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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>CD_DGN</title>
<link rel="stylesheet" type="text/css" href="../../style.css">
</head>
<body>
<h2>CD_DGN - MicroStation Design File Driver (cddgn.h)</h2>
<p>This driver allows generating a MicroStation design file. The file name usually has an extension .DGN. The driver
supports only MicroStation version 4.0 or later. The format's copyrights are property of
<a href="http://www.bentley.com" target="_top">Bentley Systems</a>.</p>
<h3>Use</h3>
<p>The file is created and opened by calling function <font face="Courier">
<a href="../func/init.html#cdCreateCanvas"><strong>cdCreateCanvas</strong></a>(CD_DGN,
Data)</font>, in which <font face="Courier">Data</font> contains the filename and canvas dimensions. This function
opens the file and writes its header. Then, other functions in the CD library can be called as usual. The
<font face="Courier">Data</font> parameter string has the following format:</p>
<pre><em>"filename [widthxheight] [resolution] [-f] [-sseedfile]" </em>or in C <em>"<strong><tt>%s %gx%g %g %s</tt></strong>"</em></pre>
<p>Only the parameter <font face="Courier">filename</font> is required. The filename must be inside double quotes (")
if it has spaces.<font face="Courier"> Width</font> and <font face="Courier">height</font> are provided in millimeters
(note the lowercase "x" between them), and their default value in pixels is <font face="Courier">INT_MAX</font> for
both dimensions. <font face="Courier">Resolution </font>is the number of pixels per millimeter; its default value is
"3.78 pixels/mm" (96 DPI). <font face="Courier">Width</font>, <font face="Courier">height</font> and
<font face="Courier">resolution</font> are real values. Parameter <font face="Courier">-f</font> modifies the polygon
filling's behavior. Just as in MicroStation, you can specify a seed file using parameter <font face="Courier">-s</font>.
<font face="Courier">Width</font>, <font face="Courier">height</font> and <font face="Courier">resolution</font> are
used only by <a href="../func/coordinates.html#cdGetCanvasSize">
<font face="Courier"><strong>cdCanvasGetSize</strong></font></a><font face="Courier"><strong> </strong></font>and in
pixel-millimeter conversion. </p>
<p>Any amount of such canvases may exist simultaneously. It is important to note that a call to function
<a href="../func/init.html#cdKillCanvas"><font face="Courier"><strong>
cdKillCanvas</strong></font></a> is required to close the file properly.</p>
<p><b>Images and Colors</b> - The DGN format does not support server images and works with an indexed-color format.
Color quality is limited to 256 colors, and the format uses a uniform palette to convert RGB colors into palette
indices. If you configure a palette, the color conversion process will become slower.</p>
<p><b>Filling</b> - Up to version 5.0, MicroStation presents some limitations for polygon filling. You can disable
filling by means of string "<font face="Courier">-f</font>" in the <font face="Courier">Data</font> parameter. Filled
polygons can only have around 10,000 vertices; if the value is larger, the polygon style changes to closed lines.</p>
<p><b>Seed</b> - In the seed file, several DGN parameters can be defined to be used in the drawing. The library offers
a default seed file, called "SEED2D.DGN". The file's location depends on the environment variable <strong>CDDIR</strong>.</p>
<h3>Behavior of Functions</h3>
<h4>Control</h4>
<ul>
<li><a href="../func/control.html#cdClear"><font face="Courier"><strong>Clear</strong></font></a>:
does nothing.</li>
<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/clipping.html#cdClip"><font face="Courier"><strong>Clip</strong></font></a>:
does nothing (no clipping function is supported), returns <font face="Courier">CD_CLIPOFF</font>.</li>
<li><a href="../func/coordinates.html#cdUpdateYAxis"><font face="Courier">
<strong>UpdateYAxis</strong></font></a>: does nothing. The axis orientation is the same as the CD library.</li>
<li><strong>Transformation Matrix</strong>: not supported.</li>
</ul>
