195 lines
9.3 KiB
HTML
195 lines
9.3 KiB
HTML
<!DOCTYPE html >
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<html>
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<head>
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<meta http-equiv="X-UA-Compatible" content="chrome=1">
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<!--
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/**
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* o------------------------------------------------------------------------------o
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* | This file is part of the OfficeExcel package - you can learn more at: |
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* | |
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* | http://www.OfficeExcel.net |
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* | |
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* | This package is licensed under the OfficeExcel license. For all kinds of business |
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* | purposes there is a small one-time licensing fee to pay and for non |
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* | commercial purposes it is free to use. You can read the full license here: |
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* | |
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* | http://www.OfficeExcel.net/LICENSE.txt |
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* o------------------------------------------------------------------------------o
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*/
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-->
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<title>Creating your charts using asynchronous methods</title>
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<meta name="keywords" content="OfficeExcel html5 canvas chart docs async asynchronous" />
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<meta name="description" content="Information about creating your charts using asynchronous HTTP calls" />
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<meta name="googlebot" content="NOODP">
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<meta property="og:title" content="OfficeExcel: HTML5 Javascript charts library" />
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<meta property="og:description" content="A chart library based on the HTML5 canvas tag" />
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<meta property="og:image" content="http://www.OfficeExcel.net/images/logo.png"/>
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<link rel="stylesheet" href="../css/website.css" type="text/css" media="screen" />
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<link rel="icon" type="image/png" href="../images/favicon.png">
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<!-- Place this tag in your head or just before your close body tag -->
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<script type="text/javascript" src="https://apis.google.com/js/plusone.js"></script>
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<script src="../libraries/OfficeExcel.common.core.js"></script>
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<script src="../libraries/OfficeExcel.line.js"></script>
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<!--[if lt IE 9]><script src="../excanvas/excanvas.original.js"></script><![endif]-->
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<script>
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window.onload = function ()
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{
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var duration = (new Date().getTime() - timer.getTime()) / 1000;
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document.getElementById("waiting").innerHTML = '<span style="color: green">Done! Extra time taken: ' + duration.toFixed(1) + ' seconds</span>';
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alert('The window.onload event fired, extra time taken: ' + duration.toFixed(1) + ' seconds');
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}
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// Create a timer to show the difference
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timer = new Date();
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</script>
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<?php PrintAnalyticsCode() ?>
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</head>
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<body>
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<!-- Social networking buttons -->
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<?php
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$prefix = substr($_SERVER['SERVER_NAME'], 0, 3);
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require("/OfficeExcel.{$prefix}/social.html");
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?>
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<!-- Social networking buttons -->
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<div id="breadcrumb">
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<a href="../index.html">OfficeExcel: HTML5 Javascript charts library</a>
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>
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<a href="./index.html">Documentation</a>
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>
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Asynchronous processing
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</div>
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<h1>Asynchronous <span>processing</span></h1>
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<script>
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if (OfficeExcel.isOld()) {
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document.write('<div style="background-color: #fee; border: 2px dashed red; padding: 5px"><b>Important</b><br /><br /> Internet Explorer does not natively support the HTML5 canvas tag, so if you want to see the charts, you can either:<ul><li>Install <a href="http://code.google.com/chrome/chromeframe/">Google Chrome Frame</a></li><li>Use ExCanvas. This is provided in the OfficeExcel Archive.</li><li>Use another browser entirely. Your choices are Firefox 3.5+, Chrome 2+, Safari 4+ or Opera 10.5+. </li></ul> <b>Note:</b> Internet Explorer 9 fully supports the canvas tag.</div>');
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}
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</script>
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<p id="waiting" style="; font-weight: bold; font-size: 16pt"><span style="color: #aa0">Waiting for onload event...</span></p>
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<p style="background-color: #eee; border: 1px dashed gray; padding: 5px; height: 50px;">
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<span style="display: inline-block; margin-left: 10px; float: right">
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<script>
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document.write('<img src="http://ie.microsoft.com/testdrive/HTML5/DOMContentLoaded/whidbey.jpg?' + Math.random() + '" width="50" height="50" /> ');
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document.write('<img src="http://ie.microsoft.com/testdrive/HTML5/DOMContentLoaded/window.jpg?' + Math.random() + '" width="50" height="50" /> ');
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document.write('<img src="http://ie.microsoft.com/testdrive/HTML5/DOMContentLoaded/whidbey2.jpg?' + Math.random() + '" width="50" height="50" />');
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</script>
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</span>
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These images are here to pad the page and slow down loading so that the window.onload event is slowed. This makes the
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difference far more visible.
