Make gfx::Rect class operations consistently mutate the class they are called on.

ui/gfx/rect_base_impl.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/gfx/rect_base.h"
 
 #include "base/logging.h"
 #include "base/stringprintf.h"
 
 // This file provides the implementation for RectBaese template and
@@ skipping 147 matching lines @@
     const Class& rect) const {
   return !(rect.x() >= right() || rect.right() <= x() ||
            rect.y() >= bottom() || rect.bottom() <= y());
 }
 
 template<typename Class,
          typename PointClass,
          typename SizeClass,
          typename InsetsClass,
          typename Type>
-Class RectBase<Class, PointClass, SizeClass, InsetsClass, Type>::Intersect(
-    const Class& rect) const {
+void RectBase<Class, PointClass, SizeClass, InsetsClass, Type>::Intersect(
+    const Class& rect) {
+  if (IsEmpty() || rect.IsEmpty()) {
+    SetRect(0, 0, 0, 0);
+    return;
+  }
+
   Type rx = std::max(x(), rect.x());
   Type ry = std::max(y(), rect.y());
   Type rr = std::min(right(), rect.right());
   Type rb = std::min(bottom(), rect.bottom());
 
   if (rx >= rr || ry >= rb)
     rx = ry = rr = rb = 0;  // non-intersecting
 
-  return Class(rx, ry, rr - rx, rb - ry);
+  SetRect(rx, ry, rr - rx, rb - ry);
 }
 
 template<typename Class,
          typename PointClass,
          typename SizeClass,
          typename InsetsClass,
          typename Type>
-Class RectBase<Class, PointClass, SizeClass, InsetsClass, Type>::Union(
-    const Class& rect) const {
-  // special case empty rects...
-  if (IsEmpty())
-    return rect;
+void RectBase<Class, PointClass, SizeClass, InsetsClass, Type>::Union(
+    const Class& rect) {
+  if (IsEmpty()) {
+    *this = rect;
+    return;
+  }
   if (rect.IsEmpty())
-    return *static_cast<const Class*>(this);
+    return;
 
   Type rx = std::min(x(), rect.x());
   Type ry = std::min(y(), rect.y());
   Type rr = std::max(right(), rect.right());
   Type rb = std::max(bottom(), rect.bottom());
 
-  return Class(rx, ry, rr - rx, rb - ry);
+  SetRect(rx, ry, rr - rx, rb - ry);
 }
 
 template<typename Class,
          typename PointClass,
          typename SizeClass,
          typename InsetsClass,
          typename Type>
-Class RectBase<Class, PointClass, SizeClass, InsetsClass, Type>::Subtract(
-    const Class& rect) const {
-  // boundary cases:
+void RectBase<Class, PointClass, SizeClass, InsetsClass, Type>::Subtract(
+    const Class& rect) {
   if (!Intersects(rect))
-    return *static_cast<const Class*>(this);
-  if (rect.Contains(*static_cast<const Class*>(this)))
-    return Class();
+    return;
+  if (rect.Contains(*static_cast<const Class*>(this))) {
+    SetRect(0, 0, 0, 0);
+    return;
+  }
 
   Type rx = x();
   Type ry = y();
   Type rr = right();
   Type rb = bottom();
 
   if (rect.y() <= y() && rect.bottom() >= bottom()) {
     // complete intersection in the y-direction
     if (rect.x() <= x()) {
       rx = rect.right();
     } else {
       rr = rect.x();
     }
   } else if (rect.x() <= x() && rect.right() >= right()) {
     // complete intersection in the x-direction
     if (rect.y() <= y()) {
       ry = rect.bottom();
     } else {
       rb = rect.y();
     }
   }
-  return Class(rx, ry, rr - rx, rb - ry);
+  SetRect(rx, ry, rr - rx, rb - ry);
 }
 
 template<typename Class,
          typename PointClass,
          typename SizeClass,
          typename InsetsClass,
          typename Type>
-Class RectBase<Class, PointClass, SizeClass, InsetsClass, Type>::AdjustToFit(
-    const Class& rect) const {
+void RectBase<Class, PointClass, SizeClass, InsetsClass, Type>::AdjustToFit(
+    const Class& rect) {
   Type new_x = x();
   Type new_y = y();
   Type new_width = width();
   Type new_height = height();
   AdjustAlongAxis(rect.x(), rect.width(), &new_x, &new_width);
   AdjustAlongAxis(rect.y(), rect.height(), &new_y, &new_height);
-  return Class(new_x, new_y, new_width, new_height);
+  SetRect(new_x, new_y, new_width, new_height);
 }
 
 template<typename Class,
          typename PointClass,
          typename SizeClass,
          typename InsetsClass,
          typename Type>
 PointClass RectBase<Class, PointClass, SizeClass, InsetsClass, Type>::
     CenterPoint() const {
   return PointClass(x() + width() / 2, y() + height() / 2);
 }
 
 template<typename Class,
          typename PointClass,
          typename SizeClass,
          typename InsetsClass,
          typename Type>
-Class RectBase<Class, PointClass, SizeClass, InsetsClass, Type>::Center(
-    const SizeClass& size) const {
+void RectBase<Class, PointClass, SizeClass, InsetsClass, Type>::
+    ClampToCenteredSize(const SizeClass& size) {
   Type new_width = std::min(width(), size.width());
   Type new_height = std::min(height(), size.height());
   Type new_x = x() + (width() - new_width) / 2;
   Type new_y = y() + (height() - new_height) / 2;
-  return Class(new_x, new_y, new_width, new_height);
+  SetRect(new_x, new_y, new_width, new_height);
 }
 
 template<typename Class,
          typename PointClass,
          typename SizeClass,
          typename InsetsClass,
          typename Type>
 void RectBase<Class, PointClass, SizeClass, InsetsClass, Type>::SplitVertically(
     Class* left_half, Class* right_half) const {
   DCHECK(left_half);
@@ skipping 13 matching lines @@
          typename Type>
 bool RectBase<Class, PointClass, SizeClass, InsetsClass, Type>::SharesEdgeWith(
     const Class& rect) const {
   return (y() == rect.y() && height() == rect.height() &&
              (x() == rect.right() || right() == rect.x())) ||
          (x() == rect.x() && width() == rect.width() &&
              (y() == rect.bottom() || bottom() == rect.y()));
 }
 
 }  // namespace gfx