GTK Theme: Make inactive titlebar legible.

I'm pretty certain we'll never be able to match the text color on custom popup
windows, but at the very least make it legible. Tested in both light and dark
themes.

http://crbug.com/18856

Review URL: http://codereview.chromium.org/173061

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@23734 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 123 insertions, 9 deletions

diff --git a/chrome/browser/gtk/browser_titlebar.cc b/chrome/browser/gtk/browser_titlebar.cc
index 24567f4..98c440e 100644
--- a/chrome/browser/gtk/browser_titlebar.cc
+++ b/chrome/browser/gtk/browser_titlebar.cc
@@ -17,12 +17,15 @@
 #include "chrome/browser/browser.h"
 #include "chrome/browser/gtk/browser_window_gtk.h"
 #include "chrome/browser/gtk/custom_button.h"
+#include "chrome/browser/gtk/gtk_theme_provider.h"
 #include "chrome/browser/gtk/menu_gtk.h"
 #include "chrome/browser/gtk/nine_box.h"
 #include "chrome/browser/gtk/standard_menus.h"
 #include "chrome/browser/gtk/tabs/tab_strip_gtk.h"
 #include "chrome/browser/profile.h"
 #include "chrome/browser/tab_contents/tab_contents.h"
+#include "chrome/common/gtk_util.h"
+#include "chrome/common/notification_service.h"
 #include "chrome/common/pref_names.h"
 #include "chrome/common/pref_service.h"
 #include "grit/app_resources.h"
@@ -90,6 +93,34 @@ GdkPixbuf* GetOTRAvatar() {
   return otr_avatar;
 }
 
+// Converts a GdkColor to a skia::HSL.
+skia::HSL GdkColorToHSL(const GdkColor* color) {
+  skia::HSL hsl;
+  skia::SkColorToHSL(SkColorSetRGB(color->red >> 8,
+                                   color->green >> 8,
+                                   color->blue >> 8), hsl);
+  return hsl;
+}
+
+// Returns either |one| or |two| based on which has a greater difference in
+// luminosity.
+GdkColor PickLuminosityContrastingColor(const GdkColor* base,
+                                        const GdkColor* one,
+                                        const GdkColor* two) {
+  // Convert all GdkColors to skia::HSLs.
+  skia::HSL baseHSL = GdkColorToHSL(base);
+  skia::HSL oneHSL = GdkColorToHSL(one);
+  skia::HSL twoHSL = GdkColorToHSL(two);
+  double one_difference = fabs(baseHSL.l - oneHSL.l);
+  double two_difference = fabs(baseHSL.l - twoHSL.l);
+
+  // Be biased towards the first color presented.
+  if (two_difference > one_difference + 0.1)
+    return *two;
+  else
+    return *one;
+}
+
 }  // namespace
 
 BrowserTitlebar::BrowserTitlebar(BrowserWindowGtk* browser_window,
@@ -97,7 +128,9 @@ BrowserTitlebar::BrowserTitlebar(BrowserWindowGtk* browser_window,
     : browser_window_(browser_window), window_(window),
       app_mode_favicon_(NULL),
       app_mode_title_(NULL),
-      using_custom_frame_(false) {
+      using_custom_frame_(false),
+      window_has_focus_(false),
+      theme_provider_(NULL) {
   Init();
 }
 
@@ -189,6 +222,14 @@ void BrowserTitlebar::Init() {
     gtk_misc_set_alignment(GTK_MISC(app_mode_title_), 0.0, 0.5);
     gtk_box_pack_start(GTK_BOX(app_mode_hbox), app_mode_title_, TRUE, TRUE,
                        0);
+
+    // Register with the theme provider to set the |app_mode_title_| label
+    // color.
+    theme_provider_ = GtkThemeProvider::GetFrom(
+        browser_window_->browser()->profile());
+    registrar_.Add(this, NotificationType::BROWSER_THEME_CHANGED,
+                   NotificationService::AllSources());
+    theme_provider_->InitThemesFor(this);
     UpdateTitle();
   }
 
@@ -230,6 +271,9 @@ void BrowserTitlebar::Init() {
                    FALSE, 0);
 
   gtk_widget_show_all(container_);
+
+  registrar_.Add(this, NotificationType::ACTIVE_WINDOW_CHANGED,
+                 NotificationService::AllSources());
 }
 
 CustomDrawButton* BrowserTitlebar::BuildTitlebarButton(int image,
@@ -263,13 +307,7 @@ void BrowserTitlebar::UpdateTitle() {
 
   // Get the page title and elide it to the available space.
   string16 title = browser_window_->browser()->GetWindowTitleForCurrentTab();
-
-  // TODO(tc): Seems like this color should be themable, but it's hardcoded to
-  // white on Windows.  http://crbug.com/18093
-  gchar* label_markup = g_markup_printf_escaped("<span color='white'>%s</span>",
-      UTF16ToUTF8(title).c_str());
-  gtk_label_set_markup(GTK_LABEL(app_mode_title_), label_markup);
-  g_free(label_markup);
+  gtk_label_set_text(GTK_LABEL(app_mode_title_), UTF16ToUTF8(title).c_str());
 }
 
 void BrowserTitlebar::UpdateThrobber(TabContents* tab_contents) {
@@ -343,6 +381,41 @@ void BrowserTitlebar::UpdateTitlebarAlignment() {
                               restore_button_req.height);
 }
 
