Composite fonts in Java

Generate QR Code 2d barcode in Java Composite fonts

A composite font obtains its glyphs from a font-like object called a CIDFont. A composite font is represented by a font dictionary with subtype /Type0. The Type 0 font is known as the root font, and its associated CIDFont is called its descendant.

Please compare figure 11.6 with figure 11.5. The content of the page is identical, but now Arial-BoldMT only appears once in the list of fonts, as a CIDFont with Identity-H encoding. The code to create this PDF is almost identical to the code in listing 11.4; you need only to replace the encoding.

BaseFont bf; for (int i = 0; i < 4; i++) { bf = BaseFont.createFont(FONT, BaseFont.IDENTITY_H, BaseFont.EMBEDDED); document.add(new Paragraph("Font: " + bf.getPostscriptFontName() + " with encoding: " + bf.getEncoding())); document.add(new Paragraph(MOVIES[i][1])); document.add(new Paragraph(MOVIES[i][2])); document.add(new Paragraph(MOVIES[i][3], new Font(bf, 12))); document.add(Chunk.NEWLINE); }

CID stands for character identifier. A character identifier is used as the index of the char-

acter collection to access the glyphs in the font. For simple fonts, you had an index ranging from 0 to 255; in contrast, a CID can be a number from 0 to 65,535. This is a great advantage when dealing with languages that have huge character sets, such as Chinese, Japanese, and Korean.

Note that 65,535 is less than the number of code points available in Unicode (1,114,112). The association between the Unicode code points and their CIDs in the font is specified in a CMap, which is like a very large code page. In listing 11.5, you have used the CMap named Identity-H. This is a generic identity mapping for 2-byte CIDs in a horizontal writing system. The same mapping also exists for vertical writing systems: Identity-V. You ll use Identity-V when we discuss vertical writing systems. You ll use other CMaps in an example that uses a CJKFont.

As you can see in table 11.2, there are two types of CIDFonts:

Type 0 CIDFonts These contain glyphs based on the Compact Font Format (CFF; this is a Type 2 font in PostScript terms). If you want to embed such a font, you ll need to buy an .otf file that supports this format. You won t find many free fonts that support this format. Type 2 CIDFonts These contain glyphs based on the TrueType format. You can embed such a font if you have a file containing an OpenType font with TrueType outlines (.ttf) or a TrueType collection (.ttc).

Note that the way fonts are named can be very confusing: Type 0 in the context of CIDFonts has a different meaning than for Type 0 fonts; Type 2 in PostScript has a different meaning than for CIDFonts. Moreover, when you look at the Fonts tab in the Document properties, you ll see that a font with subtype CIDFontType0 is listed as a Type 1 (CID) font. Font technology isn t simple, but it s described in great detail in ISO-32000-1 and in additional technical notes published by Adobe. Right now, we re more interested in the way iText deals with these different types of fonts.

In the previous sections, we had a short overview of the different font files that can be used to create a BaseFont object, as well as the different font types one can find inside a PDF file. You saw some examples using different files resulting in different font types, but we ve overlooked some types: we haven t discussed Type 3 fonts yet, and we should also take a look at CMaps other than Identity-H. Before we can do this, we must have a look at the different iText classes that deal with fonts.