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<!doctype HTML PUBLIC "-//IETF//DTD HTML//EN">
<html>

<head>
<meta http-equiv="Content-Language" content="en-us">
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
<title>CAIRO</title>
<link rel="stylesheet" type="text/css" href="../../style.css">
</head>

<body>

<h2>CAIRO Base Driver</h2>

  <p>This driver represents a basic driver for all system-dependent drivers 
  implemented in the X-Windows and MS-Windows systems. The implementation uses the
  <a href="http://library.gnome.org/devel/pango/">Cairo</a> API 
  functions and some GTK functions to support Unicode text. This driver can be 
  compiled and used in all systems Cairo is supported.</p>
<p>The main motivation for the use of Cairo was transparency for all the 
primitives. Beyond that we got other features like anti-aliasing, gradient 
filling, transformations and back-ends (support to rendering: PDF, PS, SVG and 
PNG surfaces).</p>
<p>This driver still does not completely replace the X-Windows and GDI Windows 
base drivers, because Cairo does not have support for bitwise XOR operations and 
for complex clipping regions.</p>

<h3>Behavior of Functions</h3>
<h4>Control&nbsp; </h4>
<ul>
  <li><a href="../func/other.html#cdPlay">
  <font face="Courier"><strong>Play</strong></font></a>: does nothing, returns
  <font face="Courier">CD_ERROR</font>. </li>
</ul>
<h4>Coordinate System and Clipping </h4>
<ul>
  <li>
  <a href="../func/coordinates.html#cdUpdateYAxis">
  <font face="Courier"><strong>UpdateYAxis</strong></font></a>: the 
  orientation of axis Y is the opposite to its orientation in the CD library.</li>
</ul>
<h4>Attributes </h4>
<ul>
  <li>
  <a href="http://www.tecgraf.puc-rio.br/cd/en/func/attributes.html#cdWriteMode">
  <font face="Courier"><strong>WriteMode</strong></font></a>: does nothing. 
  There is no support for XOR or NOT_XOR.</li>
  <li>
  <a href="../func/text.html#cdNativeFont">
  <font face="Courier"><strong>NativeFont</strong></font></a>: also accepts the 
  X-Windows font string format.</li>
    <li><a href="../func/text.html#cdFont">
  <font face="Courier"><strong>Font</strong></font></a>: &quot;Courier&quot; is mapped to 
	&quot;Courier New&quot;, &quot;Helvetica&quot; is mapped to &quot;Arial&quot;, and &quot;Times&quot; is mapped to 
	&quot;Times New Roman&quot;. Underline and Strikeout are NOT supported.</li>
</ul>
<h4>Colors </h4>
<ul>
  <li>
  <a href="../func/color.html#cdPalette">
  <font face="Courier"><strong>Palette</strong></font></a>: NOT supported.</li>
</ul>
<h4>Exclusive Attributes</h4>

<ul>
  <li>&quot;<b><font face="Courier">ANTIALIAS</font></b>&quot;:&nbsp;controls 
  the use of anti-aliasing for the text and drawing shapes. Assumes values &quot;1&quot; 
  (active) and &quot;0&quot; (inactive). Default value: &quot;1&quot;.</li>
</ul>

<ul>
  <li>&quot;<b><font face="Courier">CAIRODC</font></b>&quot;:&nbsp;returns the 
  Cairo drawing context (get only). In Lua is returned as a user data.</li>
</ul>

<ul>
    <li><b><font face="Courier">&quot;CAIROVERSION&quot;: </font></b>returns a string with 
  the Cairo version number. It is empty if the Cairo is not available.</li>
</ul>

<ul>
  <li><strong><span style="font-family: Courier">&quot;HATCHBOXSIZE&quot;</span></strong>: 
  defines the size of smallest hatch box pattern. This affects the spacing 
  between the hatch lines. The value passed must be a string containing an 
  integer (&quot;%d&quot;). If the value of the attribute passed is NULL, the value is 
  rest to the default. When consulted returns the current value (&quot;%d&quot;). Default: 
  &quot;8&quot;.</li>
</ul>

<ul>
  <li>&quot;<b><font face="Courier">IMGINTERP</font></b>&quot;:&nbsp;changes how 
  interpolation is used in image scale. Can be &quot;BEST&quot; (highest-quality), 
  &quot;BILINEAR&quot; (linear interpolation), &quot;GOOD&quot; (quality similar to BILINEAR), 
  &quot;NEAREST&quot; (nearest-neighbor filtering) or &quot;FAST&quot; (quality similar to NEAREST). 
  Default: &quot;GOOD&quot;.</li>
</ul>

<ul>
  <li>&quot;<b><font face="Courier">LINEGRADIENT</font></b>&quot;:&nbsp;defines 
  a filled interior style that uses a line gradient between two colors. It uses 
  2 points (&quot;%d %d %d %d&quot; = x1 y1 x2 y2), one for the starting point using 
  (using the foreground color), and another one for the end point (using the 
  background color).</li>
</ul>

<ul>
  <li>&quot;<b><font face="Courier">POLYHOLE</font></b>&quot;:&nbsp;defines the index of 
  the vertex where there is a hole in a closed polygon. It will affect the next
  <strong>cdEnd</strong>. Can be called several times between <strong>cdBegin</strong> 
  and <strong>cdEnd</strong> to define holes. The value passed must be a string 
  containing an integer (&quot;%d&quot;). If the value of the attribute passed is NULL, 
  all holes will no longer be considered.&nbsp;When consulted returns the current 
  number of holes (&quot;%d&quot;). It can have a maximum of 500 holes. Default: NULL.</li>
</ul>

<ul>
  <li>&quot;<b><font face="Courier">RADIALGRADIENT</font></b>&quot;:&nbsp;defines 
  a filled interior style that uses a radial gradient between two colors. It 
  uses 2 points and 2 radius (&quot;%d %d %g %d %d %g&quot; = x1 y1 rad1 x2 y2 rad2), one 
  for the starting point using (using the foreground color), and another one for 
  the end point (using the background color).</li>
</ul>

<ul>
  <li>&quot;<b><font face="Courier">ROTATE</font></b>&quot;:&nbsp; allows the usage of 1 
	angle and 1 coordinate (x, y), that define a global rotation transformation 
	centered in the specified coordinate. Use 1 real and 2 integer values inside 
	a string (&quot;%g %d %d&quot; = angle x y). Can not be set if a transformation is 
	already set.</li>
</ul>

</body>

</html>