Gradient shaders: make fPtsToUnit const, pre-cache getType().

src/effects/gradients/SkLinearGradient.cpp

 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkLinearGradient.h"
 
 static inline int repeat_bits(int x, const int bits) {
@@ skipping 21 matching lines @@
     if (x & 256) {
         x = ~x;
     }
     return x & 255;
 }
 
 #if defined(_MSC_VER) && (_MSC_VER >= 1600)
 #pragma optimize("", on)
 #endif
 
-static void pts_to_unit_matrix(const SkPoint pts[2], SkMatrix* matrix) {
+static SkMatrix pts_to_unit_matrix(const SkPoint pts[2]) {
     SkVector    vec = pts[1] - pts[0];
     SkScalar    mag = vec.length();
     SkScalar    inv = mag ? SkScalarInvert(mag) : 0;
 
     vec.scale(inv);
-    matrix->setSinCos(-vec.fY, vec.fX, pts[0].fX, pts[0].fY);
-    matrix->postTranslate(-pts[0].fX, -pts[0].fY);
-    matrix->postScale(inv, inv);
+    SkMatrix matrix;
+    matrix.setSinCos(-vec.fY, vec.fX, pts[0].fX, pts[0].fY);
+    matrix.postTranslate(-pts[0].fX, -pts[0].fY);
+    matrix.postScale(inv, inv);
+    return matrix;
 }
 
 ///////////////////////////////////////////////////////////////////////////////
 
 SkLinearGradient::SkLinearGradient(const SkPoint pts[2], const Descriptor& desc)
-    : SkGradientShaderBase(desc)
+    : SkGradientShaderBase(desc, pts_to_unit_matrix(pts))
     , fStart(pts[0])
-    , fEnd(pts[1])
-{
-    pts_to_unit_matrix(pts, &fPtsToUnit);
+    , fEnd(pts[1]) {
 }
 
 SkFlattenable* SkLinearGradient::CreateProc(SkReadBuffer& buffer) {
     DescriptorScope desc;
     if (!desc.unflatten(buffer)) {
         return NULL;
     }
     SkPoint pts[2];
     pts[0] = buffer.readPoint();
     pts[1] = buffer.readPoint();
@@ skipping 528 matching lines @@
     str->append("SkLinearGradient (");
 
     str->appendf("start: (%f, %f)", fStart.fX, fStart.fY);
     str->appendf(" end: (%f, %f) ", fEnd.fX, fEnd.fY);
 
     this->INHERITED::toString(str);
 
     str->append(")");
 }
 #endif