Refactor InRenderedText() with LayoutText::ContainsCaretOffset()

This patch refactors InRenderedText() by moving the work on InlineTextBox to
LayoutText::ContainsCaretOffset(), so that InRenderedText() no longer works
on InlineTextBox directly.

A follow-up patch will introduce a LayoutNG version of
LayoutText::ContainsCaretOffset().

Bug: 771398
Change-Id: If786ff57cf881869632e72e2347741433f6a4a17
Reviewed-on: https://chromium-review.googlesource.com/721629
Commit-Queue: Xiaocheng Hu <xiaochengh@chromium.org>
Commit-Queue: Koji Ishii <kojii@chromium.org>
Reviewed-by: Koji Ishii <kojii@chromium.org>
Reviewed-by: Yoshifumi Inoue <yosin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#509342}

third_party/WebKit/Source/core/editing/VisibleUnits.cpp

@@ -826,24 +826,15 @@ static bool InRenderedText(const PositionTemplate<Strategy>& position) {
   const LayoutText* text_layout_object = ToLayoutText(layout_object);
   const int text_offset =
       offset_in_node - text_layout_object->TextStartOffset();
-  for (InlineTextBox* box : InlineTextBoxesOf(*text_layout_object)) {
-    if (text_offset < static_cast<int>(box->Start()) &&
-        !text_layout_object->ContainsReversedText()) {
-      // The offset we're looking for is before this node
-      // this means the offset must be in content that is
-      // not laid out. Return false.
-      return false;
-    }
-    if (box->ContainsCaretOffset(text_offset)) {
-      // Return false for offsets inside composed characters.
-      return text_offset == text_layout_object->CaretMinOffset() ||
-             text_offset == NextGraphemeBoundaryOf(
-                                *anchor_node, PreviousGraphemeBoundaryOf(
-                                                  *anchor_node, text_offset));
-    }
-  }
-
-  return false;
+  if (!text_layout_object->ContainsCaretOffset(text_offset))
+    return false;
+  // Return false for offsets inside composed characters.
+  // TODO(editing-dev): Previous/NextGraphemeBoundaryOf() work on DOM offsets,
+  // So they should use |offset_in_node| instead of |text_offset|.
+  return text_offset == text_layout_object->CaretMinOffset() ||
+         text_offset == NextGraphemeBoundaryOf(*anchor_node,
+                                               PreviousGraphemeBoundaryOf(
+                                                   *anchor_node, text_offset));
 }
 
 static FloatQuad LocalToAbsoluteQuadOf(const LocalCaretRect& caret_rect) {

third_party/WebKit/Source/core/layout/LayoutText.cpp

@@ -1985,6 +1985,22 @@ bool LayoutText::HasNonCollapsedText() const {
   return FirstTextBox();
 }
 
+bool LayoutText::ContainsCaretOffset(int text_offset) const {
+  // TODO(crbug.com/771398): Add LayoutNG alternative.
+  for (InlineTextBox* box : InlineTextBoxesOf(*this)) {
+    if (text_offset < static_cast<int>(box->Start()) &&
+        !ContainsReversedText()) {
+      // The offset we're looking for is before this node
+      // this means the offset must be in content that is
+      // not laid out. Return false.
+      return false;
+    }
+    if (box->ContainsCaretOffset(text_offset))
+      return true;
+  }
+  return false;
+}
+
 void LayoutText::MomentarilyRevealLastTypedCharacter(
     unsigned last_typed_character_offset) {
   if (!g_secure_text_timers)

third_party/WebKit/Source/core/layout/LayoutText.h

@@ -201,6 +201,13 @@ class CORE_EXPORT LayoutText : public LayoutObject {
   // whitespace) output.
   bool HasTextBoxes() const { return FirstTextBox(); }
 
+  // Returns true if the offset (0-based in the |text_| string) is next to a
+  // non-collapsed non-linebreak character, or before a forced linebreak (<br>,
+  // or segment break in node with style white-space: pre/pre-line/pre-wrap).
+  // TODO(editing-dev): The behavior is introduced by crrev.com/e3eb4e in
+  // InlineTextBox::ContainsCaretOffset(). Try to understand it.
+  bool ContainsCaretOffset(int) const;
+
   int CaretMinOffset() const override;
   int CaretMaxOffset() const override;
   virtual unsigned ResolvedTextLength() const;

third_party/WebKit/Source/core/layout/LayoutTextTest.cpp

@@ -134,4 +134,54 @@ TEST_F(LayoutTextTest, ResolvedTextLengthNG) {
   EXPECT_EQ(3u, GetBasicText()->ResolvedTextLength());
 }
 
