зеркало из https://github.com/mozilla/gecko-dev.git
278 строки
9.5 KiB
C
278 строки
9.5 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_DashedCornerFinder_h_
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#define mozilla_DashedCornerFinder_h_
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#include "mozilla/gfx/2D.h"
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#include "mozilla/gfx/BezierUtils.h"
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namespace mozilla {
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// Calculate {OuterT_i, InnerT_i} for each 1 < i < n, that
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// (OuterL_i + InnerL_i) / 2 == dashLength * (W_i + W_{i-1}) / 2
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// where
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// OuterP_i: OuterCurve(OuterT_i)
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// InnerP_i: InnerCurve(OuterT_i)
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// OuterL_i: Elliptic arc length between OuterP_i - OuterP_{i-1}
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// InnerL_i: Elliptic arc length between InnerP_i - InnerP_{i-1}
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// W_i = |OuterP_i - InnerP_i|
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// 1.0 < dashLength < 3.0
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//
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// OuterP_1 OuterP_0
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// _+__-----------+ OuterCurve
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// OuterP_2 __---- | OuterL_1 |
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// __+--- | |
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// __--- | OuterL_2 | |
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// OuterP_3 _-- | | W_1 | W_0
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// _+ | | |
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// / \ W_2 | | |
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// / \ | | InnerL_1 |
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// | \ | InnerL_2|____-------+ InnerCurve
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// | \ |____----+ InnerP_0
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// | . \ __---+ InnerP_1
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// | \ / InnerP_2
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// | . /+ InnerP_3
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// | |
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// | . |
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// | |
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// | |
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// | |
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// OuterP_{n-1} +--------+ InnerP_{n-1}
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// | |
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// | |
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// | |
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// | |
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// | |
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// OuterP_n +--------+ InnerP_n
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//
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// Returns region with [OuterCurve((OuterT_{2j} + OuterT_{2j-1}) / 2),
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// OuterCurve((OuterT_{2j} + OuterT_{2j-1}) / 2),
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// InnerCurve((OuterT_{2j} + OuterT_{2j+1}) / 2),
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// InnerCurve((OuterT_{2j} + OuterT_{2j+1}) / 2)],
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// to start and end with half segment.
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//
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// _+__----+------+ OuterCurve
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// _+---- | |######|
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// __+---#| | |######|
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// _+---##|####| | |######|
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// _-- |#####|#####| | |#####|
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// _+ |#####|#####| | |#####|
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// / \ |#####|####| | |#####|
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// / \ |####|#####| | |#####|
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// | \ |####|####| |____-+-----+ InnerCurve
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// | \ |####|____+---+
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// | . \ __+---+
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// | \ /
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// | . /+
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// | |
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// | . |
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// | |
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// | |
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// | |
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// +--------+
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// | |
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// | |
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// +--------+
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// |########|
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// |########|
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// +--------+
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class DashedCornerFinder
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{
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typedef mozilla::gfx::Bezier Bezier;
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typedef mozilla::gfx::Float Float;
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typedef mozilla::gfx::Point Point;
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typedef mozilla::gfx::Size Size;
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public:
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struct Result
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{
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// Control points for the outer curve and the inner curve.
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//
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// outerSectionBezier
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// |
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// v _+ 3
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// ___---#|
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// 0 +---#######|
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// |###########|
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// |###########|
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// |##########|
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// |##########|
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// |#########|
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// |#####____+ 3
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// 0 +----
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// ^
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// |
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// innerSectionBezier
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Bezier outerSectionBezier;
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Bezier innerSectionBezier;
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Result(const Bezier& aOuterSectionBezier,
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const Bezier& aInnerSectionBezier)
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: outerSectionBezier(aOuterSectionBezier),
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innerSectionBezier(aInnerSectionBezier)
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{}
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};
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// aCornerDim.width
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// |<----------------->|
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// | |
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// --+-------------___---+--
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// ^ | __-- | ^
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// | | _- | |
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// | | / | | aBorderWidthH
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// | | / | |
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// | | | | v
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// | | | __--+--
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// aCornerDim.height | || _-
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// | || /
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// | | /
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// | | |
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// | | |
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// | | |
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// | | |
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// v | |
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// --+---------+
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// | |
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// |<------->|
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// aBorderWidthV
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DashedCornerFinder(const Bezier& aOuterBezier, const Bezier& aInnerBezier,
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Float aBorderWidthH, Float aBorderWidthV,
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const Size& aCornerDim);
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bool HasMore(void) const;
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Result Next(void);
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private:
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static const size_t MAX_LOOP = 32;
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// Bezier control points for the outer curve and the inner curve.