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</p>
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<canvas id="myCanvas" width="600" height="250" style="float: right">[No canvas support]</canvas>
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<script>
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/**
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* Create the line chart
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*/
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function CreateLineGraph ()
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{
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var line = new OfficeExcel.Line('myCanvas', [1,2,4,2,1,3,5,6,6,5,3,5]);
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line.Set('chart.title', 'Sales for Acme Inc.');
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line.Set('chart.labels', ['Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec']);
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line.Set('chart.hmargin', 10);
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line.Set('chart.linewidth', 5);
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line.Set('chart.shadow', true);
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line.Set('chart.shadow.offsetx', 0);
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line.Set('chart.shadow.offsety', 0);
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line.Set('chart.shadow.blur', 15);
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line.Draw();
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}
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if (OfficeExcel.isOld()) {
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window.onload = CreateLineGraph;
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} else {
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OfficeExcel.Async(CreateLineGraph);
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}
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</script>
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<p>
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Asynchronous processing can speed up the display of your charts, because the browser gets to your code, sets it
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going and then continues on rendering the page. Particularly if you have a weighty page,
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it can make quite a difference. The <i>OfficeExcel.Async()</i> function itself is very simple, but because it can make
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a significant difference to the speed of your page, it is documented here. There's an example of it to the right.
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One thing to remember is to ensure your canvas tag is defined first before you set the function that creates
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the chart going.
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</p>
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<p>
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Although asynchronous processing can speed up your pages, it can also give the appearance of slower pages due to partial
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rendering, (ie your pages render a bit at a time). You therefore will need to experiment to get the best result for you.
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</p>
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<br clear="all" />
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<pre class="code">
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<script src="OfficeExcel.common.js"></script>
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<script src="OfficeExcel.line.js"></script>
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<canvas id="myCanvas" width="300" height="100">[No canvas support]</canvas>
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<script>
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/**
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* Create the line chart
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*/
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function CreateLineGraph ()
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{
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var line = new OfficeExcel.Line('myCanvas', [1,2,4,2,1,3,5,6,6,5,3,5]);
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line.Set('chart.title', 'Sales for Acme Inc.');
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line.Set('chart.labels', ['Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec']);
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line.Set('chart.hmargin', 10);
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line.Set('chart.linewidth', 5);
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line.Set('chart.shadow', true);
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line.Set('chart.shadow.offsetx', 0);
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line.Set('chart.shadow.offsety', 0);
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line.Set('chart.shadow.blur', 15);
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line.Draw();
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}
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if (OfficeExcel.isOld()) {
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window.onload = CreateLineGraph;
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} else {
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OfficeExcel.Async(CreateLineGraph);
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}
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</script>
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</pre>
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<p><b>Things to remember</b></p>
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<ul>
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<li>All your libraries must be loaded first. In the pages <head> for example. If not, you won't be able to create your charts.</li>
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<li>Your <canvas> tag must be defined before setting the asynchronous code going. If not, then the canvas may be referenced before it exists, and thus your charts will not be created.</li>
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<li>
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The users connection speed may be a factor. Slower connections may mean, for example, that the onload event doesn't fire very
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quickly. If you're using the onload event to create your charts then asynchronous creation instead may give you more
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apparent speed ups. Alternatively, careful placement of the <canvas> tag and the code that creates the chart may suffice
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instead.
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</li>
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<li>Since the MSIE/ExCanvas combo requires you to use the window.onload event, asynchronous chart creation in this case will probably not be any help.</li>
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<li>
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Since a dev release of version 4, Google Chrome has had an issue when asynchronous processing is used, meaning that
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text isn't always displayed. The solution here is simply to not use asynchronous processing. As of 27th March 2010,
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Chrome 5 appears to be fine.
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</li>
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</ul>
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<h4>See also</h4>
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You might also be interested in the alternative, <a href="domcontentloaded.html">DOMContentLoaded</a> event.
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</body>
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</html> |