Rect utility functions

* left_center()/top_center()/right_center()/bottom center()
  return the center of each edge.
* Transpose()
  swap x/y axis

Bug: None
Test: covered by unittests
Change-Id: Icd63578dfe236caf6376c043fc1a0ffe74dfe6cc
Reviewed-on: https://chromium-review.googlesource.com/1176861
Reviewed-by: Ian Vollick <vollick@chromium.org>
Commit-Queue: Mitsuru Oshima (OOO) <oshima@chromium.org>
Cr-Commit-Position: refs/heads/master@{#585065}

ui/gfx/geometry/rect.cc

@@ -257,6 +257,10 @@ void Rect::ClampToCenteredSize(const Size& size) {
   SetRect(new_x, new_y, new_width, new_height);
 }
 
+void Rect::Transpose() {
+  SetRect(y(), x(), height(), width());
+}
+
 void Rect::SplitVertically(Rect* left_half, Rect* right_half) const {
   DCHECK(left_half);
   DCHECK(right_half);

ui/gfx/geometry/rect.h

@@ -103,6 +103,15 @@ class GFX_EXPORT Rect {
   constexpr Point bottom_left() const { return Point(x(), bottom()); }
   constexpr Point bottom_right() const { return Point(right(), bottom()); }
 
+  constexpr Point left_center() const { return Point(x(), y() + height() / 2); }
+  constexpr Point top_center() const { return Point(x() + width() / 2, y()); }
+  constexpr Point right_center() const {
+    return Point(right(), y() + height() / 2);
+  }
+  constexpr Point bottom_center() const {
+    return Point(x() + width() / 2, bottom());
+  }
+
   Vector2d OffsetFromOrigin() const { return Vector2d(x(), y()); }
 
   void SetRect(int x, int y, int width, int height) {
@@ -189,6 +198,9 @@ class GFX_EXPORT Rect {
   // at given |size|.
   void ClampToCenteredSize(const Size& size);
 
+  // Transpose x and y axis.
+  void Transpose();
+
   // Splits |this| in two halves, |left_half| and |right_half|.
   void SplitVertically(Rect* left_half, Rect* right_half) const;
 

ui/gfx/geometry/rect_f.cc

@@ -183,6 +183,10 @@ void RectF::ClampToCenteredSize(const SizeF& size) {
   SetRect(new_x, new_y, new_width, new_height);
 }
 
+void RectF::Transpose() {
+  SetRect(y(), x(), height(), width());
+}
+
 void RectF::SplitVertically(RectF* left_half, RectF* right_half) const {
   DCHECK(left_half);
   DCHECK(right_half);

ui/gfx/geometry/rect_f.h

@@ -70,6 +70,17 @@ class GFX_EXPORT RectF {
   constexpr PointF bottom_left() const { return PointF(x(), bottom()); }
   constexpr PointF bottom_right() const { return PointF(right(), bottom()); }
 
+  constexpr PointF left_center() const {
+    return PointF(x(), y() + height() / 2);
+  }
+  constexpr PointF top_center() const { return PointF(x() + width() / 2, y()); }
+  constexpr PointF right_center() const {
+    return PointF(right(), y() + height() / 2);
+  }
+  constexpr PointF bottom_center() const {
+    return PointF(x() + width() / 2, bottom());
+  }
+
   Vector2dF OffsetFromOrigin() const { return Vector2dF(x(), y()); }
 
   void SetRect(float x, float y, float width, float height) {
@@ -149,6 +160,9 @@ class GFX_EXPORT RectF {
   // at given |size|.
   void ClampToCenteredSize(const SizeF& size);
 
+  // Transpose x and y axis.
+  void Transpose();
+
   // Splits |this| in two halves, |left_half| and |right_half|.
   void SplitVertically(RectF* left_half, RectF* right_half) const;
 

ui/gfx/geometry/rect_unittest.cc

@@ -869,6 +869,31 @@ TEST(RectTest, Corners) {
   EXPECT_EQ(PointF(4.2f, 6.2f), f.bottom_right());
 }
 
+TEST(RectTest, Centers) {
+  Rect i(10, 20, 30, 40);
+  EXPECT_EQ(Point(10, 40), i.left_center());
+  EXPECT_EQ(Point(25, 20), i.top_center());
+  EXPECT_EQ(Point(40, 40), i.right_center());
+  EXPECT_EQ(Point(25, 60), i.bottom_center());
+
+  RectF f(10.1f, 20.2f, 30.3f, 40.4f);
+  EXPECT_EQ(PointF(10.1f, 40.4f), f.left_center());
+  EXPECT_EQ(PointF(25.25f, 20.2f), f.top_center());
+  EXPECT_EQ(PointF(40.4f, 40.4f), f.right_center());
+  EXPECT_EQ(25.25f, f.bottom_center().x());
+  EXPECT_NEAR(60.6f, f.bottom_center().y(), 0.001f);
+}
+
+TEST(RectTest, Transpose) {
+  Rect i(10, 20, 30, 40);
+  i.Transpose();
+  EXPECT_EQ(Rect(20, 10, 40, 30), i);
+
+  RectF f(10.1f, 20.2f, 30.3f, 40.4f);
+  f.Transpose();
+  EXPECT_EQ(RectF(20.2f, 10.1f, 40.4f, 30.3f), f);
+}
+
 TEST(RectTest, ManhattanDistanceToPoint) {
   Rect i(1, 2, 3, 4);
   EXPECT_EQ(0, i.ManhattanDistanceToPoint(Point(1, 2)));