specialize setConcat for scale+translate

include/core/SkMatrix.h

 
 /*
  * 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.
  */
 
 
 #ifndef SkMatrix_DEFINED
@@ skipping 628 matching lines @@
         kAllMasks = kTranslate_Mask |
                     kScale_Mask |
                     kAffine_Mask |
                     kPerspective_Mask |
                     kRectStaysRect_Mask
     };
 
     SkScalar         fMat[9];
     mutable SkTRacy<uint32_t> fTypeMask;
 
+    void setScaleTranslate(SkScalar sx, SkScalar sy, SkScalar tx, SkScalar ty) {
+        fMat[kMScaleX] = sx;
+        fMat[kMSkewX]  = 0;
+        fMat[kMTransX] = tx;
+        
+        fMat[kMSkewY]  = 0;
+        fMat[kMScaleY] = sy;
+        fMat[kMTransY] = ty;
+        
+        fMat[kMPersp0] = 0;
+        fMat[kMPersp1] = 0;
+        fMat[kMPersp2] = 1;
+        
+        unsigned mask = 0;
+        if (sx != 1 || sy != 1) {
+            mask |= kScale_Mask;
+        }
+        if (tx || ty) {
+            mask |= kTranslate_Mask;
+        }
+        this->setTypeMask(mask | kRectStaysRect_Mask);
+    }
+
     uint8_t computeTypeMask() const;
     uint8_t computePerspectiveTypeMask() const;
 
     void setTypeMask(int mask) {
         // allow kUnknown or a valid mask
         SkASSERT(kUnknown_Mask == mask || (mask & kAllMasks) == mask ||
                  ((kUnknown_Mask | kOnlyPerspectiveValid_Mask) & mask)
                  == (kUnknown_Mask | kOnlyPerspectiveValid_Mask));
         fTypeMask = SkToU8(mask);
     }
@@ skipping 52 matching lines @@
     static void RotTrans_pts(const SkMatrix&, SkPoint dst[], const SkPoint[],
                              int count);
     static void Persp_pts(const SkMatrix&, SkPoint dst[], const SkPoint[], int);
 
     static const MapPtsProc gMapPtsProcs[];
 
     friend class SkPerspIter;
 };
 
 #endif