firefox/dom/svg/SVGPathElement.cpp

/* -*- 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/. */

#include "mozilla/dom/SVGPathElement.h"

#include <algorithm>

#include "SVGGeometryProperty.h"
#include "gfx2DGlue.h"
#include "gfxPlatform.h"
#include "mozAutoDocUpdate.h"
#include "nsGkAtoms.h"
#include "nsIFrame.h"
#include "nsStyleConsts.h"
#include "nsStyleStruct.h"
#include "nsWindowSizes.h"
#include "mozilla/dom/SVGPathElementBinding.h"
#include "mozilla/dom/SVGPathSegment.h"
#include "mozilla/gfx/2D.h"
#include "mozilla/RefPtr.h"
#include "mozilla/SVGContentUtils.h"
#include "SVGArcConverter.h"
#include "SVGPathSegUtils.h"

NS_IMPL_NS_NEW_SVG_ELEMENT(Path)

using namespace mozilla::gfx;

namespace mozilla::dom {

//----------------------------------------------------------------------
// Helper class: AutoChangePathSegListNotifier
// Stack-based helper class to pair calls to WillChangePathSegList and
// DidChangePathSegList.
class MOZ_RAII AutoChangePathSegListNotifier : public mozAutoDocUpdate {
 public:
  explicit AutoChangePathSegListNotifier(SVGPathElement* aSVGPathElement)
      : mozAutoDocUpdate(aSVGPathElement->GetComposedDoc(), true),
        mSVGElement(aSVGPathElement) {
    MOZ_ASSERT(mSVGElement, "Expecting non-null value");
    mEmptyOrOldValue = mSVGElement->WillChangePathSegList(*this);
  }

  ~AutoChangePathSegListNotifier() {
    mSVGElement->DidChangePathSegList(mEmptyOrOldValue, *this);
    if (mSVGElement->GetAnimPathSegList()->IsAnimating()) {
      mSVGElement->AnimationNeedsResample();
    }
  }

 private:
  SVGPathElement* const mSVGElement;
  nsAttrValue mEmptyOrOldValue;
};

JSObject* SVGPathElement::WrapNode(JSContext* aCx,
                                   JS::Handle<JSObject*> aGivenProto) {
  return SVGPathElement_Binding::Wrap(aCx, this, aGivenProto);
}

//----------------------------------------------------------------------
// Implementation

SVGPathElement::SVGPathElement(
    already_AddRefed<mozilla::dom::NodeInfo>&& aNodeInfo)
    : SVGPathElementBase(std::move(aNodeInfo)) {}

//----------------------------------------------------------------------
// memory reporting methods

void SVGPathElement::AddSizeOfExcludingThis(nsWindowSizes& aSizes,
                                            size_t* aNodeSize) const {
  SVGPathElementBase::AddSizeOfExcludingThis(aSizes, aNodeSize);
  *aNodeSize += mD.SizeOfExcludingThis(aSizes.mState.mMallocSizeOf);
}

//----------------------------------------------------------------------
// nsINode methods

NS_IMPL_ELEMENT_CLONE_WITH_INIT(SVGPathElement)

already_AddRefed<SVGPathSegment> SVGPathElement::GetPathSegmentAtLength(
    float aDistance) {
  FlushIfNeeded();
  RefPtr<SVGPathSegment> segment;
  if (SVGGeometryProperty::DoForComputedStyle(
          this, [&](const ComputedStyle* s) {
            const auto& d = s->StyleSVGReset()->mD;
            if (d.IsPath()) {
              segment = SVGPathData::GetPathSegmentAtLength(
                  this, d.AsPath()._0.AsSpan(), aDistance);
            }
          })) {
    return segment.forget();
  }
  return SVGPathData::GetPathSegmentAtLength(this, mD.GetAnimValue().AsSpan(),
                                             aDistance);
}

