Adding gfx::Rect::SplitVertically() method.

1) Code was replicated in dragged_tab_controller_gtk.cc and
dragged_tab_controller.cc, this allows the same code to be reused. Also removing the corresponding TODO.
2) The old SplitRectangleInTwo() function was violating the styleguide by having not const references as parameters.

BUG=NONE
TEST=NONE

Review URL: http://codereview.chromium.org/8137018

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@104199 0039d316-1c4b-4281-b951-d872f2087c98

3 files changed, 39 insertions, 0 deletions

diff --git a/ui/gfx/rect.cc b/ui/gfx/rect.cc
index bc0a8a9..81d4e09 100644
--- a/ui/gfx/rect.cc
+++ b/ui/gfx/rect.cc
@@ -15,6 +15,7 @@
 #include <cairo.h>
 #endif
 
+#include "base/logging.h"
 #include "base/stringprintf.h"
 #include "ui/gfx/insets.h"
 
@@ -266,6 +267,17 @@ Rect Rect::Center(const gfx::Size& size) const {
   return Rect(new_x, new_y, new_width, new_height);
 }
 
+void Rect::SplitVertically(gfx::Rect* left_half, gfx::Rect* right_half) const {
+  DCHECK(left_half);
+  DCHECK(right_half);
+
+  left_half->SetRect(this->x(), this->y(), this->width() / 2, this->height());
+  right_half->SetRect(left_half->right(),
+                      this->y(),
+                      this->width() - left_half->width(),
+                      this->height());
+}
+
 bool Rect::SharesEdgeWith(const gfx::Rect& rect) const {
   return (y() == rect.y() && height() == rect.height() &&
              (x() == rect.right() || right() == rect.x())) ||
diff --git a/ui/gfx/rect.h b/ui/gfx/rect.h
index d77d2f6..d19074c 100644
--- a/ui/gfx/rect.h
+++ b/ui/gfx/rect.h
@@ -181,6 +181,9 @@ class UI_EXPORT Rect {
   // at given |size|.
   Rect Center(const gfx::Size& size) const;
 
+  // Splits |this| in two halves, |left_half| and |right_half|.
+  void SplitVertically(gfx::Rect* left_half, gfx::Rect* right_half) const;
+
   // Returns true if this rectangle shares an entire edge (i.e., same width or
   // same height) with the given rectangle, and the rectangles do not overlap.
   bool SharesEdgeWith(const gfx::Rect& rect) const;
diff --git a/ui/gfx/rect_unittest.cc b/ui/gfx/rect_unittest.cc
index 4ad3f74..4eefdd6 100644
--- a/ui/gfx/rect_unittest.cc
+++ b/ui/gfx/rect_unittest.cc
@@ -280,6 +280,30 @@ TEST(RectTest, IsEmpty) {
   EXPECT_FALSE(gfx::Rect(0, 0, 10, 10).size().IsEmpty());
 }
 
+TEST(RectTest, SplitVertically) {
+  gfx::Rect left_half, right_half;
+
+  // Splitting when origin is (0, 0).
+  gfx::Rect(0, 0, 20, 20).SplitVertically(&left_half, &right_half);
+  EXPECT_TRUE(left_half.Equals(gfx::Rect(0, 0, 10, 20)));
+  EXPECT_TRUE(right_half.Equals(gfx::Rect(10, 0, 10, 20)));
+
+  // Splitting when origin is arbitrary.
+  gfx::Rect(10, 10, 20, 10).SplitVertically(&left_half, &right_half);
+  EXPECT_TRUE(left_half.Equals(gfx::Rect(10, 10, 10, 10)));
+  EXPECT_TRUE(right_half.Equals(gfx::Rect(20, 10, 10, 10)));
+
+  // Splitting a rectangle of zero width.
+  gfx::Rect(10, 10, 0, 10).SplitVertically(&left_half, &right_half);
+  EXPECT_TRUE(left_half.Equals(gfx::Rect(10, 10, 0, 10)));
+  EXPECT_TRUE(right_half.Equals(gfx::Rect(10, 10, 0, 10)));
+
+  // Splitting a rectangle of odd width.
+  gfx::Rect(10, 10, 5, 10).SplitVertically(&left_half, &right_half);
+  EXPECT_TRUE(left_half.Equals(gfx::Rect(10, 10, 2, 10)));
+  EXPECT_TRUE(right_half.Equals(gfx::Rect(12, 10, 3, 10)));
+}
+
 TEST(RectTest, SharesEdgeWith) {
   gfx::Rect r(2, 3, 4, 5);