Issue #2737 - Part 1: Base implementation of SVGGeometryElement.

Mostly mechanical changes to generalize path geometry for all SVG draw
elements. No user-exposed changes.

dom/svg/SVGGeometryElement.cpp

@@ -0,0 +1,185 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* 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 "SVGGeometryElement.h"
+
+#include "DOMSVGPoint.h"
+#include "gfxPlatform.h"
+#include "mozilla/gfx/2D.h"
+#include "nsComputedDOMStyle.h"
+#include "nsSVGUtils.h"
+#include "nsSVGLength2.h"
+#include "SVGContentUtils.h"
+
+using namespace mozilla;
+using namespace mozilla::gfx;
+
+nsSVGElement::NumberInfo SVGGeometryElement::sNumberInfo =
+{ &nsGkAtoms::pathLength, 0, false };
+
+//----------------------------------------------------------------------
+// Implementation
+
+SVGGeometryElement::SVGGeometryElement(already_AddRefed<mozilla::dom::NodeInfo>& aNodeInfo)
+  : SVGGeometryElementBase(aNodeInfo)
+{
+}
+
+nsSVGElement::NumberAttributesInfo
+SVGGeometryElement::GetNumberInfo()
+{
+  return NumberAttributesInfo(&mPathLength, &sNumberInfo, 1);
+}
+
+nsresult
+SVGGeometryElement::AfterSetAttr(int32_t aNamespaceID, nsIAtom* aName,
+                                 const nsAttrValue* aValue,
+                                 const nsAttrValue* aOldValue, bool aNotify)
+{
+  if (mCachedPath &&
+      aNamespaceID == kNameSpaceID_None &&
+      AttributeDefinesGeometry(aName)) {
+    mCachedPath = nullptr;
+  }
+  return SVGGeometryElementBase::AfterSetAttr(aNamespaceID, aName,
+                                              aValue, aOldValue, aNotify);
+}
+
+bool
+SVGGeometryElement::AttributeDefinesGeometry(const nsIAtom *aName)
+{
+  if (aName == nsGkAtoms::pathLength) {
+    return true;
+  }
+
+  // Check for nsSVGLength2 attribute
+  LengthAttributesInfo info = GetLengthInfo();
+  for (uint32_t i = 0; i < info.mLengthCount; i++) {
+    if (aName == *info.mLengthInfo[i].mName) {
+      return true;
+    }
+  }
+
+  return false;
+}
+
+bool
+SVGGeometryElement::GeometryDependsOnCoordCtx()
+{
+  // Check the nsSVGLength2 attribute
+  LengthAttributesInfo info = const_cast<SVGGeometryElement*>(this)->GetLengthInfo();
+  for (uint32_t i = 0; i < info.mLengthCount; i++) {
+    if (info.mLengths[i].GetSpecifiedUnitType() == nsIDOMSVGLength::SVG_LENGTHTYPE_PERCENTAGE) {
+      return true;
+    }   
+  }
+  return false;
+}
+
+bool
+SVGGeometryElement::IsMarkable()
+{
+  return false;
+}
+
+void
+SVGGeometryElement::GetMarkPoints(nsTArray<nsSVGMark> *aMarks)
+{
+}
+
+already_AddRefed<Path>
+SVGGeometryElement::GetOrBuildPath(const DrawTarget& aDrawTarget,
+                                   FillRule aFillRule)
+{
+  // We only cache the path if it matches the backend used for screen painting:
+  bool cacheable  = aDrawTarget.GetBackendType() ==
+                    gfxPlatform::GetPlatform()->GetDefaultContentBackend();
+
+  // Checking for and returning mCachedPath before checking the pref means
+  // that the pref is only live on page reload (or app restart for SVG in
+  // chrome). The benefit is that we avoid causing a CPU memory cache miss by
+  // looking at the global variable that the pref's stored in.
+  if (cacheable && mCachedPath) {
+    if (aDrawTarget.GetBackendType() == mCachedPath->GetBackendType()) {
+      RefPtr<Path> path(mCachedPath);
+      return path.forget();
+    }
+  }
+  RefPtr<PathBuilder> builder = aDrawTarget.CreatePathBuilder(aFillRule);
+  RefPtr<Path> path = BuildPath(builder);
+  if (cacheable && NS_SVGPathCachingEnabled()) {
+    mCachedPath = path;
+  }
+  return path.forget();
+}
+
+already_AddRefed<Path>
+SVGGeometryElement::GetOrBuildPathForMeasuring()
+{
+  return nullptr;
+}
+
+FillRule
+SVGGeometryElement::GetFillRule()
+{
+  FillRule fillRule = FillRule::FILL_WINDING; // Equivalent to StyleFillRule::Nonzero
+
+  RefPtr<nsStyleContext> styleContext =
+    nsComputedDOMStyle::GetStyleContextForElementNoFlush(this, nullptr,
+                                                         nullptr);
+  
+  if (styleContext) {
+    MOZ_ASSERT(styleContext->StyleSVG()->mFillRule == StyleFillRule::Nonzero ||
+               styleContext->StyleSVG()->mFillRule == StyleFillRule::Evenodd);
+
+    if (styleContext->StyleSVG()->mFillRule == StyleFillRule::Evenodd) {
+      fillRule = FillRule::FILL_EVEN_ODD;
+    }
+  } else {
+    // ReportToConsole
+    NS_WARNING("Couldn't get style context for content in GetFillRule");
+  }
+
+  return fillRule;
+}
+
+float
+SVGGeometryElement::GetTotalLength()
+{
+  RefPtr<Path> flat = GetOrBuildPathForMeasuring();
+  return flat ? flat->ComputeLength() : 0.f;
+}
+
+already_AddRefed<nsISVGPoint>
+SVGGeometryElement::GetPointAtLength(float distance, ErrorResult& rv)
+{
+  RefPtr<Path> path = GetOrBuildPathForMeasuring();
+  if (!path) {
+    rv.Throw(NS_ERROR_FAILURE);
+    return nullptr;
+  }
+
+  float totalLength = path->ComputeLength();
+  if (mPathLength.IsExplicitlySet()) {
+    float pathLength = mPathLength.GetAnimValue();
+    if (pathLength <= 0) {
+      rv.Throw(NS_ERROR_FAILURE);
+      return nullptr;
+    }
+    distance *= totalLength / pathLength;
+  }
+  distance = std::max(0.f,         distance);
+  distance = std::min(totalLength, distance);
+
+  nsCOMPtr<nsISVGPoint> point =
+    new DOMSVGPoint(path->ComputePointAtLength(distance));
+  return point.forget();
+}
+
+already_AddRefed<SVGAnimatedNumber>
+SVGGeometryElement::PathLength()
+{
+  return mPathLength.ToDOMAnimatedNumber(this);
+}