layout/svg/SVGContextPaint.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 LAYOUT_SVG_SVGCONTEXTPAINT_H_
   8 #define LAYOUT_SVG_SVGCONTEXTPAINT_H_
   9
  10 #include "DrawMode.h"
  11 #include "gfxMatrix.h"
  12 #include "gfxPattern.h"
  13 #include "gfxTypes.h"
  14 #include "gfxUtils.h"
  15 #include "mozilla/AlreadyAddRefed.h"
  16 #include "mozilla/Assertions.h"
  17 #include "mozilla/gfx/2D.h"
  18 #include "nsColor.h"
  19 #include "nsStyleStruct.h"
  20 #include "nsTArray.h"
  21 #include "ImgDrawResult.h"
  22 #include "nsRefPtrHashtable.h"
  23
  24 class gfxContext;
  25
  26 namespace mozilla {
  27 class SVGPaintServerFrame;
  28
  29 namespace dom {
  30 class Document;
  31 }
  32
  33 /**
  34  * This class is used to pass information about a context element through to
  35  * SVG painting code in order to resolve the 'context-fill' and related
  36  * keywords. See:
  37  *
  38  *   https://www.w3.org/TR/SVG2/painting.html#context-paint
  39  *
  40  * This feature allows the color in an SVG-in-OpenType glyph to come from the
  41  * computed style for the text that is being drawn, for example, or for color
  42  * in an SVG embedded by an <img> element to come from the embedding <img>
  43  * element.
  44  *
  45  * This class is reference counted so that it can be shared among many similar
  46  * SVGImageContext objects. (SVGImageContext objects are frequently
  47  * copy-constructed with small modifications, and we'd like for those copies to
  48  * be able to share their context-paint data cheaply.)  However, in most cases,
  49  * SVGContextPaint instances are stored in a local RefPtr and only last for the
  50  * duration of a function call.
  51  * XXX Note: SVGImageContext doesn't actually have a SVGContextPaint member yet,
  52  * but it will in a later patch in the patch series that added this comment.
  53  */
  54 class SVGContextPaint : public RefCounted<SVGContextPaint> {
  55  protected:
  56   using DrawTarget = mozilla::gfx::DrawTarget;
  57   using Float = mozilla::gfx::Float;
  58   using imgDrawingParams = mozilla::image::imgDrawingParams;
  59
  60   SVGContextPaint() : mDashOffset(0.0f), mStrokeWidth(0.0f) {}
  61
  62  public:
  63   MOZ_DECLARE_REFCOUNTED_TYPENAME(SVGContextPaint)
  64
  65   virtual ~SVGContextPaint() = default;
  66
  67   virtual already_AddRefed<gfxPattern> GetFillPattern(
  68       const DrawTarget* aDrawTarget, float aOpacity, const gfxMatrix& aCTM,
  69       imgDrawingParams& aImgParams) = 0;
  70   virtual already_AddRefed<gfxPattern> GetStrokePattern(
  71       const DrawTarget* aDrawTarget, float aOpacity, const gfxMatrix& aCTM,
  72       imgDrawingParams& aImgParams) = 0;
  73   virtual float GetFillOpacity() const = 0;
  74   virtual float GetStrokeOpacity() const = 0;
  75
  76   already_AddRefed<gfxPattern> GetFillPattern(const DrawTarget* aDrawTarget,
  77                                               const gfxMatrix& aCTM,
  78                                               imgDrawingParams& aImgParams) {
  79     return GetFillPattern(aDrawTarget, GetFillOpacity(), aCTM, aImgParams);
  80   }
  81
  82   already_AddRefed<gfxPattern> GetStrokePattern(const DrawTarget* aDrawTarget,
  83                                                 const gfxMatrix& aCTM,
  84                                                 imgDrawingParams& aImgParams) {
  85     return GetStrokePattern(aDrawTarget, GetStrokeOpacity(), aCTM, aImgParams);
  86   }
  87
  88   static SVGContextPaint* GetContextPaint(nsIContent* aContent);
  89
  90   // XXX This gets the geometry params from the gfxContext.  We should get that
  91   // information from the actual paint context!
