1 files changed, 386 insertions, 0 deletions
diff --git a/gfx/src/nsCoord.h b/gfx/src/nsCoord.h
new file mode 100644
index 0000000000..6c2cd62be1
--- /dev/null
+++ b/gfx/src/nsCoord.h
@@ -0,0 +1,386 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* 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 <algorithm>
+#include <cstdint>
+#include <cstdlib>
+#include <math.h>
+
+#include "mozilla/Assertions.h"
+#include "mozilla/gfx/Coord.h"
+#include "nsMathUtils.h"
+
+/*
+ * 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.
+ */
+
+using nscoord = int32_t;
+inline constexpr nscoord nscoord_MAX = (1 << 30) - 1;
+inline constexpr nscoord nscoord_MIN = -nscoord_MAX;
+
+namespace mozilla {
+struct AppUnit {};
+
+// Declare AppUnit as a coordinate system tag.
+template <>
+struct IsPixel<AppUnit> : std::true_type {};
+
+namespace detail {
+template <typename Rep>
+struct AuCoordImpl : public gfx::IntCoordTyped<AppUnit, Rep> {
+  using Super = gfx::IntCoordTyped<AppUnit, Rep>;
+
+  constexpr AuCoordImpl() : Super() {}
+  constexpr MOZ_IMPLICIT AuCoordImpl(Rep aValue) : Super(aValue) {}
+  constexpr MOZ_IMPLICIT AuCoordImpl(Super aValue) : Super(aValue) {}
+
+  template <typename F>
+  static AuCoordImpl FromRound(F aValue) {
+    // Note: aValue is *not* rounding to nearest integer if it is negative. See
+    // https://bugzilla.mozilla.org/show_bug.cgi?id=410748#c14
+    return AuCoordImpl(std::floor(aValue + 0.5f));
+  }
+
+  template <typename F>
+  static AuCoordImpl FromTruncate(F aValue) {
+    return AuCoordImpl(std::trunc(aValue));
+  }
+
+  template <typename F>
+  static AuCoordImpl FromCeil(F aValue) {
+    return AuCoordImpl(std::ceil(aValue));
+  }
+
+  template <typename F>
+  static AuCoordImpl FromFloor(F aValue) {
+    return AuCoordImpl(std::floor(aValue));
+  }
+
+  // Note: this returns the result of the operation, without modifying the
+  // original value.
+  [[nodiscard]] AuCoordImpl ToMinMaxClamped() const {
+    return std::clamp(this->value, kMin, kMax);
+  }
+
+  static constexpr Rep kMax = nscoord_MAX;
+  static constexpr Rep kMin = nscoord_MIN;
+};
+}  // namespace detail
+
+using AuCoord = detail::AuCoordImpl<int32_t>;
+using AuCoord64 = detail::AuCoordImpl<int64_t>;
+
+}  // namespace mozilla
+
+/**
+ * Divide aSpace by aN.  Assign the resulting quotient to aQuotient and
+ * return the remainder.
