dom/svg/SVGGeometryElement.h

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #ifndef DOM_SVG_SVGGEOMETRYELEMENT_H_
   8 #define DOM_SVG_SVGGEOMETRYELEMENT_H_
   9
  10 #include "mozilla/dom/SVGGraphicsElement.h"
  11 #include "mozilla/gfx/2D.h"
  12 #include "mozilla/dom/SVGAnimatedNumber.h"
  13
  14 namespace mozilla {
  15
  16 struct SVGMark {
  17   enum Type {
  18     eStart,
  19     eMid,
  20     eEnd,
  21
  22     eTypeCount
  23   };
  24
  25   float x, y, angle;
  26   Type type;
  27   SVGMark(float aX, float aY, float aAngle, Type aType)
  28       : x(aX), y(aY), angle(aAngle), type(aType) {}
  29 };
  30
  31 namespace dom {
  32
  33 class DOMSVGAnimatedNumber;
  34 class DOMSVGPoint;
  35
  36 using SVGGeometryElementBase = mozilla::dom::SVGGraphicsElement;
  37
  38 class SVGGeometryElement : public SVGGeometryElementBase {
  39  protected:
  40   using CapStyle = mozilla::gfx::CapStyle;
  41   using DrawTarget = mozilla::gfx::DrawTarget;
  42   using FillRule = mozilla::gfx::FillRule;
  43   using Float = mozilla::gfx::Float;
  44   using Matrix = mozilla::gfx::Matrix;
  45   using Path = mozilla::gfx::Path;
  46   using Point = mozilla::gfx::Point;
  47   using PathBuilder = mozilla::gfx::PathBuilder;
  48   using Rect = mozilla::gfx::Rect;
  49   using StrokeOptions = mozilla::gfx::StrokeOptions;
  50
  51  public:
  52   explicit SVGGeometryElement(
  53       already_AddRefed<mozilla::dom::NodeInfo>&& aNodeInfo);
  54
  55   NS_IMPL_FROMNODE_HELPER(SVGGeometryElement, IsSVGGeometryElement())
  56
  57   void AfterSetAttr(int32_t aNamespaceID, nsAtom* aName,
  58                     const nsAttrValue* aValue, const nsAttrValue* aOldValue,
  59                     nsIPrincipal* aSubjectPrincipal, bool aNotify) override;
  60   bool IsSVGGeometryElement() const override { return true; }
  61
  62   /**
  63    * Causes this element to discard any Path object that GetOrBuildPath may
  64    * have cached.
  65    */
  66   void ClearAnyCachedPath() final { mCachedPath = nullptr; }
  67
  68   virtual bool AttributeDefinesGeometry(const nsAtom* aName);
  69
  70   /**
  71    * Returns true if this element's geometry depends on the width or height of
  72    * its coordinate context (typically the viewport established by its nearest
  73    * <svg> ancestor). In other words, returns true if one of the attributes for
  74    * which AttributeDefinesGeometry returns true has a percentage value.
  75    *
  76    * This could be moved up to a more general class so it can be used for
  77    * non-leaf elements, but that would require care and for now there's no need.
  78    */
  79   bool GeometryDependsOnCoordCtx();
  80
  81   virtual bool IsMarkable();
  82   virtual void GetMarkPoints(nsTArray<SVGMark>* aMarks);
  83
  84   /**
  85    * A method that can be faster than using a Moz2D Path and calling GetBounds/
  86    * GetStrokedBounds on it.  It also helps us avoid rounding error for simple
  87    * shapes and simple transforms where the Moz2D Path backends can fail to
  88    * produce the clean integer bounds that content authors expect in some cases.
  89    *
  90    * If |aToNonScalingStrokeSpace| is non-null then |aBounds|, which is computed
  91    * in bounds space, has the property that it's the smallest (axis-aligned)
  92    * rectangular bound containing the image of this shape as stroked in
  93    * non-scaling-stroke space.  (When all transforms involved are rectilinear
  94    * the bounds of the image of |aBounds| in non-scaling-stroke space will be
  95    * tight, but if there are non-rectilinear transforms involved then that may
  96    * be impossible and this method will return false).
