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      SECTION 5.1                                             Organization and Use of Fonts



5.1.1 Basics of Showing Text

      Example 5.1 illustrates the most straightforward use of a font. The text ABC is
      placed 10 inches from the bottom of the page and 4 inches from the left edge, us-
      ing 12-point Helvetica.

      Example 5.1

         BT
              /F13 12 Tf
              288 720 Td
              ( ABC ) Tj
         ET

      The five lines of this example perform the following steps:

      1. Begin a text object.
      2. Set the font and font size to use, installing them as parameters in the text state.
         (The font resource identified by the name F13 specifies the font externally
         known as Helvetica.)
      3. Specify a starting position on the page, setting parameters in the text object.
      4. Paint the glyphs for a string of characters at that position.
      5. End the text object.

      The following paragraphs explain these operations in more detail.

      To paint glyphs, a content stream must first identify the font to be used. The Tf
      operator specifies the name of a font resource—that is, an entry in the Font
      subdictionary of the current resource dictionary. The value of that entry is a font
      dictionary. The font dictionary identifies the font’s externally known name, such
      as Helvetica, and supplies some additional information that the application needs
      to paint glyphs from that font. The font dictionary optionally provides the defini-
      tion of the font program itself.

      Note: The font resource name presented to the Tf operator is arbitrary, as are the
      names for all kinds of resources. It bears no relationship to an actual font name,
      such as Helvetica.

      Example 5.2 illustrates an excerpt from the current page’s resource dictionary,
      which defines the font dictionary that is referenced as F13 in Example 5.1.

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