LabelButton: cache the last computed preferred size

ui/views/controls/button/label_button.h

Index: ui/views/controls/button/label_button.h
diff --git a/ui/views/controls/button/label_button.h b/ui/views/controls/button/label_button.h
index bceaf715654a99e288ae0f677d463a2c16a5d6de..84b8fabcae6b7d7b96b7d2751d73d1f0317b95f4 100644
--- a/ui/views/controls/button/label_button.h
+++ b/ui/views/controls/button/label_button.h
@@ -65,9 +65,9 @@ class VIEWS_EXPORT LabelButton : public CustomButton,
   gfx::HorizontalAlignment GetHorizontalAlignment() const;
   void SetHorizontalAlignment(gfx::HorizontalAlignment alignment);
 
-  // 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; }
+  // Call SetMinSize(gfx::Size()) to clear the monotonically increasing size.
+  void SetMinSize(const gfx::Size& min_size);
+  void SetMaxSize(const gfx::Size& min_size);

[msw, 2014/07/23 19:20:16]

nit: |max_size|

[noms (inactive), 2014/07/24 14:20:25]

Done.

 
   // Get or set the option to handle the return key; false by default.
   bool is_default() const { return is_default_; }
@@ -144,6 +144,9 @@ class VIEWS_EXPORT LabelButton : public CustomButton,
   virtual ui::NativeTheme::State GetForegroundThemeState(
       ui::NativeTheme::ExtraParams* params) const OVERRIDE;
 
+  // Resets |button_size_| and marks |button_size_valid_| as false.
+  void ResetCachedSize();

[sky, 2014/07/23 22:42:36]

Is it possible to override ChildPreferredSizeChanged to mark the cached state as
out of date? That way you don't need to explicitly reset this state as it's
implicitly communicated from the label.

[noms (inactive), 2014/07/24 14:20:26]

Hmm, but shouldn't actions on the LabelButton also invalidate the cached size?
For example changing the image or the border? It would definitely decrease the
calls to ResetCachedSize(), though, so I've done that.

On 2014/07/23 22:42:36, sky wrote:

[sky, 2014/07/24 15:38:05]

Yes, sorry, you may need a mix of the two. But it seems ideal to leverage
ChildPreferredSizeChanged as much as possible.

+
   // The image and label shown in the button.
   ImageView* image_;
   Label* label_;
@@ -164,6 +167,10 @@ class VIEWS_EXPORT LabelButton : public CustomButton,
   // |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_;

[sky, 2014/07/23 22:42:36]

Can you name this better. It's the preferred size. Maybe cached_preferred_size_.

[noms (inactive), 2014/07/24 14:20:26]

Done.

+  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;