  97    *
  98    * If |aToNonScalingStrokeSpace| is non-null then |*aToNonScalingStrokeSpace|
  99    * must be non-singular.
 100    */
 101   virtual bool GetGeometryBounds(
 102       Rect* aBounds, const StrokeOptions& aStrokeOptions,
 103       const Matrix& aToBoundsSpace,
 104       const Matrix* aToNonScalingStrokeSpace = nullptr) {
 105     return false;
 106   }
 107
 108   /**
 109    * For use with GetAsSimplePath.
 110    */
 111   class SimplePath {
 112    public:
 113     SimplePath()
 114         : mX(0.0), mY(0.0), mWidthOrX2(0.0), mHeightOrY2(0.0), mType(NONE) {}
 115     bool IsPath() const { return mType != NONE; }
 116     void SetRect(Float x, Float y, Float width, Float height) {
 117       mX = x;
 118       mY = y;
 119       mWidthOrX2 = width;
 120       mHeightOrY2 = height;
 121       mType = RECT;
 122     }
 123     Rect AsRect() const {
 124       MOZ_ASSERT(mType == RECT);
 125       return Rect(mX, mY, mWidthOrX2, mHeightOrY2);
 126     }
 127     bool IsRect() const { return mType == RECT; }
 128     void SetLine(Float x1, Float y1, Float x2, Float y2) {
 129       mX = x1;
 130       mY = y1;
 131       mWidthOrX2 = x2;
 132       mHeightOrY2 = y2;
 133       mType = LINE;
 134     }
 135     Point Point1() const {
 136       MOZ_ASSERT(mType == LINE);
 137       return Point(mX, mY);
 138     }
 139     Point Point2() const {
 140       MOZ_ASSERT(mType == LINE);
 141       return Point(mWidthOrX2, mHeightOrY2);
 142     }
 143     bool IsLine() const { return mType == LINE; }
 144     void Reset() { mType = NONE; }
 145
 146    private:
 147     enum Type { NONE, RECT, LINE };
 148     Float mX, mY, mWidthOrX2, mHeightOrY2;
 149     Type mType;
 150   };
 151
 152   /**
 153    * For some platforms there is significant overhead to creating and painting
 154    * a Moz2D Path object. For Rects and lines it is better to get the path data
 155    * using this method and then use the optimized DrawTarget methods for
 156    * filling/stroking rects and lines.
 157    */
 158   virtual void GetAsSimplePath(SimplePath* aSimplePath) {
 159     aSimplePath->Reset();
 160   }
 161
 162   /**
 163    * Returns a Path that can be used to paint, hit-test or calculate bounds for
 164    * this element. May return nullptr if there is no [valid] path. The path
 165    * that is created may be cached and returned on subsequent calls.
 166    */
 167   virtual already_AddRefed<Path> GetOrBuildPath(const DrawTarget* aDrawTarget,
 168                                                 FillRule fillRule);
 169
 170   /**
 171    * The same as GetOrBuildPath, but bypasses the cache (neither returns any
 172    * previously cached Path, nor caches the Path that in does return).
 173    * this element. May return nullptr if there is no [valid] path.
 174    */
 175   virtual already_AddRefed<Path> BuildPath(PathBuilder* aBuilder) = 0;
 176
 177   /**
 178    * Get the distances from the origin of the path segments.
 179    * For non-path elements that's just 0 and the total length of the shape.
 180    */
 181   virtual bool GetDistancesFromOriginToEndsOfVisibleSegments(
 182       FallibleTArray<double>* aOutput) {
 183     aOutput->Clear();
 184     double distances[] = {0.0, GetTotalLength()};
 185     return aOutput->AppendElements(Span<double>(distances), fallible);
 186   }
 187
 188   /**
 189    * Returns a Path that can be used to measure the length of this elements
 190    * path, or to find the position at a given distance along it.
