OTS解析错误：表目录的entrySelector不正确（OpenType字体错误）

【问题标题】：OTS parsing error: incorrect entrySelector for table directory (OpenType font error)OTS解析错误：表目录的entrySelector不正确（OpenType字体错误）
【发布时间】：2019-06-10 12:23:14
【问题描述】：

我大概有这张cmap表：

{ name: 'cmap',
   fields:
    { version: { type: 'USHORT', value: 0 },
      numTables: { type: 'USHORT', value: 1 },
      platformID: { type: 'USHORT', value: 0 },
      encodingID: { type: 'USHORT', value: 6 },
      offset: { type: 'ULONG', value: 12 },
      format: { type: 'USHORT', value: 4 },
      cmap4Length: { type: 'USHORT', value: 16 },
      language: { type: 'USHORT', value: 0 },
      segCountX2: { type: 'USHORT', value: 126 },
      searchRange: { type: 'USHORT', value: 64 },
      entrySelector: { type: 'USHORT', value: 5 },
      rangeShift: { type: 'USHORT', value: 62 },
      end_0: { type: 'USHORT', value: 48 },
      end_1: { type: 'USHORT', value: 49 },
      end_2: { type: 'USHORT', value: 50 },
      end_3: { type: 'USHORT', value: 51 },
      end_4: { type: 'USHORT', value: 52 },
      end_5: { type: 'USHORT', value: 53 },
      end_6: { type: 'USHORT', value: 54 },
      end_7: { type: 'USHORT', value: 55 },
      end_8: { type: 'USHORT', value: 56 },
      end_9: { type: 'USHORT', value: 57 },
      end_10: { type: 'USHORT', value: 65 },
      end_11: { type: 'USHORT', value: 66 },
      end_12: { type: 'USHORT', value: 67 },
      end_13: { type: 'USHORT', value: 68 },
      end_14: { type: 'USHORT', value: 69 },
      end_15: { type: 'USHORT', value: 70 },
      end_16: { type: 'USHORT', value: 71 },
      end_17: { type: 'USHORT', value: 72 },
      end_18: { type: 'USHORT', value: 73 },
      end_19: { type: 'USHORT', value: 74 },
      end_20: { type: 'USHORT', value: 75 },
      end_21: { type: 'USHORT', value: 76 },
      end_22: { type: 'USHORT', value: 77 },
      end_23: { type: 'USHORT', value: 78 },
      end_24: { type: 'USHORT', value: 79 },
      end_25: { type: 'USHORT', value: 80 },
      end_26: { type: 'USHORT', value: 81 },
      end_27: { type: 'USHORT', value: 82 },
      end_28: { type: 'USHORT', value: 83 },
      end_29: { type: 'USHORT', value: 84 },
      end_30: { type: 'USHORT', value: 85 },
      end_31: { type: 'USHORT', value: 86 },
      end_32: { type: 'USHORT', value: 87 },
      end_33: { type: 'USHORT', value: 88 },
      end_34: { type: 'USHORT', value: 89 },
      end_35: { type: 'USHORT', value: 90 },
      end_36: { type: 'USHORT', value: 97 },
      end_37: { type: 'USHORT', value: 98 },
      end_38: { type: 'USHORT', value: 99 },
      end_39: { type: 'USHORT', value: 100 },
      end_40: { type: 'USHORT', value: 101 },
      end_41: { type: 'USHORT', value: 102 },
      end_42: { type: 'USHORT', value: 103 },
      end_43: { type: 'USHORT', value: 104 },
      end_44: { type: 'USHORT', value: 105 },
      end_45: { type: 'USHORT', value: 106 },
      end_46: { type: 'USHORT', value: 107 },
      end_47: { type: 'USHORT', value: 108 },
      end_48: { type: 'USHORT', value: 109 },
      end_49: { type: 'USHORT', value: 110 },
      end_50: { type: 'USHORT', value: 111 },
      end_51: { type: 'USHORT', value: 112 },
      end_52: { type: 'USHORT', value: 113 },
      end_53: { type: 'USHORT', value: 114 },
      end_54: { type: 'USHORT', value: 115 },
