Make GetRectsForRange provide more detailed/nuanced metrics through RectStyle enum.

lib/ui/text/paragraph.cc

@@ -85,7 +85,8 @@ void Paragraph::paint(Canvas* canvas, double x, double y) {
 }
 
 std::vector<TextBox> Paragraph::getRectsForRange(unsigned start, unsigned end) {
-  return m_paragraphImpl->getRectsForRange(start, end);
+  return m_paragraphImpl->getRectsForRange(start, end,
+                                           txt::Paragraph::RectStyle::kTight);
 }
 
 Dart_Handle Paragraph::getPositionForOffset(double dx, double dy) {

lib/ui/text/paragraph_impl.h

@@ -7,6 +7,7 @@
 
 #include "flutter/lib/ui/painting/canvas.h"
 #include "flutter/lib/ui/text/text_box.h"
+#include "flutter/third_party/txt/src/txt/paragraph.h"
 
 namespace blink {
 
@@ -32,8 +33,10 @@ class ParagraphImpl {
 
   virtual void paint(Canvas* canvas, double x, double y) = 0;
 
-  virtual std::vector<TextBox> getRectsForRange(unsigned start,
-                                                unsigned end) = 0;
+  virtual std::vector<TextBox> getRectsForRange(
+      unsigned start,
+      unsigned end,
+      txt::Paragraph::RectStyle rect_style) = 0;
 
   virtual Dart_Handle getPositionForOffset(double dx, double dy) = 0;
 

lib/ui/text/paragraph_impl_txt.cc

@@ -61,11 +61,13 @@ void ParagraphImplTxt::paint(Canvas* canvas, double x, double y) {
   m_paragraph->Paint(sk_canvas, x, y);
 }
 
-std::vector<TextBox> ParagraphImplTxt::getRectsForRange(unsigned start,
-                                                        unsigned end) {
+std::vector<TextBox> ParagraphImplTxt::getRectsForRange(
+    unsigned start,
+    unsigned end,
+    txt::Paragraph::RectStyle rect_style) {
   std::vector<TextBox> result;
   std::vector<txt::Paragraph::TextBox> boxes =
-      m_paragraph->GetRectsForRange(start, end);
+      m_paragraph->GetRectsForRange(start, end, rect_style);
   for (const txt::Paragraph::TextBox& box : boxes) {
     result.emplace_back(box.rect,
                         static_cast<blink::TextDirection>(box.direction));

lib/ui/text/paragraph_impl_txt.h

@@ -8,7 +8,6 @@
 #include "flutter/lib/ui/painting/canvas.h"
 #include "flutter/lib/ui/text/paragraph_impl.h"
 #include "flutter/lib/ui/text/text_box.h"
-#include "flutter/third_party/txt/src/txt/paragraph.h"
 
 namespace blink {
 
@@ -29,7 +28,10 @@ class ParagraphImplTxt : public ParagraphImpl {
   void layout(double width) override;
   void paint(Canvas* canvas, double x, double y) override;
 
-  std::vector<TextBox> getRectsForRange(unsigned start, unsigned end) override;
+  std::vector<TextBox> getRectsForRange(
+      unsigned start,
+      unsigned end,
+      txt::Paragraph::RectStyle rect_style) override;
   Dart_Handle getPositionForOffset(double dx, double dy) override;
   Dart_Handle getWordBoundary(unsigned offset) override;
 

third_party/txt/src/txt/paragraph.cc

@@ -674,11 +674,10 @@ void Paragraph::Layout(double width, bool force) {
               word_start_position = std::numeric_limits<double>::quiet_NaN();
             }
           }
-        }
+        }  // for each in glyph_blob
 
         if (glyph_positions.empty())
           continue;
-
         SkPaint::FontMetrics metrics;
         paint.getFontMetrics(&metrics);
         paint_records.emplace_back(run.style(), SkPoint::Make(run_x_offset, 0),
@@ -701,10 +700,10 @@ void Paragraph::Layout(double width, bool force) {
             Range<double>(glyph_positions.front().x_pos.start,
                           glyph_positions.back().x_pos.end),
             line_number, metrics, run.direction());
-      }
+      }  // for each in glyph_blobs
 
