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