1<!DOCTYPE html> 2<html> 3<head> 4<meta http-equiv="Content-Type" content="text/html; charset=US-ASCII"> 5<meta name="generator" content="hevea 2.18"> 6<link rel="stylesheet" type="text/css" href="manual.css"> 7<title>Chapter 30  The graphics library</title> 8</head> 9<body> 10<a href="libthreads.html"><img src="previous_motif.gif" alt="Previous"></a> 11<a href="index.html"><img src="contents_motif.gif" alt="Up"></a> 12<a href="libdynlink.html"><img src="next_motif.gif" alt="Next"></a> 13<hr> 14<h1 class="chapter" id="sec536">Chapter 30  The graphics library</h1> 15<p>The <span class="c003">graphics</span> library provides a set of portable drawing primitives. 16Drawing takes place 17in a separate window that is created when <span class="c003">Graphics.open_graph</span> is called.</p><blockquote class="quote"><span class="c007">Unix:</span>   18This library is implemented under the X11 windows system. 19Programs that use the <span class="c003">graphics</span> library must be linked as follows: 20<pre> 21 ocamlc <span class="c009">other options</span> graphics.cma <span class="c009">other files</span> 22</pre> 23For interactive use of the <span class="c003">graphics</span> library, do: 24<pre> 25 ocamlmktop -o mytop graphics.cma 26 ./mytop 27</pre> 28or (if dynamic linking of C libraries is supported on your platform), 29start <span class="c003">ocaml</span> and type <span class="c003">#load "graphics.cma";;</span>.<p>Here are the graphics mode specifications supported by 30<span class="c003">Graphics.open_graph</span> on 31the X11 implementation of this library: 32the argument to <span class="c003">Graphics.open_graph</span> has the format 33<span class="c003">"</span><span class="c009">display-name geometry</span><span class="c003">"</span>, 34where <span class="c009">display-name</span> is the name of the X-windows display to 35connect to, and <span class="c009">geometry</span> is a standard X-windows geometry 36specification. The two components are separated by a space. Either can 37be omitted, or both. Examples: 38</p><dl class="description"><dt class="dt-description"> 39<span class="c006">Graphics.open_graph "foo:0"</span></dt><dd class="dd-description"> 40connects to the display <span class="c003">foo:0</span> and creates a window with the default geometry 41</dd><dt class="dt-description"><span class="c006">Graphics.open_graph "foo:0 300x100+50-0"</span></dt><dd class="dd-description"> 42connects to the display <span class="c003">foo:0</span> and creates a window 300 pixels wide 43by 100 pixels tall, at location (50,0) 44</dd><dt class="dt-description"><span class="c006">Graphics.open_graph " 300x100+50-0"</span></dt><dd class="dd-description"> 45connects to the default display and creates a window 300 pixels wide 46by 100 pixels tall, at location (50,0) 47</dd><dt class="dt-description"><span class="c006">Graphics.open_graph ""</span></dt><dd class="dd-description"> 48connects to the default display and creates a window with the default 49geometry. 50</dd></dl></blockquote><blockquote class="quote"><span class="c007">Windows:</span>   51This library is available both for standalone compiled programs and 52under the toplevel application <span class="c003">ocamlwin.exe</span>. For the latter, this 53library must be loaded in-core by typing 54<pre> #load "graphics.cma";; 55</pre></blockquote><p>The screen coordinates are interpreted as shown in the figure below. 56Notice that the coordinate system used is the same as in mathematics: 57<span class="c009">y</span> increases from the bottom of the screen to the top of the screen, 58and angles are measured counterclockwise (in degrees). 59Drawing is clipped to the screen. 60</p><div class="center"> 61<img src="libgraph.gif"> 62</div><ul class="ftoc2"><li class="li-links"> 63<a href="libref/Graphics.html">Module <span class="c003">Graphics</span>: machine-independent graphics primitives</a> 64</li></ul> 65<hr> 66<a href="libthreads.html"><img src="previous_motif.gif" alt="Previous"></a> 67<a href="index.html"><img src="contents_motif.gif" alt="Up"></a> 68<a href="libdynlink.html"><img src="next_motif.gif" alt="Next"></a> 69</body> 70</html> 71