 191    *
 192    * This is currently equivalent to calling GetOrBuildPath, but it may not be
 193    * in the future. The reason for this function to be separate from
 194    * GetOrBuildPath is because SVGPathData::BuildPath inserts small lines into
 195    * the path if zero length subpaths are encountered, in order to implement
 196    * the SVG specifications requirements that zero length subpaths should
 197    * render circles/squares if stroke-linecap is round/square, respectively.
 198    * In principle these inserted lines could interfere with path measurement,
 199    * so we keep callers that are looking to do measurement separate in case we
 200    * run into problems with the inserted lines negatively affecting measuring
 201    * for content.
 202    */
 203   virtual already_AddRefed<Path> GetOrBuildPathForMeasuring();
 204
 205   /**
 206    * If this shape element is a closed loop, this returns true. If it is an
 207    * unclosed interval, this returns false. This function is used for motion
 208    * path especially.
 209    *
 210    * 1. SVG Paths are closed loops only if the final command in the path list is
 211    *    a closepath command ("z" or "Z"), otherwise they are unclosed intervals.
 212    * 2. SVG circles, ellipses, polygons and rects are closed loops.
 213    * 3. SVG lines and polylines are unclosed intervals.
 214    *
 215    * https://drafts.fxtf.org/motion/#path-distance
 216    */
 217   virtual bool IsClosedLoop() const { return false; }
 218
 219   /**
 220    * Return |true| if some geometry properties (|x|, |y|, etc) are changed
 221    * because of CSS change.
 222    */
 223   bool IsGeometryChangedViaCSS(ComputedStyle const& aNewStyle,
 224                                ComputedStyle const& aOldStyle) const;
 225
 226   /**
 227    * Returns the current computed value of the CSS property 'fill-rule' for
 228    * this element.
 229    */
 230   FillRule GetFillRule();
 231
 232   enum PathLengthScaleForType { eForTextPath, eForStroking };
 233
 234   /**
 235    * Gets the ratio of the actual element's length to the content author's
 236    * estimated length (as provided by the element's 'pathLength' attribute).
 237    * This is used to scale stroke dashing, and to scale offsets along a
 238    * textPath.
 239    */
 240   float GetPathLengthScale(PathLengthScaleForType aFor);
 241
 242   // WebIDL
 243   already_AddRefed<DOMSVGAnimatedNumber> PathLength();
 244   MOZ_CAN_RUN_SCRIPT bool IsPointInFill(const DOMPointInit& aPoint);
 245   MOZ_CAN_RUN_SCRIPT bool IsPointInStroke(const DOMPointInit& aPoint);
 246   MOZ_CAN_RUN_SCRIPT float GetTotalLengthForBinding();
 247   MOZ_CAN_RUN_SCRIPT already_AddRefed<DOMSVGPoint> GetPointAtLength(
 248       float distance, ErrorResult& rv);
 249
 250  protected:
 251   // SVGElement method
 252   NumberAttributesInfo GetNumberInfo() override;
 253
 254   // d is a presentation attribute, so we would like to make sure style is
 255   // up-to-date. This function flushes the style if the path attribute is d.
 256   MOZ_CAN_RUN_SCRIPT void FlushStyleIfNeeded();
 257
 258   SVGAnimatedNumber mPathLength;
 259   static NumberInfo sNumberInfo;
 260   mutable RefPtr<Path> mCachedPath;
 261
 262  private:
 263   already_AddRefed<Path> GetOrBuildPathForHitTest();
 264
 265   float GetTotalLength();
 266 };
 267
 268 }  // namespace dom
 269 }  // namespace mozilla
 270
 271 #endif  // DOM_SVG_SVGGEOMETRYELEMENT_H_