      end_55: { type: 'USHORT', value: 116 },
      end_56: { type: 'USHORT', value: 117 },
      end_57: { type: 'USHORT', value: 118 },
      end_58: { type: 'USHORT', value: 119 },
      end_59: { type: 'USHORT', value: 120 },
      end_60: { type: 'USHORT', value: 121 },
      end_61: { type: 'USHORT', value: 122 },
      end_62: { type: 'USHORT', value: 65535 },
      reservedPad: { type: 'USHORT', value: 0 },
      start_0: { type: 'USHORT', value: 48 },
      start_1: { type: 'USHORT', value: 49 },
      start_2: { type: 'USHORT', value: 50 },
      start_3: { type: 'USHORT', value: 51 },
      start_4: { type: 'USHORT', value: 52 },
      start_5: { type: 'USHORT', value: 53 },
      start_6: { type: 'USHORT', value: 54 },
      start_7: { type: 'USHORT', value: 55 },
      start_8: { type: 'USHORT', value: 56 },
      start_9: { type: 'USHORT', value: 57 },
      start_10: { type: 'USHORT', value: 65 },
      start_11: { type: 'USHORT', value: 66 },
      start_12: { type: 'USHORT', value: 67 },
      start_13: { type: 'USHORT', value: 68 },
      start_14: { type: 'USHORT', value: 69 },
      start_15: { type: 'USHORT', value: 70 },
      start_16: { type: 'USHORT', value: 71 },
      start_17: { type: 'USHORT', value: 72 },
      start_18: { type: 'USHORT', value: 73 },
      start_19: { type: 'USHORT', value: 74 },
      start_20: { type: 'USHORT', value: 75 },
      start_21: { type: 'USHORT', value: 76 },
      start_22: { type: 'USHORT', value: 77 },
      start_23: { type: 'USHORT', value: 78 },
      start_24: { type: 'USHORT', value: 79 },
      start_25: { type: 'USHORT', value: 80 },
      start_26: { type: 'USHORT', value: 81 },
      start_27: { type: 'USHORT', value: 82 },
      start_28: { type: 'USHORT', value: 83 },
      start_29: { type: 'USHORT', value: 84 },
      start_30: { type: 'USHORT', value: 85 },
      start_31: { type: 'USHORT', value: 86 },
      start_32: { type: 'USHORT', value: 87 },
      start_33: { type: 'USHORT', value: 88 },
      start_34: { type: 'USHORT', value: 89 },
      start_35: { type: 'USHORT', value: 90 },
      start_36: { type: 'USHORT', value: 97 },
      start_37: { type: 'USHORT', value: 98 },
      start_38: { type: 'USHORT', value: 99 },
      start_39: { type: 'USHORT', value: 100 },
      start_40: { type: 'USHORT', value: 101 },
      start_41: { type: 'USHORT', value: 102 },
      start_42: { type: 'USHORT', value: 103 },
      start_43: { type: 'USHORT', value: 104 },
      start_44: { type: 'USHORT', value: 105 },
      start_45: { type: 'USHORT', value: 106 },
      start_46: { type: 'USHORT', value: 107 },
      start_47: { type: 'USHORT', value: 108 },
      start_48: { type: 'USHORT', value: 109 },
      start_49: { type: 'USHORT', value: 110 },
      start_50: { type: 'USHORT', value: 111 },
      start_51: { type: 'USHORT', value: 112 },
      start_52: { type: 'USHORT', value: 113 },
      start_53: { type: 'USHORT', value: 114 },
      start_54: { type: 'USHORT', value: 115 },
      start_55: { type: 'USHORT', value: 116 },
      start_56: { type: 'USHORT', value: 117 },
      start_57: { type: 'USHORT', value: 118 },
      start_58: { type: 'USHORT', value: 119 },
      start_59: { type: 'USHORT', value: 120 },
