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/*
* Copyright (C) 2025 Apple Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
* OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#pragma once
#include <algorithm>
#include <wtf/Vector.h>
namespace WTF {
class TextStream;
}
namespace WebCore {
struct FloatSegment {
float begin { 0.f };
float end { 0.f };
bool operator==(const FloatSegment&) const = default;
float length() const { return end - begin; }
FloatSegment dilate(float length) { return { begin - length, end + length }; }
};
// Computes difference between a line segment `a` and list of line segments `bs` that are dilated by
// dilationAmount.
// The difference list is further filtered to only results > dilationAmount.
//
// Vector<FloatSegment> intersections = ...;
// Vector<FloatSegment> solidLine { { 0, totalWidth } };
// Vector<FloatSegment> diff = difference(solidLine, dilate(intersections, dilationAmount));
// return filter(diff, [](auto&& s) { return s.length() > dilationAmount });
// <=>
// return differenceWithDilation({ 0, totalWidth }, intersections);
inline Vector<FloatSegment> differenceWithDilation(FloatSegment a, Vector<FloatSegment>&& bs, float dilationAmount)
{
std::sort(bs.begin(), bs.end(), [](auto&& a, auto&& b) {
return a.begin < b.begin;
});
auto result = bs.begin();
for (auto b : bs) {
if (a.begin >= a.end)
break;
b = b.dilate(dilationAmount);
if (b.begin >= a.end)
break;
FloatSegment candidate { a.begin, b.begin };
if (candidate.length() > dilationAmount) {
*result = candidate;
result = std::next(result);
}
a.begin = std::max(a.begin, b.end);
}
bs.shrink(result - bs.begin());
if (a.length() > dilationAmount)
bs.append(a);
return WTFMove(bs);
}
WEBCORE_EXPORT TextStream& operator<<(TextStream&, FloatSegment);
} // namespace WebCore
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