gfx_layout.cpp

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/*
 * This file is part of OpenTTD.
 * OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
 * OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 * See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <https://www.gnu.org/licenses/old-licenses/gpl-2.0>.
 */

 
#include "stdafx.h"
#include "core/math_func.hpp"
#include "gfx_layout.h"
#include "string_func.h"
#include "strings_func.h"
#include "core/utf8.hpp"
#include "debug.h"
 
#include "table/control_codes.h"
 
#include "gfx_layout_fallback.h"
 
#if defined(WITH_ICU_I18N) && defined(WITH_HARFBUZZ)
#include "gfx_layout_icu.h"
#endif /* WITH_ICU_I18N && WITH_HARFBUZZ */
 
#ifdef WITH_UNISCRIBE
#include "os/windows/string_uniscribe.h"
#endif /* WITH_UNISCRIBE */
 
#ifdef WITH_COCOA
#include "os/macosx/string_osx.h"
#endif
 
#include "safeguards.h"
 

std::unique_ptr<Layouter::LineCache> Layouter::linecache;

Layouter::FontColourMap Layouter::fonts[FS_END];
 

Font::Font(FontSize size, TextColour colour) :
    fc(FontCache::Get(size)), colour(colour)
{
  assert(size < FS_END);
}

template <typename T>
static inline void GetLayouter(Layouter::LineCacheItem &line, std::string_view str, FontState &state)
{
  typename T::CharType *buff_begin = new typename T::CharType[str.size() + 1];
  /* Move ownership of buff_begin into the Buffer/unique_ptr. */
  line.buffer = Layouter::LineCacheItem::Buffer(buff_begin, [](void *p) { delete[] reinterpret_cast<T::CharType *>(p); });
 
  const typename T::CharType *buffer_last = buff_begin + str.size() + 1;
  typename T::CharType *buff = buff_begin;
  FontMap &font_mapping = line.runs;
  Font *f = Layouter::GetFont(state.fontsize, state.cur_colour);
 
  font_mapping.clear();
 
  /*
   * Go through the whole string while adding Font instances to the font map
   * whenever the font changes, and convert the wide characters into a format
   * usable by ParagraphLayout.
   */
  for (char32_t c : Utf8View(str)) {
    if (c == '\0' || c == '\n') {
      /* Caller should already have filtered out these characters. */
      NOT_REACHED();
    } else if (c >= SCC_BLUE && c <= SCC_BLACK) {
      state.SetColour((TextColour)(c - SCC_BLUE));
    } else if (c == SCC_PUSH_COLOUR) {
      state.PushColour();
    } else if (c == SCC_POP_COLOUR) {
      state.PopColour();
    } else if (c >= SCC_FIRST_FONT && c <= SCC_LAST_FONT) {
      state.SetFontSize((FontSize)(c - SCC_FIRST_FONT));
    } else {
      /* Filter out non printable characters */
      if (!IsPrintable(c)) continue;
      /* Filter out text direction characters that shouldn't be drawn, and
       * will not be handled in the fallback case because they are mostly
       * needed for RTL languages which need more proper shaping support. */
      if (!T::SUPPORTS_RTL && IsTextDirectionChar(c)) continue;
      buff += T::AppendToBuffer(buff, buffer_last, c);
      if (buff >= buffer_last) break;
      continue;
    }
 
    if (font_mapping.empty() || font_mapping.back().first != buff - buff_begin) {
      font_mapping.emplace_back(buff - buff_begin, f);
    }
    f = Layouter::GetFont(state.fontsize, state.cur_colour);
  }
 
  /* Better safe than sorry. */
  *buff = '\0';
 
  if (font_mapping.empty() || font_mapping.back().first != buff - buff_begin) {
    font_mapping.emplace_back(buff - buff_begin, f);
  }
  line.layout = T::GetParagraphLayout(buff_begin, buff, font_mapping);
  line.state_after = state;
}

Layouter::Layouter(std::string_view str, int maxw, FontSize fontsize) : string(str)
{
  FontState state(TC_INVALID, fontsize);
 
  while (true) {
    auto line_length = str.find_first_of('\n');
    auto str_line = str.substr(0, line_length);
 