      start_60: { type: 'USHORT', value: 121 },
      start_61: { type: 'USHORT', value: 122 },
      start_62: { type: 'USHORT', value: 65535 },
      idDelta_0: { type: 'SHORT', value: 4 },
      idDelta_1: { type: 'SHORT', value: 4 },
      idDelta_2: { type: 'SHORT', value: 4 },
      idDelta_3: { type: 'SHORT', value: 4 },
      idDelta_4: { type: 'SHORT', value: 4 },
      idDelta_5: { type: 'SHORT', value: 4 },
      idDelta_6: { type: 'SHORT', value: 4 },
      idDelta_7: { type: 'SHORT', value: 4 },
      idDelta_8: { type: 'SHORT', value: 4 },
      idDelta_9: { type: 'SHORT', value: 4 },
      idDelta_10: { type: 'SHORT', value: -39 },
      idDelta_11: { type: 'SHORT', value: -39 },
      idDelta_12: { type: 'SHORT', value: -39 },
      idDelta_13: { type: 'SHORT', value: -39 },
      idDelta_14: { type: 'SHORT', value: -39 },
      idDelta_15: { type: 'SHORT', value: -39 },
      idDelta_16: { type: 'SHORT', value: -39 },
      idDelta_17: { type: 'SHORT', value: -39 },
      idDelta_18: { type: 'SHORT', value: -39 },
      idDelta_19: { type: 'SHORT', value: -39 },
      idDelta_20: { type: 'SHORT', value: -39 },
      idDelta_21: { type: 'SHORT', value: -39 },
      idDelta_22: { type: 'SHORT', value: -39 },
      idDelta_23: { type: 'SHORT', value: -39 },
      idDelta_24: { type: 'SHORT', value: -39 },
      idDelta_25: { type: 'SHORT', value: -39 },
      idDelta_26: { type: 'SHORT', value: -39 },
      idDelta_27: { type: 'SHORT', value: -39 },
      idDelta_28: { type: 'SHORT', value: -39 },
      idDelta_29: { type: 'SHORT', value: -39 },
      idDelta_30: { type: 'SHORT', value: -39 },
      idDelta_31: { type: 'SHORT', value: -39 },
      idDelta_32: { type: 'SHORT', value: -39 },
      idDelta_33: { type: 'SHORT', value: -39 },
      idDelta_34: { type: 'SHORT', value: -39 },
      idDelta_35: { type: 'SHORT', value: -39 },
      idDelta_36: { type: 'SHORT', value: -97 },
      idDelta_37: { type: 'SHORT', value: -97 },
      idDelta_38: { type: 'SHORT', value: -97 },
      idDelta_39: { type: 'SHORT', value: -97 },
      idDelta_40: { type: 'SHORT', value: -97 },
      idDelta_41: { type: 'SHORT', value: -97 },
      idDelta_42: { type: 'SHORT', value: -97 },
      idDelta_43: { type: 'SHORT', value: -97 },
      idDelta_44: { type: 'SHORT', value: -97 },
      idDelta_45: { type: 'SHORT', value: -97 },
      idDelta_46: { type: 'SHORT', value: -97 },
      idDelta_47: { type: 'SHORT', value: -97 },
      idDelta_48: { type: 'SHORT', value: -97 },
      idDelta_49: { type: 'SHORT', value: -97 },
      idDelta_50: { type: 'SHORT', value: -97 },
      idDelta_51: { type: 'SHORT', value: -97 },
      idDelta_52: { type: 'SHORT', value: -97 },
      idDelta_53: { type: 'SHORT', value: -97 },
      idDelta_54: { type: 'SHORT', value: -97 },
      idDelta_55: { type: 'SHORT', value: -97 },
      idDelta_56: { type: 'SHORT', value: -97 },
      idDelta_57: { type: 'SHORT', value: -97 },
      idDelta_58: { type: 'SHORT', value: -97 },
      idDelta_59: { type: 'SHORT', value: -97 },
      idDelta_60: { type: 'SHORT', value: -97 },
      idDelta_61: { type: 'SHORT', value: -97 },
      idDelta_62: { type: 'SHORT', value: 1 },
      idRangeOffset_0: { type: 'USHORT', value: 0 },
      idRangeOffset_1: { type: 'USHORT', value: 0 },
