.mFloat;
 }
 inline bool NS_IEEEIsNan(float aF) {
   union { uint32_t mBits; float mFloat; } pun;
   pun.mFloat = aF;
   return (pun.mBits & 0x7F800000) == 0x7F800000 &&
     (pun.mBits & 0x007FFFFF) != 0;
 }
 #ifdef NS_COORD_IS_FLOAT
 typedef float nscoord;
 #define nscoord_MAX NS_IEEEPositiveInfinity()
 #else
 typedef int32_t nscoord;
 #define nscoord_MAX nscoord(1 << 30)
 #endif
 #define nscoord_MIN (-nscoord_MAX)
 inline void VERIFY_COORD(nscoord aCoord) {
 #ifdef NS_COORD_IS_FLOAT
   NS_ASSERTION(floorf(aCoord) == aCoord,
                "Coords cannot have fractions");
 #endif
 }
 inline nscoord NSToCoordRound(float aValue)
 {
 #if defined(XP_WIN32) && defined(_M_IX86) && !defined(__GNUC__)
   return NS_lroundup30(aValue);
 #else
   return nscoord(floorf(aValue + 0.5f));
 #endif /* XP_WIN32 && _M_IX86 && !__GNUC__ */
 }
 inline nscoord NSToCoordRound(double aValue)
 {
 #if defined(XP_WIN32) && defined(_M_IX86) && !defined(__GNUC__)
   return NS_lroundup30((float)aValue);
 #else
   return nscoord(floor(aValue + 0.5f));
 #endif /* XP_WIN32 && _M_IX86 && !__GNUC__ */
 }
 inline nscoord NSToCoordRoundWithClamp(float aValue)
 {
 #ifndef NS_COORD_IS_FLOAT
   // Bounds-check before converting out of float, to avoid overflow
   if (aValue >= nscoord_MAX) {
     return nscoord_MAX;
   }
   if (aValue <= nscoord_MIN) {
     return nscoord_MIN;
   }
 #endif
   return NSToCoordRound(aValue);
 }
 /**
  * Returns aCoord * aScale, capping the product to nscoord_MAX or nscoord_MIN as
  * appropriate for the signs of aCoord and aScale.  If requireNotNegative is
  * true, this method will enforce that aScale is not negative; use that
  * parametrization to get a check of that fact in debug builds.
  */
 inline nscoord _nscoordSaturatingMultiply(nscoord aCoord, float aScale,
                                           bool requireNotNegative) {
   VERIFY_COORD(aCoord);
   if (requireNotNegative) {
     NS_ABORT_IF_FALSE(aScale >= 0.0f,
                       "negative scaling factors must be handled manually");
   }
 #ifdef NS_COORD_IS_FLOAT
   return floorf(aCoord * aScale);
 #else
   float product = aCoord * aScale;
   if (requireNotNegative ? aCoord > 0 : (aCoord > 0) == (aScale > 0))
     return NSToCoordRoundWithClamp(std::min<float>(nscoord_MAX, product));
   return NSToCoordRoundWithClamp(std::max<float>(nscoord_MIN, product));
 #endif
 }
 /**
  * Returns aCoord * aScale, capping the product to nscoord_MAX or nscoord_MIN as
  * appropriate for the sign of aCoord.  This method requires aScale to not be
  * negative; use this method when you know that aScale should never be
  * negative to get a sanity check of that invariant in debug builds.
  */
 inline nscoord NSCoordSaturatingNonnegativeMultiply(nscoord aCoord, float aScale) {
   return _nscoordSaturatingMultiply(aCoord, aScale, true);
 }
 /**
  * Returns aCoord * aScale, capping the product to nscoord_MAX or nscoord_MIN as
  * appropriate for the signs of aCoord and aScale.
  */
 inline nscoord NSCoordSaturatingMultiply(nscoord aCoord, float aScale) {
   return _nscoordSaturatingMultiply(aCoord, aScale, false);
 }
 /**
  * Returns a + b, capping the sum to nscoord_MAX.
  *
  * This function assumes that neither argument is nscoord_MIN.
