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      1 // Copyright 2014 PDFium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 // Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
      6 
      7 #include "core/fxcrt/fx_bidi.h"
      8 #include "core/fxcrt/fx_ucd.h"
      9 
     10 #include <algorithm>
     11 
     12 CFX_BidiChar::CFX_BidiChar()
     13     : m_CurrentSegment({0, 0, NEUTRAL}), m_LastSegment({0, 0, NEUTRAL}) {}
     14 
     15 bool CFX_BidiChar::AppendChar(FX_WCHAR wch) {
     16   uint32_t dwProps = FX_GetUnicodeProperties(wch);
     17   int32_t iBidiCls = (dwProps & FX_BIDICLASSBITSMASK) >> FX_BIDICLASSBITS;
     18   Direction direction = NEUTRAL;
     19   switch (iBidiCls) {
     20     case FX_BIDICLASS_L:
     21     case FX_BIDICLASS_AN:
     22     case FX_BIDICLASS_EN:
     23       direction = LEFT;
     24       break;
     25     case FX_BIDICLASS_R:
     26     case FX_BIDICLASS_AL:
     27       direction = RIGHT;
     28       break;
     29   }
     30 
     31   bool bChangeDirection = (direction != m_CurrentSegment.direction);
     32   if (bChangeDirection)
     33     StartNewSegment(direction);
     34 
     35   m_CurrentSegment.count++;
     36   return bChangeDirection;
     37 }
     38 
     39 bool CFX_BidiChar::EndChar() {
     40   StartNewSegment(NEUTRAL);
     41   return m_LastSegment.count > 0;
     42 }
     43 
     44 void CFX_BidiChar::StartNewSegment(CFX_BidiChar::Direction direction) {
     45   m_LastSegment = m_CurrentSegment;
     46   m_CurrentSegment.start += m_CurrentSegment.count;
     47   m_CurrentSegment.count = 0;
     48   m_CurrentSegment.direction = direction;
     49 }
     50 
     51 CFX_BidiString::CFX_BidiString(const CFX_WideString& str)
     52     : m_Str(str),
     53       m_pBidiChar(new CFX_BidiChar),
     54       m_eOverallDirection(CFX_BidiChar::LEFT) {
     55   for (int i = 0; i < m_Str.GetLength(); ++i) {
     56     if (m_pBidiChar->AppendChar(m_Str.GetAt(i)))
     57       m_Order.push_back(m_pBidiChar->GetSegmentInfo());
     58   }
     59   if (m_pBidiChar->EndChar())
     60     m_Order.push_back(m_pBidiChar->GetSegmentInfo());
     61 
     62   size_t nR2L = std::count_if(m_Order.begin(), m_Order.end(),
     63                               [](const CFX_BidiChar::Segment& seg) {
     64                                 return seg.direction == CFX_BidiChar::RIGHT;
     65                               });
     66 
     67   size_t nL2R = std::count_if(m_Order.begin(), m_Order.end(),
     68                               [](const CFX_BidiChar::Segment& seg) {
     69                                 return seg.direction == CFX_BidiChar::LEFT;
     70                               });
     71 
     72   if (nR2L > 0 && nR2L >= nL2R)
     73     SetOverallDirectionRight();
     74 }
     75 
     76 CFX_BidiString::~CFX_BidiString() {}
     77 
     78 void CFX_BidiString::SetOverallDirectionRight() {
     79   if (m_eOverallDirection != CFX_BidiChar::RIGHT) {
     80     std::reverse(m_Order.begin(), m_Order.end());
     81     m_eOverallDirection = CFX_BidiChar::RIGHT;
     82   }
     83 }
     84