+void BrowserTitlebar::UpdateTextColor() {
+  if (app_mode_title_) {
+    if (theme_provider_ && theme_provider_->UseGtkTheme()) {
+      // We don't really have any good options here.
+      //
+      // Colors from window manager themes aren't exposed in GTK; the window
+      // manager is a separate component and when there is information sharing
+      // (in the case of metacity), it's one way where the window manager reads
+      // data from the GTK theme (which allows us to do a decent job with
+      // picking the frame color).
+      //
+      // We probably won't match in the majority of cases, but we can at the
+      // very least make things legible. The default metacity and xfwm themes
+      // on ubuntu have white text hardcoded. Determine whether black or white
+      // has more luminosity contrast and then set that color as the text
+      // color.
+      GdkColor frame_color;
+      if (window_has_focus_) {
+        frame_color = theme_provider_->GetGdkColor(
+          BrowserThemeProvider::COLOR_FRAME);
+      } else {
+        frame_color = theme_provider_->GetGdkColor(
+          BrowserThemeProvider::COLOR_FRAME_INACTIVE);
+      }
+      GdkColor text_color = PickLuminosityContrastingColor(
+          &frame_color, &gfx::kGdkWhite, &gfx::kGdkBlack);
+      gtk_util::SetLabelColor(app_mode_title_, &text_color);
+    } else {
+      // TODO(tc): Seems like this color should be themable, but it's hardcoded
+      // to white on Windows.  http://crbug.com/18093
+      gtk_util::SetLabelColor(app_mode_title_, &gfx::kGdkWhite);
+    }
+  }
+}
+
 // static
 gboolean BrowserTitlebar::OnWindowStateChanged(GtkWindow* window,
     GdkEventWindowState* event, BrowserTitlebar* titlebar) {
@@ -355,6 +428,7 @@ gboolean BrowserTitlebar::OnWindowStateChanged(GtkWindow* window,
     gtk_widget_show(titlebar->maximize_button_->widget());
   }
   titlebar->UpdateTitlebarAlignment();
+  titlebar->UpdateTextColor();
   return FALSE;
 }
 
@@ -455,6 +529,24 @@ void BrowserTitlebar::ExecuteCommand(int command_id) {
   }
 }
 
+void BrowserTitlebar::Observe(NotificationType type,
+                              const NotificationSource& source,
+                              const NotificationDetails& details) {
+  switch (type.value) {
+    case NotificationType::BROWSER_THEME_CHANGED:
+      UpdateTextColor();
+      break;
+    case NotificationType::ACTIVE_WINDOW_CHANGED: {
+      const GdkWindow* active_window = Details<const GdkWindow>(details).ptr();
+      window_has_focus_ = GTK_WIDGET(window_)->window == active_window;
+      UpdateTextColor();
+      break;
+    }
+    default:
+      NOTREACHED();
+  }
+}
+
 ///////////////////////////////////////////////////////////////////////////////
 // BrowserTitlebar::Throbber implementation
 // TODO(tc): Handle anti-clockwise spinning when waiting for a connection.
diff --git a/chrome/browser/gtk/browser_titlebar.h b/chrome/browser/gtk/browser_titlebar.h
index 29b3cb2..7263aec 100644
--- a/chrome/browser/gtk/browser_titlebar.h
+++ b/chrome/browser/gtk/browser_titlebar.h
@@ -14,13 +14,17 @@
 
 #include "base/scoped_ptr.h"
 #include "chrome/browser/gtk/menu_gtk.h"
+#include "chrome/common/notification_observer.h"
+#include "chrome/common/notification_registrar.h"
 
 class BrowserWindowGtk;
 class CustomDrawButton;
+class GtkThemeProvider;
 class TabContents;
 class TabStripGtk;
 
-class BrowserTitlebar : public MenuGtk::Delegate {
+class BrowserTitlebar : public MenuGtk::Delegate,
+                        public NotificationObserver {
  public:
   BrowserTitlebar(BrowserWindowGtk* browser_window, GtkWindow* window);
   virtual ~BrowserTitlebar() { }
@@ -83,6 +87,10 @@ class BrowserTitlebar : public MenuGtk::Delegate {
   // Update the titlebar spacing based on the custom frame and maximized state.
   void UpdateTitlebarAlignment();
 
+  // Updates the color of the title bar. Called whenever we have a state
+  // change in the window.
+  void UpdateTextColor();
+
   // Callback for changes to window state.  This includes
   // maximizing/restoring/minimizing the window.
   static gboolean OnWindowStateChanged(GtkWindow* window,
@@ -103,6 +111,11 @@ class BrowserTitlebar : public MenuGtk::Delegate {
   virtual bool IsItemChecked(int command_id) const;
   virtual void ExecuteCommand(int command_id);
 
+  // Overridden from NotificationObserver:
+  virtual void Observe(NotificationType type,
+                       const NotificationSource& source,
+                       const NotificationDetails& details);
+
   // Pointers to the browser window that owns us and it's GtkWindow.
   BrowserWindowGtk* browser_window_;
   GtkWindow* window_;
@@ -127,6 +140,10 @@ class BrowserTitlebar : public MenuGtk::Delegate {
   // Whether we are using a custom frame.
   bool using_custom_frame_;
 
+  // Whether we have focus (gtk_window_is_active() sometimes returns the wrong
+  // value, so manually track the focus-in and focus-out events.)
+  bool window_has_focus_;
+
   // We change the size of these three buttons when the window is maximized, so
   // we use these structs to keep track of their original size.
   GtkRequisition close_button_req_;
@@ -144,6 +161,11 @@ class BrowserTitlebar : public MenuGtk::Delegate {
 
   // The throbber used when the window is in app mode or popup window mode.
   Throbber throbber_;
+
+  // Theme provider for building buttons.
+  GtkThemeProvider* theme_provider_;
+
+  NotificationRegistrar registrar_;
 };
 
 #endif  // CHROME_BROWSER_GTK_BROWSER_TITLEBAR_H_