LabelButton: cache the last computed preferred size

ui/views/controls/button/label_button.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_VIEWS_CONTROLS_BUTTON_LABEL_BUTTON_H_
 #define UI_VIEWS_CONTROLS_BUTTON_LABEL_BUTTON_H_
 
 #include "base/compiler_specific.h"
 #include "base/memory/scoped_ptr.h"
 #include "third_party/skia/include/core/SkColor.h"
@@ skipping 51 matching lines @@
 
   // Get or set the horizontal alignment used for the button; reversed in RTL.
   // The optional image will lead the text, unless the button is right-aligned.
   gfx::HorizontalAlignment GetHorizontalAlignment() const;
   void SetHorizontalAlignment(gfx::HorizontalAlignment alignment);
 
   // Set the directionality mode used for the button text.
   void SetDirectionalityMode(gfx::DirectionalityMode mode);
 
   // Call set_min_size(gfx::Size()) to clear the monotonically increasing size.
-  void set_min_size(const gfx::Size& min_size) { min_size_ = min_size; }
-  void set_max_size(const gfx::Size& max_size) { max_size_ = max_size; }
+  void set_min_size(const gfx::Size& min_size) {
+    min_size_ = min_size;
+    ResetCachedSize();
+  }
+  void set_max_size(const gfx::Size& max_size) {
+    max_size_ = max_size;
+    ResetCachedSize();
+  }
 
   // Get or set the option to handle the return key; false by default.
   bool is_default() const { return is_default_; }
   void SetIsDefault(bool is_default);
 
   // Get or set the button's overall style; the default is |STYLE_TEXTBUTTON|.
   ButtonStyle style() const { return style_; }
   void SetStyle(ButtonStyle style);
 
   void SetFocusPainter(scoped_ptr<Painter> focus_painter);
@@ skipping 55 matching lines @@
   // NativeThemeDelegate:
   virtual ui::NativeTheme::Part GetThemePart() const OVERRIDE;
   virtual ui::NativeTheme::State GetThemeState(
       ui::NativeTheme::ExtraParams* params) const OVERRIDE;
   virtual const gfx::Animation* GetThemeAnimation() const OVERRIDE;
   virtual ui::NativeTheme::State GetBackgroundThemeState(
       ui::NativeTheme::ExtraParams* params) const OVERRIDE;
   virtual ui::NativeTheme::State GetForegroundThemeState(
       ui::NativeTheme::ExtraParams* params) const OVERRIDE;
 
+  // Resets |button_size_| and marks |button_size_valid_| as false.
+  void ResetCachedSize();
+
   // The image and label shown in the button.
   ImageView* image_;
   Label* label_;
 
   // The cached font lists in the normal and bold style.
   gfx::FontList cached_normal_font_list_;
   gfx::FontList cached_bold_font_list_;
 
   // The images and colors for each button state.
   gfx::ImageSkia button_state_images_[STATE_COUNT];
   SkColor button_state_colors_[STATE_COUNT];
 
   // Used to track whether SetTextColor() has been invoked.
   bool explicitly_set_colors_[STATE_COUNT];
 
   // |min_size_| increases monotonically with the preferred size.
   mutable gfx::Size min_size_;
   // |max_size_| may be set to clamp the preferred size.
   gfx::Size max_size_;
 
+  // Cache the last computed preferred size.
+  mutable gfx::Size button_size_;
+  mutable bool button_size_valid_;
+
   // Flag indicating default handling of the return key via an accelerator.
   // Whether or not the button appears or behaves as the default button in its
   // current context;
   bool is_default_;
 
   // The button's overall style.
   ButtonStyle style_;
 
   // True if current border was set by UpdateThemedBorder. Defaults to true.
   bool border_is_themed_border_;
 
   scoped_ptr<Painter> focus_painter_;
 
   DISALLOW_COPY_AND_ASSIGN(LabelButton);
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_CONTROLS_BUTTON_LABEL_BUTTON_H_