  92   void InitStrokeGeometry(gfxContext* aContext, float devUnitsPerSVGUnit);
  93
  94   const FallibleTArray<Float>& GetStrokeDashArray() const { return mDashes; }
  95
  96   Float GetStrokeDashOffset() const { return mDashOffset; }
  97
  98   Float GetStrokeWidth() const { return mStrokeWidth; }
  99
 100   virtual uint32_t Hash() const {
 101     MOZ_ASSERT_UNREACHABLE(
 102         "Only VectorImage needs to hash, and that should "
 103         "only be operating on our SVGEmbeddingContextPaint "
 104         "subclass");
 105     return 0;
 106   }
 107
 108   /**
 109    * Returns true if image context paint is allowed to be used in an image that
 110    * has the given URI, else returns false.
 111    */
 112   static bool IsAllowedForImageFromURI(nsIURI* aURI);
 113
 114  private:
 115   // Member-vars are initialized in InitStrokeGeometry.
 116   FallibleTArray<Float> mDashes;
 117   MOZ_INIT_OUTSIDE_CTOR Float mDashOffset;
 118   MOZ_INIT_OUTSIDE_CTOR Float mStrokeWidth;
 119 };
 120
 121 /**
 122  * RAII class used to temporarily set and remove an SVGContextPaint while a
 123  * piece of SVG is being painted.  The context paint is set on the SVG's owner
 124  * document, as expected by SVGContextPaint::GetContextPaint.  Any pre-existing
 125  * context paint is restored after this class removes the context paint that it
 126  * set.
 127  */
 128 class MOZ_RAII AutoSetRestoreSVGContextPaint {
 129  public:
 130   AutoSetRestoreSVGContextPaint(const SVGContextPaint* aContextPaint,
 131                                 dom::Document* aDocument);
 132   ~AutoSetRestoreSVGContextPaint();
 133
 134  private:
 135   dom::Document* mDocument;
 136   // The context paint that needs to be restored by our dtor after it removes
 137   // aContextPaint:
 138   const SVGContextPaint* mOuterContextPaint;
 139 };
 140
 141 /**
 142  * This class should be flattened into SVGContextPaint once we get rid of the
 143  * other sub-class (SimpleTextContextPaint).
 144  */
 145 struct SVGContextPaintImpl : public SVGContextPaint {
 146  protected:
 147   using DrawTarget = mozilla::gfx::DrawTarget;
 148
 149  public:
 150   DrawMode Init(const DrawTarget* aDrawTarget, const gfxMatrix& aContextMatrix,
 151                 nsIFrame* aFrame, SVGContextPaint* aOuterContextPaint,
 152                 imgDrawingParams& aImgParams);
 153
 154   already_AddRefed<gfxPattern> GetFillPattern(
 155       const DrawTarget* aDrawTarget, float aOpacity, const gfxMatrix& aCTM,
 156       imgDrawingParams& aImgParams) override;
 157   already_AddRefed<gfxPattern> GetStrokePattern(
 158       const DrawTarget* aDrawTarget, float aOpacity, const gfxMatrix& aCTM,
 159       imgDrawingParams& aImgParams) override;
 160
 161   void SetFillOpacity(float aOpacity) { mFillOpacity = aOpacity; }
 162   float GetFillOpacity() const override { return mFillOpacity; }
 163
 164   void SetStrokeOpacity(float aOpacity) { mStrokeOpacity = aOpacity; }
 165   float GetStrokeOpacity() const override { return mStrokeOpacity; }
 166
 167   struct Paint {
 168     enum class Tag : uint8_t {
 169       None,
 170       Color,
 171       PaintServer,
 172       ContextFill,
 173       ContextStroke,
 174     };
 175
 176     Paint() : mPaintDefinition{}, mPaintType(Tag::None) {}
 177
 178     void SetPaintServer(nsIFrame* aFrame, const gfxMatrix& aContextMatrix,
 179                         SVGPaintServerFrame* aPaintServerFrame) {
 180       mPaintType = Tag::PaintServer;
 181       mPaintDefinition.mPaintServerFrame = aPaintServerFrame;
 182       mFrame = aFrame;
 183       mContextMatrix = aContextMatrix;
 184     }
 185
 186     void SetColor(const nscolor& aColor) {
 187       mPaintType = Tag::Color;
 188       mPaintDefinition.mColor = aColor;
 189     }
 190
 191     void SetContextPaint(SVGContextPaint* aContextPaint, Tag aTag) {
 192       MOZ_ASSERT(aTag == Tag::ContextFill || aTag == Tag::ContextStroke);
 193       mPaintType = aTag;
 194       mPaintDefinition.mContextPaint = aContextPaint;
 195     }
 196
 197     union {
 198       SVGPaintServerFrame* mPaintServerFrame;
 199       SVGContextPaint* mContextPaint;
 200       nscolor mColor;
 201     } mPaintDefinition;
 202
 203     // Initialized (if needed) in SetPaintServer():
 204     MOZ_INIT_OUTSIDE_CTOR nsIFrame* mFrame;
 205     // CTM defining the user space for the pattern we will use.