       run_x_offset += layout.getAdvance();
-    }
+    }  // for each in line_runs
 
     // Adjust the glyph positions based on the alignment of the line.
     double line_x_offset = GetLineXOffset(run_x_offset);
@@ -772,7 +771,7 @@ void Paragraph::Layout(double width, bool force) {
           SkPoint::Make(paint_record.offset().x() + line_x_offset, y_offset));
       records_.emplace_back(std::move(paint_record));
     }
-  }
+  }  // for each line_number
 
   if (paragraph_style_.max_lines == 1 ||
       (paragraph_style_.unlimited_lines() && paragraph_style_.ellipsized())) {
@@ -1067,8 +1066,10 @@ void Paragraph::PaintBackground(SkCanvas* canvas,
   canvas->drawRect(rect, record.style().background);
 }
 
-std::vector<Paragraph::TextBox> Paragraph::GetRectsForRange(size_t start,
-                                                            size_t end) const {
+std::vector<Paragraph::TextBox> Paragraph::GetRectsForRange(
+    size_t start,
+    size_t end,
+    RectStyle rect_style) const {
   std::map<size_t, std::vector<Paragraph::TextBox>> line_boxes;
 
   for (const CodeUnitRun& run : code_unit_runs_) {
@@ -1123,7 +1124,23 @@ std::vector<Paragraph::TextBox> Paragraph::GetRectsForRange(size_t start,
 
   std::vector<Paragraph::TextBox> boxes;
   for (const auto& kv : line_boxes) {
-    boxes.insert(boxes.end(), kv.second.begin(), kv.second.end());
+    if (rect_style & RectStyle::kTight) {
+      // Ignore line max height and width and generate tight bounds.
+      boxes.insert(boxes.end(), kv.second.begin(), kv.second.end());
+    } else {
+      // Set each box to the max height of each line to ensure continuity.
+      float min_top = DBL_MAX;
+      float max_bottom = 0;
+      for (const Paragraph::TextBox& box : kv.second) {
+        min_top = std::min(box.rect.fTop, min_top);
+        max_bottom = std::max(box.rect.fBottom, max_bottom);
+      }
+      for (const Paragraph::TextBox& box : kv.second) {
+        boxes.emplace_back(SkRect::MakeLTRB(box.rect.fLeft, min_top,
+                                            box.rect.fRight, max_bottom),
+                           box.direction);
+      }
+    }
   }
   return boxes;
 }

third_party/txt/src/txt/paragraph.h

@@ -55,6 +55,25 @@ class Paragraph {
 
   enum Affinity { UPSTREAM, DOWNSTREAM };
 
+  // TODO(garyq): Implement kIncludeLineSpacing and kExtendEndOfLine
+
+  // Options for various types of bounding boxes provided by
+  // GetRectsForRange(...).
+  // These options can be individually enabled, for example:
+  //
+  //   (RectStyle::kTight | RectStyle::kExtendEndOfLine)
+  //
+  // provides tight bounding boxes and extends the last box per line to the end
+  // of the layout area.
+  enum RectStyle {
+    kNone = 0x0,  // kNone cannot be combined with |.
+
+    // Provide tight bounding boxes that fit heights per span. Otherwise, the
+    // heights of spans are the max of the heights of the line the span belongs
+    // in.
+    kTight = 0x1
+  };
+
   struct PositionWithAffinity {
     const size_t position;
     const Affinity affinity;
@@ -137,7 +156,9 @@ class Paragraph {
 
   // Returns a vector of bounding boxes that enclose all text between start and
   // end glyph indexes, including start and excluding end.
-  std::vector<TextBox> GetRectsForRange(size_t start, size_t end) const;
+  std::vector<TextBox> GetRectsForRange(size_t start,
+                                        size_t end,
+                                        RectStyle rect_style) const;
 
   // Returns the index of the glyph that corresponds to the provided coordinate,
   // with the top left corner as the origin, and +y direction as down.