static void CreatePathSegments(SVGPathElement* aPathElement,
                               const StyleSVGPathData& aPathData,
                               nsTArray<RefPtr<SVGPathSegment>>& aValues,
                               bool aNormalize) {
  if (aNormalize) {
    StyleSVGPathData normalizedPathData;
    Servo_SVGPathData_NormalizeAndReduce(&aPathData, &normalizedPathData);
    Point pathStart(0.0, 0.0);
    Point segStart(0.0, 0.0);
    Point segEnd(0.0, 0.0);
    for (const auto& cmd : normalizedPathData._0.AsSpan()) {
      switch (cmd.tag) {
        case StylePathCommand::Tag::Close:
          segEnd = pathStart;
          aValues.AppendElement(new SVGPathSegment(aPathElement, cmd));
          break;
        case StylePathCommand::Tag::Move:
          pathStart = segEnd = cmd.move.point.ToGfxPoint();
          aValues.AppendElement(new SVGPathSegment(aPathElement, cmd));
          break;
        case StylePathCommand::Tag::Line:
          segEnd = cmd.line.point.ToGfxPoint();
          aValues.AppendElement(new SVGPathSegment(aPathElement, cmd));
          break;
        case StylePathCommand::Tag::CubicCurve:
          segEnd = cmd.cubic_curve.point.ToGfxPoint();
          aValues.AppendElement(new SVGPathSegment(aPathElement, cmd));
          break;
        case StylePathCommand::Tag::Arc: {
          const auto& arc = cmd.arc;
          segEnd = arc.point.ToGfxPoint();
          SVGArcConverter converter(segStart, arc.point.ToGfxPoint(),
                                    arc.radii.ToGfxPoint(), arc.rotate,
                                    arc.arc_size == StyleArcSize::Large,
                                    arc.arc_sweep == StyleArcSweep::Cw);
          Point cp1, cp2;
          while (converter.GetNextSegment(&cp1, &cp2, &segEnd)) {
            auto curve = StylePathCommand::CubicCurve(
                StyleByTo::To,
                StyleCoordinatePair<StyleCSSFloat>{segEnd.x, segEnd.y},
                StyleCoordinatePair<StyleCSSFloat>{cp1.x, cp1.y},
                StyleCoordinatePair<StyleCSSFloat>{cp2.x, cp2.y});
            aValues.AppendElement(new SVGPathSegment(aPathElement, curve));
          }
          break;
        }
        default:
          MOZ_ASSERT_UNREACHABLE("Unexpected path command");
          break;
      }
      segStart = segEnd;
    }
    return;
  }
  for (const auto& cmd : aPathData._0.AsSpan()) {
    aValues.AppendElement(new SVGPathSegment(aPathElement, cmd));
  }
}

void SVGPathElement::GetPathData(const SVGPathDataSettings& aOptions,
                                 nsTArray<RefPtr<SVGPathSegment>>& aValues) {
  FlushIfNeeded();
  if (SVGGeometryProperty::DoForComputedStyle(
          this, [&](const ComputedStyle* s) {
            const auto& d = s->StyleSVGReset()->mD;
            if (d.IsPath()) {
              CreatePathSegments(this, d.AsPath(), aValues,
                                 aOptions.mNormalize);
            }
          })) {
    return;
  }
  CreatePathSegments(this, mD.GetAnimValue().RawData(), aValues,
                     aOptions.mNormalize);
}

void SVGPathElement::SetPathData(const Sequence<SVGPathSegmentInit>& aValues) {
  AutoChangePathSegListNotifier notifier(this);
  mD.SetBaseValueFromPathSegments(aValues);
}

//----------------------------------------------------------------------
// SVGElement methods

/* virtual */
bool SVGPathElement::HasValidDimensions() const {
  bool hasPath = false;
  auto callback = [&](const ComputedStyle* s) {
    const nsStyleSVGReset* styleSVGReset = s->StyleSVGReset();
    hasPath =
        styleSVGReset->mD.IsPath() && !styleSVGReset->mD.AsPath()._0.IsEmpty();
  };

  SVGGeometryProperty::DoForComputedStyle(this, callback);
  // If hasPath is false, we may disable the pref of d property, so we fallback
  // to check mD.
  return hasPath || !mD.GetAnimValue().IsEmpty();
}

//----------------------------------------------------------------------
// nsIContent methods

NS_IMETHODIMP_(bool)
SVGPathElement::IsAttributeMapped(const nsAtom* name) const {
  return name == nsGkAtoms::d || SVGPathElementBase::IsAttributeMapped(name);
}

already_AddRefed<Path> SVGPathElement::GetOrBuildPathForMeasuring() {
  RefPtr<Path> path;
  bool success = SVGGeometryProperty::DoForComputedStyle(
      this, [&path](const ComputedStyle* s) {
        const auto& d = s->StyleSVGReset()->mD;
        if (d.IsNone()) {
          return;
        }
        path = SVGPathData::BuildPathForMeasuring(d.AsPath()._0.AsSpan(),
                                                  s->EffectiveZoom().ToFloat());
      });
  return success ? path.forget()
                 : mD.GetAnimValue().BuildPathForMeasuring(1.0f);
}

//----------------------------------------------------------------------
// SVGGeometryElement methods

bool SVGPathElement::AttributeDefinesGeometry(const nsAtom* aName) {
  return aName == nsGkAtoms::d || aName == nsGkAtoms::pathLength;
}

bool SVGPathElement::IsMarkable() { return true; }

void SVGPathElement::GetMarkPoints(nsTArray<SVGMark>* aMarks) {
  auto callback = [aMarks](const ComputedStyle* s) {
    const nsStyleSVGReset* styleSVGReset = s->StyleSVGReset();
    if (styleSVGReset->mD.IsPath()) {
      Span<const StylePathCommand> path =
          styleSVGReset->mD.AsPath()._0.AsSpan();
      SVGPathData::GetMarkerPositioningData(path, s->EffectiveZoom().ToFloat(),
                                            aMarks);
    }
  };

