Make various gfx classes more amenable to use as compile-time constants.

ui/gfx/geometry/insets.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.
 
 #ifndef UI_GFX_GEOMETRY_INSETS_H_
 #define UI_GFX_GEOMETRY_INSETS_H_
 
 #include <string>
 
 #include "ui/gfx/geometry/insets_f.h"
 #include "ui/gfx/gfx_export.h"
 
 namespace gfx {
 
 class GFX_EXPORT Insets {
  public:
-  Insets();
-  explicit Insets(int all);
-  Insets(int vertical, int horizontal);
-  Insets(int top, int left, int bottom, int right);
+  constexpr Insets() : top_(0), left_(0), bottom_(0), right_(0) {}
+  constexpr explicit Insets(int all)
+      : top_(all), left_(all), bottom_(all), right_(all) {}
+  constexpr Insets(int vertical, int horizontal)
+      : top_(vertical),
+        left_(horizontal),
+        bottom_(vertical),
+        right_(horizontal) {}
+  constexpr Insets(int top, int left, int bottom, int right)
+      : top_(top), left_(left), bottom_(bottom), right_(right) {}
 
-  ~Insets();
-
-  int top() const { return top_; }
-  int left() const { return left_; }
-  int bottom() const { return bottom_; }
-  int right() const { return right_; }
+  constexpr int top() const { return top_; }
+  constexpr int left() const { return left_; }
+  constexpr int bottom() const { return bottom_; }
+  constexpr int right() const { return right_; }
 
   // Returns the total width taken up by the insets, which is the sum of the
   // left and right insets.
-  int width() const { return left_ + right_; }
+  constexpr int width() const { return left_ + right_; }
 
   // Returns the total height taken up by the insets, which is the sum of the
   // top and bottom insets.
-  int height() const { return top_ + bottom_; }
+  constexpr int height() const { return top_ + bottom_; }
 
   // Returns true if the insets are empty.
   bool IsEmpty() const { return width() == 0 && height() == 0; }
 
   void Set(int top, int left, int bottom, int right) {
     top_ = top;
     left_ = left;
     bottom_ = bottom;
     right_ = right;
   }
 
   bool operator==(const Insets& insets) const {
     return top_ == insets.top_ && left_ == insets.left_ &&
            bottom_ == insets.bottom_ && right_ == insets.right_;
   }
 
   bool operator!=(const Insets& insets) const {
     return !(*this == insets);
   }
 
   void operator+=(const Insets& insets) {
     top_ += insets.top_;
     left_ += insets.left_;
     bottom_ += insets.bottom_;
     right_ += insets.right_;
   }
 
+  void operator-=(const Insets& insets) {
+    top_ -= insets.top_;
+    left_ -= insets.left_;
+    bottom_ -= insets.bottom_;
+    right_ -= insets.right_;
+  }
+
   Insets operator-() const {
     return Insets(-top_, -left_, -bottom_, -right_);
   }
 
   Insets Scale(float scale) const {
     return Scale(scale, scale);
   }
 
   Insets Scale(float x_scale, float y_scale) const {
     return Insets(static_cast<int>(top() * y_scale),
@@ skipping 10 matching lines @@
   // Returns a string representation of the insets.
   std::string ToString() const;
 
  private:
   int top_;
   int left_;
   int bottom_;
   int right_;
 };
 
+inline Insets operator+(Insets lhs, const Insets& rhs) {
+  lhs += rhs;
+  return lhs;
+}
+
+inline Insets operator-(Insets lhs, const Insets& rhs) {
+  lhs -= rhs;
+  return lhs;
+}
+
 }  // namespace gfx
 
 #endif  // UI_GFX_GEOMETRY_INSETS_H_