commit 6fc321a18acc8c6437735007240eefe7054e83b0
author reed@google.com <reed@google.com@2bbb7eff-a529-9590-31e7-b0007b416f81> Wed Jul 27 13:54:36 2011 +0000
committer reed@google.com <reed@google.com@2bbb7eff-a529-9590-31e7-b0007b416f81> Wed Jul 27 13:54:36 2011 +0000
tree ad730bde45542ca2053d1b9267c5ba855a71391d
parent 9510ccc06bbfa5e888f66578042674be98d8ac60

add test for SkConvertQuadToCubic



git-svn-id: http://skia.googlecode.com/svn/trunk@1967 2bbb7eff-a529-9590-31e7-b0007b416f81

src/core/SkGeometry.cpp

diff --git a/src/core/SkGeometry.cpp b/src/core/SkGeometry.cpp
index 3c9e9f9..57ce2fd 100644
--- a/src/core/SkGeometry.cpp
+++ b/src/core/SkGeometry.cpp
@@ -448,18 +448,20 @@
     }
 }
 
-void SkConvertQuadToCubic(const SkPoint src[3], SkPoint dst[4])
-{
-    SkScalar two = SkIntToScalar(2);
-    SkScalar one_third = SkScalarDiv(SK_Scalar1, SkIntToScalar(3));
-    dst[0].set(src[0].fX, src[0].fY);
-    dst[1].set(
-        SkScalarMul(SkScalarMulAdd(src[1].fX, two, src[0].fX), one_third),
-        SkScalarMul(SkScalarMulAdd(src[1].fY, two, src[0].fY), one_third));
-    dst[2].set(
-        SkScalarMul(SkScalarMulAdd(src[1].fX, two, src[2].fX), one_third),
-        SkScalarMul(SkScalarMulAdd(src[1].fY, two, src[2].fY), one_third));
-    dst[3].set(src[2].fX, src[2].fY);
+#ifdef SK_SCALAR_IS_FLOAT
+    #define SK_ScalarTwoThirds  (0.666666666f)
+#else
+    #define SK_ScalarTwoThirds  ((SkFixed)(43691))
+#endif
+
+void SkConvertQuadToCubic(const SkPoint src[3], SkPoint dst[4]) {
+    const SkScalar scale = SK_ScalarTwoThirds;
+    dst[0] = src[0];
+    dst[1].set(src[0].fX + SkScalarMul(src[1].fX - src[0].fX, scale),
+               src[0].fY + SkScalarMul(src[1].fY - src[0].fY, scale));
+    dst[2].set(src[2].fX + SkScalarMul(src[1].fX - src[2].fX, scale),
+               src[2].fY + SkScalarMul(src[1].fY - src[2].fY, scale));
+    dst[3] = src[2];
 }
 
 ////////////////////////////////////////////////////////////////////////////////////////

tests/GeometryTest.cpp

diff --git a/tests/GeometryTest.cpp b/tests/GeometryTest.cpp
index 5b05952..1465288 100644
--- a/tests/GeometryTest.cpp
+++ b/tests/GeometryTest.cpp
@@ -1,6 +1,10 @@
 #include "Test.h"
 #include "SkGeometry.h"
 
+static bool nearly_equal(const SkPoint& a, const SkPoint& b) {
+    return SkScalarNearlyEqual(a.fX, b.fX) && SkScalarNearlyEqual(a.fY, b.fY);
+}
+
 static void TestGeometry(skiatest::Reporter* reporter) {
     SkPoint pts[3], dst[5];
 
@@ -10,6 +14,20 @@
 
     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]));
+    }
 }
 
 #include "TestClassDef.h"