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<h1><a href="http://freetype.org/index.html">FreeType</a>
Tutorial / II</h1>
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<h2>II. Managing Glyphs</h2>
<h3 id="section-1">1. Glyph Metrics</h3>
<p>Glyph metrics are, as the name suggests, certain
distances associated with each glyph that describe how to
position this glyph while creating a text layout.</p>
<p>There are usually two sets of metrics for a single glyph:
Those used to represent glyphs in horizontal text layouts
(Latin, Cyrillic, Arabic, Hebrew, etc.), and those used to
represent glyphs in vertical text layouts (Chinese,
Japanese, Korean, Mongolian, etc.).</p>
<p>Note that only a few font formats provide vertical
metrics. You can test whether a given face object
contains them by using the
macro <a href="../reference/ft2-base_interface.html#FT_HAS_VERTICAL"><tt>FT_HAS_VERTICAL</tt></a>,
which returns true if appropriate.</p>
<p>Individual glyph metrics can be accessed by first loading
the glyph in a face's glyph slot, then accessing them
through the <tt>face->glyph->metrics</tt> structure,
whose type
is <a href="../reference/ft2-base_interface.html#FT_Glyph_Metrics"><tt>FT_Glyph_Metrics</tt></a>.
We will discuss this in more detail below; for now, we
only note that it contains the following fields.</p>
<dl>
<dt>width</dt>
<dd>This is the width of the glyph image's bounding box.
It is independent of the layout direction.</dd>
<dt>height</dt>
<dd>This is the height of the glyph image's bounding box.
It is independent of the layout direction. Be careful
not to confuse it with the ‘height’ field in
the <a href="../reference/ft2-base_interface.html#FT_Size_Metrics">
<tt>FT_Size_Metrics</tt></a> structure.</dd>
<dt>horiBearingX</dt>
<dd>For <em>horizontal text layouts</em>, this is the
horizontal distance from the current cursor position to
the leftmost border of the glyph image's bounding
box.</dd>
<dt>horiBearingY</dt>
<dd>For <em>horizontal text layouts</em>, this is the
vertical distance from the current cursor position (on
the baseline) to the topmost border of the glyph image's
bounding box.</dd>
<dt>horiAdvance</dt>
<dd>For <em>horizontal text layouts</em>, this is the
horizontal distance to increment the pen position when
the glyph is drawn as part of a string of text.</dd>
<dt>vertBearingX</dt>
<dd>For <em>vertical text layouts</em>, this is the
horizontal distance from the current cursor position to
the leftmost border of the glyph image's bounding
box.</dd>
<dt>vertBearingY</dt>
<dd>For <em>vertical text layouts</em>, this is the
vertical distance from the current cursor position (on
the baseline) to the topmost border of the glyph image's
bounding box.</dd>
<dt>vertAdvance</dt>
<dd>For <em>vertical text layouts</em>, this is the
vertical distance used to increment the pen position
when the glyph is drawn as part of a string of
text.</dd>
</dl>
<p class="warning">As not all fonts do contain vertical
metrics, the values of <tt>vertBearingX</tt>,
<tt>vertBearingY</tt> and <tt>vertAdvance</tt> should not
be considered reliable if <tt>FT_HAS_VERTICAL</tt> returns
false.</p>
<p>The following graphics illustrate the metrics more
clearly. In case a distance is directed, it is marked
with a single arrow, indicating a positive value. The
first image displays horizontal metrics, where the
baseline is the horizontal axis.</p>
<div class="figure">
<img src="metrics.png"
alt="horizontal layout"
width=388
height=253>
</div>
<p>For vertical text layouts, the baseline is vertical,
identical to the vertical axis. Contrary to all other
arrows, <tt>bearingX</tt> shows a negative value in this
image.</p>
<div class="figure">
<img src="metrics2.png"
alt="vertical layout"
width=294
height=278>
</div>
<p>The metrics found in <tt>face->glyph->metrics</tt>
are normally expressed in 26.6 pixel format (i.e., 1/64th
of pixels), unless you use the <tt>FT_LOAD_NO_SCALE</tt>
flag when calling <tt>FT_Load_Glyph</tt>
or <tt>FT_Load_Char</tt>. In this case, the metrics are
expressed in original font units.</p>
<p>The glyph slot object has also a few other interesting
fields that eases a developer's work. You can access them
through <tt>face->glyph->xxx</tt>,
where <tt>xxx</tt> is one of the following fields.</p>
<dl>
<dt>advance</dt>
<dd>This field is a <tt>FT_Vector</tt> that holds the
transformed advance for the glyph. That is useful when
you are using a transformation
through <tt>FT_Set_Transform</tt>, as shown in the
<a href="step1.html#transformed-text">rotated text
example</a> of part I. Other than that, its value
is by default (metrics.horiAdvance,0), unless you
specify <tt>FT_LOAD_VERTICAL</tt> when loading the glyph
image; it is then (0,metrics.vertAdvance).</dd>
<dt>linearHoriAdvance</dt>
<dd>This field contains the linearly scaled value of the
glyph's horizontal advance width. Indeed, the value of
<tt>metrics.horiAdvance</tt> that is returned in the
glyph slot is normally rounded to integer pixel
coordinates (i.e., being a multiple of 64) by the
font driver that actually loads the glyph
image. <tt>linearHoriAdvance</tt> is a 16.16
fixed-point number that gives the value of the original
glyph advance width in 1/65536th of pixels. It can be
use to perform pseudo device-independent text
layouts.</dd>
<dt>linearVertAdvance</dt>
<dd>This is the similar to <tt>linearHoriAdvance</tt> but
for the glyph's vertical advance height. Its value is
only reliable if the font face contains vertical
metrics.</dd>
</dl>
<h3 id="section-2">2. Managing Glyph Images</h3>
<p>The glyph image that is loaded in a glyph slot can be
converted into a bitmap, either by
using <tt>FT_LOAD_RENDER</tt> when loading it, or by
calling <a href="../reference/ft2-base_interface.html#FT_Render_Glyph"><tt>FT_Render_Glyph</tt></a>.
