FreeType2 which size does FT_Request_Size actaully set?

Question

I'm not clear on what I'm actually specifying when I call FT_Request_Size (or FT_Set_Pixel_Sizes). This appears to be some kind of maximum size for the glyph. That is, depends on the proportional size, ascenders, etc. the resulting glyph can, and will, actually be smaller than this size.

Is my interpretation correct? I can't find anything in the API docs which says precisely what it does.

Answer 1

Based on answers from the FreeType maintainers I got the docs updated to add a bit of clarification. Basically the font itself determines the resulting sizes.

For RT_Request_Size

The relation between the requested size and the resulting glyph size is dependent entirely on how the size is defined in the source face. The font designer chooses the final size of each glyph relative to this size. For more information refer to ‘http://www.freetype.org/freetype2/docs/glyphs/glyphs-2.html’

For FT_Set_Pixel_Sizes

You should not rely on the resulting glyphs matching, or being constrained, to this pixel size. Refer to FT_Request_Size to understand how requested sizes relate to actual sizes.