Stateful PathRenderer implementation

src/gpu/GrPathRenderer.h

Index: src/gpu/GrPathRenderer.h
===================================================================
--- src/gpu/GrPathRenderer.h	(revision 13379)
+++ src/gpu/GrPathRenderer.h	(working copy)
@@ -74,70 +74,108 @@
         GrPathRendererChain::kNoRestriction_StencilSupport;
 
     /**
-     * This function is to get the stencil support for a particular path. The path's fill must
+     * This function is to get the stencil support for the current path. The path's fill must
      * not be an inverse type.
      *
+     * @param stroke    the stroke information (width, join, cap).
      * @param target    target that the path will be rendered to
-     * @param path      the path that will be drawn
-     * @param stroke    the stroke information (width, join, cap).
      */
-    StencilSupport getStencilSupport(const SkPath& path,
-                                     const SkStrokeRec& stroke,
+    StencilSupport getStencilSupport(const SkStrokeRec& stroke,
                                      const GrDrawTarget* target) const {
-        SkASSERT(!path.isInverseFillType());
-        return this->onGetStencilSupport(path, stroke, target);
+        SkASSERT(!fPath.isInverseFillType());
+        return this->onGetStencilSupport(stroke, target);
     }
 
+    // Set the path and fill type the path renderer is to use.
+    // 'fillType' is included as a parameter b.c. we often want to draw
+    // inverse filled paths normally filled.
+    void setPath(const SkPath& path, SkPath::FillType fillType) {
+        SkASSERT(fPath.isEmpty());
+        fPath = path;
+        fPath.setFillType(fillType);
+    }
+
+    void resetPath() {
+        fPath.reset();
+    }
+
     /**
-     * Returns true if this path renderer is able to render the path. Returning false allows the
-     * caller to fallback to another path renderer This function is called when searching for a path
-     * renderer capable of rendering a path.
+     * Returns true if this path renderer is able to render the current path. Returning false 
+     * allows the caller to fallback to another path renderer This function is called when 
+     * searching for a path renderer capable of rendering a path.
      *
-     * @param path       The path to draw
      * @param stroke     The stroke information (width, join, cap)
      * @param target     The target that the path will be rendered to
      * @param antiAlias  True if anti-aliasing is required.
      *
      * @return  true if the path can be drawn by this object, false otherwise.
      */
-    virtual bool canDrawPath(const SkPath& path,
-                             const SkStrokeRec& rec,
+    virtual bool canDrawPath(const SkStrokeRec& stroke,
                              const GrDrawTarget* target,
                              bool antiAlias) const = 0;
     /**
-     * Draws the path into the draw target. If getStencilSupport() would return kNoRestriction then
-     * the subclass must respect the stencil settings of the target's draw state.
+     * Draws the current path into the draw target. If getStencilSupport() would return 
+     * kNoRestriction then the subclass must respect the stencil settings of the 
+     * target's draw state.
      *
-     * @param path                  the path to draw.
      * @param stroke                the stroke information (width, join, cap)
      * @param target                target that the path will be rendered to
      * @param antiAlias             true if anti-aliasing is required.
      */
-    bool drawPath(const SkPath& path,
-                  const SkStrokeRec& stroke,
+    bool drawPath(const SkStrokeRec& stroke,
                   GrDrawTarget* target,
                   bool antiAlias) {
-        SkASSERT(!path.isEmpty());
-        SkASSERT(this->canDrawPath(path, stroke, target, antiAlias));
+        SkASSERT(!fPath.isEmpty());
+        SkASSERT(this->canDrawPath(stroke, target, antiAlias));
         SkASSERT(target->drawState()->getStencil().isDisabled() ||
-                 kNoRestriction_StencilSupport == this->getStencilSupport(path, stroke, target));
-        return this->onDrawPath(path, stroke, target, antiAlias);
+                 kNoRestriction_StencilSupport == this->getStencilSupport(stroke, target));
+        return this->onDrawPath(stroke, target, antiAlias);
     }
 