third_party/txt/tests/paragraph_unittests.cc

@@ -983,13 +983,13 @@ TEST_F(ParagraphTest, DISABLE_ON_WINDOWS(GetRectsForRangeParagraph)) {
   // are adjusted.
   paint.setColor(SK_ColorRED);
   std::vector<txt::Paragraph::TextBox> boxes =
-      paragraph->GetRectsForRange(0, 0);
+      paragraph->GetRectsForRange(0, 0, Paragraph::RectStyle::kNone);
   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);
+  boxes = paragraph->GetRectsForRange(0, 1, Paragraph::RectStyle::kNone);
   for (size_t i = 0; i < boxes.size(); ++i) {
     GetCanvas()->drawRect(boxes[i].rect, paint);
   }
@@ -1000,7 +1000,7 @@ TEST_F(ParagraphTest, DISABLE_ON_WINDOWS(GetRectsForRangeParagraph)) {
   EXPECT_FLOAT_EQ(boxes[0].rect.bottom(), 59);
 
   paint.setColor(SK_ColorBLUE);
-  boxes = paragraph->GetRectsForRange(2, 8);
+  boxes = paragraph->GetRectsForRange(2, 8, Paragraph::RectStyle::kNone);
   for (size_t i = 0; i < boxes.size(); ++i) {
     GetCanvas()->drawRect(boxes[i].rect, paint);
   }
@@ -1011,7 +1011,7 @@ TEST_F(ParagraphTest, DISABLE_ON_WINDOWS(GetRectsForRangeParagraph)) {
   EXPECT_FLOAT_EQ(boxes[0].rect.bottom(), 59);
 
   paint.setColor(SK_ColorGREEN);
-  boxes = paragraph->GetRectsForRange(8, 21);
+  boxes = paragraph->GetRectsForRange(8, 21, Paragraph::RectStyle::kNone);
   for (size_t i = 0; i < boxes.size(); ++i) {
     GetCanvas()->drawRect(boxes[i].rect, paint);
   }
@@ -1022,7 +1022,7 @@ TEST_F(ParagraphTest, DISABLE_ON_WINDOWS(GetRectsForRangeParagraph)) {
   EXPECT_FLOAT_EQ(boxes[0].rect.bottom(), 59);
 
   paint.setColor(SK_ColorRED);
-  boxes = paragraph->GetRectsForRange(30, 100);
+  boxes = paragraph->GetRectsForRange(30, 100, Paragraph::RectStyle::kNone);
   for (size_t i = 0; i < boxes.size(); ++i) {
     GetCanvas()->drawRect(boxes[i].rect, paint);
   }
@@ -1040,7 +1040,7 @@ TEST_F(ParagraphTest, DISABLE_ON_WINDOWS(GetRectsForRangeParagraph)) {
   EXPECT_FLOAT_EQ(boxes[3].rect.bottom(), 295);
 
   paint.setColor(SK_ColorBLUE);
-  boxes = paragraph->GetRectsForRange(19, 22);
+  boxes = paragraph->GetRectsForRange(19, 22, Paragraph::RectStyle::kNone);
   for (size_t i = 0; i < boxes.size(); ++i) {
     GetCanvas()->drawRect(boxes[i].rect, paint);
   }
@@ -1051,7 +1051,7 @@ TEST_F(ParagraphTest, DISABLE_ON_WINDOWS(GetRectsForRangeParagraph)) {
   EXPECT_FLOAT_EQ(boxes[0].rect.bottom(), 59);
 
   paint.setColor(SK_ColorRED);
-  boxes = paragraph->GetRectsForRange(21, 21);
+  boxes = paragraph->GetRectsForRange(21, 21, Paragraph::RectStyle::kNone);
   for (size_t i = 0; i < boxes.size(); ++i) {
     GetCanvas()->drawRect(boxes[i].rect, paint);
   }
@@ -1060,10 +1060,93 @@ TEST_F(ParagraphTest, DISABLE_ON_WINDOWS(GetRectsForRangeParagraph)) {
   ASSERT_TRUE(Snapshot());
 }
 
