cumulative pathops patch

Replace the implicit curve intersection with a geometric curve intersection. The implicit intersection proved mathematically unstable and took a long time to zero in on an answer.

Use pointers instead of indices to refer to parts of curves. Indices required awkward renumbering.

Unify t and point values so that small intervals can be eliminated in one pass.

Break cubics up front to eliminate loops and cusps.

Make the Simplify and Op code more regular and eliminate arbitrary differences.

Add a builder that takes an array of paths and operators.

Delete unused code.

BUG=skia:3588
R=reed@google.com

Review URL: https://codereview.chromium.org/1037573004

1 files changed, 36 insertions, 6 deletions

diff --git a/include/pathops/SkPathOps.h b/include/pathops/SkPathOps.h
index ba18f4ba72..61a7076964 100644
--- a/include/pathops/SkPathOps.h
+++ b/include/pathops/SkPathOps.h
@@ -8,6 +8,8 @@
 #define SkPathOps_DEFINED
 
 #include "SkPreConfig.h"
+#include "SkTArray.h"
+#include "SkTDArray.h"
 
 class SkPath;
 struct SkRect;
@@ -17,11 +19,11 @@ struct SkRect;
   *  The logical operations that can be performed when combining two paths.
   */
 enum SkPathOp {
-    kDifference_PathOp,         //!< subtract the op path from the first path
-    kIntersect_PathOp,          //!< intersect the two paths
-    kUnion_PathOp,              //!< union (inclusive-or) the two paths
-    kXOR_PathOp,                //!< exclusive-or the two paths
-    kReverseDifference_PathOp,  //!< subtract the first path from the op path
+    kDifference_SkPathOp,         //!< subtract the op path from the first path
+    kIntersect_SkPathOp,          //!< intersect the two paths
+    kUnion_SkPathOp,              //!< union (inclusive-or) the two paths
+    kXOR_SkPathOp,                //!< exclusive-or the two paths
+    kReverseDifference_SkPathOp,  //!< subtract the first path from the op path
 };
 
 /** Set this path to the result of applying the Op to this path and the
@@ -35,9 +37,10 @@ enum SkPathOp {
 
     @param one The first operand (for difference, the minuend)
     @param two The second operand (for difference, the subtrahend)
+    @param op The operator to apply.
     @param result The product of the operands. The result may be one of the
                   inputs.
-    @return True if operation succeeded.
+    @return True if the operation succeeded.
   */
 bool SK_API Op(const SkPath& one, const SkPath& two, SkPathOp op, SkPath* result);
 
@@ -63,4 +66,31 @@ bool SK_API Simplify(const SkPath& path, SkPath* result);
   */
 bool SK_API TightBounds(const SkPath& path, SkRect* result);
 
+/** Perform a series of path operations, optimized for unioning many paths together.
+  */
+class SK_API SkOpBuilder {
+public:
+    /** Add one or more paths and their operand. The builder is empty before the first
+        path is added, so the result of a single add is (emptyPath OP path).
+
+        @param path The second operand.
+        @param _operator The operator to apply to the existing and supplied paths.
+     */ 
+    void add(const SkPath& path, SkPathOp _operator);
+
+    /** Computes the sum of all paths and operands, and resets the builder to its
+        initial state.
+ 
+        @param result The product of the operands.
+        @return True if the operation succeeded.
+      */
+    bool resolve(SkPath* result);
+
+private:
+    SkTArray<SkPath> fPathRefs;
+    SkTDArray<SkPathOp> fOps;
+
+    void reset();
+};
+
 #endif