LabelButton: cache the last computed preferred size

ui/views/controls/button/label_button.cc

Index: ui/views/controls/button/label_button.cc
diff --git a/ui/views/controls/button/label_button.cc b/ui/views/controls/button/label_button.cc
index 5ee97918dc9f794c1d1189ffa3e570449e6c16f7..5f0e78c2d6920c6b87f1936d2b7d733abc2a9257 100644
--- a/ui/views/controls/button/label_button.cc
+++ b/ui/views/controls/button/label_button.cc
@@ -89,6 +89,7 @@ const base::string16& LabelButton::GetText() const {
 void LabelButton::SetText(const base::string16& text) {
   SetAccessibleName(text);
   label_->SetText(text);
+  ResetCachedSize();
 }
 
 void LabelButton::SetTextColor(ButtonState for_state, SkColor color) {
@@ -114,6 +115,7 @@ bool LabelButton::GetTextMultiLine() const {
 
 void LabelButton::SetTextMultiLine(bool text_multi_line) {
   label_->SetMultiLine(text_multi_line);
+  ResetCachedSize();
 }
 
 const gfx::FontList& LabelButton::GetFontList() const {
@@ -129,10 +131,12 @@ void LabelButton::SetFontList(const gfx::FontList& font_list) {
   label_->SetFontList(
       style_ == STYLE_BUTTON && is_default_ ?
       cached_bold_font_list_ : cached_normal_font_list_);
+  ResetCachedSize();
 }
 
 void LabelButton::SetElideBehavior(gfx::ElideBehavior elide_behavior) {
   label_->SetElideBehavior(elide_behavior);
+  ResetCachedSize();
 }
 
 gfx::HorizontalAlignment LabelButton::GetHorizontalAlignment() const {
@@ -141,6 +145,7 @@ gfx::HorizontalAlignment LabelButton::GetHorizontalAlignment() const {
 
 void LabelButton::SetHorizontalAlignment(gfx::HorizontalAlignment alignment) {
   label_->SetHorizontalAlignment(alignment);
+  ResetCachedSize();
   InvalidateLayout();
 }
 
@@ -173,7 +178,7 @@ void LabelButton::SetStyle(ButtonStyle style) {
   }
   if (style == STYLE_BUTTON)
     set_min_size(gfx::Size(70, 33));
-
+  ResetCachedSize();

[msw, 2014/07/21 16:28:26]

Call this after OnNativeThemeChanged.

[noms (inactive), 2014/07/21 17:18:51]

Done.

   OnNativeThemeChanged(GetNativeTheme());
 }
 
@@ -182,6 +187,9 @@ void LabelButton::SetFocusPainter(scoped_ptr<Painter> focus_painter) {
 }
 
 gfx::Size LabelButton::GetPreferredSize() const {
+  if (button_size_valid_)
+    return button_size_;
+
   // Use a temporary label copy for sizing to avoid calculation side-effects.
   Label label(GetText(), cached_normal_font_list_);
   label.SetShadows(label_->shadows());
@@ -217,7 +225,11 @@ gfx::Size LabelButton::GetPreferredSize() const {
     size.set_width(std::min(max_size_.width(), size.width()));
   if (max_size_.height() > 0)
     size.set_height(std::min(max_size_.height(), size.height()));
-  return size;
+
+  // Cache this computed size, as recomputing it is an expensive operation.
+  button_size_valid_ = true;
+  button_size_ = size;
+  return button_size_;
 }
 
 int LabelButton::GetHeightForWidth(int w) const {
@@ -292,6 +304,7 @@ scoped_ptr<LabelButtonBorder> LabelButton::CreateDefaultBorder() const {
 void LabelButton::SetBorder(scoped_ptr<Border> border) {
   border_is_themed_border_ = false;
   View::SetBorder(border.Pass());
+  ResetCachedSize();
 }
 
 gfx::Rect LabelButton::GetChildAreaBounds() {
@@ -411,6 +424,7 @@ void LabelButton::StateChanged() {
 }
 
 void LabelButton::ChildPreferredSizeChanged(View* child) {
+  ResetCachedSize();
   PreferredSizeChanged();
 }
 
@@ -458,4 +472,9 @@ ui::NativeTheme::State LabelButton::GetForegroundThemeState(
   return ui::NativeTheme::kHovered;
 }
 
+void LabelButton::ResetCachedSize() {
+  button_size_valid_ = false;
+  button_size_= gfx::Size();
+}
+
 }  // namespace views