Fix caret being at left edge when newline pressed on centered text (#7875)

third_party/txt/src/txt/paragraph.cc

@@ -1302,6 +1302,11 @@ std::vector<Paragraph::TextBox> Paragraph::GetRectsForRange(
       if (line.end != line.end_including_newline && line.end >= start &&
           line.end_including_newline <= end) {
         SkScalar x = line_widths_[line_number];
+        // Move empty box to center if center aligned and is an empty line.
+        if (x == 0 && !isinf(width_) &&
+            paragraph_style_.effective_align() == TextAlign::center) {
+          x = width_ / 2;
+        }
         SkScalar top = (line_number > 0) ? line_heights_[line_number - 1] : 0;
         SkScalar bottom = line_heights_[line_number];
         line_metrics[line_number].boxes.emplace_back(

third_party/txt/tests/paragraph_unittests.cc

@@ -1780,6 +1780,83 @@ TEST_F(ParagraphTest, DISABLE_ON_WINDOWS(GetRectsForRangeCenterParagraph)) {
   ASSERT_TRUE(Snapshot());
 }
 
+TEST_F(ParagraphTest,
+       DISABLE_ON_WINDOWS(GetRectsForRangeCenterParagraphNewlineCentered)) {
+  const char* text = "01234\n";
+  auto icu_text = icu::UnicodeString::fromUTF8(text);
+  std::u16string u16_text(icu_text.getBuffer(),
+                          icu_text.getBuffer() + icu_text.length());
+
+  txt::ParagraphStyle paragraph_style;
+  paragraph_style.max_lines = 10;
+  paragraph_style.text_align = TextAlign::center;
+  txt::ParagraphBuilder builder(paragraph_style, GetTestFontCollection());
+
+  txt::TextStyle text_style;
+  text_style.font_families = std::vector<std::string>(1, "Roboto");
+  text_style.font_size = 50;
+  text_style.letter_spacing = 0;
+  text_style.font_weight = FontWeight::w500;
+  text_style.word_spacing = 0;
+  text_style.color = SK_ColorBLACK;
+  text_style.height = 1;
+  builder.PushStyle(text_style);
+
+  builder.AddText(u16_text);
+
+  builder.Pop();
+
+  auto paragraph = builder.Build();
+  paragraph->Layout(550);
+
+  paragraph->Paint(GetCanvas(), 0, 0);
+
+  SkPaint paint;
+  paint.setStyle(SkPaint::kStroke_Style);
+  paint.setAntiAlias(true);
+  paint.setStrokeWidth(1);
+
+  // Tests for GetRectsForRange()
+  Paragraph::RectHeightStyle rect_height_style =
+      Paragraph::RectHeightStyle::kMax;
+  Paragraph::RectWidthStyle rect_width_style =
+      Paragraph::RectWidthStyle::kTight;
+  paint.setColor(SK_ColorRED);
+  std::vector<txt::Paragraph::TextBox> boxes =
+      paragraph->GetRectsForRange(0, 0, rect_height_style, rect_width_style);
+  for (size_t i = 0; i < boxes.size(); ++i) {
+    GetCanvas()->drawRect(boxes[i].rect, paint);
+  }
+  EXPECT_EQ(boxes.size(), 0ull);
+
+  boxes =
+      paragraph->GetRectsForRange(0, 1, rect_height_style, rect_width_style);
+  for (size_t i = 0; i < boxes.size(); ++i) {
+    GetCanvas()->drawRect(boxes[i].rect, paint);
+  }
+  EXPECT_EQ(boxes.size(), 1ull);
+  EXPECT_FLOAT_EQ(boxes[0].rect.left(), 203.95508);
+  EXPECT_FLOAT_EQ(boxes[0].rect.top(), 0.40625);
+  EXPECT_FLOAT_EQ(boxes[0].rect.right(), 232.37305);
+  EXPECT_FLOAT_EQ(boxes[0].rect.bottom(), 59);
+
+  paint.setColor(SK_ColorGREEN);
+  boxes =
+      paragraph->GetRectsForRange(6, 7, rect_height_style, rect_width_style);
+  for (size_t i = 0; i < boxes.size(); ++i) {
+    GetCanvas()->drawRect(boxes[i].rect, paint);
+  }
+  EXPECT_EQ(boxes.size(), 1ull);
+  EXPECT_FLOAT_EQ(boxes[0].rect.left(), 275);
+  EXPECT_FLOAT_EQ(boxes[0].rect.right(), 275);
+  EXPECT_FLOAT_EQ(boxes[0].rect.bottom(),
+                  75);  // TODO(garyq): This value can be improved... Should be
+                        // taller, but we need a good way to obtain a height
+                        // without any glyphs on the line.
+
+  ASSERT_TRUE(Snapshot());
+}
+
 TEST_F(ParagraphTest,
        DISABLE_ON_WINDOWS(GetRectsForRangeCenterMultiLineParagraph)) {
   const char* text = "01234  　 \n0123　        ";  // includes ideographic