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 <center>
 <h1>
 FreeType 2.0 Tutorial</h1></center>

 <center>
 <h3>
 &copy; 2000 David Turner (<a href="mailto:david@freetype.org">david@freetype.org</a>)<br>
 &copy; 2000 The FreeType Development Team
 (<a href="http://www.freetype.org">www.freetype.org</a>)
 </h3></center>

 <p><br>
 <hr WIDTH="100%">
 <br>&nbsp;
 <h2>Introduction:</h2>
 <ul>
     This simple tutorial will teach you how to use the FreeType 2 library
     in your own applications.
 </ul>

 <p><hr><p>

 <h3>1. Header files :</h3>
 <ul>
   You only need to include the public header file named <tt>freetype.h</tt>
   in your source code. Depending on how the library was installed on your
   system, you might need to use :<p>
   <ul><font color="blue"><tt>
       #include &lt;freetype.h&gt;<p>
   </tt></font></ul>
   or
   <ul><font color="blue"><tt>
       #include &lt;freetype2/freetype.h&gt;<p>
   </tt></font></ul>
   in your application to include the public interface to FreeType.<p>
 </ul>

 <p><hr><p>

 <h3>2. Initialise the library:</h3>
 <ul>
   Simply create a variable of type <tt>FT_Library</tt> named, for example,
   <tt>library</tt>, and call the function <tt>FT_Init_FreeType</tt> as in:

   <font color="blue"><pre>
        #include &lt;freetype.h&gt;

        FT_Library  library;

        ....

        {
          ..
          error = FT_Init_FreeType( &library );
          if (error) { .. an error occured during library initialisation .. }
        }
   </pre></font>
   <p>
   This function is in charge of the following:<p>
   <ul>
       <li>Creating a new instance of the FreeType 2 library, and set
           the handle <tt>library</tt> to it.
           <p>

       <li>Load each font driver that FreeType knows about in the library.
           This means that by default, your new <tt>library</tt> object is
           able to handle TrueType and Type 1 fonts gracefully.
           <p>
   </ul>
   <p>
   As you can see, the function returns an error code, like most others in the
   FreeType API. An error code of 0 <em>always</em> means that the operation
   was succesful; otherwise, the value describes the error, and <tt>library</tt>
   is set to NULL.
 </ul>

 <p><hr><p>

 <h3>3. Load a font face:</h3>
 <ul>
   <h4>a. From a font file:</h4>
   <ul>
     Create a new <em>face</em> object by calling <tt>FT_New_Face</tt>. A
     <em>face</em> describes a given typeface and style. For example,
     "Times New Roman Regular" and "Times New Roman Italic" correspond to
     two different faces.
     <p>
     <font color="blue"><pre>

           FT_Library   library;   /* handle to library     */
           FT_Face      face;      /* handle to face object */

           error = FT_Init_FreeType( &library );
           if (error) { ..... }

           error = FT_New_Face( library,
                                "/usr/share/fonts/truetype/arial.ttf",
                                0,
                                &face );
           if (error == FT_Err_Unknown_File_Format)
           {
              .... the font file could be opened and read, but it appears
              .... that its font format is unsupported
           }
           else if (error)
           {
              .... another error code means that the font file could not
              .... be opened, read or simply that it is broken..
           }
     </pre></font>
     <p>
     As you certainly imagine, <tt>FT_New_Face</tt> opens a font file then
     tries to extract one face from it. Its parameters are :<p>
     <ul>
     <table cellpadding=5>
     <tr valign="top"><td><tt><b>library</b></tt>
         <td>handle to the FreeType library instance where the face object is
             created

     <tr valign="top"><td><tt><b>filepathname</b></tt>
         <td>the font file pathname (standard C string).

     <tr valign="top"><td><tt><b>face_index</b></tt>
         <td>Certain font formats allow several font faces to be embedded in
             a single file.<br>
             This index tells which face you want to load. An
             error will be returned if its value is too large.<br>
             Index 0 always work though.

     <tr><td><tt><b>face</b></tt>
         <td>A <em>pointer</em> to the handle that will be set to
             describe the new face object.<br>
             It is set to NULL in case of error.
     </table>
     </ul>
     <p>
     To known how many faces a given font file contains, simply load its
     first face (use <tt>face_index</tt>=0), then see the value of
     <tt>face->num_faces</tt> which indicates how many faces are embedded in
     the font file.
   </ul>
   <p>

   <h4>b. From memory:</h4>
   <ul>
     In the case where you have already loaded the font file in memory, you
     can similarly create a new face object for it by calling
     <tt>FT_New_Memory_Face</tt> as in:
     <p>
     <font color="blue"><pre>

           FT_Library   library;   /* handle to library     */
           FT_Face      face;      /* handle to face object */

           error = FT_Init_FreeType( &library );
           if (error) { ..... }

           error = FT_New_Memory_Face( library,
                                       buffer,    /* first byte in memory */
                                       size,      /* size in bytes        */
                                       0,         /* face_index           */
                                       &face );
           if (error) { ... }
     </pre></font>
     <p>
     As you can see, <tt>FT_New_Memory_Face</tt> simply takes a pointer to
     the font file buffer and its size in bytes instead of a file pathname.
     Other than that, it has exactly the same semantics than
     <tt>FT_New_Face</tt>.
   </ul>
   <p>

   <h4>c. From other sources:</h4>
   <ul>
     There are cases where using a filepathname or preloading the file in
     memory is simply not enough. With FreeType 2, it is possible to provide
     your own implementation of i/o routines through the <tt>FT_Stream</tt>
     type.
     <p>
     Basically, one has to set up a <tt>FT_Stream</tt> object, according to
     the rules defined in the document named
     <a href="#">FreeType 2 System Interface</a>, then pass it to the function
     <tt>FT_Open_Face</tt> as in:
     <p>
     <font color="blue"><pre>

