Add ability to underline links on hover in Views

ui/views/controls/link.cc

 // 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/views/controls/link.h"
 
 #include "build/build_config.h"
 
 #include "base/logging.h"
 #include "base/utf_string_conversions.h"
@@ skipping 76 matching lines @@
 
     if (listener_)
       listener_->LinkClicked(this, event.flags());
   }
 }
 
 void Link::OnMouseCaptureLost() {
   SetPressed(false);
 }
 
+void Link::OnMouseEntered(const ui::MouseEvent& event) {
+  mouse_inside_ = true;
+  RecalculateFont();
+}
+
+void Link::OnMouseExited(const ui::MouseEvent& event) {
+  mouse_inside_ = false;
+  RecalculateFont();
+}
+
 bool Link::OnKeyPressed(const ui::KeyEvent& event) {
   bool activate = ((event.key_code() == ui::VKEY_SPACE) ||
                    (event.key_code() == ui::VKEY_RETURN));
   if (!activate)
     return false;
 
   SetPressed(false);
 
   // Focus the link on key pressed.
   RequestFocus();
@@ skipping 42 matching lines @@
   if (!pressed_)
     Label::SetEnabledColor(requested_enabled_color_);
 }
 
 void Link::SetPressedColor(SkColor color) {
   requested_pressed_color_ = color;
   if (pressed_)
     Label::SetEnabledColor(requested_pressed_color_);
 }
 
+void Link::SetUnderlineOnHover(bool underline_on_hover) {
+  underline_on_hover_ = underline_on_hover;
+  RecalculateFont();
+}
+
 void Link::Init() {
   static bool initialized = false;
   static SkColor kDefaultEnabledColor;
   static SkColor kDefaultDisabledColor;
   static SkColor kDefaultPressedColor;
   if (!initialized) {
 #if defined(OS_WIN)
     kDefaultEnabledColor = color_utils::GetSysSkColor(COLOR_HOTLIGHT);
     kDefaultDisabledColor = color_utils::GetSysSkColor(COLOR_WINDOWTEXT);
     kDefaultPressedColor = SkColorSetRGB(200, 0, 0);
 #else
     // TODO(beng): source from theme provider.
     kDefaultEnabledColor = SkColorSetRGB(0, 51, 153);
     kDefaultDisabledColor = SK_ColorBLACK;
     kDefaultPressedColor = SK_ColorRED;
 #endif
 
     initialized = true;
   }
 
   listener_ = NULL;
   pressed_ = false;
+  underline_on_hover_ = false;
+  mouse_inside_ = false;
   SetEnabledColor(kDefaultEnabledColor);
   SetDisabledColor(kDefaultDisabledColor);
   SetPressedColor(kDefaultPressedColor);
   RecalculateFont();
   set_focusable(true);
 }
 
 void Link::SetPressed(bool pressed) {
   if (pressed_ != pressed) {
     pressed_ = pressed;
     Label::SetEnabledColor(pressed_ ?
         requested_pressed_color_ : requested_enabled_color_);
     RecalculateFont();
     SchedulePaint();
   }
 }
 
 void Link::RecalculateFont() {
-  // The font should be underlined iff the link is enabled.
-  if (enabled() == !(font().GetStyle() & gfx::Font::UNDERLINED)) {
+  if (underline_on_hover_) {
+    // For underline on hover, the font should be underlined iff the link is
+    // enabled and the mouse is hovering over it.
+    Label::SetFont(font().DeriveFont(0, enabled() && mouse_inside_ ?
+        (font().GetStyle() | gfx::Font::UNDERLINED) :
+        (font().GetStyle() & ~gfx::Font::UNDERLINED)));
+  } else if (enabled() == !(font().GetStyle() & gfx::Font::UNDERLINED)) {
+    // For constant underlining, the font should be underlined iff the link is
+    // enabled.
     Label::SetFont(font().DeriveFont(0, enabled() ?
         (font().GetStyle() | gfx::Font::UNDERLINED) :
         (font().GetStyle() & ~gfx::Font::UNDERLINED)));
   }
 }
 
 }  // namespace views