Each time you load a new glyph image, the previous one is
erased from the glyph slot.</p>
<p>There are situations, however, where you may need to
extract this image from the glyph slot in order to cache
it within your application, and even perform additional
transformations and measures on it before converting it to
a bitmap.</p>
<p>The FreeType 2 API has a specific extension that is
capable of dealing with glyph images in a flexible and
generic way. To use it, you first need to include
the <a href="../reference/ft2-header_file_macros.html#FT_GLYPH_H"><tt>FT_GLYPH_H</tt></a>
header file.</p>
<pre>
#include FT_GLYPH_H</pre>
<h4>a.Extracting the Glyph Image</h4>
<p>You can extract a single glyph image very easily. Here
some code that shows how to do it.</p>
<pre>
FT_Glyph glyph; <span class="comment">/* a handle to the glyph image */</span>
...
error = FT_Load_Glyph( face, glyph_index, FT_LOAD_NORMAL );
if ( error ) { ... }
error = FT_Get_Glyph( face->glyph, &glyph );
if ( error ) { ... }</pre>
<p>The following steps are performed.</p>
<ul>
<li>Create a variable named <tt>glyph</tt>, of
type <a href="../reference/ft2-glyph_management.html#FT_Glyph"><tt>FT_Glyph</tt></a>.
This is a handle (pointer) to an individual glyph
image.</li>
<li>Load the glyph image in the normal way into the face's
glyph slot. We don't use <tt>FT_LOAD_RENDER</tt>
because we want to grab a scalable glyph image that we
can transform later on.</li>
<li>Copy the glyph image from the slot into a
new <tt>FT_Glyph</tt> object by
calling <a href="../reference/ft2-glyph_management.html#FT_Get_Glyph"><tt>FT_Get_Glyph</tt></a>.
This function returns an error code and
sets <tt>glyph</tt>.</li>
</ul>
<p>It is important to note that the extracted glyph is in
the same format as the original one that is still in the
slot. For example, if we are loading a glyph from a
TrueType font file, the glyph image is really a scalable
vector outline. You can access the
field <tt>glyph->format</tt> if you want to know
exactly how the glyph is modeled and stored.</p>
<p>A new glyph object can be destroyed with a call
to <a href="../reference/ft2-glyph_management.html#FT_Done_Glyph"><tt>FT_Done_Glyph</tt></a>.</p>
<p>The glyph object contains exactly one glyph image and a
2D vector representing the glyph's advance in 16.16
fixed-point coordinates. The latter can be accessed
directly as <tt>glyph->advance</tt></p>
<p class="warning">Note that unlike other FreeType objects,
the library doesn't keep a list of all allocated glyph
objects. This means you have to destroy them yourself
instead of relying on <tt>FT_Done_FreeType</tt> doing all
the clean-up.</p>
<h4>b. Transforming & Copying the Glyph Image</h4>
<p>If the glyph image is scalable (i.e.,
if <tt>glyph->format</tt> is not equal
to <tt>FT_GLYPH_FORMAT_BITMAP</tt>), it is possible to
transform the image anytime by a call
to <a href="../reference/ft2-glyph_management.html#FT_Glyph_Transform"><tt>FT_Glyph_Transform</tt></a>.</p>
<p>You can also copy a single glyph image
with <a href="../reference/ft2-glyph_management.html#FT_Glyph_Copy"><tt>FT_Glyph_Copy</tt></a>.</p>
<pre>
FT_Glyph glyph, glyph2;
FT_Matrix matrix;
FT_Vector delta;
... load glyph image in `glyph' ...
<span class="comment">/* copy glyph to glyph2 */</span>
error = FT_Glyph_Copy( glyph, &glyph2 );
if ( error ) { ... could not copy (out of memory) ... }
<span class="comment">/* translate `glyph' */</span>
delta.x = -100 * 64; <span class="comment">/* coordinates are in 26.6 pixel format */</span>
delta.y = 50 * 64;
FT_Glyph_Transform( glyph, 0, &delta );
<span class="comment">/* transform glyph2 (horizontal shear) */</span>
matrix.xx = 0x10000L;
matrix.xy = 0.12 * 0x10000L;
matrix.yx = 0;
matrix.yy = 0x10000L;
FT_Glyph_Transform( glyph2, &matrix, 0 );</pre>
<p>Note that the 2×2 transformation matrix is always
applied to the 16.16 advance vector in the glyph; you thus
don't need to recompute it.</p>
<h4>c. Measuring the Glyph Image</h4>
<p>You can also retrieve the control (bounding) box of any
glyph image (scalable or not) through
the <a href="../reference/ft2-glyph_management.html#FT_Glyph_Get_CBox"><tt>FT_Glyph_Get_CBox</tt></a>
function.</p>
<pre>
FT_BBox bbox;
...
FT_Glyph_Get_CBox( glyph, <em>bbox_mode</em>, &bbox );</pre>
<p>Coordinates are relative to the glyph origin (0,0), using
the y upwards convention. This function takes a
special argument, the <em>bbox mode</em>, to indicate how
box coordinates are expressed.</p>
<p>If the glyph has been loaded
with <tt>FT_LOAD_NO_SCALE</tt>, <tt>bbox_mode</tt> must be
set to <tt>FT_GLYPH_BBOX_UNSCALED</tt> to get unscaled
font units in 26.6 pixel format. The
value <tt>FT_GLYPH_BBOX_SUBPIXELS</tt> is another name for
this constant.</p>
<p>Note that the box's maximum coordinates are exclusive,
which means that you can always compute the width and
height of the glyph image (regardless of using integer or
26.6 coordinates) with a simple subtraction.</p>
<pre class="example">
width = bbox.xMax - bbox.xMin;
height = bbox.yMax - bbox.yMin;</pre>
<p>Note also that for 26.6 coordinates, if
<tt>FT_GLYPH_BBOX_GRIDFIT</tt> is used as the bbox mode,
the coordinates are also grid-fitted, which corresponds to
the following four lines.</p>
<pre class="example">
bbox.xMin = FLOOR( bbox.xMin )
bbox.yMin = FLOOR( bbox.yMin )
bbox.xMax = CEILING( bbox.xMax )
bbox.yMax = CEILING( bbox.yMax )</pre>
<p>To get the bbox in <em>integer</em> pixel coordinates,
set <tt>bbox_mode</tt>
to <tt>FT_GLYPH_BBOX_TRUNCATE</tt>.</p>
<p>Finally, to get the bounding box in grid-fitted pixel
coordinates, set <tt>bbox_mode</tt>
to <tt>FT_GLYPH_BBOX_PIXELS</tt>.</p>
<p>[Computing <em>exact</em> bounding boxes can be done with
function <a href="../reference/ft2-outline_processing.html#FT_Outline_Get_BBox"><tt>FT_Outline_Get_BBox</tt></a>,
at the cost of slower execution. You probably don't need
with the possible exception of rotated glyphs.]</p>
<h4>d. Converting the Glyph Image to a Bitmap</h4>
<p>You may need to convert the glyph object to a bitmap once
you have conveniently cached or transformed it. This can
be done easily with
the <a href="../reference/ft2-glyph_management.html"><tt>FT_Glyph_To_Bitmap</tt></a>
function, which handles any glyph object.</p>
<pre>
FT_Vector origin;
origin.x = 32; <span class="comment">/* 1/2 pixel in 26.6 format */</span>
origin.y = 0;
error = FT_Glyph_To_Bitmap(
&glyph,
<em>render_mode</em>,
&origin,
1 ); <span class="comment">/* destroy original image == true */</span></pre>
<p>Some notes.</p>
<ul>
<li>The first parameter is the address of the source
