combine setRectFan and mapRect

src/core/SkMatrixPriv.h

Index: src/core/SkMatrixPriv.h
diff --git a/src/core/SkMatrixPriv.h b/src/core/SkMatrixPriv.h
index 91185f08d148771b21b3e4d14afc8e634defabfb..4c39957922c731a1346d361fa8904f3aaa15d958 100644
--- a/src/core/SkMatrixPriv.h
+++ b/src/core/SkMatrixPriv.h
@@ -65,6 +65,38 @@ public:
             pts = (SkPoint*)((intptr_t)pts + stride);
         }
     }
+

[robertphillips, 2016/08/23 19:50:19]

Would the mx, rect, quad parameter order be more pleasing ? 

[bsalomon, 2016/08/23 20:15:40]

I'd be in favor of any order that had the two input params next to each other.

+    static void SetMappedRectFan(const SkMatrix& mx, SkPoint quad[4], const SkRect& rect) {
+        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