gecko-dev/gfx/2d/PathCairo.h
Lee Salzman b2d67698b9 Bug 1846079 - Ensure pruned point begins first sub-path if necessary. r=aosmond
The Canvas2D specification says that if a path has no active sub-paths, and a
primitive is drawn, that the first point of that primitive becomes the start of
the newly created sub-path that will be created for it.

So if we prune a point when a path has no active sub-paths, and then a new
primitive comes in that does not start with that same point, we risk not
installing the pruned point as the start of that new sub-path.

To solve this, we need to detect if a path has no active sub-paths while
we are building it. This adds PathBuilder::IsActive() to help with that.
Then before we go to add a primitive, we check if there is a pruned point
on a path that is not active yet, and if so, install the correct start
point with a MoveTo.

This also makes IsActive and IsEmpty required so to ensure all our path
implementations behave consistently rather than having any surprising
unimplemented behavior.

Differential Revision: https://phabricator.services.mozilla.com/D184891
2023-07-30 14:31:09 +00:00

102 lines
3.2 KiB
C++

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* 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_GFX_PATH_CAIRO_H_
#define MOZILLA_GFX_PATH_CAIRO_H_
#include "2D.h"
#include "cairo.h"
#include <vector>
namespace mozilla {
namespace gfx {
class PathCairo;
class PathBuilderCairo : public PathBuilder {
public:
MOZ_DECLARE_REFCOUNTED_VIRTUAL_TYPENAME(PathBuilderCairo, override)
explicit PathBuilderCairo(FillRule aFillRule);
void MoveTo(const Point& aPoint) override;
void LineTo(const Point& aPoint) override;
void BezierTo(const Point& aCP1, const Point& aCP2,
const Point& aCP3) override;
void QuadraticBezierTo(const Point& aCP1, const Point& aCP2) override;
void Close() override;
void Arc(const Point& aOrigin, float aRadius, float aStartAngle,
float aEndAngle, bool aAntiClockwise = false) override;
already_AddRefed<Path> Finish() override;
BackendType GetBackendType() const override { return BackendType::CAIRO; }
bool IsActive() const override { return !mPathData.empty(); }
static already_AddRefed<PathBuilder> Create(FillRule aFillRule);
private: // data
friend class PathCairo;
FillRule mFillRule;
std::vector<cairo_path_data_t> mPathData;
};
class PathCairo : public Path {
public:
MOZ_DECLARE_REFCOUNTED_VIRTUAL_TYPENAME(PathCairo, override)
PathCairo(FillRule aFillRule, std::vector<cairo_path_data_t>& aPathData,
const Point& aCurrentPoint, const Point& aBeginPoint);
explicit PathCairo(cairo_t* aContext);
virtual ~PathCairo();
BackendType GetBackendType() const override { return BackendType::CAIRO; }
already_AddRefed<PathBuilder> CopyToBuilder(
FillRule aFillRule) const override;
already_AddRefed<PathBuilder> TransformedCopyToBuilder(
const Matrix& aTransform, FillRule aFillRule) const override;
bool ContainsPoint(const Point& aPoint,
const Matrix& aTransform) const override;
bool StrokeContainsPoint(const StrokeOptions& aStrokeOptions,
const Point& aPoint,
const Matrix& aTransform) const override;
Rect GetBounds(const Matrix& aTransform = Matrix()) const override;
Rect GetStrokedBounds(const StrokeOptions& aStrokeOptions,
const Matrix& aTransform = Matrix()) const override;
void StreamToSink(PathSink* aSink) const override;
FillRule GetFillRule() const override { return mFillRule; }
void SetPathOnContext(cairo_t* aContext) const;
void AppendPathToBuilder(PathBuilderCairo* aBuilder,
const Matrix* aTransform = nullptr) const;
bool IsEmpty() const override;
private:
void EnsureContainingContext(const Matrix& aTransform) const;
FillRule mFillRule;
std::vector<cairo_path_data_t> mPathData;
mutable cairo_t* mContainingContext;
mutable Matrix mContainingTransform;
Point mCurrentPoint;
Point mBeginPoint;
};
} // namespace gfx
} // namespace mozilla
#endif /* MOZILLA_GFX_PATH_CAIRO_H_ */