Modifications to GrPatherRenderer(Chain) interfaces to support clip mask manager.

R=robertphillips@google.com
Review URL: https://codereview.appspot.com/6904069

git-svn-id: http://skia.googlecode.com/svn/trunk@6741 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/include/gpu/GrPathRendererChain.h b/include/gpu/GrPathRendererChain.h
new file mode 100644
index 0000000..8b74ba3
--- /dev/null
+++ b/include/gpu/GrPathRendererChain.h
@@ -0,0 +1,83 @@
+
+/*
+ * Copyright 2011 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+
+#ifndef GrPathRendererChain_DEFINED
+#define GrPathRendererChain_DEFINED
+
+#include "GrRefCnt.h"
+#include "SkTArray.h"
+
+class GrContext;
+class GrDrawTarget;
+class GrPathRenderer;
+class SkPath;
+class SkStroke;
+
+/**
+ * Keeps track of an ordered list of path renderers. When a path needs to be
+ * drawn this list is scanned to find the most preferred renderer. To add your
+ * path renderer to the list implement the GrPathRenderer::AddPathRenderers
+ * function.
+ */
+class GrPathRendererChain : public SkRefCnt {
+public:
+    // See comments in GrPathRenderer.h
+    enum StencilSupport {
+        kNoSupport_StencilSupport,
+        kStencilOnly_StencilSupport,
+        kNoRestriction_StencilSupport,
+    };
+
+    SK_DECLARE_INST_COUNT(GrPathRendererChain)
+
+    GrPathRendererChain(GrContext* context);
+
+    ~GrPathRendererChain();
+
+    // takes a ref and unrefs in destructor
+    GrPathRenderer* addPathRenderer(GrPathRenderer* pr);
+
+    /** Documents how the caller plans to use a GrPathRenderer to draw a path. It affects the PR
+        returned by getPathRenderer */
+    enum DrawType {
+        kColor_DrawType,                    // draw to the color buffer, no AA
+        kColorAntiAlias_DrawType,           // draw to color buffer, with partial coverage AA
+        kStencilOnly_DrawType,              // draw just to the stencil buffer
+        kStencilAndColor_DrawType,          // draw the stencil and color buffer, no AA
+        kStencilAndColorAntiAlias_DrawType  // draw the stencil and color buffer, with partial
+                                            // coverage AA.
+    };
+    /** Returns a GrPathRenderer compatible with the request if one is available. If the caller
+        is drawing the path to the stencil buffer then stencilSupport can be used to determine
+        whether the path can be rendered with arbitrary stencil rules or not. See comments on
+        StencilSupport in GrPathRenderer.h. */     
+    GrPathRenderer* getPathRenderer(const SkPath& path,
+                                    const SkStroke& stroke,
+                                    const GrDrawTarget* target,
+                                    DrawType drawType,
+                                    StencilSupport* stencilSupport);
+
+private:
+
+    GrPathRendererChain();
+
+    void init();
+
+    enum {
+        kPreAllocCount = 8,
+    };
+    bool fInit;
+    GrContext*                                          fOwner;
+    SkSTArray<kPreAllocCount, GrPathRenderer*, true>    fChain;
+
+    typedef SkRefCnt INHERITED;
+};
+
+
+#endif