           FT_Library   library;   /* handle to library     */
           FT_Face      face;      /* handle to face object */

           error = FT_Init_FreeType( &library );
           if (error) { ..... }

           ... set up stream object, with handle "stream" ...

           error = FT_Open_Face( library,
                                 stream,    /* handle to stream objects */
                                 0,         /* face_index               */
                                 &face );
           if (error) { ... }
     </pre></font>
     <p>
     custom implementations of <tt>FT_Stream</tt> are great to provide advanced
     features like automatic support of compressed files, network transparency,
     using UTF-16 file pathnames, etc..
     <p>
   </ul>
   <p>
 </ul>

 <p><hr><p>

 <h3>4. Accessing face content:</h3>
 <ul>
   A <em>face object</em> models all information that globally describes
   the face. Usually, this data can be accessed directly by dereferencing
   a handle, like :
   <p>
   <table cellpadding=5>
   <tr valign="top">
      <td><tt><b>face&minus;>num_glyphs</b></tt>
      <td>gives the number of <em>glyphs</em> available in the font face. A glyph
          is simply a character image. It doesn't necessarily correspond to
          a <em>character code</em> though.

   <tr valign="top">
      <td><tt><b>face&minus;>flags</b></tt>
      <td>a 32-bit integer containing bit flags used to describe some face
          properties. For example, the flag <tt>FT_FACE_FLAG_SCALABLE</tt> is
          used to indicate that the face's font format is scalable and that
          glyph images can be rendered for all character pixel sizes. For more
          information on face flags, please read the <a href="#">FreeType API
          Reference</a>

   <tr valign="top">
      <td><tt><b>face&minus;>units_per_EM</b></tt>
      <td>This field is only valid for scalable formats (it is set to 0
          otherwise). It indicates the number of font units covered by the
          EM.

   <tr valign="top">
      <td><tt><b>face&minus;>num_fixed_sizes</b></tt>
      <td>this field gives the number of embedded bitmap <em>strikes</em> in
          the current face. A <em>strike</em> is simply a series of glyph
          images for a given character pixel size. For example, a font face
          could include strikes for pixel sizes 10, 12 and 14. Note that even
          scalable font formats can embedded bitmap strikes !

   <tr valign="top">
      <td><tt><b>face&minus;>fixed_sizes</b></tt>
      <td>this is a pointer to an array of <tt>FT_Bitmap_Size</tt> element.
          each <tt>FT_Bitmap_Size</tt> indicates the horizontal and vertical
          <em>pixel sizes</em> for each of the strikes that are present in the face.

   </table>
   <p>
   For a complete listing of all face properties and fields, please read
   the <a href="#">FreeType 2 API Reference</a>.
   <p>
 </ul>

 <p><hr><p>
 <h3>5. Setting the current pixel size:</h3>
 <ul>
   A face object also holds a handle to a <em>size object</em> in its
   <tt>face->size</tt> field. The <em>size</em> object is used to model
   all information for the face that is relative to a given character
   size.
   <p>
   When a new face object is created, its size object defaults to the
   character size of 10 pixels (both horizontall and vertically) for
   scalable formats. For fixed-sizes formats, the size is more or less
   undefined, which is why you must set it before trying to load a
   glyph.
   <p>
   To do that, simply call <tt>FT_Set_Char_Size</tt>. Here's an example
   where the character size is set to 16 pts for a 300x300 dpi device:
   <p>
   <font color="blue"><pre>
         error = FT_Set_Char_Size( face,    /* handle to face object           */
                                   0,       /* char_width in 1/64th of points  */
                                   16*64,   /* char_height in 1/64th of points */
                                   300,     /* horizontal device resolution    */
                                   300 );   /* vertical device resolution      */
   </pre></font>
   <p>
   You'll notice that:<p>
   <ul>
      <li>The character width and heights are specified in 1/64th of points.<p>

      <li>The horizontal and vertical device resolutions are expressed in
          <em>dots-per-inch</em>, or <em>dpi</em>. You can use 72 or 96 dpi
          for display devices like the screen.<p>

      <li>A value of 0 for the character width means "<em>same as character
          height</em>", a value of 0 for the character height means
          "<em>same as character width</em>". Otherwise, it is possible to
          specify different char width and height.<p>

      <li>Using a value of 0 for the horizontal or vertical resolution means
          72 dpi, which is the default.
 	 <p>
   </ul>
   <p>
   This function computes the character pixel size that corresponds to the
   character width and height and device resolutions. However, if you want
   to specify the pixel sizes yourself, you can simply call
   <tt>FT_Set_Pixel_Sizes</tt>, as in:
   <p>
   <font color="blue"><pre>
      error = FT_Set_Pixel_Sizes( face,   /* handle to face object            */
                                  0,      /* pixel_width                      */
                                  16 );   /* pixel_height                     */
   </pre></font>
   <p>
   This example will set the character pixel sizes to 16x16 pixels. As
   previously, a value of 0 for one of the dimensions means "<em>same as
   the other</em>".
   <p>
   Note that both functions return an error code. Usually, an error occurs
   with a fixed-size font format (like FNT or PCF) when trying to set the
   pixel size to a value that is not listed in the
   <tt><b>face->fixed_sizes</b></tt> array.
 </ul>

