Change signature of |ui::ElideText()|. Add a truncate mode.

The new truncate mode is needed by my upcoming changes to
rewrite CanvasSkia::DrawText().

Part of the change is changing the binary search code to a
more traditional form that also makes the truncate mode
work correctly. This is covered by the new unit tests.

BUG=105550
TEST=New and existing tests in text_elider_unittest.cc.
Review URL: http://codereview.chromium.org/8917011

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@114063 0039d316-1c4b-4281-b951-d872f2087c98

3 files changed, 66 insertions, 28 deletions

diff --git a/ui/base/text/text_elider.cc b/ui/base/text/text_elider.cc
index 17f41c4..13ee279 100644
--- a/ui/base/text/text_elider.cc
+++ b/ui/base/text/text_elider.cc
@@ -94,7 +94,7 @@ string16 ElideComponentizedPath(const string16& url_path_prefix,
         url_path_elements, url_filename, i);
     if (available_pixel_width >= font.GetStringWidth(elided_path))
       return ElideText(elided_path + url_query,
-          font, available_pixel_width, false);
+          font, available_pixel_width, ui::ELIDE_AT_END);
   }
 
   return string16();
@@ -125,7 +125,7 @@ string16 ElideUrl(const GURL& url,
 
   // If non-standard or not file type, return plain eliding.
   if (!(url.SchemeIsFile() || url.IsStandard()))
-    return ElideText(url_string, font, available_pixel_width, false);
+    return ElideText(url_string, font, available_pixel_width, ui::ELIDE_AT_END);
 
   // Now start eliding url_string to fit within available pixel width.
   // Fist pass - check to see whether entire url_string fits.
@@ -142,7 +142,7 @@ string16 ElideUrl(const GURL& url,
   // Return general elided text if url minus the query fits.
   string16 url_minus_query = url_string.substr(0, path_start_index + path_len);
   if (available_pixel_width >= font.GetStringWidth(url_minus_query))
-    return ElideText(url_string, font, available_pixel_width, false);
+    return ElideText(url_string, font, available_pixel_width, ui::ELIDE_AT_END);
 
   // Get Host.
   string16 url_host = UTF8ToUTF16(url.host());
@@ -213,7 +213,7 @@ string16 ElideUrl(const GURL& url,
         pixel_width_url_domain + pixel_width_url_path -
         font.GetStringWidth(url_query))) {
       return ElideText(url_subdomain + url_domain + url_path_query_etc,
-                       font, available_pixel_width, false);
+                       font, available_pixel_width, ui::ELIDE_AT_END);
     }
   }
 
@@ -241,7 +241,7 @@ string16 ElideUrl(const GURL& url,
     // No path to elide, or too long of a path (could overflow in loop below)
     // Just elide this as a text string.
     return ElideText(url_subdomain + url_domain + url_path_query_etc, font,
-                     available_pixel_width, false);
+                     available_pixel_width, ui::ELIDE_AT_END);
   }
 
   // Start eliding the path and replacing elements by ".../".
@@ -288,7 +288,8 @@ string16 ElideUrl(const GURL& url,
     final_elided_url_string += url_path;
   }
 
-  return ElideText(final_elided_url_string, font, available_pixel_width, false);
+  return ElideText(final_elided_url_string, font, available_pixel_width,
+                   ui::ELIDE_AT_END);
 }
 
 string16 ElideFilename(const FilePath& filename,
@@ -313,7 +314,7 @@ string16 ElideFilename(const FilePath& filename,
 
   if (rootname.empty() || extension.empty()) {
     string16 elided_name = ElideText(filename_utf16, font,
-                                     available_pixel_width, false);
+                                     available_pixel_width, ui::ELIDE_AT_END);
     return base::i18n::GetDisplayStringInLTRDirectionality(elided_name);
   }
 
