Elide long emails in the wrench and profile menus.

NOTE: This CL now only adds eliding functionality, but doesn't use it in the UI just yet.

Refer to bug 113133 for details (refer to comment 22 for a screenshot of the result: http://code.google.com/p/chromium/issues/detail?id=113133#c22).

BUG=113133
TEST=Make sure ui_unittests (ElideEmail and ElideEmailMoreSpace) pass.

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=126445

Review URL: http://codereview.chromium.org/9489011

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@127175 0039d316-1c4b-4281-b951-d872f2087c98

3 files changed, 159 insertions, 12 deletions

diff --git a/ui/base/text/text_elider.cc b/ui/base/text/text_elider.cc
index 525cea0..62ad7d0 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,
diff --git a/ui/base/text/text_elider.h b/ui/base/text/text_elider.h
index caac9d8..68c392f 100644
--- a/ui/base/text/text_elider.h
+++ b/ui/base/text/text_elider.h
@@ -25,13 +25,28 @@ namespace ui {
 
 UI_EXPORT extern const char kEllipsis[];
 
+// Elides a well-formed email address (e.g. username@domain.com) to fit into
+// |available_pixel_width| using the specified |font|.
+// This function guarantees that the string returned will contain at least one
+// character, other than the ellipses, on either side of the '@'. If it is
+// impossible to achieve these requirements: only an ellipsis will be returned.
+// If possible: this elides only the username portion of the |email|. Otherwise,
+// the domain is elided in the middle so that it splits the available width
+// equally with the elided username (should the username be short enough that it
+// doesn't need half the available width: the elided domain will occupy that
+// extra width).
+UI_EXPORT string16 ElideEmail(const string16& email,
+                              const gfx::Font& font,
+                              int available_pixel_width);
+
 // 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, empty
-// string is returned. |languages| is a comma separated list of ISO 639
-// language codes and is used to determine what characters are understood
-// by a user. It should come from |prefs::kAcceptLanguages|.
+// than the |available_pixel_width|. For |available_pixel_width| == 0, a
+// formatted, but un-elided, string is returned. |languages| is a comma
+// separated list of ISO 639 language codes and is used to determine what
+// characters are understood by a user. It should come from
+// |prefs::kAcceptLanguages|.
 //
 // Note: in RTL locales, if the URL returned by this function is going to be
 // displayed in the UI, then it is likely that the string needs to be marked
diff --git a/ui/base/text/text_elider_unittest.cc b/ui/base/text/text_elider_unittest.cc
index 217170c..aad021e 100644
--- a/ui/base/text/text_elider_unittest.cc
+++ b/ui/base/text/text_elider_unittest.cc
@@ -55,6 +55,86 @@ void RunUrlTest(Testcase* testcases, size_t num_testcases) {
 
 }  // namespace
 
+TEST(TextEliderTest, ElideEmail) {
+  const std::string kEllipsisStr(kEllipsis);
+
+  // Test emails and their expected elided forms (from which the available
+  // widths will be derived).
+  // For elided forms in which both the username and domain must be elided:
+  // the result (how many characters are left on each side) can be font
+  // dependent. To avoid this, the username is prefixed with the characters
+  // expected to remain in the domain.
+  Testcase testcases[] = {
+      {"g@g.c", "g@g.c"},
+      {"g@g.c", kEllipsisStr},
+      {"ga@co.ca", "ga@c" + kEllipsisStr + "a"},
+      {"short@small.com", "s" + kEllipsisStr + "@s" + kEllipsisStr},
+      {"short@small.com", "s" + kEllipsisStr + "@small.com"},
+      {"short@longbutlotsofspace.com", "short@longbutlotsofspace.com"},
+      {"short@longbutnotverymuchspace.com",
+       "short@long" + kEllipsisStr + ".com"},
+      {"la_short@longbutverytightspace.ca",
+       "la" + kEllipsisStr + "@l" + kEllipsisStr + "a"},
+      {"longusername@gmail.com", "long" + kEllipsisStr + "@gmail.com"},
+      {"elidetothemax@justfits.com", "e" + kEllipsisStr + "@justfits.com"},
+      {"thatom_somelongemail@thatdoesntfit.com",
+       "thatom" + kEllipsisStr + "@tha" + kEllipsisStr + "om"},
+      {"namefits@butthedomaindoesnt.com",
+       "namefits@butthedo" + kEllipsisStr + "snt.com"},
+      {"widthtootight@nospace.com", kEllipsisStr},
+      {"nospaceforusername@l", kEllipsisStr},
+      {"little@littlespace.com", "l" + kEllipsisStr + "@l" + kEllipsisStr},
+      {"l@llllllllllllllllllllllll.com", "l@lllll" + kEllipsisStr + ".com"},
+      {"messed\"up@whyanat\"++@notgoogley.com",
+       "messed\"up@whyanat\"++@notgoogley.com"},
+      {"messed\"up@whyanat\"++@notgoogley.com",
+       "messed\"up@why" + kEllipsisStr + "@notgoogley.com"},
+      {"noca_messed\"up@whyanat\"++@notgoogley.ca",
+       "noca" + kEllipsisStr + "@no" + kEllipsisStr + "ca"},
+      {"at\"@@@@@@@@@...@@.@.@.@@@\"@madness.com",
+       "at\"@@@@@@@@@...@@.@." + kEllipsisStr + "@madness.com"},
+      // Special case: "m..." takes more than half of the available width; thus
+      // the domain must elide to "l..." and not "l...l" as it must allow enough
+      // space for the minimal username elision although its half of the
+      // available width would normally allow it to elide to "l...l".
+      {"mmmmm@llllllllll", "m" + kEllipsisStr + "@l" + kEllipsisStr},
+  };
+
+  const gfx::Font font;
+  for (size_t i = 0; i < arraysize(testcases); ++i) {
+    const string16 expected_output = UTF8ToUTF16(testcases[i].output);
+    EXPECT_EQ(expected_output,
+              ElideEmail(UTF8ToUTF16(testcases[i].input),
+                         font,
+                         font.GetStringWidth(expected_output)));
+  }
+}
+
+TEST(TextEliderTest, ElideEmailMoreSpace) {
+  const int test_width_factors[] = {
+      100,
+      10000,
+      1000000,
+  };
+  const std::string test_emails[] = {
+      "a@c",
+      "test@email.com",
+      "short@verysuperdupperlongdomain.com",
+      "supermegalongusername@withasuperlonnnggggdomain.gouv.qc.ca",
+  };
+
+  const gfx::Font font;
+  for (size_t i = 0; i < arraysize(test_width_factors); ++i) {
+    const int test_width = test_width_factors[i] *
+                           font.GetAverageCharacterWidth();
+    for (size_t j = 0; j < arraysize(test_emails); ++j) {
+      // Extra space is available: the email should not be elided.
+      const string16 test_email = UTF8ToUTF16(test_emails[j]);
+      EXPECT_EQ(test_email, ElideEmail(test_email, font, test_width));
+    }
+  }
+}
+
 // Test eliding of commonplace URLs.
 TEST(TextEliderTest, TestGeneralEliding) {
   const std::string kEllipsisStr(kEllipsis);