icuSources/layout/ScriptAndLanguage.cpp

   1 /*
   2  * (C) Copyright IBM Corp. 1998-2013 - All Rights Reserved
   3  *
   4  */
   5
   6 #include "LETypes.h"
   7 #include "OpenTypeTables.h"
   8 #include "OpenTypeUtilities.h"
   9 #include "ScriptAndLanguage.h"
  10 #include "LESwaps.h"
  11
  12 U_NAMESPACE_BEGIN
  13
  14 LEReferenceTo<LangSysTable> ScriptTable::findLanguage(const LETableReference& base, LETag languageTag, LEErrorCode &success, le_bool exactMatch) const
  15 {
  16     le_uint16 count = SWAPW(langSysCount);
  17     Offset langSysTableOffset = exactMatch? 0 : SWAPW(defaultLangSysTableOffset);
  18
  19     if (count > 0) {
  20       LEReferenceToArrayOf<TagAndOffsetRecord> langSysRecords(base, success, langSysRecordArray, count);
  21       Offset foundOffset =
  22         OpenTypeUtilities::getTagOffset(languageTag, langSysRecords, success);
  23
  24       if (foundOffset != 0 && LE_SUCCESS(success)) {
  25         langSysTableOffset = foundOffset;
  26       }
  27     }
  28
  29     if (langSysTableOffset != 0) {
  30       return LEReferenceTo<LangSysTable>(base, success, langSysTableOffset);
  31     }
  32
  33     return LEReferenceTo<LangSysTable>();
  34 }
  35
  36 LEReferenceTo<ScriptTable> ScriptListTable::findScript(const LETableReference &base, LETag scriptTag, LEErrorCode &success) const
  37 {
  38     if (LE_FAILURE(success) ) {
  39       return LEReferenceTo<ScriptTable>(); // get out
  40     }
  41     /*
  42      * There are some fonts that have a large, bogus value for scriptCount. To try
  43      * and protect against this, we use the offset in the first scriptRecord,
  44      * which we know has to be past the end of the scriptRecordArray, to compute
  45      * a value which is greater than or equal to the actual script count.
  46      *
  47      * Note: normally, the first offset will point to just after the scriptRecordArray,
  48      * but there's no guarantee of this, only that it's *after* the scriptRecordArray.
  49      * Because of this, a binary serach isn't safe, because the new count may include
  50      * data that's not actually in the scriptRecordArray and hence the array will appear
  51      * to be unsorted.
  52      */
  53     le_uint16 count = SWAPW(scriptCount);
  54
  55     if (count == 0) {
  56       return LEReferenceTo<ScriptTable>(); // no items, no search
  57     }
  58
  59     // attempt to construct a ref with at least one element
  60     LEReferenceToArrayOf<ScriptRecord> oneElementTable(base, success, &scriptRecordArray[0], 1);
  61
  62     if( LE_FAILURE(success) ) {
  63       return LEReferenceTo<ScriptTable>(); // couldn't even read the first record - bad font.
  64     }
  65
  66     le_uint16 limit = ((SWAPW(scriptRecordArray[0].offset) - sizeof(ScriptListTable)) / sizeof(scriptRecordArray)) + ANY_NUMBER;
  67     Offset scriptTableOffset = 0;
  68
  69
  70     if (count > limit) {
  71         // the scriptCount value is bogus; do a linear search
  72         // because limit may still be too large.
  73         LEReferenceToArrayOf<ScriptRecord> scriptRecordArrayRef(base, success, &scriptRecordArray[0], limit);
  74         for(le_int32 s = 0; (s < limit)&&LE_SUCCESS(success); s += 1) {
  75           if (SWAPT(scriptRecordArrayRef(s,success).tag) == scriptTag) {
  76             scriptTableOffset = SWAPW(scriptRecordArrayRef(s,success).offset);
  77             break;
  78           }
  79         }
  80     } else {
  81       LEReferenceToArrayOf<ScriptRecord> scriptRecordArrayRef(base, success, &scriptRecordArray[0], count);
  82
  83       scriptTableOffset = OpenTypeUtilities::getTagOffset(scriptTag, scriptRecordArrayRef, success);
  84     }
  85
  86     if (scriptTableOffset != 0) {
  87       return LEReferenceTo<ScriptTable>(base, success, scriptTableOffset);
  88     }
  89
  90   return LEReferenceTo<ScriptTable>();
  91 }
  92
  93 LEReferenceTo<LangSysTable>  ScriptListTable::findLanguage(const LETableReference &base, LETag scriptTag, LETag languageTag, LEErrorCode &success, le_bool exactMatch) const
  94 {
  95   const LEReferenceTo<ScriptTable> scriptTable = findScript(base, scriptTag, success);
  96
  97   if (scriptTable.isEmpty()) {
  98     return LEReferenceTo<LangSysTable>();
  99   }
 100
 101   return scriptTable->findLanguage(scriptTable, languageTag, success, exactMatch).reparent(base);
 102 }
 103
 104 U_NAMESPACE_END