Elides the beginning of tab titles that have common prefixes. ...

chrome/browser/ui/views/tabs/base_tab.cc

Index: chrome/browser/ui/views/tabs/base_tab.cc
===================================================================
--- chrome/browser/ui/views/tabs/base_tab.cc	(revision 76049)
+++ chrome/browser/ui/views/tabs/base_tab.cc	(working copy)
@@ -434,6 +434,7 @@
 
 void BaseTab::PaintTitle(gfx::Canvas* canvas, SkColor title_color) {
   // Paint the Title.
+  const gfx::Rect& title_bounds = GetTitleBounds();
   string16 title = data().title;
   if (title.empty()) {
     title = data().loading ?
@@ -441,8 +442,15 @@
         TabContentsWrapper::GetDefaultTitle();
   } else {
     Browser::FormatTitleForDisplay(&title);
+    // If we'll need to truncate, check if we should also truncate
+    // a common prefix, but only if there is enough room for it.
+    // We arbitrarily choose to request enough room for 10 average chars.
+    if (data().common_prefix_length > 0 &&
+        font_->GetExpectedTextWidth(10) < title_bounds.width() &&

[sky, 2011/02/25 21:04:44]

I thought this became more important once the strings got smaller. Although, is
there a reason why we shouldn't always do this?

[MAD, 2011/02/25 21:49:24]

Because we may end up with something like ...x... which isn't very useful...

[sky, 2011/02/25 22:59:27]

Good point.
Different suggestion then. For folks with lots of tabs all this work is useless.
Would be nice to have a check that avoids doing anything if all the tabs are
small.

[MAD, 2011/03/10 19:03:44]

That would be hard, since the title_bounds and font are not public. Would it be
worth making them public so that the tab_strip could use them to make this
decision?

[sky, 2011/03/11 00:00:45]

Do you even need that? For horizontal tabs (TabStrip) couldn't you only do if
the width of each tab is > some value? For vertical tabs (SideTabStrip) you
probably never want to do this. I think.

If you do this you would have to be careful to recalculate things on layout.
This is a pretty expensive computation. Is it worth trying to avoid it?

[MAD, 2011/03/11 03:01:37]

Hum... I'm not sure what would be a good "some value"... But I could try
something...

I guess I could keep an extra boolean identifying if I need to recompute the
prefixes or not, and only compute them when I need to and when I have enough
room for them... What do you think?

+        font_->GetStringWidth(title) > title_bounds.width()) {
+      title.replace(0, data().common_prefix_length, ASCIIToUTF16("..."));

[sky, 2011/02/25 21:04:44]

I think you should use the same string as in text_elider for this (kEllipsis).

[MAD, 2011/02/25 21:49:24]

Ho, thanks, I didn't know about that...
Done...

+    }
   }
-  const gfx::Rect& title_bounds = GetTitleBounds();
   canvas->DrawStringInt(title, *font_, title_color,
                         title_bounds.x(), title_bounds.y(),
                         title_bounds.width(), title_bounds.height());