111 lines
2.9 KiB
C
111 lines
2.9 KiB
C
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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
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* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#ifndef MOZILLA_GFX_BASECOORD_H_
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#define MOZILLA_GFX_BASECOORD_H_
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#include "mozilla/Attributes.h"
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namespace mozilla {
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namespace gfx {
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/**
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* Do not use this class directly. Subclass it, pass that subclass as the
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* Sub parameter, and only use that subclass. This allows methods to safely
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* cast 'this' to 'Sub*'.
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*/
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template <class T, class Sub>
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struct BaseCoord {
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T value;
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// Constructors
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constexpr BaseCoord() : value(0) {}
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explicit constexpr BaseCoord(T aValue) : value(aValue) {}
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// Note that '=' isn't defined so we'll get the
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// compiler generated default assignment operator
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operator T() const { return value; }
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friend bool operator==(Sub aA, Sub aB) {
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return aA.value == aB.value;
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}
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friend bool operator!=(Sub aA, Sub aB) {
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return aA.value != aB.value;
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}
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friend Sub operator+(Sub aA, Sub aB) {
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return Sub(aA.value + aB.value);
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}
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friend Sub operator-(Sub aA, Sub aB) {
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return Sub(aA.value - aB.value);
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}
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friend Sub operator*(Sub aCoord, T aScale) {
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return Sub(aCoord.value * aScale);
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}
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friend Sub operator*(T aScale, Sub aCoord) {
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return Sub(aScale * aCoord.value);
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}
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friend Sub operator/(Sub aCoord, T aScale) {
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return Sub(aCoord.value / aScale);
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}
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// 'scale / coord' is intentionally omitted because it doesn't make sense.
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Sub& operator+=(Sub aCoord) {
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value += aCoord.value;
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return *static_cast<Sub*>(this);
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}
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Sub& operator-=(Sub aCoord) {
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value -= aCoord.value;
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return *static_cast<Sub*>(this);
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}
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Sub& operator*=(T aScale) {
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value *= aScale;
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return *static_cast<Sub*>(this);
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}
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Sub& operator/=(T aScale) {
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value /= aScale;
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return *static_cast<Sub*>(this);
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}
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// Since BaseCoord is implicitly convertible to its value type T, we need
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// mixed-type operator overloads to avoid ambiguities at mixed-type call
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// sites. As we transition more of our code to strongly-typed classes, we
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// may be able to remove some or all of these overloads.
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friend bool operator==(Sub aA, T aB) {
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return aA.value == aB;
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}
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friend bool operator==(T aA, Sub aB) {
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return aA == aB.value;
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}
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friend bool operator!=(Sub aA, T aB) {
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return aA.value != aB;
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}
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friend bool operator!=(T aA, Sub aB) {
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return aA != aB.value;
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}
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friend T operator+(Sub aA, T aB) {
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return aA.value + aB;
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}
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friend T operator+(T aA, Sub aB) {
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return aA + aB.value;
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}
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friend T operator-(Sub aA, T aB) {
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return aA.value - aB;
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}
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friend T operator-(T aA, Sub aB) {
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return aA - aB.value;
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}
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Sub operator-() const {
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return Sub(-value);
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}
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};
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} // namespace gfx
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} // namespace mozilla
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#endif /* MOZILLA_GFX_BASECOORD_H_ */
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