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Generation of AFM Information

Next lets consider how to generate the AFM information. It is a series of entirely independent steps: At the end of this procedure, there is a data area identical to what would have been built when reading an AFM file without kerning-section and ligature specifications.

The decision of building AFM data is done on the fly without any user interaction. Here is what happens on the metrics-area when loading a font:

It should be noted that generating metric information the way described above takes significant amount of time since every character has to be rastered at 1000 bp.

If the T1_NO_AFM flag is passed to T1_InitLib(), t1lib will neither attempt to open AFM files nor generate AFM information. This is useful to speed up applications which do not need the metrics data. However, this slows down access to certain features, mostly related to the string processing functions, and completely disables the features that only are contained in AFM files (like kerning and ligatures).

Obivously, the t1lib functions that use the AFM data will not work correctly in this case and should not be used.


next up previous contents index
Next: Writing AFM Files Up: Missing or Invalid AFM Previous: Remarks on AFM Files   Contents   Index
2005-01-12