      idRangeOffset_2: { type: 'USHORT', value: 0 },
      idRangeOffset_3: { type: 'USHORT', value: 0 },
      idRangeOffset_4: { type: 'USHORT', value: 0 },
      idRangeOffset_5: { type: 'USHORT', value: 0 },
      idRangeOffset_6: { type: 'USHORT', value: 0 },
      idRangeOffset_7: { type: 'USHORT', value: 0 },
      idRangeOffset_8: { type: 'USHORT', value: 0 },
      idRangeOffset_9: { type: 'USHORT', value: 0 },
      idRangeOffset_10: { type: 'USHORT', value: 0 },
      idRangeOffset_11: { type: 'USHORT', value: 0 },
      idRangeOffset_12: { type: 'USHORT', value: 0 },
      idRangeOffset_13: { type: 'USHORT', value: 0 },
      idRangeOffset_14: { type: 'USHORT', value: 0 },
      idRangeOffset_15: { type: 'USHORT', value: 0 },
      idRangeOffset_16: { type: 'USHORT', value: 0 },
      idRangeOffset_17: { type: 'USHORT', value: 0 },
      idRangeOffset_18: { type: 'USHORT', value: 0 },
      idRangeOffset_19: { type: 'USHORT', value: 0 },
      idRangeOffset_20: { type: 'USHORT', value: 0 },
      idRangeOffset_21: { type: 'USHORT', value: 0 },
      idRangeOffset_22: { type: 'USHORT', value: 0 },
      idRangeOffset_23: { type: 'USHORT', value: 0 },
      idRangeOffset_24: { type: 'USHORT', value: 0 },
      idRangeOffset_25: { type: 'USHORT', value: 0 },
      idRangeOffset_26: { type: 'USHORT', value: 0 },
      idRangeOffset_27: { type: 'USHORT', value: 0 },
      idRangeOffset_28: { type: 'USHORT', value: 0 },
      idRangeOffset_29: { type: 'USHORT', value: 0 },
      idRangeOffset_30: { type: 'USHORT', value: 0 },
      idRangeOffset_31: { type: 'USHORT', value: 0 },
      idRangeOffset_32: { type: 'USHORT', value: 0 },
      idRangeOffset_33: { type: 'USHORT', value: 0 },
      idRangeOffset_34: { type: 'USHORT', value: 0 },
      idRangeOffset_35: { type: 'USHORT', value: 0 },
      idRangeOffset_36: { type: 'USHORT', value: 0 },
      idRangeOffset_37: { type: 'USHORT', value: 0 },
      idRangeOffset_38: { type: 'USHORT', value: 0 },
      idRangeOffset_39: { type: 'USHORT', value: 0 },
      idRangeOffset_40: { type: 'USHORT', value: 0 },
      idRangeOffset_41: { type: 'USHORT', value: 0 },
      idRangeOffset_42: { type: 'USHORT', value: 0 },
      idRangeOffset_43: { type: 'USHORT', value: 0 },
      idRangeOffset_44: { type: 'USHORT', value: 0 },
      idRangeOffset_45: { type: 'USHORT', value: 0 },
      idRangeOffset_46: { type: 'USHORT', value: 0 },
      idRangeOffset_47: { type: 'USHORT', value: 0 },
      idRangeOffset_48: { type: 'USHORT', value: 0 },
      idRangeOffset_49: { type: 'USHORT', value: 0 },
      idRangeOffset_50: { type: 'USHORT', value: 0 },
      idRangeOffset_51: { type: 'USHORT', value: 0 },
      idRangeOffset_52: { type: 'USHORT', value: 0 },
      idRangeOffset_53: { type: 'USHORT', value: 0 },
      idRangeOffset_54: { type: 'USHORT', value: 0 },
      idRangeOffset_55: { type: 'USHORT', value: 0 },
      idRangeOffset_56: { type: 'USHORT', value: 0 },
      idRangeOffset_57: { type: 'USHORT', value: 0 },
      idRangeOffset_58: { type: 'USHORT', value: 0 },
      idRangeOffset_59: { type: 'USHORT', value: 0 },
      idRangeOffset_60: { type: 'USHORT', value: 0 },
      idRangeOffset_61: { type: 'USHORT', value: 0 },
      idRangeOffset_62: { type: 'USHORT', value: 0 } } }