 <p><hr><p>

 <h3>6. Loading a glyph image:</h3>
 <ul>
   <h4>a. Converting a character code into a glyph index:</h4>
   <ul>
      Usually, an application wants to load a glyph image based on its
      <em>character code</em>, which is a unique value that defines the
      character for a given <em>encoding</em>. For example, the character
      code 65 represents the 'A' in the ASCII encoding.
      <p>
      A face object contains one or more tables, called <em>charmaps</em>,
      that are used to convert character codes to glyph indices. For example,
      most TrueType fonts contain two charmaps. One is used to convert Unicode
      character codes to glyph indices, the other is used to convert
      Apple Roman encoding into glyph indices. Such fonts can then be used
      either on Windows (which uses Unicode) and Macintosh (which uses
      Apple Roman, bwerk..). Note also that a given charmap might not map to all
      the glyphs present in the font.
      <p>
      By default, when a new face object is created, it lists all the charmaps
      contained in the font face and selects the one that supports Unicode
      character codes if it finds one. Otherwise, it tries to find support for
      Latin-1, then ASCII.
      <p>
      We'll describe later how to look for specific charmaps in a face. For
      now, we'll assume that the face contains at least a Unicode charmap that
      was selected during <tt>FT_New_Face</tt>. To convert a Unicode character
      code to a font glyph index, we use <tt>FT_Get_Char_Index</tt> as in:
      <p>
      <font color="blue"><pre>
          glyph_index = FT_Get_Char_Index( face, charcode );
      </pre></font>
      <p>
      This will look the glyph index corresponding to the given <tt>charcode</tt>
      in the charmap that is currently selected for the face. If charmap is
      selected, the function simply returns the charcode.
      <p>
      Note that this is one of the rare FreeType functions that do not return
      an error code. However, when a given character code has no glyph image in
      the face, the value 0 is returned. By convention, it always correspond to
      a special glyph image called the <b>missing glyph</b>, which usually is
      represented as a box or a space.
      <p>
   </ul>
   <p>

   <h4>b. Loading a glyph from the face:</h4>
   <ul>
      Once you have a glyph index, you can load the corresponding glyph image.
      Note that the glyph image can be in several formats. For example, it will
      be a bitmap for fixed-size formats like FNT, FON or PCF. It will also
      be a scalable vector outline for formats like TrueType or Type 1. The
      glyph image can also be stored in an alternate way that is not known
      at the time of writing this documentation.
      <p>
      The glyph image is always stored in a special object called a
      <em>glyph slot</em>. As it names suggests, a glyph slot is simply a
      container that is able to hold one glyph image at a time, be it a bitmap,
      an outline, or something else. Each face object has a single glyph
      object that can be accessed as <b><tt>face&minus;&gt;glyph</tt></b>.
      <p>
      Loading a glyph image into the slot is performed by calling
      <tt>FT_Load_Glyph</tt> as in:
      <p>
      <font color="blue"><pre>
         error = FT_Load_Glyph( face,          /* handle to face object */
                                glyph_index,   /* glyph index           */
                                load_flags );  /* load flags, see below */
      </pre></font>
      <p>
      The <tt>load_flags</tt> value is a set of bit flags used to indicate
      some special operations. The default value <tt>FT_LOAD_DEFAULT</tt> is
      0. The function performs the following :<p>
      <ul>
          <li>if there is a bitmap for the corresponding glyph and size, load
              it in the glyph slot, unless the <tt>FT_LOAD_NO_BITMAP</tt> flag
              is set. This is even <em>true</em> for scalable formats (embedded
              bitmaps are favored over outlines as they usually correspond to
              higher-quality images of the same glyph).
              <p>

          <li>if there is an outline for the corresponding glyph, load it
              unless <tt>FT_LOAD_NO_OUTLINE</tt> is set. Otherwise, scale it
              to the current size, unless the <tt>FT_LOAD_NO_SCALE</tt> flag
              is set.
              <p>

          <li>if the outline was loaded and scaled, try to grid-fit it (which
              dramatically improves its quality) unless the flag
              <tt>FT_LOAD_NO_HINTING</tt> is set.
      </ul>
      <p>
      There are a few others <tt>FT_LOAD_xxx</tt> flags defined. For more
      details see the <a href="#">FreeType 2 API Reference</a>.
   </ul>
   <p>

   <h4>c. Using other charmaps:</h4>
   <ul>
     As said before, when a new face object is created, it will look for
     a Unicode, Latin-1 or ASCII charmap and select it. The currently
     selected charmap is accessed via <b><tt>face&minus;&gt;charmap</tt></b>. This
     field is NULL when no charmap is selected.
     <p>
     The field <b><tt>face&minus;&gt;num_charmaps</tt></b> and
     <b><tt>face&minus;&gt;charmaps</tt></b> (notice the 's') can be used by
     client applications to look at what charmaps are available in a given
     face.
     <p>
     <b><tt>face&minus;charmaps</tt></b> is an array of <em>pointers</em>
     to the <tt><b>face&minus;&gt;num_charmaps</b></tt> charmaps contained in the
     font face.
     <p>
     Each charmap has a few visible fields used to describe it in more details.
     For example, <tt><b>charmap->encoding</b></tt> is an enumeration type
     that describes the charmap with FreeType codes. One can also look at
     <tt><b>charmap->platform_id</b></tt> and
     <tt><b>charmap->encoding_id</b></tt> for more exotic needs.
     <p>
     Here's an example code that looks for a chinese Big5 charmap then
     selects it via <tt>FT_Set_CharMap</tt>:
     <p>
     <font color="blue"><pre>
         FT_CharMap  found = 0;
         FT_CharMap  charmap;
         int         n;

         for ( n = 0; n &lt; face-&gt;num_charmaps; n++ )
         {
           charmap = face&gt;charmaps[n];
           if (charmap->encoding == ft_encoding_big5)
           {
             found = charmap;
             break;
           }
         }

         if (!found) { ... }

         /* now, select the charmap for the face object */
         error = FT_Set_CharMap( face, found );
         if (error) { .... }
     </pre></font>
     <p>
     One might now call <tt>FT_Get_Char_Index</tt> with Big5 character codes
     to retrieve glyph indices.
     <p>
   </ul>
   <p>
 </ul>

