Move gfx::ElideText functionality to RenderText.

ui/gfx/render_text.cc

Index: ui/gfx/render_text.cc
diff --git a/ui/gfx/render_text.cc b/ui/gfx/render_text.cc
index c7871ee7a05ed4e1da574e2d6ffb1d6ca03e147a..7ed4edfe514ac023cf7af9ee0fd2e1774517dee4 100644
--- a/ui/gfx/render_text.cc
+++ b/ui/gfx/render_text.cc
@@ -22,7 +22,6 @@
 #include "ui/gfx/scoped_canvas.h"
 #include "ui/gfx/skia_util.h"
 #include "ui/gfx/switches.h"
-#include "ui/gfx/text_constants.h"
 #include "ui/gfx/text_elider.h"
 #include "ui/gfx/text_utils.h"
 #include "ui/gfx/utf16_indexing.h"
@@ -873,6 +872,104 @@ SelectionModel RenderText::GetSelectionModelForSelectionStart() {
                         sel.is_reversed() ? CURSOR_BACKWARD : CURSOR_FORWARD);
 }
 
+base::string16 RenderText::Elide(const base::string16& text,
+                                 float available_width,
+                                 ElideBehavior behavior) {
+  if (text.empty() || behavior == FADE_TAIL)
+    return text;
+  if (available_width <= 0)
+    return base::string16();
+  if (behavior == ELIDE_EMAIL)
+    return ElideEmail(text, available_width);
+
+  // Create a RenderText copy with attributes that affect the rendering width.
+  scoped_ptr<RenderText> render_text(CreateInstance());
+  render_text->SetFontList(font_list_);
+  render_text->SetDirectionalityMode(directionality_mode_);
+  render_text->SetCursorEnabled(cursor_enabled_);
+  render_text->styles_ = styles_;
+  render_text->colors_ = colors_;
+  render_text->SetText(text);
+  const int current_text_pixel_width = render_text->GetContentWidth();
+
+  const base::string16 ellipsis = base::string16(kEllipsisUTF16);
+  const bool insert_ellipsis = (behavior != TRUNCATE);
+  const bool elide_in_middle = (behavior == ELIDE_MIDDLE);
+  const bool elide_at_beginning = (behavior == ELIDE_HEAD);
+  StringSlicer slicer(text, ellipsis, elide_in_middle, elide_at_beginning);
+
+  // Pango will return 0 width for absurdly long strings. Cut the string in
+  // half and try again.
+  // This is caused by an int overflow in Pango (specifically, in
+  // pango_glyph_string_extents_range). It's actually more subtle than just
+  // returning 0, since on super absurdly long strings, the int can wrap and
+  // return positive numbers again. Detecting that is probably not worth it
+  // (eliding way too much from a ridiculous string is probably still
+  // ridiculous), but we should check other widths for bogus values as well.
+  if (current_text_pixel_width <= 0 && !text.empty())
+    return Elide(slicer.CutString(text.length() / 2, insert_ellipsis),
+    available_width, behavior);
+
+  if (current_text_pixel_width <= available_width)
+    return text;
+
+  render_text->SetText(ellipsis);
+  const int ellipsis_width = render_text->GetContentWidth();
+
+  if (insert_ellipsis && (ellipsis_width > available_width))
+    return base::string16();
+
+  // Use binary search to compute the elided text.
+  size_t lo = 0;
+  size_t hi = text.length() - 1;
+  const base::i18n::TextDirection text_direction = GetTextDirection();
+  for (size_t guess = (lo + hi) / 2; lo <= hi; guess = (lo + hi) / 2) {
+    // Restore styles and colors. They will be truncated to size by SetText.
+    render_text->styles_ = styles_;
+    render_text->colors_ = colors_;
+    base::string16 new_text =
+      slicer.CutString(guess, insert_ellipsis && behavior != ELIDE_TAIL);
+    render_text->SetText(new_text);
+
+    // This has to be an additional step so that the ellipsis is rendered with
+    // same style as trailing part of the text.
+    if (insert_ellipsis && behavior == ELIDE_TAIL) {
+      // When ellipsis follows text whose directionality is not the same as that
+      // of the whole text, it will be rendered with the directionality of the
+      // whole text. Since we want ellipsis to indicate continuation of the
+      // preceding text, we force the directionality of ellipsis to be same as
+      // the preceding text using LTR or RTL markers.
+      base::i18n::TextDirection trailing_text_direction =
+        base::i18n::GetLastStrongCharacterDirection(new_text);
+      new_text.append(ellipsis);
+      if (trailing_text_direction != text_direction) {
+        if (trailing_text_direction == base::i18n::LEFT_TO_RIGHT)
+          new_text += base::i18n::kLeftToRightMark;
+        else
+          new_text += base::i18n::kRightToLeftMark;
+      }
+      render_text->SetText(new_text);
+    }
+
+    // We check the width of the whole desired string at once to ensure we
+    // handle kerning/ligatures/etc. correctly.
+    const int guess_width = render_text->GetContentWidth();
+    if (guess_width == available_width)
+      break;
+    if (guess_width > available_width) {
+      hi = guess - 1;
+      // Move back if we are on loop terminating condition, and guess is wider
+      // than available.
+      if (hi < lo)
+        lo = hi;
+    } else {
+      lo = guess + 1;
+    }
+  }
+
+  return render_text->text();
+}
+
 RenderText::RenderText()
     : horizontal_alignment_(base::i18n::IsRTL() ? ALIGN_RIGHT : ALIGN_LEFT),
       directionality_mode_(DIRECTIONALITY_FROM_TEXT),
@@ -1169,101 +1266,66 @@ void RenderText::UpdateLayoutText() {
       GetContentWidth() > display_rect_.width()) {
     // This doesn't trim styles so ellipsis may get rendered as a different
     // style than the preceding text. See crbug.com/327850.
-    layout_text_.assign(ElideText(layout_text_));
+    layout_text_.assign(
+        Elide(layout_text_, display_rect_.width(), elide_behavior_));
   }
 