glyph's handle. When the function is called, it reads
it to access the source glyph object. After the call,
the handle points to a <em>new</em> glyph object that
contains the rendered bitmap.</li>
<li>The second parameter is a standard render mode to
specify what kind of bitmap we want. For example, it
can be <tt>FT_RENDER_MODE_DEFAULT</tt> for an 8-bit
anti-aliased pixmap, or <tt>FT_RENDER_MODE_MONO</tt> for
a 1-bit monochrome bitmap.</li>
<li>The third parameter is a pointer to a two-dimensional
vector to translate the source glyph image before the
conversion. After the call, the source image is
translated back to its original position (and is thus
left unchanged). If you do not need to translate the
source glyph before rendering, set this pointer
to NULL.</li>
<li>The last parameter is a boolean that indicates whether
the source glyph object should be destroyed by the
function. If false, the original glyph object is never
destroyed, even if its handle is lost (it is up to
client applications to keep it).</li>
</ul>
<p>The new glyph object always contains a bitmap (if no
error is returned), and you must <em>typecast</em> its
handle to the <tt>FT_BitmapGlyph</tt> type in order to
access its content. This type is a sort of
‘subclass’ of <tt>FT_Glyph</tt> that contains
additional fields
(see <a href="../reference/ft2-glyph_management.html#FT_BitmapGlyphRec"><tt>FT_BitmapGlyphRec</tt></a>).</p>
<dl>
<dt>left</dt>
<dd>Just like the <tt>bitmap_left</tt> field of a glyph
slot, this is the horizontal distance from the glyph
origin (0,0) to the leftmost pixel of the glyph bitmap.
It is expressed in integer pixels.</dd>
<dt>top</dt>
<dd>Just like the <tt>bitmap_top</tt> field of a glyph
slot, this is the vertical distance from the glyph
origin (0,0) to the topmost pixel of the glyph bitmap
(more precise, to the pixel just above the bitmap).
This distance is expressed in integer pixels, and is
positive for upwards y.</dd>
<dt>bitmap</dt>
<dd>This is a bitmap descriptor for the glyph object, just
like the <tt>bitmap</tt> field in a glyph slot.</dd>
</dl>
<h3 id="section-3">3. Global Glyph Metrics</h3>
<p>Unlike glyph metrics, global metrics are used to describe
distances and features of a whole font face. They can be
expressed either in 26.6 pixel format or in (unscaled)
font units for scalable formats.</p>
<h4> a. Design global metrics</h4>
<p>For scalable formats, all global metrics are expressed in
font units in order to be later scaled to the device
space, according to the rules described in the last
section of this tutorial part. You can access them
directly as fields of a <tt>FT_Face</tt> handle.</p>
<p>However, you need to check that the font face's format is
scalable before using them. One can do it with
macro <tt>FT_IS_SCALABLE</tt>, which returns true when
appropriate.</p>
<p>Here a table of the global design metrics for scalable
faces.</p>
<dl>
<dt>units_per_EM</dt>
<dd>This is the size of the EM square for the font face.
It is used by scalable formats to scale design
coordinates to device pixels, as described in the last
section of this tutorial part. Its value usually is
2048 (for TrueType) or 1000 (for Type 1 or CFF),
but other values are possible, too. It is set to 1
for fixed-size formats like FNT, FON, PCF, or BDF.</dd>
<dt>bbox</dt>
<dd>The global bounding box is defined as the smallest
rectangle that can enclose all the glyphs in a font
face.</dd>
<dt>ascender</dt>
<dd>The ascender is the vertical distance from the
horizontal baseline to the highest
‘character’ coordinate in a font face.
Unfortunately, font formats don't define the ascender in
a uniform way. For some formats, it represents the
ascent of all capital latin characters (without
accents), for others it is the ascent of the highest
accented character, and finally, other formats define it
as being equal to <tt>bbox.yMax</tt>.</dd>
<dt>descender</dt>
<dd>The descender is the vertical distance from the
horizontal baseline to the lowest
‘character’ coordinate in a font face.
Unfortunately, font formats don't define the descender
in a uniform way. For some formats, it represents the
descent of all capital latin characters (without
accents), for others it is the ascent of the lowest
accented character, and finally, other formats define it
as being equal to <tt>bbox.yMin</tt>. This field is
negative for values below the baseline.</dd>
<dt>height</dt>
<dd>This field represents a <em>default line spacing</em>
(i.e., the baseline-to-baseline distance) when writing
text with this font. Note that it usually is larger
than the sum of the ascender and descender taken as
absolute values. There is also no guarantee that no
glyphs extend above or below subsequent baselines when
using this distance – think of it as a value the
designer of the font finds appropriate.</dd>
<dt>max_advance_width</dt>
<dd>This field gives the maximum horizontal cursor advance
for all glyphs in the font. It can be used to quickly
compute the maximum advance width of a string of
text. <em>It doesn't correspond to the maximum glyph
image width!</em></dd>
<dt>max_advance_height</dt>
<dd>Same as <tt>max_advance_width</tt> but for vertical
text layout.</dd>
<dt>underline_position</dt>
<dd>When displaying or rendering underlined text, this
value corresponds to the vertical position, relative to
the baseline, of the underline bar's center. It is
negative if it is below the baseline.</dd>
<dt>underline_thickness</dt>
<dd>When displaying or rendering underlined text, this
value corresponds to the vertical thickness of the
underline.</dd>
</dl>
<p>Notice that the values of the ascender and the descender
are not reliable (due to various discrepancies in font
formats), unfortunately.</p>
<h4>b. Scaled Global Metrics</h4>
<p>Each size object also contains a scaled version of some
of the global metrics described above, to be directly
accessed through the <tt>face->size->metrics</tt>
structure (of type <a href="../reference/ft2-base_interface.html#FT_Size_Metrics">
<tt>FT_Size_Metrics</tt></a>). <em>No rounding or
grid-fitting is performed for those values</em>. They are
also completely independent of any hinting process. In
other words, don't rely on them to get exact metrics at
the pixel level. They are expressed in 26.6 pixel
format.</p>
<dl>
<dt>ascender</dt>
<dd>The scaled version of the original design
ascender.</dd>
<dt>descender</dt>
<dd>The scaled version of the original design
descender.</dd>
<dt>height</dt>
<dd>
<p>The scaled version of the original design text height
(the vertical distance from one baseline to the next).