编码输出为 8 位整数数组，如下所示：

0 0 0 1 0 0 0 6 0 0 0 12 0 4 0 16 0 0 0 126 0 64 0 5 0 62 0 48 0 49 0 50 0 51 0 52 0 53 0 54 0 55 0 56 0 57 0 65 0 66 0 67 0 68 0 69 0 70 0 71 0 72 0 73 0 74 0 75 0 76 0 77 0 78 0 79 0 80 0 81 0 82 0 83 0 84 0 85 0 86 0 87 0 88 0 89 0 90 0 97 0 98 0 99 0 100 0 101 0 102 0 103 0 104 0 105 0 106 0 107 0 108 0 109 0 110 0 111 0 112 0 113 0 114 0 115 0 1216 0 1190 0 1216 0 11170 121 0 122 255 255 0 0 0 48 0 49 0 50 0 51 0 52 0 53 0 54 0 55 0 56 0 57 0 65 0 66 0 67 0 68 0 69 0 70 0 71 0 72 0 73 0 74 0 5 76 0 77 0 78 0 79 0 80 0 81 0 82 0 83 0 84 0 85 0 86 0 87 0 88 0 89 0 90 0 97 0 98 0 99 0 100 0 101 0 102 0 103 0 1064 0 105 0 107 0 108 0 109 0 110 0 111 0 112 0 113 0 114 0 115 0 116 0 117 0 118 0 119 0 120 0 121 0 122 255 255 0 4 0 4 0 4 0 4 0 4 0 0 4 4 0 4 255 217 255 217 255 217 255 217 255 217 21 21 21 21 21 21 21 21 21 217 255 217 255 217 21 21 217 255 217 255 217 255 1 59 255 159 255 159 255 159 255 159 255 151 1595 15/159 255 151 159 15 15 15/1259 255 15955 15/15955 159 255 151 1511duff 255 159 255 15955 15/159 255 159 255 15955 159 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

我不确定如何最好地调试它，但我想问一下这看起来是否正确，或者我应该如何调试。不询问确切的值是否正确，但我非常确定我正确输入的值是rangeShift 之前的所有值。之后就生成了。但是从segCountX2 到rangeShift 的那些值，即使我认为我做对了，我仍然收到这个错误：OTS parsing error: incorrect entrySelector for table directory，即使我只是让字体文件只有所有字段观点！所以字体文件很小，但仍然是同样的错误。我是按照spec做计算的，像这样：

var numTables = tables.length
var highestPowerOf2 = Math.pow(2, Math.log2(numTables))
var searchRange = 16 * highestPowerOf2
var entrySelector = Math.log2(highestPowerOf2) * 16
var rangeShift = (numTables * 16) - searchRange

var fields = {
  sfntVersion: { type: 'TAG', value: 'OTTO'},
  numTables: { type: 'USHORT', value: numTables},
  searchRange: { type: 'USHORT', value: searchRange},
  entrySelector: { type: 'USHORT', value: entrySelector},
  rangeShift: { type: 'USHORT', value: rangeShift},
}

但仍然无法正常工作。我也试过this。

【问题讨论】：

    标签： fonts binary byte


    【解决方案1】：

    似乎已通过改用 Apple 参考而不是 Microsoft 进行计算来解决：

    https://developer.apple.com/fonts/TrueType-Reference-Manual/RM06/Chap6.html

    表 4 中记录的偏移子表以字体的缩放类型开始。 'sfnt' 中标记表的数量如下。表目录本身和任何子表不包括在此计数中。 searchRange、entrySelector 和 rangeShift 的条目用于促进对随后的表目录进行快速二进制搜索。除非字体有大量表格，否则顺序搜索就足够快了。

    如果需要更快的搜索，二分法搜索最容易对多个为 2 的幂的条目进行。这使得可以通过移位将要搜索的项目数量减少一半。剩余的偏移量子表项应设置如下：

    searchRange 是小于等于表中项目数的 2 的最大幂，即可以轻松搜索到的最大项目数。 rangeShift 是项目数减去 searchRange；即，如果您只查看 searchRange 项目，则不会查看的项目数。 在搜索循环开始之前，将目标项目与编号为 rangeShift 的项目进行比较。如果目标项小于 rangeShift，则从表的开头开始搜索。如果更大，则从编号为 rangeShift 的项目开始搜索。

    entrySelector 是 log2(searchRange)。它告诉搜索循环需要多少次迭代。 （即将范围减半的次数） 请注意，searchRange、entrySelector 和 rangeShift 都乘以 16，表示目录条目的大小。

    【讨论】：

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