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authorscuri <scuri>2008-10-17 06:10:33 +0000
committerscuri <scuri>2008-10-17 06:10:33 +0000
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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_CGM</title>
+<link rel="stylesheet" type="text/css" href="../../style.css">
+</head>
+
+<body>
+
+<h2>CD_CGM - <em>Computer Graphics Metafile Driver </em>(cdcgm.h)</h2>
+
+ <p>This driver allows generating a Computer Graphics Metafile, which is an ANSI standard for the persistent storage of
+ graphics primitives. The file usually has an extension .CGM.</p>
+
+<h3>Use</h3>
+
+ <p>The file file is created by means of a call to the function <font face="Courier">
+ <a href="../func/init.html#cdCreateCanvas"><strong>cdCreateCanvas</strong></a>(CD_CGM,
+ Data)</font>, which <b>opens</b> 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>&quot;filename [widthxheight] [resolution] [-t] -p[precision]&quot; or in C style &quot;<strong><tt>%s %gx%g %g %s</tt></strong>&quot;</em></pre>
+
+ <p>Only the parameter <font face="Courier">filename</font> is required. The filename must be inside double quotes (&quot;)
+ if it has spaces.<font face="Courier"> Width</font> and <font face="Courier">height</font> are provided in millimeters
+ (note the lowercase &quot;x&quot; between them), and their default value in pixels is <font face="Courier">INT_MAX</font> for
+ both dimensions. When the canvas' size is not specified, the VDC Extension saved to the file is the image's bounding
+ rectangle. The resolution is the number of pixels per millimeter; its default value is &quot;3.78 pixels/mm&quot; (96 DPI).
+ <font face="Courier">Width</font>, <font face="Courier">height</font> and <font face="Courier">resolution</font> are
+ real values. <font face="Courier">Width</font>, <font face="Courier">height</font> and <font face="Courier">resolution</font>
+ are used only by <strong><font face="Courier">cdGetCanvasSize</font> </strong>and in pixel-millimeter conversion.
+ Parameter <font face="Courier">-t</font> modifies the codification. Parameter <font face="Courier">-p</font> specifies
+ the precision of integers, which can be 16 (default) or 32.</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 <b>close</b> the file properly.</p>
+ <p><strong>Coding -</strong> The CGM format supports binary and text coding. If you are not sure what to do, use
+ binary coding, which is the default. Should you prefer text coding, add a &quot;<font face="Courier">-t</font>&quot; string to
+ the <font face="Courier">Data</font> parameter.</p>
+ <p><strong>Precision of Coordinates -</strong> The primitives can use coordinates in real numbers. However, for
+ compatibility reasons, we use coordinates in integers.</p>
+
+<h3>Behavior of Functions</h3>
+<h4>Control&nbsp; </h4>
+<ul>
+ <li><a href="../func/control.html#cdClear"><font face="Courier"><strong>Clear</strong></font></a>:
+ does nothing.</li>
+ <li><a href="../func/control.html#cdFlush"><font face="Courier"><strong>Flush</strong></font></a>:
+ creates a new image, preserving the previous one. The CGM format supports multiple images in a file.</li>
+ <li><a href="../func/other.html#cdPlay"><font face="Courier"><strong>Play</strong></font></a>:
+ works with files created with text or binary coding. There are several callbacks for this driver. If one of the
+ callbacks returns a value different from zero, <font face="Courier">cdPlay</font>'s processing is interrupted. The
+ driver implements the callback <tt><strong><font face="Courier">CD_SIZECB</font> </strong></tt>and other callbacks
+ associated to CGM:<br>
+ <tt><font face="Courier"><strong>CD_COUNTERCB</strong></font> - int(*cdcgmcountercb)(cdContext *driver, double
+ percent) - </tt>Executed for each header of CGM commands; returns the percentage (0-100%) of headers read.<br>
+ <font face="Times New Roman"><code><strong><span style="font-family: Courier">CD_SCLMDECB</span></strong></code></font><tt> - int(*cdcgmsclmdecb)(cdContext
+ *driver, short scl_mde, short *drw_mode, double *factor)</tt> <font face="Courier">-</font> Executed for the command
+ CGM SCALE MODE. Returns the current CGM scale mode and allows the callback to modify the scale mode used by the