+ */
+inline nscoord NSCoordDivRem(nscoord aSpace, size_t aN, nscoord* aQuotient) {
+  div_t result = div(aSpace, aN);
+  *aQuotient = nscoord(result.quot);
+  return nscoord(result.rem);
+}
+
+inline nscoord NSCoordMulDiv(nscoord aMult1, nscoord aMult2, nscoord aDiv) {
+  return (int64_t(aMult1) * int64_t(aMult2) / int64_t(aDiv));
+}
+
+inline nscoord NSToCoordRound(float aValue) {
+#if defined(XP_WIN) && defined(_M_IX86) && !defined(__GNUC__) && \
+    !defined(__clang__)
+  return NS_lroundup30(aValue);
+#else
+  return nscoord(floorf(aValue + 0.5f));
+#endif /* XP_WIN && _M_IX86 && !__GNUC__ */
+}
+
+inline nscoord NSToCoordRound(double aValue) {
+#if defined(XP_WIN) && defined(_M_IX86) && !defined(__GNUC__) && \
+    !defined(__clang__)
+  return NS_lroundup30((float)aValue);
+#else
+  return nscoord(floor(aValue + 0.5f));
+#endif /* XP_WIN && _M_IX86 && !__GNUC__ */
+}
+
+inline nscoord NSToCoordRoundWithClamp(float aValue) {
+  // Bounds-check before converting out of float, to avoid overflow
+  if (aValue >= float(nscoord_MAX)) {
+    return nscoord_MAX;
+  }
+  if (aValue <= float(nscoord_MIN)) {
+    return nscoord_MIN;
+  }
+  return NSToCoordRound(aValue);
+}
+
+inline nscoord NSToCoordRoundWithClamp(double aValue) {
+  // Bounds-check before converting out of double, to avoid overflow
+  if (aValue >= double(nscoord_MAX)) {
+    return nscoord_MAX;
+  }
+  if (aValue <= double(nscoord_MIN)) {
+    return nscoord_MIN;
+  }
+  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) {
+  if (requireNotNegative) {
+    MOZ_ASSERT(aScale >= 0.0f,
+               "negative scaling factors must be handled manually");
+  }
+  float product = aCoord * aScale;
+  if (requireNotNegative ? aCoord > 0 : (aCoord > 0) == (aScale > 0))
+    return NSToCoordRoundWithClamp(
+        std::min<float>((float)nscoord_MAX, product));
+  return NSToCoordRoundWithClamp(std::max<float>((float)nscoord_MIN, product));
+}
+
+/**
+ * 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.
+ */
+inline nscoord NSCoordSaturatingAdd(nscoord a, nscoord b) {
+  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);
+  }
+}
+
+/**
+ * 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
+ */
+inline nscoord NSCoordSaturatingSubtract(nscoord a, nscoord b,
+                                         nscoord infMinusInfResult) {
+  if (b == nscoord_MAX) {
+    if (a == nscoord_MAX) {
+      // case (a)
+      return infMinusInfResult;
+    } else {
+      // case (b)
+      return 0;
+    }
+  } 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);
+    }
+  }
+}
+
+inline float NSCoordToFloat(nscoord aCoord) { 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) {
+  // Bounds-check before converting out of float, to avoid overflow
+  if (aValue >= float(nscoord_MAX)) {
+    return nscoord_MAX;
+  }
+  if (aValue <= float(nscoord_MIN)) {
+    return nscoord_MIN;
+  }
+  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) {
+  // Bounds-check before converting out of double, to avoid overflow
+  if (aValue >= nscoord_MAX) {
+    return nscoord_MAX;
+  }
+  if (aValue <= nscoord_MIN) {
+    return nscoord_MIN;
+  }
+  return NSToCoordCeil(aValue);
+}
+
+// The NSToCoordTrunc* functions remove the fractional component of
+// aValue, and are thus equivalent to NSToCoordFloor* for positive
+// values and NSToCoordCeil* for negative values.
+
+inline nscoord NSToCoordTrunc(float aValue) {
+  // There's no need to use truncf() since it matches the default
+  // rules for float to integer conversion.
+  return nscoord(aValue);
+}
+
+inline nscoord NSToCoordTrunc(double aValue) {
+  // There's no need to use trunc() since it matches the default
+  // rules for float to integer conversion.
+  return nscoord(aValue);
+}
+
+inline nscoord NSToCoordTruncClamped(float aValue) {
+  // Bounds-check before converting out of float, to avoid overflow
+  if (aValue >= float(nscoord_MAX)) {
+    return nscoord_MAX;
+  }
+  if (aValue <= float(nscoord_MIN)) {
+    return nscoord_MIN;
+  }
+  return NSToCoordTrunc(aValue);
+}
+
+inline nscoord NSToCoordTruncClamped(double aValue) {
+  // Bounds-check before converting out of double, to avoid overflow
+  if (aValue >= float(nscoord_MAX)) {
+    return nscoord_MAX;
+  }
+  if (aValue <= float(nscoord_MIN)) {
+    return nscoord_MIN;
+  }
+  return NSToCoordTrunc(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;
+  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 */