This is probably the only field you should really use
in this structure.</p>
<p>Be careful not to confuse it with the
‘height’ field in
the <a href="../reference/ft2-base_interface.html#FT_Glyph_Metrics"><tt>FT_Glyph_Metrics</tt></a>
structure.</p>
</dd>
<dt>max_advance</dt>
<dd>The scaled version of the original design maximum
advance.</dd>
</dl>
<p>Note that the <tt>face->size->metrics</tt>
structure contains other fields that are used to scale
design coordinates to device space. They are described in
the last section.</p>
<h4>c. Kerning</h4>
<p>Kerning is the process of adjusting the position of two
subsequent glyph images in a string of text in order to
improve the general appearance of text. For example, if a
glyph for an uppercase ‘A’ is followed by a
glyph for an uppercase ‘V’, the space between
the two glyphs can be slightly reduced to avoid extra
‘diagonal whitespace’.</p>
<p>Note that in theory kerning can happen both in the
horizontal and vertical direction between two glyphs;
however, it only happens in a single direction in nearly
all cases.</p>
<p>Not all font formats contain kerning information, and not
all kerning formats are supported by FreeType; in
particular, for TrueType fonts, the API can only access
kerning via the ‘kern’
table. <span class="important">OpenType kerning via the
‘GPOS’ table is not supported!</span> You
need a higher-level library
like <a href="http://www.harfbuzz.org">HarfBuzz</a>,
<a href="http://www.pango.org">Pango</a>,
or <a href="http://www.icu-project.org">ICU</a>, since
GPOS kerning requires contextual string handling.</p>
<p>Sometimes, the font file is associated with an additional
file that contains various glyph metrics, including
kerning, but no glyph images. A good example is the
Type 1 format where glyph images are stored in files
with extension <tt>.pfa</tt> or <tt>.pfb</tt>, while
kerning metrics can be found in files with extension
<tt>.afm</tt> or <tt>.pfm</tt>.</p>
<p>FreeType 2 allows you to deal with this, by
providing
the <a href="../reference/ft2-base_interface.html#FT_Attach_File"><tt>FT_Attach_File</tt></a>
and <a href="../reference/ft2-base_interface.html#FT_Attach_Stream"><tt>FT_Attach_Stream</tt></A>
APIs. Both functions are used to load additional metrics
into a face object by reading them from an additional
format-specific file. Here an example, opening a
Type 1 font.</p>
<pre>
error = FT_New_Face( library, "/usr/share/fonts/cour.pfb",
0, &face );
if ( error ) { ... }
error = FT_Attach_File( face, "/usr/share/fonts/cour.afm" );
if ( error )
{ ... could not read kerning and additional metrics ... }</pre>
<p>Note that <tt>FT_Attach_Stream</tt> is similar to
<tt>FT_Attach_File</tt> except that it doesn't take a
C string to name the extra file but
an <a href="../reference/ft2-system_interface.html#FT_StreamRec"><tt>FT_Stream</tt></a>
handle. Also, <em>reading a metrics file is in no way
mandatory</em>.</p>
<p>Finally, the file attachment APIs are very generic and
can be used to load any kind of extra information for a
given face. The nature of the additional content is
entirely font format specific.</p>
<p>FreeType 2 allows you to retrieve the kerning
information between two glyphs through
the <a href="../reference/ft2-base_interface.html#FT_Get_Kerning"><tt>FT_Get_Kerning</tt></a>
function.</p>
<pre>
FT_Vector kerning;
...
error = FT_Get_Kerning( face, <span class="comment">/* handle to face object */</span>
left, <span class="comment">/* left glyph index */</span>
right, <span class="comment">/* right glyph index */</span>
<em>kerning_mode</em>, <span class="comment">/* kerning mode */</span>
&kerning ); <span class="comment">/* target vector */</span></pre>
<p>This function takes a handle to a face object, the
indices of the left and right glyph for which the kerning
value is desired, an integer, called the <em>kerning
mode</em>, and a pointer to a destination vector that
receives the corresponding distances.</p>
<p>The kerning mode is very similar to the <em>bbox
mode</em> described in a previous section. It is a
enumeration that indicates how the kerning distances are
expressed in the target vector.</p>
<p>The default value is <tt>FT_KERNING_DEFAULT</tt>, which
has value 0. It corresponds to kerning distances
expressed in 26.6 grid-fitted pixels (which means that the
values are multiples of 64). For scalable formats, this
means that the design kerning distance is scaled, then
rounded.</p>
<p>The value <tt>FT_KERNING_UNFITTED</tt> corresponds to
kerning distances expressed in 26.6 unfitted pixels (i.e.,
that do not correspond to integer coordinates). It is the
design kerning distance that is scaled without
rounding.</p>
<p>Finally, the value <tt>FT_KERNING_UNSCALED</tt> indicates
to return the design kerning distance, expressed in font
units. You can later scale it to the device space using
the computations explained in the last section of this
part.</p>
<p>Note that the ‘left’ and ‘right’
positions correspond to the <em>visual order</em> of the
glyphs in the string of text. This is important for
bidirectional or right-to-left text.</p>
<h3 id="section-4">4. Simple Text Rendering: Kerning and Centering</h3>
<p>In order to show off what we have just learned, we now
demonstrate how to modify
the <a href="step1.html#basic-code">example code</a> that
was provided in part I to render a string of text,
and enhance it to support kerning and delayed
rendering.</p>
<h4>a. Kerning Support</h4>
<p>Adding support for kerning to our code is trivial, as
long as we consider that we are still dealing with a
left-to-right script like Latin. We simply need to
retrieve the kerning distance between two glyphs in order
to alter the pen position appropriately.</p>
<pre>
FT_GlyphSlot slot = face->glyph; <span class="comment">/* a small shortcut */</span>
FT_UInt glyph_index;
FT_Bool use_kerning;
FT_UInt previous;
int pen_x, pen_y, n;
... initialize library ...