+ <font face="Courier">cdPlay</font> function <font face="Courier">(ABSTRACT=0, METRIC=1)</font>. Should you choose the
+ METRIC or ABSTRACT scale mode but the original scale mode is METRIC, you must provide the conversion factor in mm per
+ pixel.<br>
+ <font face="Times New Roman"><code><strong><span style="font-family: Courier">CD_VDCEXTCB</span></strong></code></font><tt> - int(*cdcgmvdcextcb)(cdContext
+ *driver, short type, void *xmn, void *ymn, void *xmx, void *ymx)</tt> <font face="Courier">-</font> Executed for the
+ CGM command CGM VDC EXTENT, returns the VDC SPACE. <br>
+ <font face="Times New Roman"><code><strong><span style="font-family: Courier">CD_BEGPICTCB</span></strong></code></font><tt> - int(*cdcgmbegpictcb)(cdContext
+ *driver, char *pict)</tt> <font face="Courier">-</font> Executed for the command BEGIN PICTURE, returns the string
+ that describes the image.<br>
+ <font face="Times New Roman"><code><strong><span style="font-family: Courier">CD_BEGPICTBCB</span></strong></code></font><tt> - int(*cdcgmbegpictbcb)(cdContext
+ *driver)</tt> <font face="Courier">-</font> Executed for the command BEGIN PICTURE BODY.<br>
+ <font face="Times New Roman"><code><strong><span style="font-family: Courier">CD_CGMBEGMTFCB</span></strong></code></font> - <font face="Times New Roman"><code>
+ int (*cdcgmbegmtfcb)(cdContext *driver, int *xmin, int *ymin, int *xmax, int *ymax)</code></font> - Executed for the
+ command BEGIN METAFILE, provides the drawing limits of the image in the file.</li>
+</ul>
+<h4>Coordinate System and Clipping</h4>
+<ul>
+ <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><b>Complex Regions</b>: not supported.</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><font face="Courier"><strong><a href="../func/marks.html#cdPixel">Pixel</a></strong></font>:
+ does not exist in CGM, is simulated using a mark with size 1.</li>
+ <li><strong><font face="Courier"><a href="../func/filled.html#cdChord">Chord</a></font></strong>:
+ does nothing.</li>
+ <li>Floating point primitives are supported.</li>
+</ul>
+<h4>Attributes </h4>
+<ul>
+ <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/text.html#cdFontDim"><font face="Courier"><strong>FontDim</strong></font></a>:
+ is simulated.</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/text.html#cdTextSize"><font face="Courier"><strong>
+ TextSize</strong></font></a>: is simulated.</li>
+ <li><a href="../func/text.html#cdTextOrientation"><font face="Courier">
+ <strong>
+ TextOrientation</strong></font></a>: does nothing.</li>
+ <li><a href="../func/text.html#cdFont"><font face="Courier"><strong>Font</strong></font></a>:
+ see the table bellow for the generated font names. No other fonts are
+ supported.</li>
+</ul>
+<div align="center">
+ <center>
+ <table border="1" cellpadding="5">
+ <caption style="text-align: center"><font size="4">Font Mapping</font></caption>
+ <tr>
+ <th rowspan="2">CD Fonts</th>
+ <th colspan="4">Generated Font Names</th>
+ </tr>
+ <tr>
+ <th>CD_PLAIN</th>
+ <th>CD_BOLD</th>
+ <th>CD_ITALIC</th>
+ <th>CD_BOLD|CD_ITALIC</th>
+ </tr>
+ <tr>
+ <td>&quot;System&quot;</td>
+ <td>&quot;SYSTEM&quot;</td>
+ <td>&quot;SYSTEM_BOLD&quot;</td>
+ <td>&quot;SYSTEM_ITALIC&quot;</td>
+ <td>&quot;SYSTEM_BOLDITALIC&quot;</td>
+ </tr>
+ <tr>
+ <td>&quot;Courier&quot;</td>
+ <td>&quot;COURIER&quot; </td>
+ <td>&quot;COURIER_BOLD&quot; </td>
+ <td>&quot;COURIER_ITALIC&quot; </td>
+ <td>&quot;COURIER_BOLDITALIC&quot;</td>
+ </tr>
+ <tr>
+ <td>&quot;Times&quot;</td>
+ <td>&quot;TIMES_ROMAN&quot; </td>
+ <td>&quot;TIMES_ROMAN_BOLD&quot;</td>
+ <td>&quot;TIMES_ROMAN_ITALIC&quot;</td>
+ <td>&quot;TIMES_ROMAN_BOLDITALIC&quot; </td>
+ </tr>
+ <tr>
+ <td>&quot;Helvetica&quot;</td>
+ <td>&quot;HELVETICA&quot; </td>
+ <td>&quot;HELVETICA_BOLD&quot;</td>
+ <td>&quot;HELVETICA_ITALIC&quot;</td>
+ <td>&quot;HELVETICA_BOLDITALIC&quot;</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 24.</li>
+ <li><a href="../func/color.html#cdPalette"><font face="Courier"><strong>Palette</strong></font></a>:
+ does nothing. </li>
+</ul>
+<h4>Client Images&nbsp; </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#cdPutImageRGBA"><font face="Courier"><strong>
+ PutImageRGBA</strong></font></a>: alpha is ignored.</li>
+</ul>
+<h4>Server Images</h4>
+<ul>
+ <li>All functions do nothing.</li>
+</ul>
+
+</body>
+
+</html>