Custom RTL handling for ghost runs, NotoNaskhArabic test font

third_party/txt/src/txt/paragraph.cc

@@ -17,14 +17,15 @@
 #include "paragraph.h"
 
 #include <hb.h>
+#include <minikin/Layout.h>
+
 #include <algorithm>
 #include <limits>
 #include <map>
 #include <numeric>
 #include <utility>
 #include <vector>
 
-#include <minikin/Layout.h>
 #include "flutter/fml/logging.h"
 #include "font_collection.h"
 #include "font_skia.h"
@@ -34,9 +35,6 @@
 #include "minikin/LayoutUtils.h"
 #include "minikin/LineBreaker.h"
 #include "minikin/MinikinFont.h"
-#include "unicode/ubidi.h"
-#include "unicode/utf16.h"
-
 #include "third_party/skia/include/core/SkCanvas.h"
 #include "third_party/skia/include/core/SkFont.h"
 #include "third_party/skia/include/core/SkFontMetrics.h"
@@ -46,6 +44,8 @@
 #include "third_party/skia/include/core/SkTypeface.h"
 #include "third_party/skia/include/effects/SkDashPathEffect.h"
 #include "third_party/skia/include/effects/SkDiscretePathEffect.h"
+#include "unicode/ubidi.h"
+#include "unicode/utf16.h"
 
 namespace txt {
 namespace {
@@ -552,12 +552,6 @@ void Paragraph::Layout(double width, bool force) {
     // Find the runs comprising this line.
     std::vector<BidiRun> line_runs;
     for (const BidiRun& bidi_run : bidi_runs) {
-      if (bidi_run.start() < line_end_index &&
-          bidi_run.end() > line_range.start) {
-        line_runs.emplace_back(std::max(bidi_run.start(), line_range.start),
-                               std::min(bidi_run.end(), line_end_index),
-                               bidi_run.direction(), bidi_run.style());
-      }
       // A "ghost" run is a run that does not impact the layout, breaking,
       // alignment, width, etc but is still "visible" though getRectsForRange.
       // For example, trailing whitespace on centered text can be scrolled
@@ -567,7 +561,28 @@ void Paragraph::Layout(double width, bool force) {
       // let it impact metrics. After layout of the whitespace run, we do not
       // add its width into the x-offset adjustment, effectively nullifying its
       // impact on the layout.
-      if (paragraph_style_.ellipsis.empty() &&
+      //
+      // RTL ghost run check (RTL ghost runs appear visually before the rest of
+      // the text)
+      if (bidi_run.direction() == TextDirection::rtl &&
+          paragraph_style_.ellipsis.empty() &&
+          line_range.end_excluding_whitespace < line_range.end &&
+          bidi_run.start() <= line_range.end &&
+          bidi_run.end() > line_end_index) {
+        line_runs.emplace_back(std::max(bidi_run.start(), line_end_index),
+                               std::min(bidi_run.end(), line_range.end),
+                               bidi_run.direction(), bidi_run.style(), true);
+      }
+      if (bidi_run.start() < line_end_index &&
+          bidi_run.end() > line_range.start) {
+        line_runs.emplace_back(std::max(bidi_run.start(), line_range.start),
+                               std::min(bidi_run.end(), line_end_index),
+                               bidi_run.direction(), bidi_run.style());
+      }
+      // LTR ghost run check. (LTR ghost runs appear visually after the rest of
+      // the text)
+      if (bidi_run.direction() == TextDirection::ltr &&
+          paragraph_style_.ellipsis.empty() &&
           line_range.end_excluding_whitespace < line_range.end &&
           bidi_run.start() <= line_range.end &&
           bidi_run.end() > line_end_index) {
@@ -587,7 +602,9 @@ void Paragraph::Layout(double width, bool force) {
 
     std::vector<GlyphPosition> line_glyph_positions;
     std::vector<CodeUnitRun> line_code_unit_runs;
+    std::vector<CodeUnitRun*> ghost_code_unit_runs;
     double run_x_offset = 0;
+    double rtl_ghost_x_offset = 0;
     double justify_x_offset = 0;
     std::vector<PaintRecord> paint_records;
 
@@ -808,22 +825,37 @@ void Paragraph::Layout(double width, bool force) {
                   [](const GlyphPosition& a, const GlyphPosition& b) {
                     return a.code_units.start < b.code_units.start;
                   });
+
         line_code_unit_runs.emplace_back(
             std::move(code_unit_positions),
             Range<size_t>(run.start(), run.end()),
             Range<double>(glyph_positions.front().x_pos.start,
                           glyph_positions.back().x_pos.end),
             line_number, metrics, run.direction());
 
-        min_left_ = std::min(min_left_, glyph_positions.front().x_pos.start);
-        max_right_ = std::max(max_right_, glyph_positions.back().x_pos.end);
+        if (run.is_rtl()) {
+          ghost_code_unit_runs.push_back(&line_code_unit_runs.back());
+        }
+        if (!run.is_ghost()) {
+          min_left_ = std::min(min_left_, glyph_positions.front().x_pos.start);
+          max_right_ = std::max(max_right_, glyph_positions.back().x_pos.end);
+        }
       }  // for each in glyph_blobs
 