 <p><hr><p>

 <h3>7. Accessing glyph image data:</h3>
 <ul>
   Glyph image data is accessible through <tt><b>face&minus;glyph</b></tt>.
   See the definition of the <tt>FT_GlyphSlot</tt> type on more details. You
   can perfectly create a shortcut to the glyph slot as in:
   <p>
   <font color="blue"><pre>
      {
        FT_GlyphSlot  glyph;

        .... load glyph ...

        glyph = face-&gt;glyph;   /* shortcut to glyph data */

        .... access glyph data as glyph-&gt;xxxx
      }
   </pre></font>
   <p>
   For example, one can access the following fields:
   <p>
   <table cellpadding=10>
     <tr valign="top">
        <td><tt><b>glyph&minus;&gt;format</b></tt>
        <td>Indicates the type of the loaded glyph image. Can be either
            <tt>ft_glyph_format_bitmap</tt>, <tt>ft_glyph_format_outline</tt>
            or other values.

     <tr valign="top">
        <td><tt><b>glyph&minus;&gt;metrics</b></tt>
        <td>A simple structure used to hold the glyph image's metrics. Note
            that <em>all distances are expressed in 1/64th of pixels !</em>
            See the API reference or User Guide for a description of the
            <tt>FT_Glyph_Metrics</tt> structure.

     <tr valign="top">
        <td><tt><b>glyph&minus;&gt;bitmap</b></tt>
        <td>When the glyph slot contains a bitmap, a simple <tt>FT_Bitmap</tt>
            that describes it. See the API reference or user guide for a
            description of the <tt>FT_Bitmap</tt> structure.

     <tr valign="top">
        <td><tt><b>glyph&minus;&gt;outline</b></tt>
        <td>When the glyph slot contains a scalable outline, this structure
            describes it. See the definition of the <tt>FT_Outline</tt>
            structure.
   </table>
   <p>
 </ul>

 <h3>8. Rendering glyph outlines into bitmaps:</h3>
 <ul>
   When the glyph image loaded in a glyph slot is a bitmap, you can use
   your favorite graphics library to blit it to your own surfaces.
   <p>
   On the other hand, when the image is a scalable outline, or something else,
   FreeType provides a function to convert the glyph image into a
   pre-existing bitmap that you'll handle to it, named
   <tt>FT_Get_Glyph_Bitmap</tt>. Here's a <em>simple</em> example code
   that renders an outline into a <b>monochrome</b> bitmap :
   <p>
   <font color="blue"><pre>
      {
        FT_GlyphSlot  glyph;

        .... load glyph ...

        glyph = face-&gt;glyph;   /* shortcut to glyph data */
        if (glyph->format == ft_glyph_format_outline )
        {
          FT_Bitmap  bit;

          /* set-up a bitmap descriptor for our target bitmap */
          bit.rows       = bitmap_height;
          bit.width      = bitmap_width;
          bit.pitch      = bitmap_row_bytes;
          bit.pixel_mode = ft_pixel_mode_mono;  /* render into a mono bitmap */
          bit.buffer     = bitmap_buffer;

          /* render the outline directly into the bitmap */
          error = FT_Get_Glyph_Bitmap( face, &bit );
          if (error) { ... }
        }
      }
   </pre></font>
   <p>
   You should note that <b><em><tt>FT_Get_Glyph_Bitmap</tt> doesn't create the
   bitmap.</em></b> It only needs a descriptor, of type <tt>FT_Bitmap</tt>,
   and writes directly into it.
   <p>
   Note that the FreeType scan-converter for outlines can also generate
   anti-aliased glyph bitmaps with 128 level of grays. For now, it is
   restricted to rendering to 8-bit gray-level bitmaps, though this may
   change in the future. Here's some code to do just that:
   <p>
   <font color="blue"><pre>
      {
        FT_GlyphSlot  glyph;

        .... load glyph ...

        glyph = face-&gt;glyph;   /* shortcut to glyph data */
        if (glyph->format == ft_glyph_format_outline )
        {
          FT_Bitmap  bit;

          /* set-up a bitmap descriptor for our target bitmap */
          bit.rows       = bitmap_height;
          bit.width      = bitmap_width;
          bit.pitch      = bitmap_row_bytes;
          bit.pixel_mode = ft_pixel_mode_gray;  /* 8-bit gray-level bitmap */
          bit.grays      = 128;                 /* MUST be 128 for now     */
          bit.buffer     = bitmap_buffer;

          /* clean the bitmap - IMPORTANT */
          memset( bit.buffer, 0, bit.rows*bit.pitch );

          /* render the outline directly into the bitmap */
          error = FT_Get_Glyph_Bitmap( face, &bit );
          if (error) { ... }
        }
      }
   </pre></font>
   <p>
   You'll notice that :<p>
   <ul>
      <li>As previously, <tt>FT_Get_Glyph_Bitmap</tt> doesn't generate the
          bitmap, it simply renders to it.<p>

      <li>The target bitmap must be cleaned before calling the function. This
          is a limitation of our current anti-aliasing algorithm and is
          EXTREMELY important.<p>

      <li>The anti-aliaser uses 128 levels of grays exclusively for now (this
          will probably change in a near future). This means that you <b>must</b>
          set <tt>bit.grays</tt> to 128. The generated image uses values from
          0 (back color) to 127 (foreground color).
          <p>

      <li>It is <b>not</b> possible to render directly an anti-aliased outline into
          a pre-existing gray-level bitmap, or even any colored-format one
          (like RGB16 or paletted 8-bits). We will not discuss this issue in
          great details here, but the reason is that we do not want to deal
          with graphics composition (or alpha-blending) within FreeType.
   </ul>
   <p>
   </ul>
 </ul>

