pdf text extraction

Question

3 begincidrange 
<20> <7e> 1 
<8140> <817e> 633 
<8180> <81ac> 696 
endcidrange 

This is a CMAP file sample.

1. How do I make a CMAP for my own data ?
2. What is 3 in 3 begincidrange
3. what is <20> <7e>? can anyone give an example

Answer 1

Your CMap table establishes all of the character code to CID mappings.

The number that appears before the begincidrange operator indicates the number of mapping lines. The endcidrange operator terminates a block of mappings.

The lines in between begincidrange and endcidrange contain the mappings. There are 3 entries for each line. The first two specify the character code range and the 3rd is the CID value they map to.

So character codes 0x20 to 0x7e map to CID 1.

Adobe Technote 5099 describes the format for CID tables.