Add homogeneous point mapping to Matrix

Adds mapping of homogeneous points (points with three scalar components,
where the last component is not 1). Includes fix for tests when
running on 32 bit debug builds

BUG=
R=bsalomon@google.com

Review URL: https://codereview.chromium.org/22816005

git-svn-id: http://skia.googlecode.com/svn/trunk@10755 2bbb7eff-a529-9590-31e7-b0007b416f81

1 files changed, 37 insertions, 1 deletions

diff --git a/src/core/SkMatrix.cpp b/src/core/SkMatrix.cpp
index 36e735309b..e5d48f022f 100644
--- a/src/core/SkMatrix.cpp
+++ b/src/core/SkMatrix.cpp
@@ -1218,7 +1218,7 @@ const SkMatrix::MapPtsProc SkMatrix::gMapPtsProcs[] = {
 };
 
 void SkMatrix::mapPoints(SkPoint dst[], const SkPoint src[], int count) const {
-    SkASSERT((dst && src && count > 0) || count == 0);
+    SkASSERT((dst && src && count > 0) || 0 == count);
     // no partial overlap
     SkASSERT(src == dst || SkAbs32((int32_t)(src - dst)) >= count);
 
@@ -1227,6 +1227,42 @@ void SkMatrix::mapPoints(SkPoint dst[], const SkPoint src[], int count) const {
 
 ///////////////////////////////////////////////////////////////////////////////
 
+void SkMatrix::mapHomogeneousPoints(SkScalar dst[], const SkScalar src[], int count) const {
+    SkASSERT((dst && src && count > 0) || 0 == count);
+    // no partial overlap
+    SkASSERT(src == dst || SkAbs32((int32_t)(src - dst)) >= 3*count);
+
+    if (count > 0) {
+        if (this->isIdentity()) {
+            memcpy(dst, src, 3*count*sizeof(SkScalar));
+            return;
+        }
+        do {
+            SkScalar sx = src[0];
+            SkScalar sy = src[1];
+            SkScalar sw = src[2];
+            src += 3;
+
+            SkScalar x = SkScalarMul(sx, fMat[kMScaleX]) +
+                         SkScalarMul(sy, fMat[kMSkewX]) +
+                         SkScalarMul(sw, fMat[kMTransX]);
+            SkScalar y = SkScalarMul(sx, fMat[kMSkewY]) +
+                         SkScalarMul(sy, fMat[kMScaleY]) +
+                         SkScalarMul(sw, fMat[kMTransY]);
+            SkScalar w = SkScalarMul(sx, fMat[kMPersp0]) +
+                         SkScalarMul(sy, fMat[kMPersp1]) +
+                         SkScalarMul(sw, fMat[kMPersp2]);
+
+            dst[0] = x;
+            dst[1] = y;
+            dst[2] = w;
+            dst += 3;
+        } while (--count);
+    }
+}
+
+///////////////////////////////////////////////////////////////////////////////
+
 void SkMatrix::mapVectors(SkPoint dst[], const SkPoint src[], int count) const {
     if (this->hasPerspective()) {
         SkPoint origin;