ios - PDF CMap : Single Glyph to Multiple-Characters Mapping

Question

根据这个article , 以下 CMap bfrange 映射是有效的:

<02> <02> [<0066006C>]

这是否意味着 PDF CMap 解析器应该识别多字符十六进制并将其解析为 02 = [0066, 006C]？

我在 PDF 规范中找不到任何证实此特定格式的内容，这与明确提到的 startChar endChar [destChar, ...] 和 startChar endChar destChar 不同.

Answer 1

I can't find anything corroborating this specific format in the PDF specification

查看 pdf 规范 ISO 32000-1 第 9.10.3 节 ToUnicode CMaps 示例 2:

2  beginbfrange 
< 0000 >< 005E >< 0020 >
< 005F >< 0061 >[ < 00660066 >  < 00660069 >  < 00660066006C > ]
endbfrange 

...

< 00 00 > to < 00 5E > are mapped to the Unicode values U+0020 to U+007E This is followed by the definition of a mapping where each character code represents more than one Unicode value:

< 005F >  < 0061 >  [ < 00660066 >  < 00660069 >  < 00660066006C > ]

In this case, the original character codes are the glyph indices for the ligatures ff, fi, and ffl. The entry defines the mapping from the character codes < 00 5F >, < 00 60 >, and < 00 61 > to the strings of Unicode values with a Unicode scalar value for each character in the ligature: U+0066 U+0066 are the Unicode values for the character sequence f f, U+0066 U+0069 for f i, and U+0066 U+0066 U+006c for f f l.