Fixes rounding bug in transform. This is needed to avoid rounding

something like -.9998 to 0 instead of -1. Without this a transformed
views bounds would end up with an extra scale-1 pixels on the left edge.

BUG=none
TEST=covered by unit test
R=ben@chromium.org,wjmaclean@chromium.org

Review URL: http://codereview.chromium.org/7066010

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@86430 0039d316-1c4b-4281-b951-d872f2087c98

ui/gfx/transform.cc

@@ -4,6 +4,8 @@
 
 #include "ui/gfx/transform.h"
 
+#include <cmath>
+
 #include "ui/gfx/point.h"
 #include "ui/gfx/rect.h"
 #include "ui/gfx/skia_util.h"
@@ -71,7 +73,8 @@ bool Transform::HasChange() const {
 bool Transform::TransformPoint(gfx::Point* point) {
   SkPoint skp;
   matrix_.mapXY(SkIntToScalar(point->x()), SkIntToScalar(point->y()), &skp);
-  point->SetPoint(static_cast<int>(skp.fX), static_cast<int>(skp.fY));
+  point->SetPoint(static_cast<int>(std::floor(skp.fX)),
+                  static_cast<int>(std::floor(skp.fY)));
   return true;
 }
 
@@ -81,7 +84,8 @@ bool Transform::TransformPointReverse(gfx::Point* point) {
   if (matrix_.invert(&inverse)) {
     SkPoint skp;
     inverse.mapXY(SkIntToScalar(point->x()), SkIntToScalar(point->y()), &skp);
-    point->SetPoint(static_cast<int>(skp.fX), static_cast<int>(skp.fY));
+    point->SetPoint(static_cast<int>(std::floor(skp.fX)),
+                    static_cast<int>(std::floor(skp.fY)));
     return true;
   }
   return false;

views/view_unittest.cc

@@ -1979,6 +1979,15 @@ TEST_F(ViewTest, ConvertPointToViewWithTransform) {
     EXPECT_EQ(5, point.x());
     EXPECT_EQ(5, point.y());
   }
+
+  // Conversions from top_view to child with a value that should be negative.
+  // This ensures we don't round up with negative numbers.
+  {
+    gfx::Point point(6, 18);
+    View::ConvertPointToView(&top_view, child, &point);
+    EXPECT_EQ(-1, point.x());
+    EXPECT_EQ(-1, point.y());
+  }
 }
 
 TEST_F(ViewTest, Contains) {