I'm trying to print with certain TrueType fonts and despite using the "Download as TrueType" or "Download as SoftFont" settings the font downloads as a bitmap. While the text is not rendered as a graphic, each character is a bitmap and can't be scaled. Some fonts, such as Arial, Times New Roman and Courier New do download as fully scalable TrueType fonts. But other fonts (e.g. Miriam) will only download as bitmaps for the specific point-size specified.
Why would the printer drivers convert the outline into a bitmap for these fonts?
When I capture the print stream (by changing the printer's port to FILE) I can view the printer code (which is PCL) to see what's going on. There's a font header which indicates how the font is downloaded. For most cases (Arial, Courier etc.) the header is in "Format 15" for TrueTypes, which is what I want. Sometimes (for fonts like Miriam) the header is in "Format 20" for "Resolution-Specified Bitmapped Font" which is bad. What makes Miriam different than Arial and the rest?
Note I'm using PCL compatible (not PostScript) drivers only.
(I suspect that something in these fonts are incompatible with how printers scale fonts, and thus the driver converts the outlines to bitmaps.)