  if (SVGGeometryProperty::DoForComputedStyle(this, callback)) {
    return;
  }

  mD.GetAnimValue().GetMarkerPositioningData(1.0f, aMarks);
}

void SVGPathElement::GetAsSimplePath(SimplePath* aSimplePath) {
  aSimplePath->Reset();
  auto callback = [&](const ComputedStyle* s) {
    const nsStyleSVGReset* styleSVGReset = s->StyleSVGReset();
    if (styleSVGReset->mD.IsPath()) {
      auto pathData = styleSVGReset->mD.AsPath()._0.AsSpan();
      auto maybeRect = SVGPathToAxisAlignedRect(pathData);
      if (maybeRect.isSome()) {
        const Rect& r = *maybeRect;
        float zoom = s->EffectiveZoom().ToFloat();
        aSimplePath->SetRect(r.x * zoom, r.y * zoom, r.width * zoom,
                             r.height * zoom);
      }
    }
  };

  SVGGeometryProperty::DoForComputedStyle(this, callback);
}

already_AddRefed<Path> SVGPathElement::BuildPath(PathBuilder* aBuilder) {
  // The Moz2D PathBuilder that our SVGPathData will be using only cares about
  // the fill rule. However, in order to fulfill the requirements of the SVG
  // spec regarding zero length sub-paths when square line caps are in use,
  // SVGPathData needs to know our stroke-linecap style and, if "square", then
  // also our stroke width. See the comment for
  // ApproximateZeroLengthSubpathSquareCaps for more info.

  auto strokeLineCap = StyleStrokeLinecap::Butt;
  Float strokeWidth = 0;
  RefPtr<Path> path;

  auto callback = [&](const ComputedStyle* s) {
    const nsStyleSVG* styleSVG = s->StyleSVG();
    // Note: the path that we return may be used for hit-testing, and SVG
    // exposes hit-testing of strokes that are not actually painted. For that
    // reason we do not check for eStyleSVGPaintType_None or check the stroke
    // opacity here.
    if (styleSVG->mStrokeLinecap != StyleStrokeLinecap::Butt) {
      strokeLineCap = styleSVG->mStrokeLinecap;
      strokeWidth = SVGContentUtils::GetStrokeWidth(this, s, nullptr);
    }

    const auto& d = s->StyleSVGReset()->mD;
    if (d.IsPath()) {
      path = SVGPathData::BuildPath(d.AsPath()._0.AsSpan(), aBuilder,
                                    strokeLineCap, strokeWidth, {}, {},
                                    s->EffectiveZoom().ToFloat());
    }
  };

  bool success = SVGGeometryProperty::DoForComputedStyle(this, callback);
  if (success) {
    return path.forget();
  }

  // Fallback to use the d attribute if it exists.
  return mD.GetAnimValue().BuildPath(aBuilder, strokeLineCap, strokeWidth,
                                     1.0f);
}

bool SVGPathElement::GetDistancesFromOriginToEndsOfVisibleSegments(
    FallibleTArray<double>* aOutput) {
  bool ret = false;
  auto callback = [&ret, aOutput](const ComputedStyle* s) {
    const auto& d = s->StyleSVGReset()->mD;
    ret = d.IsNone() ||
          SVGPathData::GetDistancesFromOriginToEndsOfVisibleSegments(
              d.AsPath()._0.AsSpan(), aOutput);
  };

  if (SVGGeometryProperty::DoForComputedStyle(this, callback)) {
    return ret;
  }

  return mD.GetAnimValue().GetDistancesFromOriginToEndsOfVisibleSegments(
      aOutput);
}

static bool PathIsClosed(Span<const StylePathCommand> aPath) {
  return !aPath.IsEmpty() && aPath.rbegin()->IsClose();
}

// Offset paths (including references to SVG Paths) are closed loops only if the
// final command in the path list is a closepath command ("z" or "Z"), otherwise
// they are unclosed intervals.
// https://drafts.fxtf.org/motion/#path-distance
bool SVGPathElement::IsClosedLoop() const {
  bool isClosed = false;

  auto callback = [&](const ComputedStyle* s) {
    const nsStyleSVGReset* styleSVGReset = s->StyleSVGReset();
    if (styleSVGReset->mD.IsPath()) {
      isClosed = PathIsClosed(styleSVGReset->mD.AsPath()._0.AsSpan());
    }
  };

  if (SVGGeometryProperty::DoForComputedStyle(this, callback)) {
    return isClosed;
  }

  return PathIsClosed(mD.GetAnimValue().AsSpan());
}

/* static */
bool SVGPathElement::IsDPropertyChangedViaCSS(const ComputedStyle& aNewStyle,
                                              const ComputedStyle& aOldStyle) {
  return aNewStyle.StyleSVGReset()->mD != aOldStyle.StyleSVGReset()->mD;
}

}  // namespace mozilla::dom