speed up maprect for scale+trans case

tests/MatrixTest.cpp

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkMath.h"
 #include "SkMatrix.h"
 #include "SkMatrixUtils.h"
@@ skipping 935 matching lines @@
     a.setTranslate(10, 20);
 
     SkMatrix b;
     b.setScale(3, 5);
 
     SkMatrix expected;
     expected.setConcat(a,b);
 
     REPORTER_ASSERT(r, expected == SkMatrix::Concat(a, b));
 }
+
+// Test that all variants of maprect are correct.
+DEF_TEST(Matrix_maprects, r) {
+    const SkScalar scale = 1000;
+    
+    SkMatrix mat;
+    mat.setScale(2, 3);
+    mat.postTranslate(1, 4);
+
+    SkRandom rand;
+    for (int i = 0; i < 10000; ++i) {
+        SkRect src = SkRect::MakeLTRB(rand.nextSScalar1() * scale,
+                                      rand.nextSScalar1() * scale,
+                                      rand.nextSScalar1() * scale,
+                                      rand.nextSScalar1() * scale);
+        SkRect dst[3];
+        
+        mat.mapPoints((SkPoint*)&dst[0].fLeft, (SkPoint*)&src.fLeft, 2);
+        dst[0].sort();
+        mat.mapRect(&dst[1], src);
+        mat.mapRectScaleTranslate(&dst[2], src);
+
+        REPORTER_ASSERT(r, dst[0] == dst[1]);
+        REPORTER_ASSERT(r, dst[0] == dst[2]);
+    }
+}