PDFlib 8 Windows COM/.NET Tutorial

0x20 will be interpreted as control characters if the symbolic font does not contain
any glyph for the code. This is true for the majority of symbolic fonts.
Character references. Character references are supported for symbolic fonts. However,
symbolic fonts generally do not include any glyph for the ampersand character U+0026
’&’ which introduces character references. The code 0x26 cannot be used either since it
could be mapped to an existing glyph in the font. For these reasons symbolic fonts
should be loaded with encoding=unicode if character references must be used. Character
references do not work with encoding=builtin.
5.4.3 Example: Selecting a Glyph from the Wingdings Symbol Font
Since there are many different ways of selecting characters from a symbol font and
some will not result in the desired output, let’s take a look at an example.
Understanding the characters in the font. First let’s collect some information about
the target character in the font, using the Windows charmap application (see Figure 5.1):
> Charmap displays the glyphs in the Wingdings font, but does not provide any Unicode
access in the Advanced view. This is a result of the fact that the font contains
symbolic glyphs for which no standardized Unicode values are registered. Instead,
the glyphs in the font use dummy Unicode values in the Private Use Area (PUA). The
charmap application does not reveal these values.
> If you look at the lower left corner of the charmap window or hover the mouse over
the smileface character, the Character code: 0x4A is displayed. This is the glyph’s byte
code.
This code corresponds to the uppercase J character in the Winansi encoding. For example,
if you copy the character to the clipboard the corresponding Unicode value
U+004A, i.e. character J will result from pasting the clipboard contents to a text-only
application. Nevertheless, this is not the character’s Unicode value and therefore
U+004A or J can not be used to select it in Unicode workflows.
> The Unicode character used internally in the font is not displayed in charmap. However,
symbolic fonts provided by Microsoft use the following simple rule:
Unicode value = U+F000 + (character code displayed in charmap)
For the smileface glyph this yields the Unicode value U+F04A.
> The corresponding glyph name can be retrieved with a font editor and similar tools.
In our example it is smileface.
You can use info_font( ) to query Unicode values, glyph names or codes, see Section 5.6.2,
»Font-specific Encoding, Unicode, and Glyph Name Queries«, page 147.
Addressing the symbol character with PDFlib. Depending on the information which is
available about the target character you can select the Wingdings smileface glyph in several
ways:
> If you know the PUA Unicode value which is assigned to the character in the font you
can use a numerical character reference (see »Numerical character references«, page
114):
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130 Chapter 5: Font Handling (Edition for COM, .NET, and REALbasic)