gecko-dev/dom/svg/SVGPathSegUtils.h
Emilio Cobos Álvarez 8da9ffec8f Bug 1906310 - Some some dead SVGPath code. r=longsonr
And do some minor clean-up while at it.

Differential Revision: https://phabricator.services.mozilla.com/D215789
2024-07-04 16:59:22 +00:00

99 lines
3.7 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 DOM_SVG_SVGPATHSEGUTILS_H_
#define DOM_SVG_SVGPATHSEGUTILS_H_
#include "mozilla/gfx/Point.h"
#include "mozilla/gfx/Rect.h"
#include "mozilla/Span.h"
namespace mozilla {
template <typename Angle, typename LP>
struct StyleGenericShapeCommand;
using StylePathCommand = StyleGenericShapeCommand<float, float>;
/**
* Code that works with path segments can use an instance of this class to
* store/provide information about the start of the current subpath and the
* last path segment (if any).
*/
struct SVGPathTraversalState {
using Point = gfx::Point;
enum TraversalMode { eUpdateAll, eUpdateOnlyStartAndCurrentPos };
SVGPathTraversalState()
: start(0.0, 0.0),
pos(0.0, 0.0),
cp1(0.0, 0.0),
cp2(0.0, 0.0),
length(0.0),
mode(eUpdateAll) {}
bool ShouldUpdateLengthAndControlPoints() { return mode == eUpdateAll; }
Point start; // start point of current sub path (reset each moveto)
Point pos; // current position (end point of previous segment)
Point cp1; // quadratic control point - if the previous segment was a
// quadratic bezier curve then this is set to the absolute
// position of its control point, otherwise its set to pos
Point cp2; // cubic control point - if the previous segment was a cubic
// bezier curve then this is set to the absolute position of
// its second control point, otherwise it's set to pos
float length; // accumulated path length
TraversalMode mode; // indicates what to track while traversing a path
};
/**
* This class is just a collection of static methods - it doesn't have any data
* members, and it's not possible to create instances of this class. This class
* exists purely as a convenient place to gather together a bunch of methods
* related to manipulating and answering questions about path segments.
* Internally we represent path segments purely as an array of floats. See the
* comment documenting SVGPathData for more info on that.
*
* The DOM wrapper classes for encoded path segments (data contained in
* instances of SVGPathData) is DOMSVGPathSeg and its sub-classes. Note that
* there are multiple different DOM classes for path segs - one for each of the
* 19 SVG 1.1 segment types.
*/
class SVGPathSegUtils {
private:
SVGPathSegUtils() = default; // private to prevent instances
public:
/**
* Traverse the given path segment and update the SVGPathTraversalState
* object. This is identical to the above one but accepts StylePathCommand.
*/
static void TraversePathSegment(const StylePathCommand&,
SVGPathTraversalState&);
};
/// Detect whether the path represents a rectangle (for both filling AND
/// stroking) and if so returns it.
///
/// This is typically useful for google slides which has many of these rectangle
/// shaped paths. It handles the same scenarios as skia's
/// SkPathPriv::IsRectContour which it is inspired from, including zero-length
/// edges and multiple points on edges of the rectangle, and doesn't attempt to
/// detect flat curves (that could easily be added but the expectation is that
/// since skia doesn't fast path it we're not likely to run into it in
/// practice).
///
/// We could implement something similar for polygons.
Maybe<gfx::Rect> SVGPathToAxisAlignedRect(Span<const StylePathCommand>);
} // namespace mozilla
#endif // DOM_SVG_SVGPATHSEGUTILS_H_