 206     gfxMatrix mContextMatrix;
 207     Tag mPaintType;
 208
 209     // Device-space-to-pattern-space
 210     gfxMatrix mPatternMatrix;
 211     nsRefPtrHashtable<nsFloatHashKey, gfxPattern> mPatternCache;
 212
 213     already_AddRefed<gfxPattern> GetPattern(
 214         const DrawTarget* aDrawTarget, float aOpacity,
 215         StyleSVGPaint nsStyleSVG::*aFillOrStroke, const gfxMatrix& aCTM,
 216         imgDrawingParams& aImgParams);
 217   };
 218
 219   Paint mFillPaint;
 220   Paint mStrokePaint;
 221
 222   float mFillOpacity;
 223   float mStrokeOpacity;
 224 };
 225
 226 /**
 227  * This class is used to pass context paint to an SVG image when an element
 228  * references that image (e.g. via HTML <img> or SVG <image>, or by referencing
 229  * it from a CSS property such as 'background-image').  In this case we only
 230  * support context colors and not paint servers.
 231  */
 232 class SVGEmbeddingContextPaint : public SVGContextPaint {
 233   using DeviceColor = gfx::DeviceColor;
 234
 235  public:
 236   SVGEmbeddingContextPaint() : mFillOpacity(1.0f), mStrokeOpacity(1.0f) {}
 237
 238   bool operator==(const SVGEmbeddingContextPaint& aOther) const {
 239     MOZ_ASSERT(GetStrokeWidth() == aOther.GetStrokeWidth() &&
 240                    GetStrokeDashOffset() == aOther.GetStrokeDashOffset() &&
 241                    GetStrokeDashArray() == aOther.GetStrokeDashArray(),
 242                "We don't currently include these in the context information "
 243                "from an embedding element");
 244     return mFill == aOther.mFill && mStroke == aOther.mStroke &&
 245            mFillOpacity == aOther.mFillOpacity &&
 246            mStrokeOpacity == aOther.mStrokeOpacity;
 247   }
 248
 249   void SetFill(nscolor aFill) { mFill.emplace(gfx::ToDeviceColor(aFill)); }
 250   const Maybe<DeviceColor>& GetFill() const { return mFill; }
 251   void SetStroke(nscolor aStroke) {
 252     mStroke.emplace(gfx::ToDeviceColor(aStroke));
 253   }
 254   const Maybe<DeviceColor>& GetStroke() const { return mStroke; }
 255
 256   /**
 257    * Returns a pattern of type PatternType::COLOR, or else nullptr.
 258    */
 259   already_AddRefed<gfxPattern> GetFillPattern(
 260       const DrawTarget* aDrawTarget, float aFillOpacity, const gfxMatrix& aCTM,
 261       imgDrawingParams& aImgParams) override;
 262
 263   /**
 264    * Returns a pattern of type PatternType::COLOR, or else nullptr.
 265    */
 266   already_AddRefed<gfxPattern> GetStrokePattern(
 267       const DrawTarget* aDrawTarget, float aStrokeOpacity,
 268       const gfxMatrix& aCTM, imgDrawingParams& aImgParams) override;
 269
 270   void SetFillOpacity(float aOpacity) { mFillOpacity = aOpacity; }
 271   float GetFillOpacity() const override { return mFillOpacity; };
 272
 273   void SetStrokeOpacity(float aOpacity) { mStrokeOpacity = aOpacity; }
 274   float GetStrokeOpacity() const override { return mStrokeOpacity; };
 275
 276   uint32_t Hash() const override;
 277
 278  private:
 279   Maybe<DeviceColor> mFill;
 280   Maybe<DeviceColor> mStroke;
 281   float mFillOpacity;
 282   float mStrokeOpacity;
 283 };
 284
 285 }  // namespace mozilla
 286
 287 #endif  // LAYOUT_SVG_SVGCONTEXTPAINT_H_