... create face object ...
... set character size ...
pen_x = 300;
pen_y = 200;
use_kerning = FT_HAS_KERNING( face );
previous = 0;
for ( n = 0; n < num_chars; n++ )
{
<span class="comment">/* convert character code to glyph index */</span>
glyph_index = FT_Get_Char_Index( face, text[n] );
<span class="comment">/* retrieve kerning distance and move pen position */</span>
if ( use_kerning && previous && glyph_index )
{
FT_Vector delta;
FT_Get_Kerning( face, previous, glyph_index,
FT_KERNING_DEFAULT, &delta );
pen_x += delta.x >> 6;
}
<span class="comment">/* load glyph image into the slot (erase previous one) */</span>
error = FT_Load_Glyph( face, glyph_index, FT_LOAD_RENDER );
if ( error )
continue; <span class="comment">/* ignore errors */</span>
<span class="comment">/* now draw to our target surface */</span>
my_draw_bitmap( &slot->bitmap,
pen_x + slot->bitmap_left,
pen_y - slot->bitmap_top );
<span class="comment">/* increment pen position */</span>
pen_x += slot->advance.x >> 6;
<span class="comment">/* record current glyph index */</span>
previous = glyph_index;
}</pre>
<p>We are done. Some notes.</p>
<ul>
<li>As kerning is determined by glyph indices, we need
to explicitly convert our character codes into glyph
indices, then later call <tt>FT_Load_Glyph</tt> instead
of <tt>FT_Load_Char</tt>.</li>
<li>We use a boolean named <tt>use_kerning</tt>, which is
set to the result of the macro <tt>FT_HAS_KERNING</tt>.
It is certainly faster not to
call <tt>FT_Get_Kerning</tt> when we know that the font
face does not contain kerning information.</li>
<li>We move the position of the pen <em>before</em> a new
glyph is drawn.</li>
<li>We initialize the variable <tt>previous</tt> with the
value 0, which always corresponds to the
‘missing glyph’ (also
called <tt>.notdef</tt> in the PostScript world). There
is never any kerning distance associated with this
glyph.</li>
<li>We do not check the error code returned by
<tt>FT_Get_Kerning</tt>. This is because the function
always sets the content of <tt>delta</tt> to (0,0) if
an error occurs.</li>
</ul>
<h4>b. Centering</h4>
<p>Our code begins to become interesting but it is still a
bit too simple for normal use. For example, the position
of the pen is determined before we do the rendering;
normally, you would rather determine the layout of the
text and measure it before computing its final position
(centering, etc.), or perform things like
word-wrapping.</p>
<p>Let us now decompose our text rendering function into two
distinct but successive parts: The first one positions
individual glyph images on the baseline, while the second
one renders the glyphs. As we will see, this has many
advantages.</p>
<p>We thus start by storing individual glyph images, as well
as their position on the baseline.</p>
<pre>
FT_GlyphSlot slot = face->glyph; <span class="comment">/* a small shortcut */</span>
FT_UInt glyph_index;
FT_Bool use_kerning;
FT_UInt previous;
int pen_x, pen_y, n;
FT_Glyph glyphs[MAX_GLYPHS]; <span class="comment">/* glyph image */</span>
FT_Vector pos [MAX_GLYPHS]; <span class="comment">/* glyph position */</span>
FT_UInt num_glyphs;
... initialize library ...
... create face object ...
... set character size ...
pen_x = 0; <span class="comment">/* start at (0,0) */</span>
pen_y = 0;
num_glyphs = 0;
use_kerning = FT_HAS_KERNING( face );
previous = 0;
for ( n = 0; n < num_chars; n++ )
{
<span class="comment">/* convert character code to glyph index */</span>
glyph_index = FT_Get_Char_Index( face, text[n] );
<span class="comment">/* retrieve kerning distance and move pen position */</span>
if ( use_kerning && previous && glyph_index )
{
FT_Vector delta;
FT_Get_Kerning( face, previous, glyph_index,
FT_KERNING_DEFAULT, &delta );
pen_x += delta.x >> 6;
}
<span class="comment">/* store current pen position */</span>
pos[num_glyphs].x = pen_x;
pos[num_glyphs].y = pen_y;
<span class="comment">/* load glyph image into the slot without rendering */</span>
error = FT_Load_Glyph( face, glyph_index, FT_LOAD_DEFAULT );
if ( error )
continue; <span class="comment">/* ignore errors, jump to next glyph */</span>
<span class="comment">/* extract glyph image and store it in our table */</span>
error = FT_Get_Glyph( face->glyph, &glyphs[num_glyphs] );
if ( error )
continue; <span class="comment">/* ignore errors, jump to next glyph */</span>
<span class="comment">/* increment pen position */</span>
pen_x += slot->advance.x >> 6;
<span class="comment">/* record current glyph index */</span>
previous = glyph_index;
<span class="comment">/* increment number of glyphs */</span>
num_glyphs++;
}</pre>
<p>This is a very slight variation of our previous code; we
extract each glyph image from the slot, then store it,
along with the corresponding position, in our tables.</p>
<p>Note also that <tt>pen_x</tt> contains the total advance
for the string of text. We can now compute the bounding
box of the text string with a simple function.</p>
<pre>
void compute_string_bbox( FT_BBox *abbox )
{
FT_BBox bbox;
FT_BBox glyph_bbox;
<span class="comment">/* initialize string bbox to "empty" values */</span>
bbox.xMin = bbox.yMin = 32000;
bbox.xMax = bbox.yMax = -32000;
<span class="comment">/* for each glyph image, compute its bounding box, */</span>
<span class="comment">/* translate it, and grow the string bbox */</span>
for ( n = 0; n < num_glyphs; n++ )
{
FT_Glyph_Get_CBox( glyphs[n], ft_glyph_bbox_pixels,
&glyph_bbox );
glyph_bbox.xMin += pos[n].x;
glyph_bbox.xMax += pos[n].x;
glyph_bbox.yMin += pos[n].y;
glyph_bbox.yMax += pos[n].y;
if ( glyph_bbox.xMin < bbox.xMin )
bbox.xMin = glyph_bbox.xMin;
if ( glyph_bbox.yMin < bbox.yMin )
bbox.yMin = glyph_bbox.yMin;
if ( glyph_bbox.xMax > bbox.xMax )
bbox.xMax = glyph_bbox.xMax;
if ( glyph_bbox.yMax > bbox.yMax )
bbox.yMax = glyph_bbox.yMax;
}
<span class="comment">/* check that we really grew the string bbox */</span>
if ( bbox.xMin > bbox.xMax )
{
bbox.xMin = 0;
bbox.yMin = 0;
bbox.xMax = 0;
bbox.yMax = 0;
}
<span class="comment">/* return string bbox */</span>
*abbox = bbox;
}</pre>
<p>The resulting bounding box dimensions are expressed in
integer pixels and can then be used to compute the final
pen position before rendering the string.</p>
<p class="warning">In general, the above function
does <em>not</em> compute an exact bounding box of a
string! As soon as hinting is involved, glyph
dimensions <em>must</em> be derived from the resulting
outlines. For anti-aliased pixmaps,
<tt>FT_Outline_Get_BBox</tt> then yields proper results.
