Add a map homogenous points to SkMatrix

src/core/SkMatrix.cpp

Index: src/core/SkMatrix.cpp
diff --git a/src/core/SkMatrix.cpp b/src/core/SkMatrix.cpp
index 36e735309bb4739bf66ead50fd2571dd8af75cf3..0d1c6ac844b4bd77177226c0ea434ec826a870d3 100644
--- a/src/core/SkMatrix.cpp
+++ b/src/core/SkMatrix.cpp
@@ -1227,6 +1227,44 @@ void SkMatrix::mapPoints(SkPoint dst[], const SkPoint src[], int count) const {
 
 ///////////////////////////////////////////////////////////////////////////////
 
+void SkMatrix::Homogenous_pts(const SkMatrix& m, SkScalar dst[],
+                         const SkScalar src[], int count) {
+
+    if (count > 0) {
+        do {
+            SkScalar sx = src[0];
+            SkScalar sy = src[1];
+            SkScalar sz = src[2];

[bsalomon, 2013/08/07 17:54:01]

Can we call this sw?

+            src += 3;
+
+            SkScalar x = SkScalarMul(sx, m.fMat[kMScaleX]) +
+                         SkScalarMul(sy, m.fMat[kMSkewX]) +
+                         SkScalarMul(sz, m.fMat[kMTransX]);
+            SkScalar y = SkScalarMul(sx, m.fMat[kMSkewY]) +
+                         SkScalarMul(sy, m.fMat[kMScaleY]) +
+                         SkScalarMul(sz, m.fMat[kMTransY]);
+            SkScalar z = SkScalarMul(sx, m.fMat[kMPersp0]) +

[bsalomon, 2013/08/07 17:54:01]

w?

+                         SkScalarMul(sy, m.fMat[kMPersp1]) +
+                         SkScalarMul(sz, m.fMat[kMPersp2]);
+
+            dst[0] = x;
+            dst[1] = y;
+            dst[2] = z;
+            dst += 3;
+        } while (--count);
+    }
+}
+
+void SkMatrix::mapHomogenousPoints(SkScalar dst[], const SkScalar src[], int count) const {
+    SkASSERT((dst && src && count > 0) || count == 0);
+    // no partial overlap
+    SkASSERT(src == dst || SkAbs32((int32_t)(src - dst)) >= 3*count);
+
+    SkMatrix::Homogenous_pts(*this, dst, src, count);
+}
+
+///////////////////////////////////////////////////////////////////////////////
+
 void SkMatrix::mapVectors(SkPoint dst[], const SkPoint src[], int count) const {
     if (this->hasPerspective()) {
         SkPoint origin;