  *
  * Note: If/when we start using floats for nscoords, this function won't be as
  * necessary.  Normal float addition correctly handles adding with infinity,
  * assuming we aren't adding nscoord_MIN. (-infinity)
  */
 inline nscoord
 NSCoordSaturatingAdd(nscoord a, nscoord b)
 {
   VERIFY_COORD(a);
   VERIFY_COORD(b);
 #ifdef NS_COORD_IS_FLOAT
   // Float math correctly handles a+b, given that neither is -infinity.
   return a + b;
 #else
   if (a == nscoord_MAX || b == nscoord_MAX) {
     // infinity + anything = anything + infinity = infinity
     return nscoord_MAX;
   } else {
     // a + b = a + b
     // Cap the result, just in case we're dealing with numbers near nscoord_MAX
     return std::min(nscoord_MAX, a + b);
   }
 #endif
 }
 /**
  * Returns a - b, gracefully handling cases involving nscoord_MAX.
  * This function assumes that neither argument is nscoord_MIN.
  *
  * The behavior is as follows:
  *
  *  a)  infinity - infinity -> infMinusInfResult
  *  b)  N - infinity        -> 0  (unexpected -- triggers NOTREACHED)
  *  c)  infinity - N        -> infinity
  *  d)  N1 - N2             -> N1 - N2
  *
  * Note: For float nscoords, cases (c) and (d) are handled by normal float
  * math.  We still need to explicitly specify the behavior for cases (a)
  * and (b), though.  (Under normal float math, those cases would return NaN
  * and -infinity, respectively.)
  */
 inline nscoord
 NSCoordSaturatingSubtract(nscoord a, nscoord b,
                           nscoord infMinusInfResult)
 {
   VERIFY_COORD(a);
   VERIFY_COORD(b);
   if (b == nscoord_MAX) {
     if (a == nscoord_MAX) {
       // case (a)
       return infMinusInfResult;
     } else {
       // case (b)
       NS_NOTREACHED("Attempted to subtract [n - nscoord_MAX]");
       return 0;
     }
   } else {
 #ifdef NS_COORD_IS_FLOAT
     // case (c) and (d) for floats.  (float math handles both)
     return a - b;
 #else
     if (a == nscoord_MAX) {
       // case (c) for integers
       return nscoord_MAX;
     } else {
       // case (d) for integers
       // Cap the result, in case we're dealing with numbers near nscoord_MAX
       return std::min(nscoord_MAX, a - b);
     }
   }
 #endif
 }
 inline float NSCoordToFloat(nscoord aCoord) {
   VERIFY_COORD(aCoord);
 #ifdef NS_COORD_IS_FLOAT
   NS_ASSERTION(!NS_IEEEIsNan(aCoord), "NaN encountered in float conversion");
 #endif
   return (float)aCoord;
 }
 /*
  * Coord Rounding Functions
  */
 inline nscoord NSToCoordFloor(float aValue)
 {
   return nscoord(floorf(aValue));
 }
 inline nscoord NSToCoordFloor(double aValue)
 {
   return nscoord(floor(aValue));
 }
 inline nscoord NSToCoordFloorClamped(float aValue)
 {
 #ifndef NS_COORD_IS_FLOAT
   // Bounds-check before converting out of float, to avoid overflow
   if (aValue >= nscoord_MAX) {
     return nscoord_MAX;
   }
   if (aValue <= nscoord_MIN) {
     return nscoord_MIN;
   }
 #endif
   return NSToCoordFloor(aValue);
 }
 inline nscoord NSToCoordCeil(float aValue)
 {
   return nscoord(ceilf(aValue));
 }
 inline nscoord NSToCoordCeil(double aValue)
 {
   return nscoord(ceil(aValue));
 }
 inline nscoord NSToCoordCeilClamped(double aValue)
