PHP GD - Dynamic Font Preview

I run a FONT website that provides opentype and truetype font files. I need a script that can read font files in these formats, and generate a character map of all the glyphs contained in the font file. An example would be, basically create this exact same script: [login to view URL] It would need to find all the glyphs in the font, and not display any characters not included in the font. For example, if the font is missing a & character, it would just skip that and not display in the output image. Project can be coded with GD library and using PHP5. Provide options at the top of the script file for size and font file.