Bug 926258 - Implement a Moz2D version of gfxPath. r=Bas

gfx/2d/2D.h

@@ -448,6 +448,11 @@ public:
    * mutable.
    */
   virtual FillRule GetFillRule() const = 0;
+
+  virtual Float ComputeLength() { return 0; }
+
+  virtual Point ComputePointAtLength(Float aLength,
+                                     Point* aTangent) { return Point(); }
 };
 
 /* The PathBuilder class allows path creation. Once finish is called on the

gfx/thebes/gfxContext.cpp

@@ -275,25 +275,31 @@ gfxContext::ClosePath()
   }
 }
 
-already_AddRefed<gfxPath> gfxContext::CopyPath() const
+already_AddRefed<gfxPath> gfxContext::CopyPath()
 {
+  nsRefPtr<gfxPath> path;
   if (mCairo) {
-    nsRefPtr<gfxPath> path = new gfxPath(cairo_copy_path(mCairo));
-    return path.forget();
+    path = new gfxPath(cairo_copy_path(mCairo));
   } else {
-    // XXX - This is not yet supported for Azure.
-    return nullptr;
+    EnsurePath();
+    path = new gfxPath(mPath);
   }
+  return path.forget();
 }
 
-void gfxContext::AppendPath(gfxPath* path)
+void gfxContext::SetPath(gfxPath* path)
 {
   if (mCairo) {
+    cairo_new_path(mCairo);
     if (path->mPath->status == CAIRO_STATUS_SUCCESS && path->mPath->num_data != 0)
         cairo_append_path(mCairo, path->mPath);
   } else {
-    // XXX - This is not yet supported for Azure.
-    return;
+    MOZ_ASSERT(path->mMoz2DPath, "Can't mix cairo and azure paths!");
+    MOZ_ASSERT(path->mMoz2DPath->GetBackendType() == mDT->GetType());
+    mPath = path->mMoz2DPath;
+    mPathBuilder = nullptr;
+    mPathIsRect = false;
+    mTransformChanged = false;
   }
 }
 

gfx/thebes/gfxContext.h

@@ -131,12 +131,12 @@ public:
     /**
      * Copies the current path and returns the copy.
      */
-    already_AddRefed<gfxPath> CopyPath() const;
+    already_AddRefed<gfxPath> CopyPath();
 
     /**
      * Appends the given path to the current path.
      */
-    void AppendPath(gfxPath* path);
+    void SetPath(gfxPath* path);
 
     /**
      * Moves the pen to a new point without drawing a line.
@@ -881,8 +881,7 @@ public:
     void Restore()
     {
         if (mPath) {
-            mContext->NewPath();
-            mContext->AppendPath(mPath);
+            mContext->SetPath(mPath);
             mPath = nullptr;
         }
     }

gfx/thebes/gfxPath.cpp

@@ -7,15 +7,25 @@
 #include "gfxPoint.h"
 #include "gfxPlatform.h"
 #include "gfxASurface.h"
+#include "mozilla/gfx/2D.h"
 
 #include "cairo.h"
 
+using namespace mozilla::gfx;
+
 gfxPath::gfxPath(cairo_path_t* aPath)
   : mPath(aPath)
   , mFlattenedPath(nullptr)
 {
 }
 
+gfxPath::gfxPath(Path* aPath)
+  : mPath(nullptr)
+  , mFlattenedPath(nullptr)
+  , mMoz2DPath(aPath)
+{
+}
+
 gfxPath::~gfxPath()
 {
     cairo_path_destroy(mPath);
@@ -75,6 +85,10 @@ CalcSubLengthAndAdvance(cairo_path_data_t *aData,
 gfxFloat
 gfxPath::GetLength()
 {
+    if (mMoz2DPath) {
+        return mMoz2DPath->ComputeLength();
+    }
+
     EnsureFlattenedPath();
 
     gfxPoint start(0, 0);     // start of current subpath
@@ -92,6 +106,20 @@ gfxPath::GetLength()
 gfxPoint
 gfxPath::FindPoint(gfxPoint aOffset, gfxFloat *aAngle)
 {
+    if (mMoz2DPath) {
+        Point tangent; // Unit vector tangent to the point we find.
+        Point result = mMoz2DPath->ComputePointAtLength(aOffset.x, &tangent);
+
+        // The y value of aOffset is the offset along the normal vector to apply
+        Point normal(-tangent.y, tangent.x);
+        result += normal * aOffset.y;
+
+        if (aAngle)
+            *aAngle = atan2(tangent.y, tangent.x);
+
+        return gfxPoint(result.x, result.y);
+    }
+
     EnsureFlattenedPath();
 
     gfxPoint start(0, 0);     // start of current subpath

gfx/thebes/gfxPath.h

@@ -8,11 +8,18 @@
 
 #include "gfxTypes.h"
 #include "nsISupportsImpl.h"
+#include "mozilla/RefPtr.h"
 
 class gfxContext;
 struct gfxPoint;
 typedef struct cairo_path cairo_path_t;
 
+namespace mozilla {
+namespace gfx {
+class Path;
+}
+}
+
 /**
  * Class representing a path. Can be created by copying the current path
  * of a gfxContext.
@@ -24,6 +31,7 @@ class gfxPath {
 
 protected:
     gfxPath(cairo_path_t* aPath);
+    gfxPath(mozilla::gfx::Path* aPath);
 
     void EnsureFlattenedPath();
 
@@ -48,6 +56,7 @@ public:
 protected:
     cairo_path_t* mPath;
     cairo_path_t* mFlattenedPath;
+    mozilla::RefPtr<mozilla::gfx::Path> mMoz2DPath;
 };
 
 #endif