> All I'm trying to do is to read in a TTF file (hence scalable > font?), specify a required size in pixel, and determine some font > metrics (as opposed to individual glyph metrics) based on the > required size. Have a look at the attached file. All I need is to > get those 22, 4, 6, 32 values (they may not be right as I didn't > collect them based on all glyphs in the font file.)
Please read the FreeType documentation files at http://freetype.freedesktop.org/freetype2/documentation.html (www.freetype.org is currently unavailable) and also check the OpenType specification. > My first question is that if FreeType is capable to distinguish for > example 'A' from the 'A' with a circle/ascent? What about > characters with descent? What do you mean with `distinguish'? If the metrics in the font are correct, you'll get a bigger height for the Aring glyph. Note that for example TeX fonts don't have metrics which exactly correspond with the smallest bounding box. > Now I get a metrics structure in ftFace->size->metrics and they are in > something called "26.6 frac. pixels". I don't understand this very > well as they are in several thousands (more like vector coordinate) > instead of something close to 30. How do these fractional pixels > related to the 30-pixel size? 26.6 frac pixels means that a 32bit integer is slit into a 26bit integer part and a 6bit fixed fractional part. With other words, you have to divide the result by 64 to get `real' numbers. Example: 1920 -> 30.0 1921 -> 30.016 > My last question would be on the numerous metrics structures. To my > understanding metrics in "FT_Face" is before scaled, whereas the > "FT_Size_Metrics" in a "ftFace->size->metrics" is scaled. How are > they related to the metrics in a TT_Face structure? Would one be > more accurate than the others? You have to distinguish between device-dependent and device-independent metrics. A glyph rendered on screen normally gets a width which is an integer pixel value -- often caused by hinting instructions during the rendering process -- while the same glyph could have a fractional value (slightly larger or smaller) if the metrics value is scaled linearly. Werner _______________________________________________ Freetype mailing list [email protected] http://lists.nongnu.org/mailman/listinfo/freetype