@@ -328,13 +329,14 @@ string16 ElideFilename(const FilePath& filename,
 
   if (ext_width >= available_pixel_width) {
     string16 elided_name = ElideText(rootname + extension, font,
-                                     available_pixel_width, true);
+                                     available_pixel_width,
+                                     ui::ELIDE_IN_MIDDLE);
     return base::i18n::GetDisplayStringInLTRDirectionality(elided_name);
   }
 
   int available_root_width = available_pixel_width - ext_width;
   string16 elided_name =
-      ElideText(rootname, font, available_root_width, false);
+      ElideText(rootname, font, available_root_width, ui::ELIDE_AT_END);
   elided_name += extension;
   return base::i18n::GetDisplayStringInLTRDirectionality(elided_name);
 }
@@ -344,11 +346,13 @@ string16 ElideFilename(const FilePath& filename,
 string16 ElideText(const string16& text,
                    const gfx::Font& font,
                    int available_pixel_width,
-                   bool elide_in_middle) {
+                   ElideBehavior elide_behavior) {
   if (text.empty())
     return text;
 
   int current_text_pixel_width = font.GetStringWidth(text);
+  bool elide_in_middle = (elide_behavior == ui::ELIDE_IN_MIDDLE);
+  bool insert_ellipsis = (elide_behavior != ui::TRUNCATE_AT_END);
 
   // Pango will return 0 width for absurdly long strings. Cut the string in
   // half and try again.
@@ -360,7 +364,7 @@ string16 ElideText(const string16& text,
   // ridiculous), but we should check other widths for bogus values as well.
   if (current_text_pixel_width <= 0 && !text.empty()) {
     return ElideText(CutString(text, text.length() / 2, elide_in_middle, false),
-                     font, available_pixel_width, false);
+                     font, available_pixel_width, elide_behavior);
   }
 
   if (current_text_pixel_width <= available_pixel_width)
@@ -372,24 +376,25 @@ string16 ElideText(const string16& text,
   // Use binary search to compute the elided text.
   size_t lo = 0;
   size_t hi = text.length() - 1;
-  for (size_t guess = (lo + hi) / 2; guess != lo; guess = (lo + hi) / 2) {
+  size_t guess;
+  for (guess = (lo + hi) / 2; lo <= hi; guess = (lo + hi) / 2) {
     // We check the length of the whole desired string at once to ensure we
     // handle kerning/ligatures/etc. correctly.
-    int guess_length = font.GetStringWidth(
-        CutString(text, guess, elide_in_middle, true));
+    string16 cut = CutString(text, guess, elide_in_middle, insert_ellipsis);
+    int guess_length = font.GetStringWidth(cut);
     // Check again that we didn't hit a Pango width overflow. If so, cut the
     // current string in half and start over.
     if (guess_length <= 0) {
       return ElideText(CutString(text, guess / 2, elide_in_middle, false),
-                       font, available_pixel_width, elide_in_middle);
+                       font, available_pixel_width, elide_behavior);
     }
     if (guess_length > available_pixel_width)
-      hi = guess;
+      hi = guess - 1;
     else
-      lo = guess;
+      lo = guess + 1;
   }
 
-  return CutString(text, lo, elide_in_middle, true);
+  return CutString(text, guess, elide_in_middle, insert_ellipsis);
 }
 
 SortedDisplayURL::SortedDisplayURL(const GURL& url,
@@ -576,6 +581,8 @@ class RectangleString {
 
   // String onto which the output is accumulated.
   string16* output_;
+
+  DISALLOW_COPY_AND_ASSIGN(RectangleString);
 };
 
 void RectangleString::AddString(const string16& input) {
diff --git a/ui/base/text/text_elider.h b/ui/base/text/text_elider.h
index 7b298ee..a1dd86a 100644
--- a/ui/base/text/text_elider.h
+++ b/ui/base/text/text_elider.h
@@ -40,13 +40,21 @@ UI_EXPORT string16 ElideUrl(const GURL& url,
                             int available_pixel_width,
                             const std::string& languages);
 