       // Do not increase x offset for trailing ghost runs as it should not
       // impact the layout of visible glyphs. We do keep the record though so
       // GetRectsForRange() can find metrics for trailing spaces.
       if (!run.is_ghost()) {
         run_x_offset += layout.getAdvance();
+      } else if (run.is_rtl()) {
+        // For RTL ghost runs, we need to shift the ghost run over here as it is
+        // the offset is calculated in reverse order from LTR.
+        rtl_ghost_x_offset += layout.getAdvance();
+        for (CodeUnitRun* code_unit_run : ghost_code_unit_runs) {
+          code_unit_run->Shift(-rtl_ghost_x_offset);
+        }
+        ghost_code_unit_runs.clear();
+        rtl_ghost_x_offset = 0;
       }
     }  // for each in line_runs
 

third_party/txt/tests/paragraph_unittests.cc

@@ -684,6 +684,7 @@ TEST_F(ParagraphTest, DISABLE_ON_WINDOWS(JustifyRTL)) {
   txt::ParagraphStyle paragraph_style;
   paragraph_style.max_lines = 14;
   paragraph_style.text_align = TextAlign::justify;
+  paragraph_style.text_direction = TextDirection::rtl;
   txt::ParagraphBuilder builder(paragraph_style, GetTestFontCollection());
 
   txt::TextStyle text_style;
@@ -703,16 +704,33 @@ TEST_F(ParagraphTest, DISABLE_ON_WINDOWS(JustifyRTL)) {
 
   paragraph->Paint(GetCanvas(), 0, 0);
 
-  ASSERT_TRUE(Snapshot());
-
   auto glyph_line_width = [&paragraph](int index) {
     size_t second_to_last_position_index =
-        paragraph->glyph_lines_[index].positions.size() - 2;
+        paragraph->glyph_lines_[index].positions.size() - 1;
     return paragraph->glyph_lines_[index]
         .positions[second_to_last_position_index]
         .x_pos.end;
   };
 
+  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, 100, rect_height_style, rect_width_style);
+  for (size_t i = 0; i < boxes.size(); ++i) {
+    GetCanvas()->drawRect(boxes[i].rect, paint);
+  }
+  ASSERT_EQ(boxes.size(), 5ull);
+  ASSERT_TRUE(Snapshot());
+
   // All lines except the last should be justified to the width of the
   // paragraph.
   for (size_t i = 0; i < paragraph->glyph_lines_.size() - 1; ++i) {
@@ -949,6 +967,74 @@ TEST_F(ParagraphTest, DISABLED_ArabicParagraph) {
   ASSERT_TRUE(Snapshot());
 }
 
+// Checks if the rects are in the correct positions after typing spaces in
+// Arabic.
+TEST_F(ParagraphTest, DISABLE_ON_WINDOWS(ArabicRectsParagraph)) {
+  const char* text = "بمباركة التقليدية قام عن. تصفح يد    ";
+  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 = 14;
+  paragraph_style.text_align = TextAlign::right;
+  paragraph_style.text_direction = TextDirection::rtl;
+  txt::ParagraphBuilder builder(paragraph_style, GetTestFontCollection());
+
+  txt::TextStyle text_style;
+  text_style.font_families = std::vector<std::string>(1, "Noto Naskh Arabic");
+  text_style.font_size = 26;
+  text_style.letter_spacing = 1;
+  text_style.word_spacing = 5;
+  text_style.color = SK_ColorBLACK;
+  text_style.height = 1;
+  text_style.decoration = TextDecoration::kUnderline;
+  text_style.decoration_color = SK_ColorBLACK;
+  builder.PushStyle(text_style);
+
+  builder.AddText(u16_text);
+
+  builder.Pop();
+
+  auto paragraph = builder.Build();
+  paragraph->Layout(GetTestCanvasWidth() - 100);
+
+  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, 100, 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(), 2ull);
+
+  EXPECT_FLOAT_EQ(boxes[0].rect.left(), 556.54688);
+  EXPECT_FLOAT_EQ(boxes[0].rect.top(), -0.26855469);
+  EXPECT_FLOAT_EQ(boxes[0].rect.right(), 900);
+  EXPECT_FLOAT_EQ(boxes[0].rect.bottom(), 44);
+
+  EXPECT_FLOAT_EQ(boxes[1].rect.left(), 510.09375);
+  EXPECT_FLOAT_EQ(boxes[1].rect.top(), -0.26855469);
+  EXPECT_FLOAT_EQ(boxes[1].rect.right(), 557.04688);
+  EXPECT_FLOAT_EQ(boxes[1].rect.bottom(), 44);
+
+  ASSERT_EQ(paragraph_style.text_align,
+            paragraph->GetParagraphStyle().text_align);
+
+  ASSERT_TRUE(Snapshot());
+}
+
 TEST_F(ParagraphTest, GetGlyphPositionAtCoordinateParagraph) {
   const char* text =
       "12345 67890 12345 67890 12345 67890 12345 67890 12345 67890 12345 "

third_party/txt/third_party/fonts/NotoNaskhArabic-LICENSE.txt

@@ -0,0 +1,92 @@
+This Font Software is licensed under the SIL Open Font License,
+Version 1.1.
+
+This license is copied below, and is also available with a FAQ at:
+http://scripts.sil.org/OFL
+
+-----------------------------------------------------------
+SIL OPEN FONT LICENSE Version 1.1 - 26 February 2007
+-----------------------------------------------------------
+
+PREAMBLE
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+development of collaborative font projects, to support the font
+creation efforts of academic and linguistic communities, and to
+provide a free and open framework in which fonts may be shared and
+improved in partnership with others.
+
+The OFL allows the licensed fonts to be used, studied, modified and
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