Elide long emails in the wrench and profile menus.

ui/base/text/text_elider.cc

Index: ui/base/text/text_elider.cc
diff --git a/ui/base/text/text_elider.cc b/ui/base/text/text_elider.cc
index 525cea0df61eb373507b91372f144dbf327cf419..62ad7d062b68cd937715e3098ceae2cdfe1fd56c 100644
--- a/ui/base/text/text_elider.cc
+++ b/ui/base/text/text_elider.cc
@@ -149,12 +149,66 @@ string16 ElideComponentizedPath(const string16& url_path_prefix,
 
 }  // namespace
 
-// This function takes a GURL object and elides it. It returns a string
-// which composed of parts from subdomain, domain, path, filename and query.
-// A "..." is added automatically at the end if the elided string is bigger
-// than the available pixel width. For available pixel width = 0, a formatted,
-// but un-elided, string is returned.
-//
+string16 ElideEmail(const string16& email,
+                    const gfx::Font& font,
+                    int available_pixel_width) {
+  if (font.GetStringWidth(email) <= available_pixel_width)
+    return email;
+
+  // Split the email into its local-part (username) and domain-part. The email
+  // spec technically allows for @ symbols in the local-part (username) of the
+  // email under some special requirements. It is guaranteed that there is no @
+  // symbol in the domain part of the email however so splitting at the last @
+  // symbol is safe.
+  const size_t split_index = email.find_last_of('@');
+  DCHECK_NE(split_index, string16::npos);
+  string16 username = email.substr(0, split_index);
+  string16 domain = email.substr(split_index + 1);
+  DCHECK(!username.empty());
+  DCHECK(!domain.empty());
+
+  const string16 kEllipsisUTF16 = UTF8ToUTF16(kEllipsis);
+
+  // Subtract the @ symbol from the available width as it is mandatory.
+  const string16 kAtSignUTF16 = ASCIIToUTF16("@");
+  available_pixel_width -= font.GetStringWidth(kAtSignUTF16);
+
+  // Check whether eliding the domain is necessary: if eliding the username
+  // is sufficient, the domain will not be elided.
+  const int full_username_width = font.GetStringWidth(username);
+  const int available_domain_width =
+      available_pixel_width -
+      std::min(full_username_width,
+               font.GetStringWidth(username.substr(0, 1) + kEllipsisUTF16));
+  if (font.GetStringWidth(domain) > available_domain_width) {
+    // Elide the domain so that it only takes half of the available width.
+    // Should the username not need all the width available in its half, the
+    // domain will occupy the leftover width.
+    // If |desired_domain_width| is greater than |available_domain_width|: the
+    // minimal username elision allowed by the specifications will not fit; thus
+    // |desired_domain_width| must be <= |available_domain_width| at all cost.
+    const int desired_domain_width =
+        std::min(available_domain_width,
+                 std::max(available_pixel_width - full_username_width,
+                          available_pixel_width / 2));
+    domain = ElideText(domain, font, desired_domain_width, ELIDE_IN_MIDDLE);
+    // Failing to elide the domain such that at least one character remains
+    // (other than the ellipsis itself) remains: return a single ellipsis.
+    if (domain.length() <= 1U)
+      return kEllipsisUTF16;
+  }
+
+  // Fit the username in the remaining width (at this point the elided username
+  // is guaranteed to fit with at least one character remaining given all the
+  // precautions taken earlier).
+  username = ElideText(username,
+                       font,
+                       available_pixel_width - font.GetStringWidth(domain),
+                       ELIDE_AT_END);
+
+  return username + kAtSignUTF16 + domain;
+}
+
 // TODO(pkasting): http://crbug.com/77883 This whole function gets
 // kerning/ligatures/etc. issues potentially wrong by assuming that the width of
 // a rendered string is always the sum of the widths of its substrings.  Also I
@@ -393,8 +447,6 @@ string16 ElideFilename(const FilePath& filename,
   return base::i18n::GetDisplayStringInLTRDirectionality(elided_name);
 }
 
-// This function adds an ellipsis at the end of the text if the text
-// does not fit the given pixel width.
 string16 ElideText(const string16& text,
                    const gfx::Font& font,
                    int available_pixel_width,