 {
 #ifndef NS_COORD_IS_FLOAT
   // Bounds-check before converting out of double, to avoid overflow
   if (aValue >= nscoord_MAX) {
     return nscoord_MAX;
   }
   if (aValue <= nscoord_MIN) {
     return nscoord_MIN;
   }
 #endif
   return NSToCoordCeil(aValue);
 }
 /*
  * Int Rounding Functions
  */
 inline int32_t NSToIntFloor(float aValue)
 {
   return int32_t(floorf(aValue));
 }
 inline int32_t NSToIntCeil(float aValue)
 {
   return int32_t(ceilf(aValue));
 }
 inline int32_t NSToIntRound(float aValue)
 {
   return NS_lroundf(aValue);
 }
 inline int32_t NSToIntRound(double aValue)
 {
   return NS_lround(aValue);
 }
 inline int32_t NSToIntRoundUp(double aValue)
 {
   return int32_t(floor(aValue + 0.5));
 }
 /*
  * App Unit/Pixel conversions
  */
 inline nscoord NSFloatPixelsToAppUnits(float aPixels, float aAppUnitsPerPixel)
 {
   return NSToCoordRoundWithClamp(aPixels * aAppUnitsPerPixel);
 }
 inline nscoord NSIntPixelsToAppUnits(int32_t aPixels, int32_t aAppUnitsPerPixel)
 {
   // The cast to nscoord makes sure we don't overflow if we ever change
   // nscoord to float
   nscoord r = aPixels * (nscoord)aAppUnitsPerPixel;
   VERIFY_COORD(r);
   return r;
 }
 inline float NSAppUnitsToFloatPixels(nscoord aAppUnits, float aAppUnitsPerPixel)
 {
   return (float(aAppUnits) / aAppUnitsPerPixel);
 }
 inline double NSAppUnitsToDoublePixels(nscoord aAppUnits, double aAppUnitsPerPixel)
 {
   return (double(aAppUnits) / aAppUnitsPerPixel);
 }
 inline int32_t NSAppUnitsToIntPixels(nscoord aAppUnits, float aAppUnitsPerPixel)
 {
   return NSToIntRound(float(aAppUnits) / aAppUnitsPerPixel);
 }
 inline float NSCoordScale(nscoord aCoord, int32_t aFromAPP, int32_t aToAPP)
 {
   return (NSCoordToFloat(aCoord) * aToAPP) / aFromAPP;
 }
 /// handy constants
 #define TWIPS_PER_POINT_INT           20
 #define TWIPS_PER_POINT_FLOAT         20.0f
 #define POINTS_PER_INCH_INT           72
 #define POINTS_PER_INCH_FLOAT         72.0f
 #define CM_PER_INCH_FLOAT             2.54f
 #define MM_PER_INCH_FLOAT             25.4f
 /*
  * Twips/unit conversions
  */
 inline float NSUnitsToTwips(float aValue, float aPointsPerUnit)
 {
   return aValue * aPointsPerUnit * TWIPS_PER_POINT_FLOAT;
 }
 inline float NSTwipsToUnits(float aTwips, float aUnitsPerPoint)
 {
   return (aTwips * (aUnitsPerPoint / TWIPS_PER_POINT_FLOAT));
 }
 /// Unit conversion macros
 //@{
 #define NS_POINTS_TO_TWIPS(x)         NSUnitsToTwips((x), 1.0f)
 #define NS_INCHES_TO_TWIPS(x)         NSUnitsToTwips((x), POINTS_PER_INCH_FLOAT)                      // 72 points per inch
 #define NS_MILLIMETERS_TO_TWIPS(x)    NSUnitsToTwips((x), (POINTS_PER_INCH_FLOAT * 0.03937f))
 #define NS_POINTS_TO_INT_TWIPS(x)     NSToIntRound(NS_POINTS_TO_TWIPS(x))
 #define NS_INCHES_TO_INT_TWIPS(x)     NSToIntRound(NS_INCHES_TO_TWIPS(x))
 #define NS_TWIPS_TO_INCHES(x)         NSTwipsToUnits((x), 1.0f / POINTS_PER_INCH_FLOAT)
 #define NS_TWIPS_TO_MILLIMETERS(x)    NSTwipsToUnits((x), 1.0f / (POINTS_PER_INCH_FLOAT * 0.03937f))
 //@}
 #endif /* NSCOORD_H */

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gfx/src/nsCoord.h@97036ab72558 (annotated)

gfx/src/nsCoord.h