<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html xmlns:fn="http://www.w3.org/2005/02/xpath-functions">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<link rel="stylesheet" href="../../../../doc/otp_doc.css" type="text/css">
<title>Erlang -- egd</title>
</head>
<body bgcolor="white" text="#000000" link="#0000ff" vlink="#ff00ff" alink="#ff0000"><div id="container">
<script id="js" type="text/javascript" language="JavaScript" src="../../../../doc/js/flipmenu/flipmenu.js"></script><script id="js2" type="text/javascript" src="../../../../doc/js/erlresolvelinks.js"></script><script language="JavaScript" type="text/javascript">
<!--
function getWinHeight() {
var myHeight = 0;
if( typeof( window.innerHeight ) == 'number' ) {
//Non-IE
myHeight = window.innerHeight;
} else if( document.documentElement && ( document.documentElement.clientWidth ||
document.documentElement.clientHeight ) ) {
//IE 6+ in 'standards compliant mode'
myHeight = document.documentElement.clientHeight;
} else if( document.body && ( document.body.clientWidth || document.body.clientHeight ) ) {
//IE 4 compatible
myHeight = document.body.clientHeight;
}
return myHeight;
}
function setscrollpos() {
var objf=document.getElementById('loadscrollpos');
document.getElementById("leftnav").scrollTop = objf.offsetTop - getWinHeight()/2;
}
function addEvent(obj, evType, fn){
if (obj.addEventListener){
obj.addEventListener(evType, fn, true);
return true;
} else if (obj.attachEvent){
var r = obj.attachEvent("on"+evType, fn);
return r;
} else {
return false;
}
}
addEvent(window, 'load', setscrollpos);
//--></script><div id="leftnav"><div class="innertube">
<img alt="Erlang logo" src="../../../../doc/erlang-logo.png"><br><small><a href="users_guide.html">User's Guide</a><br><a href="index.html">Reference Manual</a><br><a href="release_notes.html">Release Notes</a><br><a href="../pdf/percept-0.8.7.pdf">PDF</a><br><a href="../../../../doc/index.html">Top</a></small><p><strong>Percept</strong><br><strong>User's Guide</strong><br><small>Version 0.8.7</small></p>
<br><a href="javascript:openAllFlips()">Expand All</a><br><a href="javascript:closeAllFlips()">Contract All</a><p><small><strong>Chapters</strong></small></p>
<ul class="flipMenu" imagepath="../../../../doc/js/flipmenu">
<li id="no" title="Percept" expanded="false">Percept<ul>
<li><a href="percept_ug.html">
Top of chapter
</a></li>
<li title="Introduction"><a href="percept_ug.html#id57231">Introduction</a></li>
<li title="Getting started"><a href="percept_ug.html#id61101">Getting started</a></li>
</ul>
</li>
<li id="loadscrollpos" title="egd" expanded="true">egd<ul>
<li><a href="egd_ug.html">
Top of chapter
</a></li>
<li title="Introduction"><a href="egd_ug.html#id61190">Introduction</a></li>
<li title="File example"><a href="egd_ug.html#id61212">File example</a></li>
<li title="ESI example"><a href="egd_ug.html#id62010">ESI example</a></li>
</ul>
</li>
</ul>
</div></div>
<div id="content">
<div class="innertube">
<h1>2 egd</h1>
<h3><a name="id61190">2.1
Introduction</a></h3>
<p>
The egd module is an interface for 2d-image rendering and is used by
Percept to generate dynamic graphs to its web pages. All code is pure
erlang, no drivers needed.
</p>
<p>
The library is intended for small to medium image sizes with low
complexity for optimal performance. The library handles horizontal
lines better then vertical lines.
</p>
<p>
The foremost purpose for this module is to enable users to
generate images from erlang code and/or datasets and to
send these images to either files or web servers.
</p>
<h3><a name="id61212">2.2
File example</a></h3>
<p>Drawing examples:</p>
<div class="example"><pre>
-module(img).