In case you need 1-bit monochrome bitmaps, it is even
necessary to actually render the glyphs because the rules
for the conversion from outline to bitmap can also be
controlled by hinting instructions.</p>
<pre>
<span class="comment">/* compute string dimensions in integer pixels */</span>
string_width = string_bbox.xMax - string_bbox.xMin;
string_height = string_bbox.yMax - string_bbox.yMin;
<span class="comment">/* compute start pen position in 26.6 Cartesian pixels */</span>
start_x = ( ( my_target_width - string_width ) / 2 ) * 64;
start_y = ( ( my_target_height - string_height ) / 2 ) * 64;
for ( n = 0; n < num_glyphs; n++ )
{
FT_Glyph image;
FT_Vector pen;
image = glyphs[n];
pen.x = start_x + pos[n].x;
pen.y = start_y + pos[n].y;
error = FT_Glyph_To_Bitmap( &image, FT_RENDER_MODE_NORMAL,
&pen, 0 );
if ( !error )
{
FT_BitmapGlyph bit = (FT_BitmapGlyph)image;
my_draw_bitmap( bit->bitmap,
bit->left,
my_target_height - bit->top );
FT_Done_Glyph( image );
}
}</pre>
<p>Some remarks.</p>
<ul>
<li>The pen position is expressed in the Cartesian space
(i.e., y upwards).</li>
<li>We call <tt>FT_Glyph_To_Bitmap</tt> with
the <tt>destroy</tt> parameter set to 0 (false), in
order to avoid destroying the original glyph image. The
new glyph bitmap is accessed through
<tt>image</tt> after the call and is typecast to
<tt>FT_BitmapGlyph</tt>.</li>
<li>We use translation when
calling <tt>FT_Glyph_To_Bitmap</tt>. This ensures that
the <tt>left</tt> and <tt>top</tt> fields of the bitmap
glyph object are already set to the correct pixel
coordinates in the Cartesian space.</li>
<li>Of course, we still need to convert pixel coordinates
from Cartesian to device space before rendering, hence
the <tt>my_target_height - bitmap->top</tt> in the call
to <tt>my_draw_bitmap</tt>.</li>
</ul>
<p>The same loop can be used to render the string anywhere
on our display surface, without the need to reload our
glyph images each time.</p>
<h3 id="section-5">5. Advanced Text Rendering:
Transformation and Centering and Kerning</h3>
<p>We are now going to modify our code in order to be able
to easily transform the rendered string, for example, to
rotate it. First, some minor improvements.</p>
<h4>a. Packing and Translating Glyphs</h4>
<p>We start by packing the information related to a single
glyph image into a single structure instead of parallel
arrays.</p>
<pre>
typedef struct TGlyph_
{
FT_UInt index; <span class="comment">/* glyph index */</span>
FT_Vector pos; <span class="comment">/* glyph origin on the baseline */</span>
FT_Glyph image; <span class="comment">/* glyph image */</span>
} TGlyph, *PGlyph;</pre>
<p>We also translate each glyph image directly after it is
loaded to its position on the baseline at load time. As
we will see, this has several advantages. Here is our new
glyph sequence loader.</p>
<pre>
FT_GlyphSlot slot = face->glyph; <span class="comment">/* a small shortcut */</span>
FT_UInt glyph_index;
FT_Bool use_kerning;
FT_UInt previous;
int pen_x, pen_y, n;
TGlyph glyphs[MAX_GLYPHS]; <span class="comment">/* glyphs table */</span>
PGlyph glyph; <span class="comment">/* current glyph in table */</span>
FT_UInt num_glyphs;
... initialize library ...
... create face object ...
... set character size ...
pen_x = 0; <span class="comment">/* start at (0,0) */</span>
pen_y = 0;
num_glyphs = 0;
use_kerning = FT_HAS_KERNING( face );
previous = 0;
glyph = glyphs;
for ( n = 0; n < num_chars; n++ )
{
glyph->index = FT_Get_Char_Index( face, text[n] );
if ( use_kerning && previous && glyph->index )
{
FT_Vector delta;
FT_Get_Kerning( face, previous, glyph->index,
FT_KERNING_MODE_DEFAULT, &delta );
pen_x += delta.x >> 6;
}
<span class="comment">/* store current pen position */</span>
glyph->pos.x = pen_x;
glyph->pos.y = pen_y;
error = FT_Load_Glyph( face, glyph_index, FT_LOAD_DEFAULT );
if ( error ) continue;
error = FT_Get_Glyph( face->glyph, &glyph->image );
if ( error ) continue;
<span class="comment">/* translate the glyph image now */</span>
FT_Glyph_Transform( glyph->image, 0, &glyph->pos );
pen_x += slot->advance.x >> 6;
previous = glyph->index;
<span class="comment">/* increment number of glyphs */</span>
glyph++;
}
<span class="comment">/* count number of glyphs loaded */</span>
num_glyphs = glyph - glyphs;</pre>
<p>Note that translating glyphs now has several advantages.
