Add a map homogenous points to SkMatrix

src/core/SkMatrix.cpp

 /*
  * Copyright 2006 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkMatrix.h"
 #include "Sk64.h"
 #include "SkFloatBits.h"
@@ skipping 1200 matching lines @@
     SkMatrix::Rot_pts,      SkMatrix::RotTrans_pts,
     SkMatrix::Rot_pts,      SkMatrix::RotTrans_pts,
     // repeat the persp proc 8 times
     SkMatrix::Persp_pts,    SkMatrix::Persp_pts,
     SkMatrix::Persp_pts,    SkMatrix::Persp_pts,
     SkMatrix::Persp_pts,    SkMatrix::Persp_pts,
     SkMatrix::Persp_pts,    SkMatrix::Persp_pts
 };
 
 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);
 
     this->getMapPtsProc()(*this, dst, src, count);
 }
 
 ///////////////////////////////////////////////////////////////////////////////
 
+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;
 
         MapXYProc proc = this->getMapXYProc();
         proc(*this, 0, 0, &origin);
 
         for (int i = count - 1; i >= 0; --i) {
             SkPoint tmp;
 
@@ skipping 808 matching lines @@
     }
     if (NULL != rotation0) {
         *rotation0 = r0;
     }
     if (NULL != rotation1) {
         *rotation1 = r1;
     }
 
     return true;
 }