-export([do/0]).
do() ->
Im = egd:create(200,200),
Red = egd:color({255,0,0}),
Green = egd:color({0,255,0}),
Blue = egd:color({0,0,255}),
Black = egd:color({0,0,0}),
Yellow = egd:color({255,255,0}),
% Line and fillRectangle
egd:filledRectangle(Im, {20,20}, {180,180}, Red),
egd:line(Im, {0,0}, {200,200}, Black),
egd:save(egd:render(Im, png), "/home/egil/test1.png"),
egd:filledEllipse(Im, {45, 60}, {55, 70}, Yellow),
egd:filledEllipse(Im, {145, 60}, {155, 70}, Blue),
egd:save(egd:render(Im, png), "/home/egil/test2.png"),
R = 80,
X0 = 99,
Y0 = 99,
Pts = [ { X0 + trunc(R*math:cos(A*math:pi()*2/360)),
Y0 + trunc(R*math:sin(A*math:pi()*2/360))
} || A <- lists:seq(0,359,5)],
lists:map(
fun({X,Y}) ->
egd:rectangle(Im, {X-5, Y-5}, {X+5,Y+5}, Green)
end, Pts),
egd:save(egd:render(Im, png), "/home/egil/test3.png"),
% Text
Filename = filename:join([code:priv_dir(percept), "fonts", "6x11_latin1.wingsfont"]),
Font = egd_font:load(Filename),
{W,H} = egd_font:size(Font),
String = "egd says hello",
Length = length(String),
egd:text(Im, {round(100 - W*Length/2), 200 - H - 5}, Font, String, Black),
egd:save(egd:render(Im, png), "/home/egil/test4.png"),
egd:destroy(Im).
</pre></div> <img alt="IMAGE MISSING" src="test1.gif"><br>
First save.
<em>Figure
2.1:
test1.png</em>
<img alt="IMAGE MISSING" src="test2.gif"><br>
Second save.
<em>Figure
2.2:
test2.png</em>
<img alt="IMAGE MISSING" src="test3.gif"><br>
Third save.
<em>Figure
2.3:
test3.png</em>
<img alt="IMAGE MISSING" src="test4.gif"><br>
Fourth save.
<em>Figure
2.4:
test4.png</em>
<h3><a name="id62010">2.3
ESI example</a></h3>
<p>Using egd with inets ESI to generate images on the fly:</p>
<div class="example"><pre>
-module(img_esi).
-export([image/3]).
image(SessionID, _Env, _Input) ->
mod_esi:deliver(SessionID, header()),
Binary = my_image(),
mod_esi:deliver(SessionID, binary_to_list(Binary)).
my_image() ->
Im = egd:create(300,20),
Black = egd:color({0,0,0}),
Red = egd:color({255,0,0}),
egd:filledRectangle(Im, {30,14}, {270,19}, Red),
egd:rectangle(Im, {30,14}, {270,19}, Black),
Filename = filename:join([code:priv_dir(percept), "fonts", "6x11_latin1.wingsfont"]),
Font = egd_font:load(Filename),
egd:text(Im, {30, 0}, Font, "egd with esi callback", Black),
Bin = egd:render(Im, png),
egd:destroy(Im),
Bin.
header() ->
"Content-Type: image/png\r\n\r\n".
</pre></div> <img alt="IMAGE MISSING" src="img_esi_result.gif"><br>
<em>Figure
2.5:
Example of result.</em>
<p>
For more information regarding ESI, please see inets application
<span class="bold_code"><a href="javascript:erlhref('../../../../doc/../','inets','mod_esi.html');">mod_esi</a></span>.
</p>
</div>
<div class="footer">
<hr>
<p>Copyright © 2007-2012 Ericsson AB, All Rights Reserved</p>
</div>
</div>
</div></body>
</html>
distrib
>
Fedora
>
17
>
i386
>
media
>
updates
>
by-pkgid
>
675c8c8167236dfcf8d66da674f931e8
>
files
>
1172