 <p><hr>
	<!doctype html public "-//w3c//dtd html 4.0 transitional//en">
	<html>
	<head>
	<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
	<meta name="Author" content="David Turner">
	<meta name="GENERATOR" content="Mozilla/4.5 [fr] (Win98; I) [Netscape]">
	<title>FreeType 2 Tutorial</title>
	</head>
	<body>

	<body text="#000000"
	bgcolor="#FFFFFF"
	link="#0000EF"
	vlink="#51188E"
	alink="#FF0000">

	<center>
	<h1>
	FreeType 2.0 Tutorial</h1></center>

	<center>
	<h3>
	© 2000 David Turner (<a href="mailto:david@freetype.org">david@freetype.org</a>)<br>
	© 2000 The FreeType Development Team
	(<a href="http://www.freetype.org">www.freetype.org</a>)
	</h3></center>

	<p><br>
	<hr WIDTH="100%">
	<br>
	<h2>Introduction:</h2>
	<ul>
	This simple tutorial will teach you how to use the FreeType 2 library
	in your own applications.
	</ul>

	<p><hr><p>

	<h3>1. Header files :</h3>
	<ul>
	You only need to include the public header file named <tt>freetype.h</tt>
	in your source code. Depending on how the library was installed on your
	system, you might need to use :<p>
	<ul><font color="blue"><tt>
	#include <freetype.h><p>
	</tt></font></ul>
	or
	<ul><font color="blue"><tt>
	#include <freetype2/freetype.h><p>
	</tt></font></ul>
	in your application to include the public interface to FreeType.<p>
	</ul>

	<p><hr><p>

	<h3>2. Initialise the library:</h3>
	<ul>
	Simply create a variable of type <tt>FT_Library</tt> named, for example,
	<tt>library</tt>, and call the function <tt>FT_Init_FreeType</tt> as in:

	<font color="blue"><pre>
	#include <freetype.h>

	FT_Library library;

	....

	{
	..
	error = FT_Init_FreeType( &library );
	if (error) { .. an error occured during library initialisation .. }
	}
	</pre></font>
	<p>
	This function is in charge of the following:<p>
	<ul>
	<li>Creating a new instance of the FreeType 2 library, and set
	the handle <tt>library</tt> to it.
	<p>

	<li>Load each font driver that FreeType knows about in the library.
	This means that by default, your new <tt>library</tt> object is
	able to handle TrueType and Type 1 fonts gracefully.
	<p>
	</ul>
	<p>
	As you can see, the function returns an error code, like most others in the
	FreeType API. An error code of 0 <em>always</em> means that the operation
	was succesful; otherwise, the value describes the error, and <tt>library</tt>
	is set to NULL.
	</ul>

	<p><hr><p>

	<h3>3. Load a font face:</h3>
	<ul>
	<h4>a. From a font file:</h4>
	<ul>
	Create a new <em>face</em> object by calling <tt>FT_New_Face</tt>. A
	<em>face</em> describes a given typeface and style. For example,
	"Times New Roman Regular" and "Times New Roman Italic" correspond to
	two different faces.
	<p>
	<font color="blue"><pre>

	FT_Library library; /* handle to library */
	FT_Face face; /* handle to face object */

	error = FT_Init_FreeType( &library );
	if (error) { ..... }

	error = FT_New_Face( library,
	"/usr/share/fonts/truetype/arial.ttf",
	0,
	&face );
	if (error == FT_Err_Unknown_File_Format)
	{
	.... the font file could be opened and read, but it appears
	.... that its font format is unsupported
	}
	else if (error)
	{
	.... another error code means that the font file could not
	.... be opened, read or simply that it is broken..
	}
	</pre></font>
	<p>
	As you certainly imagine, <tt>FT_New_Face</tt> opens a font file then
	tries to extract one face from it. Its parameters are :<p>
	<ul>
	<table cellpadding=5>
	<tr valign="top"><td><tt><b>library</b></tt>
	<td>handle to the FreeType library instance where the face object is
	created

	<tr valign="top"><td><tt><b>filepathname</b></tt>
	<td>the font file pathname (standard C string).

	<tr valign="top"><td><tt><b>face_index</b></tt>
	<td>Certain font formats allow several font faces to be embedded in
	a single file.<br>
	This index tells which face you want to load. An
	error will be returned if its value is too large.<br>
	Index 0 always work though.

	<tr><td><tt><b>face</b></tt>
	<td>A <em>pointer</em> to the handle that will be set to
	describe the new face object.<br>
	It is set to NULL in case of error.
	</table>
	</ul>
	<p>
	To known how many faces a given font file contains, simply load its
	first face (use <tt>face_index</tt>=0), then see the value of
	<tt>face->num_faces</tt> which indicates how many faces are embedded in
	the font file.
	</ul>
	<p>

	<h4>b. From memory:</h4>
	<ul>
	In the case where you have already loaded the font file in memory, you
	can similarly create a new face object for it by calling
	<tt>FT_New_Memory_Face</tt> as in:
	<p>
	<font color="blue"><pre>

	FT_Library library; /* handle to library */
	FT_Face face; /* handle to face object */

	error = FT_Init_FreeType( &library );
	if (error) { ..... }

	error = FT_New_Memory_Face( library,
	buffer, /* first byte in memory */
	size, /* size in bytes */
	0, /* face_index */
	&face );
	if (error) { ... }
	</pre></font>
	<p>
	As you can see, <tt>FT_New_Memory_Face</tt> simply takes a pointer to
	the font file buffer and its size in bytes instead of a file pathname.
	Other than that, it has exactly the same semantics than
	<tt>FT_New_Face</tt>.
	</ul>
	<p>

