Commit 61c0e055 authored by Paul Asmuth's avatar Paul Asmuth
Browse files

re-order bidirectional text runs within a line according to the unicode rules

parent 1ce0f827

core/graphics/text_backend_linux.cc

+7 −15
Original line number Diff line number Diff line
@@ -23,6 +23,8 @@ ReturnCode text_analyze_bidi_line( 
    const TextSpan* text_end,

    TextDirection text_direction_base,

    TextLine* text_line) {

  text_line->text_direction_base = text_direction_base;



  FriBidiParType fb_basedir;

  switch (text_direction_base) {

    case TextDirection::LTR:
@@ -73,7 +75,10 @@ ReturnCode text_analyze_bidi_line( 


  // find the bidi runs in the output

  std::vector<size_t> run_bounds;

  int level_max = 0;

  for (size_t i = 0; i < fb_str_len; ++i) {

    level_max = std::max(level_max, int(fb_levels[i]));



    // split on level change

    if (i > 0 && fb_levels[i] != fb_levels[i - 1]) {

      run_bounds.emplace_back(i);
@@ -87,6 +92,7 @@ ReturnCode text_analyze_bidi_line( 
    }

  }



  std::vector<int> levels;

  for (size_t i = 0; i < run_bounds.size() + 1; ++i) {

    auto run_begin = i == 0 ? 0 : run_bounds[i - 1];

    auto run_end = i == run_bounds.size() ? fb_str_len : run_bounds[i];
@@ -99,25 +105,11 @@ ReturnCode text_analyze_bidi_line( 
        run_len,

        run.data()));



    auto run_direction =

        int(fb_levels[run_begin]) & 1 ?

            TextDirection::RTL :

            TextDirection::LTR;



    text_line->text_runs.emplace_back(run);

    text_line->text_directions.emplace_back(run_direction);

    text_line->text_spans.emplace_back(fb_to_span_map[run_begin]);

    text_line->text_bidi_levels.emplace_back(int(fb_levels[run_begin]));

  }



  text_line->text_direction_base = text_direction_base;

  text_line->visual_order.resize(text_line->text_runs.size());

  std::iota(

      text_line->visual_order.begin(),

      text_line->visual_order.end(),

      0);



  // TODO: reorder ranges according to unicode algorithm



  return OK;

}

core/graphics/text_layout.cc

+71 −3
Original line number Diff line number Diff line
@@ -16,6 +16,8 @@ 
#include "graphics/text_layout.h"

#include "graphics/text_shaper.h"



#include <numeric>



namespace fviz {

namespace text {
@@ -69,16 +71,22 @@ Status text_layout_hline( 
    double dpi,

    std::vector<GlyphSpan>* glyph_spans,

    Rectangle* bbox) {

  auto visual_order = text_get_visual_order(text_line);



  double line_top = 0.0;

  double line_bottom = 0.0;

  double line_length = 0;

  for (auto i : text_line.visual_order) {

  for (auto i : visual_order) {

    TextDirection text_direction_run =

        text_line.text_bidi_levels[i] & 1 ?

            TextDirection::RTL :

            TextDirection::LTR;



    double span_length = 0.0;

    std::vector<GlyphPlacement> span_glyphs;



    auto rc = text_layout_hrun(

        text_line.text_runs[i],

        text_line.text_directions[i],

        text_direction_run,

        text_line.text_spans[i]->language,

        text_line.text_spans[i]->script,

        font_info,
@@ -177,6 +185,66 @@ Status text_measure_span( 
      bbox);

}



// source: https://unicode.org/reports/tr9/#Reordering_Resolved_Levels

//

//   "From the highest level found in the text to the lowest odd level on each

//    line, including intermediate levels not actually present in the text,

//    reverse any contiguous sequence of characters that are at that level or

//    higher."

//

std::vector<size_t> text_get_visual_order(const TextLine& line) {

  std::vector<size_t> visual_order(line.text_runs.size(), 0);



  std::iota(

      visual_order.begin(),

      visual_order.end(),

      0);



  size_t level_max = *std::max_element(

      line.text_bidi_levels.begin(),

      line.text_bidi_levels.end());



  for (size_t level_cur = level_max; level_cur >= 1; --level_cur) {

    for (size_t range_begin = 0; range_begin < line.text_runs.size(); ) {

      // find the next contiguous range where level >= level_cur starting at

      // begin

      auto range_end = range_begin;

      for (;

          line.text_bidi_levels[range_end] >= level_cur &&

          range_end != line.text_runs.size();

          ++range_end);



      // if no such sequence starts at begin, try searching from the next index

      if (range_end == range_begin) {

        ++range_begin;

        continue;

      }



      // reverse runs in the range

      std::reverse(

          visual_order.begin() + range_begin,

          visual_order.begin() + range_end);



      // continue searching from the end of the swapped range

      range_begin = range_end;

    }

  }



  // if the base direction is RTL, reverse the direction of all runs so that

  // the "first" element in the visual order array is the one at the begining

  // of the line in our base writing direction

  switch (line.text_direction_base) {

    case TextDirection::LTR:

      break;

    case TextDirection::RTL:

      std::reverse(

          visual_order.begin(),

          visual_order.end());

  }



  return visual_order;

}



} // namespace text

} // namespace fviz

core/graphics/text_layout.h

+6 −2
Original line number Diff line number Diff line
@@ -70,9 +70,8 @@ struct TextSpan { 
struct TextLine {

  std::vector<std::string> text_runs;

  TextDirection text_direction_base;

  std::vector<TextDirection> text_directions;

  std::vector<const TextSpan*> text_spans;

  std::vector<size_t> visual_order;

  std::vector<int> text_bidi_levels;

};
@@ -135,5 +134,10 @@ Status text_measure_span( 
    Rectangle* rect);





/**

 * Determine the visual order of text runs in a line

 */

std::vector<size_t> text_get_visual_order(const TextLine& line);



} // namespace fviz::text

core/graphics/text_shaper.cc

+0 −2
Original line number Diff line number Diff line
@@ -34,8 +34,6 @@ Status text_shape_run( 
    double font_size,

    double dpi,

    std::vector<GlyphInfo>* glyphs) {

  std::cerr << "shape: " << text << std::endl;



  /* get freetype font */

  auto ft_font = static_cast<FT_Face>(font_get_freetype(font));

  auto font_size_ft = font_size * (72.0 / dpi) * 64;

tests/unit/test_graphics_text_align.cc

+8 −8
Original line number Diff line number Diff line
@@ -39,17 +39,17 @@ void draw_test( 
  std::vector<text::TextSpan> text;

  {

    text::TextSpan ts;

    ts.text = "test";

    ts.text = "helllo תל אביב 123 ";

    text.push_back(ts);

  }



  {

    text::TextSpan ts;

    ts.text += "∞ⁱ Ω תל אביב , 北京市, القاهرة‎ = testend";

    ts.script = "Arabic";

    ts.language = "Arabic";

    text.push_back(ts);

  }

  //{

  //  text::TextSpan ts;

  //  ts.text += "∞ⁱ Ω תל אביב , 北京市, القاهرة‎ = testend";

  //  ts.script = "Arabic";

  //  ts.language = "Arabic";

  //  text.push_back(ts);

  //}



  StrokeStyle ss;

  ss.line_width = from_unit(1);

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