+TEST_F(ParagraphTest, DISABLE_ON_WINDOWS(GetRectsForRangeTight)) {
+  const char* text =
+      "(　´･‿･｀)(　´･‿･｀)(　´･‿･｀)(　´･‿･｀)(　´･‿･｀)(　´･‿･｀)(　´･‿･｀)("
+      "　´･‿･｀)(　´･‿･｀)(　´･‿･｀)(　´･‿･｀)(　´･‿･｀)(　´･‿･｀)(　´･‿･｀)("
+      "　´･‿･｀)(　´･‿･｀)(　´･‿･｀)(　´･‿･｀)(　´･‿･｀)(　´･‿･｀)";
+  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::left;
+  txt::ParagraphBuilder builder(paragraph_style, GetTestFontCollection());
+
+  txt::TextStyle text_style;
+  text_style.font_family = "Noto Sans CJK JP";
+  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()
+  // NOTE: The base truth values may still need adjustment as the specifics
+  // are adjusted.
+  paint.setColor(SK_ColorRED);
+  std::vector<txt::Paragraph::TextBox> boxes =
+      paragraph->GetRectsForRange(0, 0, Paragraph::RectStyle::kTight);
+  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, Paragraph::RectStyle::kTight);
+  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(), 0);
+  EXPECT_FLOAT_EQ(boxes[0].rect.top(), 0);
+  EXPECT_FLOAT_EQ(boxes[0].rect.right(), 16.898438);
+  EXPECT_FLOAT_EQ(boxes[0].rect.bottom(), 74);
+
+  paint.setColor(SK_ColorBLUE);
+  boxes = paragraph->GetRectsForRange(2, 8, Paragraph::RectStyle::kTight);
+  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.top(), 0);
+  EXPECT_FLOAT_EQ(boxes[0].rect.right(), 264.09375);
+  EXPECT_FLOAT_EQ(boxes[0].rect.bottom(), 74);
+
+  paint.setColor(SK_ColorGREEN);
+  boxes = paragraph->GetRectsForRange(8, 21, Paragraph::RectStyle::kTight);
+  for (size_t i = 0; i < boxes.size(); ++i) {
+    GetCanvas()->drawRect(boxes[i].rect, paint);
+  }
+  EXPECT_EQ(boxes.size(), 2ull);
+  EXPECT_FLOAT_EQ(boxes[0].rect.left(), 264.09375);
+  EXPECT_FLOAT_EQ(boxes[0].rect.top(), 0);
+  EXPECT_FLOAT_EQ(boxes[0].rect.right(), 595.08594);
+  EXPECT_FLOAT_EQ(boxes[0].rect.bottom(), 74);
+
+  ASSERT_TRUE(Snapshot());
+}
+
 SkRect GetCoordinatesForGlyphPosition(const txt::Paragraph& paragraph,
                                       size_t pos) {
   std::vector<txt::Paragraph::TextBox> boxes =
-      paragraph.GetRectsForRange(pos, pos + 1);
+      paragraph.GetRectsForRange(pos, pos + 1, Paragraph::RectStyle::kNone);
   return !boxes.empty() ? boxes.front().rect : SkRect::MakeEmpty();
 }
 
@@ -1635,8 +1718,9 @@ TEST_F(ParagraphTest, UnderlineShiftParagraph) {
                 paragraph->records_[1].GetRunWidth(),
             paragraph2->records_[0].GetRunWidth());
 
-  auto rects1 = paragraph->GetRectsForRange(0, 12);
-  auto rects2 = paragraph2->GetRectsForRange(0, 12);
+  auto rects1 = paragraph->GetRectsForRange(0, 12, Paragraph::RectStyle::kNone);
+  auto rects2 =
+      paragraph2->GetRectsForRange(0, 12, Paragraph::RectStyle::kNone);
 
   for (size_t i = 0; i < 12; ++i) {
     auto r1 = GetCoordinatesForGlyphPosition(*paragraph, i);