Don't split text runs on underline style change

ui/gfx/render_text_unittest.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/gfx/render_text.h"
 
 #include <algorithm>
 
 #include "base/format_macros.h"
 #include "base/i18n/break_iterator.h"
@@ skipping 153 matching lines @@
   render_text->ApplyStyle(ITALIC, true, Range(3, 6));
   render_text->ApplyStyle(ITALIC, true, Range(7, text_length));
   std::vector<std::pair<size_t, bool> > expected_italic;
   expected_italic.push_back(std::pair<size_t, bool>(0, true));
   expected_italic.push_back(std::pair<size_t, bool>(2, false));
   expected_italic.push_back(std::pair<size_t, bool>(3, true));
   expected_italic.push_back(std::pair<size_t, bool>(6, false));
   expected_italic.push_back(std::pair<size_t, bool>(7, true));
   EXPECT_TRUE(render_text->styles()[ITALIC].EqualsForTesting(expected_italic));
 
-  // Truncating the text should trim any corresponding breaks.
+  // Changing the text should clear any breaks except for the first one.
   render_text->SetText(ASCIIToUTF16("0123456"));
-  expected_italic.resize(4);
+  expected_italic.resize(1);
   EXPECT_TRUE(render_text->styles()[ITALIC].EqualsForTesting(expected_italic));
-  render_text->SetText(ASCIIToUTF16("01234"));
-  expected_italic.resize(3);
+  render_text->ApplyStyle(ITALIC, false, Range(2, 4));
+  render_text->SetText(ASCIIToUTF16("012345678"));
+  EXPECT_TRUE(render_text->styles()[ITALIC].EqualsForTesting(expected_italic));
+  render_text->ApplyStyle(ITALIC, false, Range(0, 1));
+  render_text->SetText(ASCIIToUTF16("0123456"));
+  expected_italic.begin()->second = false;
+  EXPECT_TRUE(render_text->styles()[ITALIC].EqualsForTesting(expected_italic));
+  render_text->ApplyStyle(ITALIC, true, Range(2, 4));
+  render_text->SetText(ASCIIToUTF16("012345678"));
   EXPECT_TRUE(render_text->styles()[ITALIC].EqualsForTesting(expected_italic));
 
-  // Appending text should extend the terminal styles without changing breaks.
-  render_text->SetText(ASCIIToUTF16("012345678"));
-  EXPECT_TRUE(render_text->styles()[ITALIC].EqualsForTesting(expected_italic));
+  // TODO(tmoniuszko): Enable when RenderTextMac::IsValidCursorIndex is
+  //                   implemented.
+#if !defined(OS_MACOSX)
+  // Styles shouldn't be changed mid-grapheme.
+  render_text->SetText(WideToUTF16(
+      L"0" L"\x0915\x093f" L"1" L"\x0915\x093f" L"2"));
+  render_text->ApplyStyle(UNDERLINE, true, Range(2, 5));
+  std::vector<std::pair<size_t, bool> > expected_underline;
+  expected_underline.push_back(std::pair<size_t, bool>(0, false));
+  expected_underline.push_back(std::pair<size_t, bool>(1, true));
+  expected_underline.push_back(std::pair<size_t, bool>(6, false));
+  EXPECT_TRUE(render_text->styles()[UNDERLINE].EqualsForTesting(
+      expected_underline));
+#endif  // OS_MACOSX
 }
 
 #if defined(OS_LINUX) && !defined(USE_OZONE)
 TEST_F(RenderTextTest, PangoAttributes) {
   scoped_ptr<RenderText> render_text(RenderText::CreateNativeInstance());
   render_text->SetText(ASCIIToUTF16("012345678"));
 
   // Apply ranged BOLD/ITALIC styles and check the resulting Pango attributes.
   render_text->ApplyStyle(BOLD, true, Range(2, 4));
   render_text->ApplyStyle(ITALIC, true, Range(1, 3));
@@ skipping 2090 matching lines @@
   EXPECT_EQ(Range(0, 0), run.CharRangeToGlyphRange(Range(4, 5)));
   EXPECT_EQ(Range(0, 0), run.GetGraphemeBounds(iter.get(), 4));
   Range chars;
   Range glyphs;
   run.GetClusterAt(4, &chars, &glyphs);
   EXPECT_EQ(Range(3, 8), chars);
   EXPECT_EQ(Range(0, 0), glyphs);
 }
 
 }  // namespace gfx