用Java渲染字体：java.awt.Font行为不正确

Question

What I've encountered so far is what I can think of a "bug" in Oracle's font rendering libraries in Java. In certain fonts (like fonts embedded in PDF files), some irregular character codes are used and they have glyphs associated to them.

When trying to get glyph vector using java.awt.Font.createGlyphVector method in such cases (character codes 9, 10 and 13 which belong to tab, carriage return and new line) the correct glyph is not returned, but it works for everything else.

I tracked the issue to the CMap implementation in Java, that has a code similar to this:

         char getGlyph(int charCode) {
             if (charCode < 256) {
                 if (charCode < 0x0010) {
                     switch (charCode) {
                     case 0x0009:
                     case 0x000a:
                     case 0x000d: return CharToGlyphMapper.INVISIBLE_GLYPH_ID;
                     }
                 }
                 return (char)(0xff & cmap[charCode]);
             } else {
                 return 0;
             }
         }

So, my question is:

• IS this actually a bug?
• Does anyone know how to work around this?
• Is there a way to extract CMAP data from true type fonts, so that I can map characters (code points) to glyph codes?

Answer 1

I'm sure you've figured out the problem by now, but for those who stumble upon this page in the future, I would recommend the sfntly library . It is a free java library by google that allows you to edit sfnt based fonts that is very easy to work with. If you solved your problem another way, please enlighten us with an update. Thanks.