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/* -*- Mode: C++; tab-width: 8; 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 mozilla_AspectRatio_h
#define mozilla_AspectRatio_h
/* The aspect ratio of a box, in a "width / height" format. */
#include "mozilla/Attributes.h"
#include "nsCoord.h"
#include <algorithm>
#include <limits>
namespace mozilla {
struct AspectRatio {
AspectRatio() : mRatio(0.0f) {}
explicit AspectRatio(float aRatio) : mRatio(std::max(aRatio, 0.0f)) {}
static AspectRatio FromSize(float aWidth, float aHeight) {
if (aWidth == 0.0f || aHeight == 0.0f) {
return AspectRatio();
}
return AspectRatio(aWidth / aHeight);
}
static AspectRatio FromSize(nsSize aSize) {
return FromSize(aSize.width, aSize.height);
}
static AspectRatio FromSize(nsIntSize aSize) {
return FromSize(aSize.width, aSize.height);
}
explicit operator bool() const { return mRatio != 0.0f; }
nscoord ApplyTo(nscoord aCoord) const {
MOZ_DIAGNOSTIC_ASSERT(*this);
return NSCoordSaturatingNonnegativeMultiply(aCoord, mRatio);
}
float ApplyToFloat(float aFloat) const {
MOZ_DIAGNOSTIC_ASSERT(*this);
return mRatio * aFloat;
}
// Inverts the ratio, in order to get the height / width ratio.
MOZ_MUST_USE AspectRatio Inverted() const {
if (!*this) {
return AspectRatio();
}
// Clamp to a small epsilon, in case mRatio is absurdly large & produces
// 0.0f in the division here (so that valid ratios always generate other
// valid ratios when inverted).
return AspectRatio(
std::max(std::numeric_limits<float>::epsilon(), 1.0f / mRatio));
}
bool operator==(const AspectRatio& aOther) const {
return mRatio == aOther.mRatio;
}
bool operator!=(const AspectRatio& aOther) const {
return !(*this == aOther);
}
bool operator<(const AspectRatio& aOther) const {
return mRatio < aOther.mRatio;
}
private:
// 0.0f represents no aspect ratio.
float mRatio;
};
} // namespace mozilla
#endif // mozilla_AspectRatio_h
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