The first one is that we don't need to translate the glyph
bbox when we compute the string's bounding box.</p>
<pre>
void compute_string_bbox( FT_BBox *abbox )
{
FT_BBox bbox;
bbox.xMin = bbox.yMin = 32000;
bbox.xMax = bbox.yMax = -32000;
for ( n = 0; n < num_glyphs; n++ )
{
FT_BBox glyph_bbox;
FT_Glyph_Get_CBox( glyphs[n], ft_glyph_bbox_pixels,
&glyph_bbox );
if (glyph_bbox.xMin < bbox.xMin)
bbox.xMin = glyph_bbox.xMin;
if (glyph_bbox.yMin < bbox.yMin)
bbox.yMin = glyph_bbox.yMin;
if (glyph_bbox.xMax > bbox.xMax)
bbox.xMax = glyph_bbox.xMax;
if (glyph_bbox.yMax > bbox.yMax)
bbox.yMax = glyph_bbox.yMax;
}
if ( bbox.xMin > bbox.xMax )
{
bbox.xMin = 0;
bbox.yMin = 0;
bbox.xMax = 0;
bbox.yMax = 0;
}
*abbox = bbox;
}</pre>
<p>With the above modifications,
the <tt>compute_string_bbox</tt> function can now compute
the bounding box of a transformed glyph string, which
allows further code simplications.</p>
<pre>
FT_BBox bbox;
FT_Matrix matrix;
FT_Vector delta;
... load glyph sequence ...
... set up `matrix' and `delta' ...
<span class="comment">/* transform glyphs */</span>
for ( n = 0; n < num_glyphs; n++ )
FT_Glyph_Transform( glyphs[n].image, &matrix, &delta );
<span class="comment">/* compute bounding box of transformed glyphs */</span>
compute_string_bbox( &bbox );</pre>
<h4>b. Rendering a Transformed Glyph Sequence</h4>
<p>However, directly transforming the glyphs in our sequence
is not a good idea if we want to reuse them in order to
draw the text string with various angles or
transformations. It is better to perform the affine
transformation just before the glyph is rendered.</p>
<pre>
FT_Vector start;
FT_Matrix matrix;
FT_Glyph image;
FT_Vector pen;
FT_BBox bbox;
<span class="comment">/* get bbox of original glyph sequence */</span>
compute_string_bbox( &string_bbox );
<span class="comment">/* compute string dimensions in integer pixels */</span>
string_width = (string_bbox.xMax - string_bbox.xMin) / 64;
string_height = (string_bbox.yMax - string_bbox.yMin) / 64;
<span class="comment">/* set up start position in 26.6 Cartesian space */</span>
start.x = ( ( my_target_width - string_width ) / 2 ) * 64;
start.y = ( ( my_target_height - string_height ) / 2 ) * 64;
<span class="comment">/* set up transform (a rotation here) */</span>
matrix.xx = (FT_Fixed)( cos( angle ) * 0x10000L );
matrix.xy = (FT_Fixed)(-sin( angle ) * 0x10000L );
matrix.yx = (FT_Fixed)( sin( angle ) * 0x10000L );
matrix.yy = (FT_Fixed)( cos( angle ) * 0x10000L );
pen = start;
for ( n = 0; n < num_glyphs; n++ )
{
<span class="comment">/* create a copy of the original glyph */</span>
error = FT_Glyph_Copy( glyphs[n].image, &image );
if ( error ) continue;
<span class="comment">/* transform copy (this will also translate it to the */</span>
<span class="comment">/* correct position */</span>
FT_Glyph_Transform( image, &matrix, &pen );
<span class="comment">/* check bounding box; if the transformed glyph image */</span>
<span class="comment">/* is not in our target surface, we can avoid rendering it */</span>
FT_Glyph_Get_CBox( image, ft_glyph_bbox_pixels, &bbox );
if ( bbox.xMax <= 0 || bbox.xMin >= my_target_width ||
bbox.yMax <= 0 || bbox.yMin >= my_target_height )
continue;
<span class="comment">/* convert glyph image to bitmap (destroy the glyph copy!) */</span>
error = FT_Glyph_To_Bitmap(
&image,
FT_RENDER_MODE_NORMAL,
0, <span class="comment">/* no additional translation */</span>
1 ); <span class="comment">/* destroy copy in "image" */</span>
if ( !error )
{
FT_BitmapGlyph bit = (FT_BitmapGlyph)image;
my_draw_bitmap( bit->bitmap,
bit->left,
my_target_height - bit->top );
<span class="comment">/* increment pen position -- */</span>
<span class="comment">/* we don't have access to a slot structure, */</span>
<span class="comment">/* so we have to use advances from glyph structure */</span>
<span class="comment">/* (which are in 16.16 fixed float format) */</span>
pen.x += image.advance.x >> 10;
pen.y += image.advance.y >> 10;
FT_Done_Glyph( image );
}
}</pre>
<p>There are a few changes compared to the original version
of this code.</p>
<ul>
<li>We keep the original glyph images untouched; instead,
we transform a copy.</li>
<li>We perform clipping computations in order to avoid
rendering and drawing glyphs that are not within our
target surface.</li>
<li>We always destroy the copy when calling
<tt>FT_Glyph_To_Bitmap</tt> in order to get rid of the
transformed scalable image. Note that the image is not
destroyed if the function returns an error code (which
is why <tt>FT_Done_Glyph</tt> is only called within the
compound statement).</li>
<li>The translation of the glyph sequence to the start pen
position is integrated into the call
to <tt>FT_Glyph_Transform</tt> instead
of <tt>FT_Glyph_To_Bitmap</tt>.</li>
</ul>
<p>It is possible to call this function several times to
render the string with different angles, or even change
the way <tt>start</tt> is computed in order to move it to
different place.</p>
<p>This code is the basis of the FreeType 2
demonstration program
named <a href="http://git.savannah.gnu.org/cgit/freetype/freetype2-demos.git/tree/src/ftstring.c"><tt>ftstring.c</tt></a>.
It could be easily extended to perform advanced text
layout or word-wrapping in the first part, without
changing the second one.</p>
<p>Note, however, that a normal implementation would use a
glyph cache in order to reduce memory needs. For example,
let us assume that our text string is
‘FreeType’. We would store three identical
glyph images in our table for the letter ‘e’,
which isn't optimal (especially when you consider longer
lines of text, or even whole pages).</p>
<p>A FreeType demo program that shows how glyph caching can
be implemented
is <a href="http://git.savannah.gnu.org/cgit/freetype/freetype2-demos.git/tree/src/ftview.c"><tt>ftview.c</tt></a>.