	<h4>c. From other sources:</h4>
	<ul>
	There are cases where using a filepathname or preloading the file in
	memory is simply not enough. With FreeType 2, it is possible to provide
	your own implementation of i/o routines through the <tt>FT_Stream</tt>
	type.
	<p>
	Basically, one has to set up a <tt>FT_Stream</tt> object, according to
	the rules defined in the document named
	<a href="#">FreeType 2 System Interface</a>, then pass it to the function
	<tt>FT_Open_Face</tt> as in:
	<p>
	<font color="blue"><pre>

	FT_Library library; /* handle to library */
	FT_Face face; /* handle to face object */

	error = FT_Init_FreeType( &library );
	if (error) { ..... }

	... set up stream object, with handle "stream" ...

	error = FT_Open_Face( library,
	stream, /* handle to stream objects */
	0, /* face_index */
	&face );
	if (error) { ... }
	</pre></font>
	<p>
	custom implementations of <tt>FT_Stream</tt> are great to provide advanced
	features like automatic support of compressed files, network transparency,
	using UTF-16 file pathnames, etc..
	<p>
	</ul>
	<p>
	</ul>

	<p><hr><p>

	<h3>4. Accessing face content:</h3>
	<ul>
	A <em>face object</em> models all information that globally describes
	the face. Usually, this data can be accessed directly by dereferencing
	a handle, like :
	<p>
	<table cellpadding=5>
	<tr valign="top">
	<td><tt><b>face−>num_glyphs</b></tt>
	<td>gives the number of <em>glyphs</em> available in the font face. A glyph
	is simply a character image. It doesn't necessarily correspond to
	a <em>character code</em> though.

	<tr valign="top">
	<td><tt><b>face−>flags</b></tt>
	<td>a 32-bit integer containing bit flags used to describe some face
	properties. For example, the flag <tt>FT_FACE_FLAG_SCALABLE</tt> is
	used to indicate that the face's font format is scalable and that
	glyph images can be rendered for all character pixel sizes. For more
	information on face flags, please read the <a href="#">FreeType API
	Reference</a>

	<tr valign="top">
	<td><tt><b>face−>units_per_EM</b></tt>
	<td>This field is only valid for scalable formats (it is set to 0
	otherwise). It indicates the number of font units covered by the
	EM.

	<tr valign="top">
	<td><tt><b>face−>num_fixed_sizes</b></tt>
	<td>this field gives the number of embedded bitmap <em>strikes</em> in
	the current face. A <em>strike</em> is simply a series of glyph
	images for a given character pixel size. For example, a font face
	could include strikes for pixel sizes 10, 12 and 14. Note that even
	scalable font formats can embedded bitmap strikes !

	<tr valign="top">
	<td><tt><b>face−>fixed_sizes</b></tt>
	<td>this is a pointer to an array of <tt>FT_Bitmap_Size</tt> element.
	each <tt>FT_Bitmap_Size</tt> indicates the horizontal and vertical
	<em>pixel sizes</em> for each of the strikes that are present in the face.

	</table>
	<p>
	For a complete listing of all face properties and fields, please read
	the <a href="#">FreeType 2 API Reference</a>.
	<p>
	</ul>

	<p><hr><p>
	<h3>5. Setting the current pixel size:</h3>
	<ul>
	A face object also holds a handle to a <em>size object</em> in its
	<tt>face->size</tt> field. The <em>size</em> object is used to model
	all information for the face that is relative to a given character
	size.
	<p>
	When a new face object is created, its size object defaults to the
	character size of 10 pixels (both horizontall and vertically) for
	scalable formats. For fixed-sizes formats, the size is more or less
	undefined, which is why you must set it before trying to load a
	glyph.
	<p>
	To do that, simply call <tt>FT_Set_Char_Size</tt>. Here's an example
	where the character size is set to 16 pts for a 300x300 dpi device:
	<p>
	<font color="blue"><pre>
	error = FT_Set_Char_Size( face, /* handle to face object */
	0, /* char_width in 1/64th of points */
	1664, / char_height in 1/64th of points */
	300, /* horizontal device resolution */
	300 ); /* vertical device resolution */
	</pre></font>
	<p>
	You'll notice that:<p>
	<ul>
	<li>The character width and heights are specified in 1/64th of points.<p>

	<li>The horizontal and vertical device resolutions are expressed in
	<em>dots-per-inch</em>, or <em>dpi</em>. You can use 72 or 96 dpi
	for display devices like the screen.<p>

	<li>A value of 0 for the character width means "<em>same as character
	height</em>", a value of 0 for the character height means
	"<em>same as character width</em>". Otherwise, it is possible to
	specify different char width and height.<p>

	<li>Using a value of 0 for the horizontal or vertical resolution means
	72 dpi, which is the default.
	<p>
	</ul>
	<p>
	This function computes the character pixel size that corresponds to the
	character width and height and device resolutions. However, if you want
	to specify the pixel sizes yourself, you can simply call
	<tt>FT_Set_Pixel_Sizes</tt>, as in:
	<p>
	<font color="blue"><pre>
	error = FT_Set_Pixel_Sizes( face, /* handle to face object */
	0, /* pixel_width */
	16 ); /* pixel_height */
	</pre></font>
	<p>
	This example will set the character pixel sizes to 16x16 pixels. As
	previously, a value of 0 for one of the dimensions means "<em>same as
	the other</em>".
	<p>
	Note that both functions return an error code. Usually, an error occurs
	with a fixed-size font format (like FNT or PCF) when trying to set the
	pixel size to a value that is not listed in the
	<tt><b>face->fixed_sizes</b></tt> array.
	</ul>

