alt SkEvalQuadAt that returns its answer, using Sk2f

tests/GeometryTest.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 "SkGeometry.h"
 #include "Test.h"
+#include "SkRandom.h"
 
 static bool nearly_equal(const SkPoint& a, const SkPoint& b) {
     return SkScalarNearlyEqual(a.fX, b.fX) && SkScalarNearlyEqual(a.fY, b.fY);
 }
 
 static void testChopCubic(skiatest::Reporter* reporter) {
     /*
         Inspired by this test, which used to assert that the tValues had dups
 
         <path stroke="#202020" d="M0,0 C0,0 1,1 2190,5130 C2190,5070 2220,5010 2205,4980" />
      */
     const SkPoint src[] = {
         { SkIntToScalar(2190), SkIntToScalar(5130) },
         { SkIntToScalar(2190), SkIntToScalar(5070) },
         { SkIntToScalar(2220), SkIntToScalar(5010) },
         { SkIntToScalar(2205), SkIntToScalar(4980) },
     };
     SkPoint dst[13];
     SkScalar tValues[3];
     // make sure we don't assert internally
     int count = SkChopCubicAtMaxCurvature(src, dst, tValues);
     if (false) { // avoid bit rot, suppress warning
         REPORTER_ASSERT(reporter, count);
     }
 }
 
+static void test_evalquadat(skiatest::Reporter* reporter) {
+    SkRandom rand;
+    for (int i = 0; i < 1000; ++i) {
+        SkPoint pts[3];
+        for (int j = 0; j < 3; ++j) {
+            pts[j].set(rand.nextSScalar1() * 100, rand.nextSScalar1() * 100);
+        }
+        SkScalar t = 0;
+        const SkScalar dt = SK_Scalar1 / 128;
+        for (int j = 0; j < 128; ++j) {
+            SkPoint r0;
+            SkEvalQuadAt(pts, t, &r0);
+            SkPoint r1 = SkEvalQuadAt(pts, t);
+            bool eq = SkScalarNearlyEqual(r0.fX, r1.fX) && SkScalarNearlyEqual(r0.fY, r1.fY);
+            if (!eq) {
+                SkDebugf("[%d %g] p0 [%10.8f %10.8f] p1 [%10.8f %10.8f]\n", i, t, r0.fX, r0.fY, r1.fX, r1.fY);
+                REPORTER_ASSERT(reporter, eq);
+            }
+            t += dt;
+        }
+    }
+}
+
 DEF_TEST(Geometry, reporter) {
     SkPoint pts[3], dst[5];
 
     pts[0].set(0, 0);
     pts[1].set(100, 50);
     pts[2].set(0, 100);
 
     int count = SkChopQuadAtMaxCurvature(pts, dst);
     REPORTER_ASSERT(reporter, count == 1 || count == 2);
 
     pts[0].set(0, 0);
     pts[1].set(SkIntToScalar(3), 0);
     pts[2].set(SkIntToScalar(3), SkIntToScalar(3));
     SkConvertQuadToCubic(pts, dst);
     const SkPoint cubic[] = {
         { 0, 0, },
         { SkIntToScalar(2), 0, },
         { SkIntToScalar(3), SkIntToScalar(1), },
         { SkIntToScalar(3), SkIntToScalar(3) },
     };
     for (int i = 0; i < 4; ++i) {
         REPORTER_ASSERT(reporter, nearly_equal(cubic[i], dst[i]));
     }
 
     testChopCubic(reporter);
+    test_evalquadat(reporter);
 }