   ResetLayout();
 }
 
-// TODO(skanuj): Fix code duplication with ElideText in ui/gfx/text_elider.cc
-// See crbug.com/327846
-base::string16 RenderText::ElideText(const base::string16& text) {
-  const bool insert_ellipsis = (elide_behavior_ != TRUNCATE);
-  // Create a RenderText copy with attributes that affect the rendering width.
-  scoped_ptr<RenderText> render_text(CreateInstance());
-  render_text->SetFontList(font_list_);
-  render_text->SetDirectionalityMode(directionality_mode_);
-  render_text->SetCursorEnabled(cursor_enabled_);
-
-  render_text->styles_ = styles_;
-  render_text->colors_ = colors_;
-  render_text->SetText(text);
-  const int current_text_pixel_width = render_text->GetContentWidth();
-
-  const base::string16 ellipsis = base::string16(kEllipsisUTF16);
-  const bool elide_in_middle = false;
-  const bool elide_at_beginning = false;
-  StringSlicer slicer(text, ellipsis, elide_in_middle, elide_at_beginning);
-
-  // Pango will return 0 width for absurdly long strings. Cut the string in
-  // half and try again.
-  // This is caused by an int overflow in Pango (specifically, in
-  // pango_glyph_string_extents_range). It's actually more subtle than just
-  // returning 0, since on super absurdly long strings, the int can wrap and
-  // return positive numbers again. Detecting that is probably not worth it
-  // (eliding way too much from a ridiculous string is probably still
-  // ridiculous), but we should check other widths for bogus values as well.
-  if (current_text_pixel_width <= 0 && !text.empty())
-    return ElideText(slicer.CutString(text.length() / 2, insert_ellipsis));
-
-  if (current_text_pixel_width <= display_rect_.width())
-    return text;
-
-  render_text->SetText(base::string16());
-  render_text->SetText(ellipsis);
-  const int ellipsis_width = render_text->GetContentWidth();
-
-  if (insert_ellipsis && (ellipsis_width >= display_rect_.width()))
-    return base::string16();
-
-  // Use binary search to compute the elided text.
-  size_t lo = 0;
-  size_t hi = text.length() - 1;
-  const base::i18n::TextDirection text_direction = GetTextDirection();
-  for (size_t guess = (lo + hi) / 2; lo <= hi; guess = (lo + hi) / 2) {
-    // Restore styles and colors. They will be truncated to size by SetText.
-    render_text->styles_ = styles_;
-    render_text->colors_ = colors_;
-    base::string16 new_text = slicer.CutString(guess, false);
-    render_text->SetText(new_text);
-
-    // This has to be an additional step so that the ellipsis is rendered with
-    // same style as trailing part of the text.
-    if (insert_ellipsis) {
-      // When ellipsis follows text whose directionality is not the same as that
-      // of the whole text, it will be rendered with the directionality of the
-      // whole text. Since we want ellipsis to indicate continuation of the
-      // preceding text, we force the directionality of ellipsis to be same as
-      // the preceding text using LTR or RTL markers.
-      base::i18n::TextDirection trailing_text_direction =
-          base::i18n::GetLastStrongCharacterDirection(new_text);
-      new_text.append(ellipsis);
-      if (trailing_text_direction != text_direction) {