<h4>Primitives</h4>
<ul>
<li><a href="../func/lines.html#cdBegin"><font face="Courier"><strong>Begin</strong></font></a>:
if parameter <strong><tt>CD_CLIP</tt></strong> or <strong><tt>CD_BEZIER</tt></strong> are specified, does nothing.</li>
<li><strong><font face="Courier"><a href="../func/filled.html#cdChord">cdChord</a></font></strong>:
does nothing.</li>
</ul>
<h4>Attributes </h4>
<ul>
<li><a href="../func/filled.html#cdBackOpacity"><font face="Courier"><strong>
BackOpacity</strong></font></a>: does nothing, returns <font face="Courier">CD_OPAQUE</font>.</li>
<li><a href="../func/attributes.html#cdWriteMode"><font face="Courier">
<strong>
WriteMode</strong></font></a>: does nothing, returns <font face="Courier">CD_REPLACE</font>.</li>
<li><a href="../func/filled.html#cdInteriorStyle"><font face="Courier">
<strong>
InteriorStyle</strong></font></a>: does nothing.</li>
<li><a href="../func/filled.html#cdFillMode"><font face="Courier"><strong>
FillMode</strong></font></a>: does nothing.</li>
<li><a href="../func/filled.html#cdLineCap"><font face="Courier"><strong>
LineCap</strong></font></a>: does nothing.</li>
<li><a href="../func/filled.html#cdLineJoin"><font face="Courier"><strong>
LineJoin</strong></font></a>: does nothing.</li>
<li><a href="../func/filled.html#cdHatch"><font face="Courier"><strong>Hatch</strong></font></a>:
does nothing.</li>
<li><a href="../func/filled.html#cdStipple"><font face="Courier"><strong>
Stipple</strong></font></a>: does nothing.</li>
<li><a href="../func/filled.html#cdPattern"><font face="Courier"><strong>
Pattern</strong></font></a>: does nothing.</li>
<li><a href="../func/text.html#cdTextSize"><font face="Courier"><strong>
TextSize</strong></font></a>: returns a bounding box which is usually larger than the text (the computation is based
on the widest character).</li>
<li><a href="../func/text.html#cdTextAlignment"><font face="Courier"><strong>
TextAlignment</strong></font></a>: uses <font face="Courier"><strong>cdTextSize</strong></font>, therefore is not
precise.</li>
<li><a href="../func/text.html#cdFont"><font face="Courier"><strong>Font</strong></font></a>:
See the font mapping table for the equivalence used to map CD fonts into
MicroStation fonts. Styles are not supported.</li>
</ul>
<div align="center">
<center>
<table border="1" cellpadding="5">
<caption valign="top"><font size="4">Font Mapping</font></caption>
<tr>
<th>CD Fonts</th>
<th>MicroStation Font Index</th>
</tr>
<tr>
<td><font face="Courier">CD_SYSTEM</font></td>
<td><font face="Courier">0</font></td>
</tr>
<tr>
<td><font face="Courier">CD_COURIER</font> </td>
<td><font face="Courier">1</font></td>
</tr>
<tr>
<td><font face="Courier">CD_TIMES_ROMAN</font></td>
<td><font face="Courier">2</font></td>
</tr>
<tr>
<td><font face="Courier">CD_HELVETICA</font></td>
<td><font face="Courier">3</font></td>
</tr>
</table>
</center>
</div>
<h4>Colors </h4>
<ul>
<li><a href="../func/color.html#cdGetColorPlanes"><font face="Courier">
<strong>
GetColorPlanes</strong></font></a>: returns 8 (MicroStation uses a palette with 256 values).</li>
<li><a href="../func/attributes.html#cdBackground"><font face="Courier">
<strong>
Background</strong></font></a>: always returns <code><font face="Times New Roman">CD_WHITE</font></code>.</li>
</ul>
<h4>Client Images </h4>
<ul>
<li><a href="../func/client.html#cdGetImageRGB"><font face="Courier"><strong>
GetImageRGB</strong></font></a>: does nothing.</li>
<li><a href="../func/client.html#cdPutImageRGB"><font face="Courier"><strong>
PutImageRGB</strong></font></a>: considering that the format supports only 256 colors, image quality is quite poor.</li>
<li><a href="../func/client.html#cdPutImageRGBA"><font face="Courier"><strong>
PutImageRGBA</strong></font></a>: alpha is ignored.</li>
<li><a href="../func/client.html#cdPutImageMap"><font face="Courier"><strong>
PutImageMap</strong></font></a>: considering that the format supports only 256 colors, image quality is quite poor.</li>
</ul>
<h4>Server Images </h4>
<ul>
<li>All functions do nothing.</li>
</ul>
</body>
</html>
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