	<p><hr><p>

	<h3>6. Loading a glyph image:</h3>
	<ul>
	<h4>a. Converting a character code into a glyph index:</h4>
	<ul>
	Usually, an application wants to load a glyph image based on its
	<em>character code</em>, which is a unique value that defines the
	character for a given <em>encoding</em>. For example, the character
	code 65 represents the 'A' in the ASCII encoding.
	<p>
	A face object contains one or more tables, called <em>charmaps</em>,
	that are used to convert character codes to glyph indices. For example,
	most TrueType fonts contain two charmaps. One is used to convert Unicode
	character codes to glyph indices, the other is used to convert
	Apple Roman encoding into glyph indices. Such fonts can then be used
	either on Windows (which uses Unicode) and Macintosh (which uses
	Apple Roman, bwerk..). Note also that a given charmap might not map to all
	the glyphs present in the font.
	<p>
	By default, when a new face object is created, it lists all the charmaps
	contained in the font face and selects the one that supports Unicode
	character codes if it finds one. Otherwise, it tries to find support for
	Latin-1, then ASCII.
	<p>
	We'll describe later how to look for specific charmaps in a face. For
	now, we'll assume that the face contains at least a Unicode charmap that
	was selected during <tt>FT_New_Face</tt>. To convert a Unicode character
	code to a font glyph index, we use <tt>FT_Get_Char_Index</tt> as in:
	<p>
	<font color="blue"><pre>
	glyph_index = FT_Get_Char_Index( face, charcode );
	</pre></font>
	<p>
	This will look the glyph index corresponding to the given <tt>charcode</tt>
	in the charmap that is currently selected for the face. If charmap is
	selected, the function simply returns the charcode.
	<p>
	Note that this is one of the rare FreeType functions that do not return
	an error code. However, when a given character code has no glyph image in
	the face, the value 0 is returned. By convention, it always correspond to
	a special glyph image called the <b>missing glyph</b>, which usually is
	represented as a box or a space.
	<p>
	</ul>
	<p>

	<h4>b. Loading a glyph from the face:</h4>
	<ul>
	Once you have a glyph index, you can load the corresponding glyph image.
	Note that the glyph image can be in several formats. For example, it will
	be a bitmap for fixed-size formats like FNT, FON or PCF. It will also
	be a scalable vector outline for formats like TrueType or Type 1. The
	glyph image can also be stored in an alternate way that is not known
	at the time of writing this documentation.
	<p>
	The glyph image is always stored in a special object called a
	<em>glyph slot</em>. As it names suggests, a glyph slot is simply a
	container that is able to hold one glyph image at a time, be it a bitmap,
	an outline, or something else. Each face object has a single glyph
	object that can be accessed as <b><tt>face−>glyph</tt></b>.
	<p>
	Loading a glyph image into the slot is performed by calling
	<tt>FT_Load_Glyph</tt> as in:
	<p>
	<font color="blue"><pre>
	error = FT_Load_Glyph( face, /* handle to face object */
	glyph_index, /* glyph index */
	load_flags ); /* load flags, see below */
	</pre></font>
	<p>
	The <tt>load_flags</tt> value is a set of bit flags used to indicate
	some special operations. The default value <tt>FT_LOAD_DEFAULT</tt> is
	0. The function performs the following :<p>
	<ul>
	<li>if there is a bitmap for the corresponding glyph and size, load
	it in the glyph slot, unless the <tt>FT_LOAD_NO_BITMAP</tt> flag
	is set. This is even <em>true</em> for scalable formats (embedded
	bitmaps are favored over outlines as they usually correspond to
	higher-quality images of the same glyph).
	<p>

	<li>if there is an outline for the corresponding glyph, load it
	unless <tt>FT_LOAD_NO_OUTLINE</tt> is set. Otherwise, scale it
	to the current size, unless the <tt>FT_LOAD_NO_SCALE</tt> flag
	is set.
	<p>

	<li>if the outline was loaded and scaled, try to grid-fit it (which
	dramatically improves its quality) unless the flag
	<tt>FT_LOAD_NO_HINTING</tt> is set.
	</ul>
	<p>
	There are a few others <tt>FT_LOAD_xxx</tt> flags defined. For more
	details see the <a href="#">FreeType 2 API Reference</a>.
	</ul>
	<p>

	<h4>c. Using other charmaps:</h4>
	<ul>
	As said before, when a new face object is created, it will look for
	a Unicode, Latin-1 or ASCII charmap and select it. The currently
	selected charmap is accessed via <b><tt>face−>charmap</tt></b>. This
	field is NULL when no charmap is selected.
	<p>
	The field <b><tt>face−>num_charmaps</tt></b> and
	<b><tt>face−>charmaps</tt></b> (notice the 's') can be used by
	client applications to look at what charmaps are available in a given
	face.
	<p>
	<b><tt>face−charmaps</tt></b> is an array of <em>pointers</em>
	to the <tt><b>face−>num_charmaps</b></tt> charmaps contained in the
	font face.
	<p>
	Each charmap has a few visible fields used to describe it in more details.
	For example, <tt><b>charmap->encoding</b></tt> is an enumeration type
	that describes the charmap with FreeType codes. One can also look at
	<tt><b>charmap->platform_id</b></tt> and
	<tt><b>charmap->encoding_id</b></tt> for more exotic needs.
	<p>
	Here's an example code that looks for a chinese Big5 charmap then
	selects it via <tt>FT_Set_CharMap</tt>:
	<p>
	<font color="blue"><pre>
	FT_CharMap found = 0;
	FT_CharMap charmap;
	int n;

	for ( n = 0; n < face->num_charmaps; n++ )
	{
	charmap = face>charmaps[n];
	if (charmap->encoding == ft_encoding_big5)
	{
	found = charmap;
	break;
	}
	}

	if (!found) { ... }

	/* now, select the charmap for the face object */
	error = FT_Set_CharMap( face, found );
	if (error) { .... }
	</pre></font>
	<p>
	One might now call <tt>FT_Get_Char_Index</tt> with Big5 character codes
	to retrieve glyph indices.
	<p>
	</ul>
	<p>
	</ul>

