forked from mirrors/gecko-dev
0569fbd9be
This enables my local build to achieve 60fps on the js1k demo linked from the bug, whereas without the patch I get barely 10fps. Note: it's still possible for ComputePointAtLength would perform poorly if the caller is iterating backwards or doing random access to a long path. A potential mitigation for that would be to add an mLength field to FlatPathOp, storing the length-so-far of the path, so that ComputePointAtLength could do a binary search instead of linear accumulation. But this would add significant memory overhead, and may not be worth doing; the low-overhead cursor here appears to be enough to make text-on-a-path perform much better. Differential Revision: https://phabricator.services.mozilla.com/D168937
67 lines
1.8 KiB
C++
67 lines
1.8 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim: set ts=8 sts=2 et sw=2 tw=80: */
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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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#include "2D.h"
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#include <vector>
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namespace mozilla {
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namespace gfx {
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struct FlatPathOp {
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enum OpType {
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OP_MOVETO,
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OP_LINETO,
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};
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OpType mType;
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Point mPoint;
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};
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class FlattenedPath : public PathSink {
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public:
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MOZ_DECLARE_REFCOUNTED_VIRTUAL_TYPENAME(FlattenedPath, override)
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virtual void MoveTo(const Point& aPoint) override;
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virtual void LineTo(const Point& aPoint) override;
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virtual void BezierTo(const Point& aCP1, const Point& aCP2,
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const Point& aCP3) override;
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virtual void QuadraticBezierTo(const Point& aCP1, const Point& aCP2) override;
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virtual void Close() override;
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virtual void Arc(const Point& aOrigin, float aRadius, float aStartAngle,
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float aEndAngle, bool aAntiClockwise = false) override;
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virtual Point CurrentPoint() const override {
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return mPathOps.empty() ? Point() : mPathOps[mPathOps.size() - 1].mPoint;
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}
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Float ComputeLength();
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Point ComputePointAtLength(Float aLength, Point* aTangent);
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private:
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Float mCachedLength = 0.0f;
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bool mCalculatedLength = false;
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std::vector<FlatPathOp> mPathOps;
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// Used to accelerate ComputePointAtLength for the common case of iterating
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// forward along the path.
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struct {
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uint32_t mIndex = 0;
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Float mLength = 0.0f;
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Point mCurrentPoint;
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Point mLastPointSinceMove;
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void Reset() {
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mIndex = 0;
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mLength = 0.0f;
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mCurrentPoint = Point();
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mLastPointSinceMove = Point();
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}
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} mCursor;
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};
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} // namespace gfx
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} // namespace mozilla
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