+TEST_F(LayoutTextTest, ContainsCaretOffset) {
+  // This test records the behavior introduced in crrev.com/e3eb4e
+  SetBasicBody(" foo   bar ");
+  EXPECT_FALSE(GetBasicText()->ContainsCaretOffset(0));   // "| foo   bar "
+  EXPECT_TRUE(GetBasicText()->ContainsCaretOffset(1));    // " |foo   bar "
+  EXPECT_TRUE(GetBasicText()->ContainsCaretOffset(2));    // " f|oo   bar "
+  EXPECT_TRUE(GetBasicText()->ContainsCaretOffset(3));    // " fo|o   bar "
+  EXPECT_TRUE(GetBasicText()->ContainsCaretOffset(4));    // " foo|   bar "
+  EXPECT_TRUE(GetBasicText()->ContainsCaretOffset(5));    // " foo |  bar "
+  EXPECT_FALSE(GetBasicText()->ContainsCaretOffset(6));   // " foo  | bar "
+  EXPECT_TRUE(GetBasicText()->ContainsCaretOffset(7));    // " foo   |bar "
+  EXPECT_TRUE(GetBasicText()->ContainsCaretOffset(8));    // " foo   b|ar "
+  EXPECT_TRUE(GetBasicText()->ContainsCaretOffset(9));    // " foo   ba|r "
+  EXPECT_TRUE(GetBasicText()->ContainsCaretOffset(10));   // " foo   bar| "
+  EXPECT_FALSE(GetBasicText()->ContainsCaretOffset(11));  // " foo   bar |"
+}
+
+TEST_F(LayoutTextTest, ContainsCaretOffsetInPre) {
+  // These tests record the behavior introduced in crrev.com/e3eb4e
+
+  SetBodyInnerHTML("<pre id='target'>foo   bar</pre>");
+  EXPECT_TRUE(GetBasicText()->ContainsCaretOffset(0));  // "|foo   bar"
+  EXPECT_TRUE(GetBasicText()->ContainsCaretOffset(1));  // "f|oo   bar"
+  EXPECT_TRUE(GetBasicText()->ContainsCaretOffset(2));  // "fo|o   bar"
+  EXPECT_TRUE(GetBasicText()->ContainsCaretOffset(3));  // "foo|   bar"
+  EXPECT_TRUE(GetBasicText()->ContainsCaretOffset(4));  // "foo |  bar"
+  EXPECT_TRUE(GetBasicText()->ContainsCaretOffset(5));  // "foo  | bar"
+  EXPECT_TRUE(GetBasicText()->ContainsCaretOffset(6));  // "foo   |bar"
+  EXPECT_TRUE(GetBasicText()->ContainsCaretOffset(7));  // "foo   b|ar"
+  EXPECT_TRUE(GetBasicText()->ContainsCaretOffset(8));  // "foo   ba|r"
+  EXPECT_TRUE(GetBasicText()->ContainsCaretOffset(9));  // "foo   bar|"
+
+  SetBodyInnerHTML("<pre id='target'>foo\n</div>");
+  EXPECT_TRUE(GetBasicText()->ContainsCaretOffset(0));   // "|foo\n"
+  EXPECT_TRUE(GetBasicText()->ContainsCaretOffset(1));   // "f|oo\n"
+  EXPECT_TRUE(GetBasicText()->ContainsCaretOffset(2));   // "fo|o\n"
+  EXPECT_TRUE(GetBasicText()->ContainsCaretOffset(3));   // "foo|\n"
+  EXPECT_FALSE(GetBasicText()->ContainsCaretOffset(4));  // "foo\n|"
+
+  SetBodyInnerHTML("<pre id='target'>foo\nbar</pre>");
+  EXPECT_TRUE(GetBasicText()->ContainsCaretOffset(0));  // "|foo\nbar"
+  EXPECT_TRUE(GetBasicText()->ContainsCaretOffset(1));  // "f|oo\nbar"
+  EXPECT_TRUE(GetBasicText()->ContainsCaretOffset(2));  // "fo|o\nbar"
+  EXPECT_TRUE(GetBasicText()->ContainsCaretOffset(3));  // "foo|\nbar"
+  EXPECT_TRUE(GetBasicText()->ContainsCaretOffset(4));  // "foo\n|bar"
+  EXPECT_TRUE(GetBasicText()->ContainsCaretOffset(5));  // "foo\nb|ar"
+  EXPECT_TRUE(GetBasicText()->ContainsCaretOffset(6));  // "foo\nba|r"
+  EXPECT_TRUE(GetBasicText()->ContainsCaretOffset(7));  // "foo\nbar|"
+}
+
 }  // namespace blink