1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/gfx/2d/ScaleFactor.h Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,91 @@
1.4 +/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 2 -*-
1.5 + * This Source Code Form is subject to the terms of the Mozilla Public
1.6 + * License, v. 2.0. If a copy of the MPL was not distributed with this
1.7 + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
1.8 +
1.9 +#ifndef MOZILLA_GFX_SCALEFACTOR_H_
1.10 +#define MOZILLA_GFX_SCALEFACTOR_H_
1.11 +
1.12 +#include "mozilla/Attributes.h"
1.13 +
1.14 +#include "gfxPoint.h"
1.15 +
1.16 +namespace mozilla {
1.17 +namespace gfx {
1.18 +
1.19 +/*
1.20 + * This class represents a scaling factor between two different pixel unit
1.21 + * systems. This is effectively a type-safe float, intended to be used in
1.22 + * combination with the known-type instances of gfx::Point, gfx::Rect, etc.
1.23 + *
1.24 + * Note that some parts of the code that pre-date this class used separate
1.25 + * scaling factors for the x and y axes. However, at runtime these values
1.26 + * were always expected to be the same, so this class uses only one scale
1.27 + * factor for both axes. The two constructors that take two-axis scaling
1.28 + * factors check to ensure that this assertion holds.
1.29 + */
1.30 +template<class src, class dst>
1.31 +struct ScaleFactor {
1.32 + float scale;
1.33 +
1.34 + MOZ_CONSTEXPR ScaleFactor() : scale(1.0) {}
1.35 + MOZ_CONSTEXPR ScaleFactor(const ScaleFactor<src, dst>& aCopy) : scale(aCopy.scale) {}
1.36 + explicit MOZ_CONSTEXPR ScaleFactor(float aScale) : scale(aScale) {}
1.37 +
1.38 + explicit ScaleFactor(float aX, float aY) : scale(aX) {
1.39 + MOZ_ASSERT(fabs(aX - aY) < 1e-6);
1.40 + }
1.41 +
1.42 + ScaleFactor<dst, src> Inverse() {
1.43 + return ScaleFactor<dst, src>(1 / scale);
1.44 + }
1.45 +
1.46 + bool operator==(const ScaleFactor<src, dst>& aOther) const {
1.47 + return scale == aOther.scale;
1.48 + }
1.49 +
1.50 + bool operator!=(const ScaleFactor<src, dst>& aOther) const {
1.51 + return !(*this == aOther);
1.52 + }
1.53 +
1.54 + bool operator<(const ScaleFactor<src, dst>& aOther) const {
1.55 + return scale < aOther.scale;
1.56 + }
1.57 +
1.58 + bool operator<=(const ScaleFactor<src, dst>& aOther) const {
1.59 + return scale <= aOther.scale;
1.60 + }
1.61 +
1.62 + bool operator>(const ScaleFactor<src, dst>& aOther) const {
1.63 + return scale > aOther.scale;
1.64 + }
1.65 +
1.66 + bool operator>=(const ScaleFactor<src, dst>& aOther) const {
1.67 + return scale >= aOther.scale;
1.68 + }
1.69 +
1.70 + template<class other>
1.71 + ScaleFactor<other, dst> operator/(const ScaleFactor<src, other>& aOther) const {
1.72 + return ScaleFactor<other, dst>(scale / aOther.scale);
1.73 + }
1.74 +
1.75 + template<class other>
1.76 + ScaleFactor<src, other> operator/(const ScaleFactor<other, dst>& aOther) const {
1.77 + return ScaleFactor<src, other>(scale / aOther.scale);
1.78 + }
1.79 +
1.80 + template<class other>
1.81 + ScaleFactor<src, other> operator*(const ScaleFactor<dst, other>& aOther) const {
1.82 + return ScaleFactor<src, other>(scale * aOther.scale);
1.83 + }
1.84 +
1.85 + template<class other>
1.86 + ScaleFactor<other, dst> operator*(const ScaleFactor<other, src>& aOther) const {
1.87 + return ScaleFactor<other, dst>(scale * aOther.scale);
1.88 + }
1.89 +};
1.90 +
1.91 +}
1.92 +}
1.93 +
1.94 +#endif /* MOZILLA_GFX_SCALEFACTOR_H_ */