-        if (trailing_text_direction == base::i18n::LEFT_TO_RIGHT)
-          new_text += base::i18n::kLeftToRightMark;
-        else
-          new_text += base::i18n::kRightToLeftMark;
-      }
-      render_text->SetText(new_text);
-    }
-
-    // We check the width of the whole desired string at once to ensure we
-    // handle kerning/ligatures/etc. correctly.
-    const int guess_width = render_text->GetContentWidth();
-    if (guess_width == display_rect_.width())
-      break;
-    if (guess_width > display_rect_.width()) {
-      hi = guess - 1;
-      // Move back if we are on loop terminating condition, and guess is wider
-      // than available.
-      if (hi < lo)
-        lo = hi;
-    } else {
-      lo = guess + 1;
-    }
+base::string16 RenderText::ElideEmail(const base::string16& email,
+                                      float available_width) {
+  // The returned string will have at least one character besides the ellipses
+  // on either side of '@'; if that's impossible a single ellipsis is returned.
+  // If possible, only the username is elided. Otherwise, the domain is elided
+  // in the middle, splitting available width equally with the elided username.
+  // If the username is short enough that it doesn't need half the available
+  // width, the elided domain will occupy that extra width.
+
+  // Split the email into its local-part (username) and domain-part. The email
+  // spec allows for @ symbols in the username under some special requirements,
+  // but not in the domain part, so splitting at the last @ symbol is safe.
+  const size_t split_index = email.find_last_of('@');
+  DCHECK_NE(split_index, base::string16::npos);
+  base::string16 username = email.substr(0, split_index);
+  base::string16 domain = email.substr(split_index + 1);
+  DCHECK(!username.empty());
+  DCHECK(!domain.empty());
+
+  // Subtract the @ symbol from the available width as it is mandatory.
+  const base::string16 kAtSignUTF16 = base::ASCIIToUTF16("@");
+  available_width -= GetStringWidthF(kAtSignUTF16, font_list());
+
+  // Check whether eliding the domain is necessary: if eliding the username
+  // is sufficient, the domain will not be elided.
+  const float full_username_width = GetStringWidthF(username, font_list());
+  const float available_domain_width = available_width -
+      std::min(full_username_width,
+          GetStringWidthF(username.substr(0, 1) + kEllipsisUTF16, font_list()));
+  if (GetStringWidthF(domain, font_list()) > 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 float desired_domain_width =
+        std::min<float>(available_domain_width,
+            std::max<float>(available_width - full_username_width,
+                            available_width / 2));
+    domain = Elide(domain, desired_domain_width, ELIDE_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 base::string16(kEllipsisUTF16);
   }
 
-  return render_text->text();
+  // 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).
+  available_width -= GetStringWidthF(domain, font_list());
+  username = Elide(username, available_width, ELIDE_TAIL);
+  return username + kAtSignUTF16 + domain;
 }
 
 void RenderText::UpdateCachedBoundsAndOffset() {