combine setRectFan and mapRect

src/core/SkMatrixPriv.h

 /*
  * Copyright 2016 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkMatrixPriv_DEFINE
 #define SkMatrixPriv_DEFINE
 
@@ skipping 47 matching lines @@
         }
         // Insert other special-cases here (e.g. scale+translate)
         
         // general case
         SkMatrix::MapXYProc proc = mx.getMapXYProc();
         for (int i = 0; i < count; ++i) {
             proc(mx, pts->fX, pts->fY, pts);
             pts = (SkPoint*)((intptr_t)pts + stride);
         }
     }
+
+    static void SetMappedRectFan(const SkMatrix& mx, const SkRect& rect, SkPoint quad[4]) {
+        SkMatrix::TypeMask tm = mx.getType();
+        SkScalar l = rect.fLeft;
+        SkScalar t = rect.fTop;
+        SkScalar r = rect.fRight;
+        SkScalar b = rect.fBottom;
+        if (tm <= (SkMatrix::kScale_Mask | SkMatrix::kTranslate_Mask)) {
+            const SkScalar tx = mx.getTranslateX();
+            const SkScalar ty = mx.getTranslateY();
+            if (tm <= SkMatrix::kTranslate_Mask) {
+                l += tx;
+                t += ty;
+                r += tx;
+                b += ty;
+            } else {
+                const SkScalar sx = mx.getScaleX();
+                const SkScalar sy = mx.getScaleY();
+                l = sx * l + tx;
+                t = sy * t + ty;
+                r = sx * r + tx;
+                b = sy * b + ty;
+            }
+            quad[0].set(l, t);
+            quad[1].set(l, b);
+            quad[2].set(r, b);
+            quad[3].set(r, t);
+        } else {
+            quad[0].setRectFan(l, t, r, b);
+            mx.mapPoints(quad, quad, 4);
+        }
+    }
 };
 
 #endif