In general, ‘ftview’ is the main program used
by the FreeType developer team to check the validity of
loading, parsing, and rendering fonts.</p>
<h3 id="section-6">6. Accessing Metrics in Design Font
Units, and Scaling Them</h3>
<p>Scalable font formats usually store a single vectorial
image, called an <em>outline</em>, for each glyph in a
face. Each outline is defined in an abstract grid called
the <em>design space</em>, with coordinates expressed in
<em>font units</em>. When a glyph image is loaded, the
font driver usually scales the outline to device space
according to the current character pixel size found in
an <a href="../reference/ft2-base_interface.html#FT_Size"><tt>FT_Size</tt></a>
object. The driver may also modify the scaled outline in
order to significantly improve its appearance on a
pixel-based surface (a process known as <em>hinting</em>
or <em>grid-fitting</em>).</p>
<p>This section describes how design coordinates are scaled
to the device space, and how to read glyph outlines and
metrics in font units. This is important for a number of
things.</p>
<ul>
<li>‘True’ WYSIWYG text layout.</li>
<li>Accessing font content for conversion or analysis
purposes.</li>
</ul>
<h4>a. Scaling Distances to Device Space</h4>
<p>Design coordinates are scaled to the device space using a
simple scaling transformation whose coefficients are
computed with the help of the <em>character pixel
size</em>.</p>
<pre class="example">
device_x = design_x * x_scale
device_y = design_y * y_scale
x_scale = pixel_size_x / EM_size
y_scale = pixel_size_y / EM_size</pre>
<p>Here, the value <tt>EM_size</tt> is font-specific and
corresponds to the size of an abstract square of the
design space (called the <em>EM</em>), which is used by
font designers to create glyph images. It is thus
expressed in font units. It is also accessible directly
for scalable font formats
as <tt>face->units_per_EM</tt>. You should check that
a font face contains scalable glyph images by using
the <tt>FT_IS_SCALABLE</tt> macro, which returns true if
appropriate.</p>
<p>When you call the
function <a href="../reference/ft2-base_interface.html#FT_Set_Pixel_Sizes"><tt>FT_Set_Pixel_Sizes</tt></a>,
you are specifying the value of <tt>pixel_size_x</tt> and
<tt>pixel_size_y</tt> FreeType shall use. The library will
immediately compute the values of <tt>x_scale</tt> and
<tt>y_scale</tt>.</p>
<p>When you call the
function <a href="../reference/ft2-base_interface.html#FT_Set_Char_Size"><tt>FT_Set_Char_Size</tt></a>,
you are specifying the character size in
physical <em>points</em>, which is used, along with the
device's resolutions, to compute the character pixel size
and the corresponding scaling factors.</p>
<p>Note that after calling any of these two functions, you
can access the values of the character pixel size and
scaling factors as fields of
the <tt>face->size->metrics</tt> structure.</p>
<dl>
<dt>x_ppem</dt>
<dd>The field name stands for ‘x pixels per
EM’; this is the horizontal size in integer pixels
of the EM square, which also is the <em>horizontal
character pixel size</em>, called <tt>pixel_size_x</tt>
in the above example.</dd>
<dt>y_ppem</dt>
<dd>The field name stands for ‘y pixels per
EM’; this is the vertical size in integer pixels
of the EM square, which also is the <em>vertical
character pixel size</em>, called <tt>pixel_size_y</tt>
in the above example.</dd>
<dt>x_scale</dt>
<dd>This is a 16.16 fixed-point scale to directly scale
horizontal distances from design space to 1/64th of
device pixels.</dd>
<dt>y_scale</dt>
<dd>This is a 16.16 fixed-point scale to directly scale
vertical distances from design space to 1/64th of device
pixels.</dd>
</dl>
<p>You can scale a distance expressed in font units to 26.6
pixel format directly with the help of
the <a href="../reference/ft2-computations.html#FT_MulFix"><tt>FT_MulFix</tt></a>
function.</p>
<pre>
<span class="comment">/* convert design distances to 1/64th of pixels */</span>
pixels_x = FT_MulFix( design_x, face->size->metrics.x_scale );
pixels_y = FT_MulFix( design_y, face->size->metrics.y_scale );</pre>
<p>Alternatively, you can also scale the value directly with
more accuracy by using doubles.</p>
<pre>
FT_Size_Metrics* metrics = &face->size->metrics; <span class="comment">/* shortcut */</span>
double pixels_x, pixels_y;
double em_size, x_scale, y_scale;
<span class="comment">/* compute floating point scale factors */</span>
em_size = 1.0 * face->units_per_EM;
x_scale = metrics->x_ppem / em_size;
y_scale = metrics->y_ppem / em_size;
<span class="comment">/* convert design distances to floating point pixels */</span>
pixels_x = design_x * x_scale;
pixels_y = design_y * y_scale;</pre>
<h4>b. Accessing Design Metrics (Glyph & Global)</h4>
<p>You can access glyph metrics in font units simply by
specifying the <tt>FT_LOAD_NO_SCALE</tt> bit flag
in <tt>FT_Load_Glyph</tt> or <tt>FT_Load_Char</tt>. The
metrics returned in <tt>face->glyph->metrics</tt>
will all be in font units.</p>
<p>You can access unscaled kerning data using the
<tt>FT_KERNING_MODE_UNSCALED</tt> mode.</p>
<p>Finally, a few global metrics are available directly in
font units as fields of the <tt>FT_Face</tt> handle, as
described in <a href="#section-3">section 3</a> of
this part.</p>
<h3 id="conclusion">Conclusion</h3>
<p>This is the end of the second part of the FreeType
tutorial. You are now able to access glyph metrics,
manage glyph images, and render text much more
intelligently (kerning, measuring, transforming &
caching); this is sufficient knowledge to build a pretty
decent text service on top of FreeType.</p>
<p>The demo programs in the ‘ft2demos’ bundle
(especially ‘ftview’) are a kind of reference
implementation, and are a good resource to turn to for
answers. They also show how to use additional features,
such as the glyph stroker and cache.</p>
</div>
<!-- ************************************************** -->
<div class="updated">
<p>Last update: 12-Dec-2014</p>
</div>
</div>
</div>
<!-- ************************************************** -->
<div class="col2">
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<!-- ************************************************** -->
<div id="TOC">
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<p><a href="https://pledgie.com/campaigns/24434">
<img alt="Click here to lend your support to the FreeType project and make a donation at pledgie.com!"
src="https://pledgie.com/campaigns/24434.png?skin_name=chrome"
border="0"
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</a></p>
<p><a href="https://flattr.com/thing/421342/lemzwerg-on-Flattr"
target="_blank">
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src="http://api.flattr.com/button/flattr-badge-large.png"
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</li>
<li class="secondary">
<a href="index.html">FreeType Tutorial</a>
</li>
<li class="tertiary">
<a href="step1.html">Simple Glyph Loading</a>
</li>
<li class="tertiary">
<a href="step2.html" class="current">Managing Glyphs</a>
</li>
<li class="tertiary">
<a href="step3.html">Examples</a>
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</body>
</html>
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