     /**
-     * Draws the path to the stencil buffer. Assume the writable stencil bits are already
-     * initialized to zero. The pixels inside the path will have non-zero stencil values afterwards.
+     * Draws the current path to the stencil buffer. Assume the writable stencil bits are already
+     * initialized to zero. The pixels inside the path will have non-zero stencil values 
+     * afterwards.
      *
-     * @param path                  the path to draw.
      * @param stroke                the stroke information (width, join, cap)
      * @param target                target that the path will be rendered to
      */
-    void stencilPath(const SkPath& path, const SkStrokeRec& stroke, GrDrawTarget* target) {
-        SkASSERT(!path.isEmpty());
-        SkASSERT(kNoSupport_StencilSupport != this->getStencilSupport(path, stroke, target));
-        this->onStencilPath(path, stroke, target);
+    void stencilPath(const SkStrokeRec& stroke, GrDrawTarget* target) {
+        SkASSERT(!fPath.isEmpty());
+        SkASSERT(kNoSupport_StencilSupport != this->getStencilSupport(stroke, target));
+        this->onStencilPath(stroke, target);
     }
 
+    class AutoClearPath : ::SkNoncopyable {
+    public:
+        AutoClearPath(GrPathRenderer* renderer) : fRenderer(renderer) {}
+        AutoClearPath() : fRenderer(NULL) {}
+        ~AutoClearPath() {
+            this->reset();
+        }
+
+        GrPathRenderer* renderer() {
+            return fRenderer;
+        }
+
+        void set(GrPathRenderer* renderer) {
+            this->reset();
+            fRenderer = renderer;
+        }
+
+        GrPathRenderer* operator->() { return fRenderer; }
+
+    private:
+        void reset() {
+            if (NULL != fRenderer) {
+                fRenderer->resetPath();
+            }
+            fRenderer = NULL;
+        }
+
+        GrPathRenderer* fRenderer;
+    };
+
     // Helper for determining if we can treat a thin stroke as a hairline w/ coverage.
     // If we can, we draw lots faster (raster device does this same test).
     static bool IsStrokeHairlineOrEquivalent(const SkStrokeRec& stroke, const SkMatrix& matrix,
@@ -153,11 +191,14 @@
     }
 
 protected:
+    const SkPath& path() const {
+        return fPath;
+    }
+
     /**
      * Subclass overrides if it has any limitations of stenciling support.
      */
-    virtual StencilSupport onGetStencilSupport(const SkPath&,
-                                               const SkStrokeRec&,
+    virtual StencilSupport onGetStencilSupport(const SkStrokeRec&,
                                                const GrDrawTarget*) const {
         return kNoRestriction_StencilSupport;
     }
@@ -165,8 +206,7 @@
     /**
      * Subclass implementation of drawPath()
      */
-    virtual bool onDrawPath(const SkPath& path,
-                            const SkStrokeRec& stroke,
+    virtual bool onDrawPath(const SkStrokeRec& stroke,
                             GrDrawTarget* target,
                             bool antiAlias) = 0;
 
@@ -174,7 +214,7 @@
      * Subclass implementation of stencilPath(). Subclass must override iff it ever returns
      * kStencilOnly in onGetStencilSupport().
      */
-    virtual void onStencilPath(const SkPath& path,  const SkStrokeRec& stroke, GrDrawTarget* target) {
+    virtual void onStencilPath(const SkStrokeRec& stroke, GrDrawTarget* target) {
         GrDrawTarget::AutoStateRestore asr(target, GrDrawTarget::kPreserve_ASRInit);
         GrDrawState* drawState = target->drawState();
         GR_STATIC_CONST_SAME_STENCIL(kIncrementStencil,
@@ -186,7 +226,7 @@
                                      0xffff);
         drawState->setStencil(kIncrementStencil);
         drawState->enableState(GrDrawState::kNoColorWrites_StateBit);
-        this->drawPath(path, stroke, target, false);
+        this->drawPath(stroke, target, false);
     }
 
     // Helper for getting the device bounds of a path. Inverse filled paths will have bounds set
@@ -206,6 +246,7 @@
     }
 
 private:
+    SkPath fPath;
 
     typedef SkRefCnt INHERITED;
 };