    LineCacheItem &line = GetCachedParagraphLayout(str_line, state);
    if (line.layout != nullptr) {
      state = line.state_after;
      line.layout->Reflow();
    } else {
      /* Line is new, layout it */
      FontState old_state = state;
 
#if defined(WITH_ICU_I18N) && defined(WITH_HARFBUZZ)
      if (line.layout == nullptr) {
        GetLayouter<ICUParagraphLayoutFactory>(line, str_line, state);
        if (line.layout == nullptr) {
          state = std::move(old_state);
        }
      }
#endif
 
#ifdef WITH_UNISCRIBE
      if (line.layout == nullptr) {
        GetLayouter<UniscribeParagraphLayoutFactory>(line, str_line, state);
        if (line.layout == nullptr) {
          state = std::move(old_state);
        }
      }
#endif
 
#ifdef WITH_COCOA
      if (line.layout == nullptr) {
        GetLayouter<CoreTextParagraphLayoutFactory>(line, str_line, state);
        if (line.layout == nullptr) {
          state = std::move(old_state);
        }
      }
#endif
 
      if (line.layout == nullptr) {
        GetLayouter<FallbackParagraphLayoutFactory>(line, str_line, state);
      }
    }
 
    if (line.cached_width != maxw) {
      /* First run or width has changed, so we need to go through the layouter. Lines are moved into a cache to
       * be reused if the width is not changed. */
      line.cached_layout.clear();
      line.cached_width = maxw;
      for (;;) {
        auto l = line.layout->NextLine(maxw);
        if (l == nullptr) break;
        line.cached_layout.push_back(std::move(l));
      }
    }
 
    /* Retrieve layout from the cache. */
    for (const auto &l : line.cached_layout) {
      this->push_back(l.get());
    }
 
    /* Break out if this was the last line. */
    if (line_length == std::string_view::npos) {
      break;
    }
 
    /* Go to the next line. */
    str.remove_prefix(line_length + 1);
  }
}

Dimension Layouter::GetBounds()
{
  Dimension d = { 0, 0 };
  for (const auto &l : *this) {
    d.width = std::max<uint>(d.width, l->GetWidth());
    d.height += l->GetLeading();
  }
  return d;
}

static bool IsConsumedFormattingCode(char32_t ch)
{
  if (ch >= SCC_BLUE && ch <= SCC_BLACK) return true;
  if (ch == SCC_PUSH_COLOUR) return true;
  if (ch == SCC_POP_COLOUR) return true;
  if (ch >= SCC_FIRST_FONT && ch <= SCC_LAST_FONT) return true;
  /* All other characters defined in Unicode standard are assumed to be non-consumed. */
  return false;
}

ParagraphLayouter::Position Layouter::GetCharPosition(std::string_view::const_iterator ch) const
{
  const auto &line = this->front();
 
  /* Pointer to the end-of-string marker? Return total line width. */
  if (ch == this->string.end()) {
    Point p = {_current_text_dir == TD_LTR ? line->GetWidth() : 0, 0};
    return p;
  }
 
  /* Initial position, returned if character not found. */
  const ParagraphLayouter::Position initial_position = Point{_current_text_dir == TD_LTR ? 0 : line->GetWidth(), 0};
 
  /* Find the code point index which corresponds to the char
   * pointer into our UTF-8 source string. */
  size_t index = 0;
  {
    Utf8View view(this->string);
    const size_t offset = ch - this->string.begin();
    const auto pos = view.GetIterAtByte(offset);
 
    /* We couldn't find the code point index. */
    if (pos.GetByteOffset() != offset) return initial_position;
 
    for (auto it = view.begin(); it < pos; ++it) {
      char32_t c = *it;
      if (!IsConsumedFormattingCode(c)) index += line->GetInternalCharLength(c);
    }
  }
 
  const ParagraphLayouter::Position *position = &initial_position;
 
  /* Scan all runs until we've found our code point index. */
  size_t best_index = SIZE_MAX;
  for (size_t run_index = 0; run_index < line->CountRuns(); run_index++) {
    const ParagraphLayouter::VisualRun &run = line->GetVisualRun(run_index);
    const auto &positions = run.GetPositions();
    const auto &charmap = run.GetGlyphToCharMap();
 
    auto itp = positions.begin();
    for (auto it = charmap.begin(); it != charmap.end(); ++it, ++itp) {
      const size_t cur_index = static_cast<size_t>(*it);
      /* Found exact character match? */
      if (cur_index == index) return *itp;
 