	<p><hr><p>

	<h3>7. Accessing glyph image data:</h3>
	<ul>
	Glyph image data is accessible through <tt><b>face−glyph</b></tt>.
	See the definition of the <tt>FT_GlyphSlot</tt> type on more details. You
	can perfectly create a shortcut to the glyph slot as in:
	<p>
	<font color="blue"><pre>
	{
	FT_GlyphSlot glyph;

	.... load glyph ...

	glyph = face->glyph; /* shortcut to glyph data */

	.... access glyph data as glyph->xxxx
	}
	</pre></font>
	<p>
	For example, one can access the following fields:
	<p>
	<table cellpadding=10>
	<tr valign="top">
	<td><tt><b>glyph−>format</b></tt>
	<td>Indicates the type of the loaded glyph image. Can be either
	<tt>ft_glyph_format_bitmap</tt>, <tt>ft_glyph_format_outline</tt>
	or other values.

	<tr valign="top">
	<td><tt><b>glyph−>metrics</b></tt>
	<td>A simple structure used to hold the glyph image's metrics. Note
	that <em>all distances are expressed in 1/64th of pixels !</em>
	See the API reference or User Guide for a description of the
	<tt>FT_Glyph_Metrics</tt> structure.

	<tr valign="top">
	<td><tt><b>glyph−>bitmap</b></tt>
	<td>When the glyph slot contains a bitmap, a simple <tt>FT_Bitmap</tt>
	that describes it. See the API reference or user guide for a
	description of the <tt>FT_Bitmap</tt> structure.

	<tr valign="top">
	<td><tt><b>glyph−>outline</b></tt>
	<td>When the glyph slot contains a scalable outline, this structure
	describes it. See the definition of the <tt>FT_Outline</tt>
	structure.
	</table>
	<p>
	</ul>

	<h3>8. Rendering glyph outlines into bitmaps:</h3>
	<ul>
	When the glyph image loaded in a glyph slot is a bitmap, you can use
	your favorite graphics library to blit it to your own surfaces.
	<p>
	On the other hand, when the image is a scalable outline, or something else,
	FreeType provides a function to convert the glyph image into a
	pre-existing bitmap that you'll handle to it, named
	<tt>FT_Get_Glyph_Bitmap</tt>. Here's a <em>simple</em> example code
	that renders an outline into a <b>monochrome</b> bitmap :
	<p>
	<font color="blue"><pre>
	{
	FT_GlyphSlot glyph;

	.... load glyph ...

	glyph = face->glyph; /* shortcut to glyph data */
	if (glyph->format == ft_glyph_format_outline )
	{
	FT_Bitmap bit;

	/* set-up a bitmap descriptor for our target bitmap */
	bit.rows = bitmap_height;
	bit.width = bitmap_width;
	bit.pitch = bitmap_row_bytes;
	bit.pixel_mode = ft_pixel_mode_mono; /* render into a mono bitmap */
	bit.buffer = bitmap_buffer;

	/* render the outline directly into the bitmap */
	error = FT_Get_Glyph_Bitmap( face, &bit );
	if (error) { ... }
	}
	}
	</pre></font>
	<p>
	You should note that <b><em><tt>FT_Get_Glyph_Bitmap</tt> doesn't create the
	bitmap.</em></b> It only needs a descriptor, of type <tt>FT_Bitmap</tt>,
	and writes directly into it.
	<p>
	Note that the FreeType scan-converter for outlines can also generate
	anti-aliased glyph bitmaps with 128 level of grays. For now, it is
	restricted to rendering to 8-bit gray-level bitmaps, though this may
	change in the future. Here's some code to do just that:
	<p>
	<font color="blue"><pre>
	{
	FT_GlyphSlot glyph;

	.... load glyph ...

	glyph = face->glyph; /* shortcut to glyph data */
	if (glyph->format == ft_glyph_format_outline )
	{
	FT_Bitmap bit;

	/* set-up a bitmap descriptor for our target bitmap */
	bit.rows = bitmap_height;
	bit.width = bitmap_width;
	bit.pitch = bitmap_row_bytes;
	bit.pixel_mode = ft_pixel_mode_gray; /* 8-bit gray-level bitmap */
	bit.grays = 128; /* MUST be 128 for now */
	bit.buffer = bitmap_buffer;

	/* clean the bitmap - IMPORTANT */
	memset( bit.buffer, 0, bit.rows*bit.pitch );

	/* render the outline directly into the bitmap */
	error = FT_Get_Glyph_Bitmap( face, &bit );
	if (error) { ... }
	}
	}
	</pre></font>
	<p>
	You'll notice that :<p>
	<ul>
	<li>As previously, <tt>FT_Get_Glyph_Bitmap</tt> doesn't generate the
	bitmap, it simply renders to it.<p>

	<li>The target bitmap must be cleaned before calling the function. This
	is a limitation of our current anti-aliasing algorithm and is
	EXTREMELY important.<p>

	<li>The anti-aliaser uses 128 levels of grays exclusively for now (this
	will probably change in a near future). This means that you <b>must</b>
	set <tt>bit.grays</tt> to 128. The generated image uses values from
	0 (back color) to 127 (foreground color).
	<p>

	<li>It is <b>not</b> possible to render directly an anti-aliased outline into
	a pre-existing gray-level bitmap, or even any colored-format one
	(like RGB16 or paletted 8-bits). We will not discuss this issue in
	great details here, but the reason is that we do not want to deal
	with graphics composition (or alpha-blending) within FreeType.
	</ul>
	<p>
	</ul>
	</ul>

	<p><hr>