-// Elides |text| to fit in |available_pixel_width|.  If |elide_in_middle| is
-// set the ellipsis is placed in the middle of the string; otherwise it is
-// placed at the end.
+enum ElideBehavior {
+  // Add ellipsis at the end of the string.
+  ELIDE_AT_END,
+  // Add ellipsis in the middle of the string.
+  ELIDE_IN_MIDDLE,
+  // Truncate the end of the string.
+  TRUNCATE_AT_END
+};
+
+// Elides |text| to fit in |available_pixel_width| according to the specified
+// |elide_behavior|.
 UI_EXPORT string16 ElideText(const string16& text,
                              const gfx::Font& font,
                              int available_pixel_width,
-                             bool elide_in_middle);
+                             ElideBehavior elide_behavior);
 
 // Elide a filename to fit a given pixel width, with an emphasis on not hiding
 // the extension unless we have to. If filename contains a path, the path will
diff --git a/ui/base/text/text_elider_unittest.cc b/ui/base/text/text_elider_unittest.cc
index 60ab1f7..b716a00 100644
--- a/ui/base/text/text_elider_unittest.cc
+++ b/ui/base/text/text_elider_unittest.cc
@@ -82,8 +82,7 @@ TEST(TextEliderTest, TestGeneralEliding) {
 // both path AND file name to an ellipsis - ".../...". To avoid this result,
 // there is a hack in place that simply treats them as one string in this
 // case.
-TEST(TextEliderTest, TestTrailingEllipsisSlashEllipsisHack)
-{
+TEST(TextEliderTest, TestTrailingEllipsisSlashEllipsisHack) {
   const std::string kEllipsisStr(kEllipsis);
 
   // Very little space, would cause double ellipsis.
@@ -215,6 +214,29 @@ TEST(TextEliderTest, TestFilenameEliding) {
   }
 }
 
+TEST(TextEliderTest, ElideTextTruncate) {
+  const gfx::Font font;
+  const int kTestWidth = font.GetStringWidth(ASCIIToUTF16("Test"));
+  struct TestData {
+    const char* input;
+    int width;
+    const char* output;
+  } cases[] = {
+    { "", 0, "" },
+    { "Test", 0, "" },
+    { "", kTestWidth, "" },
+    { "Tes", kTestWidth, "Tes" },
+    { "Test", kTestWidth, "Test" },
+    { "Tests", kTestWidth, "Test" },
+  };
+
+  for (size_t i = 0; i < ARRAYSIZE_UNSAFE(cases); ++i) {
+    string16 result = ui::ElideText(UTF8ToUTF16(cases[i].input), font,
+                                    cases[i].width, ui::TRUNCATE_AT_END);
+    EXPECT_EQ(cases[i].output, UTF16ToUTF8(result));
+  }
+}
+
 TEST(TextEliderTest, ElideTextLongStrings) {
   const string16 kEllipsisStr = UTF8ToUTF16(kEllipsis);
   string16 data_scheme(UTF8ToUTF16("data:text/plain,"));
@@ -247,9 +269,10 @@ TEST(TextEliderTest, ElideTextLongStrings) {
     EXPECT_EQ(testcases_end[i].output.size(),
               ElideText(testcases_end[i].input, font,
                         font.GetStringWidth(testcases_end[i].output),
-                        false).size());
+                        ui::ELIDE_AT_END).size());
     EXPECT_EQ(kEllipsisStr,
-              ElideText(testcases_end[i].input, font, ellipsis_width, false));
+              ElideText(testcases_end[i].input, font, ellipsis_width,
+                        ui::ELIDE_AT_END));
   }
 
   size_t number_of_trailing_as = (data_scheme_length + number_of_as) / 2;
@@ -271,10 +294,10 @@ TEST(TextEliderTest, ElideTextLongStrings) {
     EXPECT_EQ(testcases_middle[i].output.size(),
               ElideText(testcases_middle[i].input, font,
                         font.GetStringWidth(testcases_middle[i].output),
-                        false).size());
+                        ui::ELIDE_AT_END).size());
     EXPECT_EQ(kEllipsisStr,
               ElideText(testcases_middle[i].input, font, ellipsis_width,
-                        false));
+                        ui::ELIDE_AT_END));
   }
 }