      /* If the character we are looking for has been combined with other characters to form a ligature then
       * we may not be able to find an exact match. We don't actually know if our character is part of a
       * ligature. In this case we will aim to select the first character of the ligature instead, so the best
       * index is the index nearest to but lower than the desired index. */
      if (cur_index < index && (best_index < cur_index || best_index == SIZE_MAX)) {
        best_index = cur_index;
        position = &*itp;
      }
    }
  }
 
  /* At the end of the run but still didn't find our character so probably a trailing ligature, use the last found position. */
  return *position;
}

ptrdiff_t Layouter::GetCharAtPosition(int x, size_t line_index) const
{
  if (line_index >= this->size()) return -1;
 
  const auto &line = this->at(line_index);
 
  for (size_t run_index = 0; run_index < line->CountRuns(); run_index++) {
    const ParagraphLayouter::VisualRun &run = line->GetVisualRun(run_index);
    const auto &glyphs = run.GetGlyphs();
    const auto &positions = run.GetPositions();
    const auto &charmap = run.GetGlyphToCharMap();
 
    for (size_t i = 0; i < run.GetGlyphCount(); i++) {
      /* Not a valid glyph (empty). */
      if (glyphs[i] == 0xFFFF) continue;
 
      int begin_x = positions[i].left;
      int end_x   = positions[i].right + 1;
 
      if (IsInsideMM(x, begin_x, end_x)) {
        /* Found our glyph, now convert to UTF-8 string index. */
        size_t index = charmap[i];
 
        size_t cur_idx = 0;
        Utf8View view(this->string);
        for (auto it = view.begin(), end = view.end(); it != end; ++it) {
          if (cur_idx == index) return it.GetByteOffset();
 
          char32_t c = *it;
          if (!IsConsumedFormattingCode(c)) cur_idx += line->GetInternalCharLength(c);
        }
      }
    }
  }
 
  return -1;
}

Font *Layouter::GetFont(FontSize size, TextColour colour)
{
  FontColourMap::iterator it = fonts[size].find(colour);
  if (it != fonts[size].end()) return it->second.get();
 
  fonts[size][colour] = std::make_unique<Font>(size, colour);
  return fonts[size][colour].get();
}

void Layouter::Initialize()
{
#if defined(WITH_ICU_I18N) && defined(WITH_HARFBUZZ)
  ICUParagraphLayoutFactory::InitializeLayouter();
#endif /* WITH_ICU_I18N && WITH_HARFBUZZ */
}

void Layouter::ResetFontCache(FontSize size)
{
  fonts[size].clear();
 
  /* We must reset the linecache since it references the just freed fonts */
  ResetLineCache();
 
#if defined(WITH_UNISCRIBE)
  UniscribeResetScriptCache(size);
#endif
#if defined(WITH_COCOA)
  MacOSResetScriptCache(size);
#endif
}

Layouter::LineCacheItem &Layouter::GetCachedParagraphLayout(std::string_view str, const FontState &state)
{
  if (linecache == nullptr) {
    /* Create linecache on first access to avoid trouble with initialisation order of static variables. */
    linecache = std::make_unique<LineCache>(4096);
  }
 
  if (auto match = linecache->GetIfValid(LineCacheQuery{state, str});
    match != nullptr) {
    return *match;
  }
 
  /* Create missing entry */
  LineCacheKey key;
  key.state_before = state;
  key.str.assign(str);
  linecache->Insert(key, {});
  return *linecache->GetIfValid(key);
}

void Layouter::ResetLineCache()
{
  if (linecache != nullptr) linecache->Clear();
}

ParagraphLayouter::Position GetCharPosInString(std::string_view str, size_t pos, FontSize start_fontsize)
{
  assert(pos <= str.size());
  auto it_ch = str.begin() + pos;
 
  Layouter layout(str, INT32_MAX, start_fontsize);
  return layout.GetCharPosition(it_ch);
}

ptrdiff_t GetCharAtPosition(std::string_view str, int x, FontSize start_fontsize)
{
  if (x < 0) return -1;
 
  Layouter layout(str, INT32_MAX, start_fontsize);
  return layout.GetCharAtPosition(x, 0);
}