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//
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// ___---+ outer curve
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// __-- |
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// _- |
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// / |
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// / |
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// | |
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// | __--+ inner curve
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// | _-
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// | /
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// | /
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// | |
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// | |
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// | |
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// | |
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// | |
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// +---------+
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Bezier mOuterBezier;
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Bezier mInnerBezier;
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Point mLastOuterP;
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Point mLastInnerP;
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Float mLastOuterT;
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Float mLastInnerT;
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// Length for each segment, ratio of the border width at that point.
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Float mBestDashLength;
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// If one of border-widths is 0, do not calculate mBestDashLength, and draw
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// segments until it reaches the other side or exceeds mMaxCount.
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bool mHasZeroBorderWidth;
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bool mHasMore;
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// The maximum number of segments.
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size_t mMaxCount;
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enum {
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// radius.width
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// |<----------------->|
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// | |
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// --+-------------___---+--
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// ^ | __-- | ^
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// | | _- | |
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// | | / + | top-width
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// | | / | |
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// | | | | v
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// | | | __--+--
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// radius.height | || _-
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// | || /
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// | | /
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// | | |
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// | | |
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// | | |
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// | | |
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// v | |
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// --+----+----+
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// | |
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// |<------->|
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// left-width
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// * top-width == left-width
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// * radius.width == radius.height
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// * top-width < radius.width * 2
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//
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// Split the perfect circle's arc into 2n segments, each segment's length is
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// top-width * dashLength. Then split the inner curve and the outer curve
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// with same angles.
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//
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// radius.width
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// |<---------------------->|
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// | | v
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// --+------------------------+--
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// ^ | | | top-width / 2
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// | | perfect | |
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// | | circle's ___---+--
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// | | arc __-+ | ^
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// | | | _- | |
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// radius.height | | | + | +--
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// | | | / \ | |
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// | | | | \ | |
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// | | | | \ | |
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// | | +->| \ | |
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// | | +---__ \ | |
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// | | | --__ \ | |
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// | | | ---__ \ | |
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// v | | --_\||
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// --+----+----+--------------+
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// | | |
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// |<-->| |
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// left-width / 2
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PERFECT,
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// Other cases.
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//
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// Split the outer curve and the inner curve into 2n segments, each segment
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// satisfies following:
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// (OuterL_i + InnerL_i) / 2 == dashLength * (W_i + W_{i-1}) / 2
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OTHER
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} mType;
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size_t mI;
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size_t mCount;
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// Determine mType from parameters.
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void DetermineType(Float aBorderWidthH, Float aBorderWidthV);
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// Reset calculation.
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void Reset(void);
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// Find next segment.
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Float FindNext(Float dashLength);
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// Find mBestDashLength for parameters.
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void FindBestDashLength(Float aMinBorderWidth, Float aMaxBorderWidth,
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Float aMinBorderRadius, Float aMaxBorderRadius);
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// Fill corner with dashes with given dash length, and return the number of
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// segments and last segment's dash length.
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bool GetCountAndLastDashLength(Float aDashLength,
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size_t* aCount, Float* aActualDashLength);
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};
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} // namespace mozilla
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#endif /* mozilla_DashedCornerFinder_h_ */
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