在这个demo中将使用html5 canvas和jQuery来制作一个动态的饼状图表。
HTML
<div id="container"> <div class="wideBox"> <h1>Widgets Sold in 2010</h1> <p>Click a colour in the chart, or an item in the table, to pull out a slice! <a href="#">Back to Tutorial</a></p> </div> <canvas id="chart" width="600" height="500"></canvas> <table id="chartData"> <tr> <th>Widget</th><th>Sales ($)</th> </tr> <tr style="color: #0DA068"> <td>SuperWidget</td><td>1862.12</td> </tr> <tr style="color: #194E9C"> <td>MegaWidget</td><td>1316.00</td> </tr> <tr style="color: #ED9C13"> <td>HyperWidget</td><td>712.49</td> </tr> <tr style="color: #ED5713"> <td>WonderWidget</td><td>3236.27</td> </tr> <tr style="color: #057249"> <td>MicroWidget</td><td>6122.06</td> </tr> <tr style="color: #5F91DC"> <td>NanoWidget</td><td>128.11</td> </tr> <tr style="color: #F88E5D"> <td>LovelyWidget</td><td>245.55</td> </tr> </table> </div>
HTML结构非常简单,它包括:
- 一个
container
作为包裹容器。 - 一个用于绘制饼状图的HTML5 canvas。
- 一个表格用于放置图表数据。
配置图表函数、参数和可用变量
// Run the code when the DOM is ready $( pieChart ); function pieChart() { // Config settings var chartSizePercent = 55; // The chart radius relative to the canvas width/height (in percent) var sliceBorderWidth = 1; // Width (in pixels) of the border around each slice var sliceBorderStyle = "#fff"; // Colour of the border around each slice var sliceGradientColour = "#ddd"; // Colour to use for one end of the chart gradient var maxPullOutDistance = 25; // How far, in pixels, to pull slices out when clicked var pullOutFrameStep = 4; // How many pixels to move a slice with each animation frame var pullOutFrameInterval = 40; // How long (in ms) between each animation frame var pullOutLabelPadding = 65; // Padding between pulled-out slice and its label var pullOutLabelFont = "bold 16px 'Trebuchet MS', Verdana, sans-serif"; // Pull-out slice label font var pullOutValueFont = "bold 12px 'Trebuchet MS', Verdana, sans-serif"; // Pull-out slice value font var pullOutValuePrefix = "$"; // Pull-out slice value prefix var pullOutShadowColour = "rgba( 0, 0, 0, .5 )"; // Colour to use for the pull-out slice shadow var pullOutShadowOffsetX = 5; // X-offset (in pixels) of the pull-out slice shadow var pullOutShadowOffsetY = 5; // Y-offset (in pixels) of the pull-out slice shadow var pullOutShadowBlur = 5; // How much to blur the pull-out slice shadow var pullOutBorderWidth = 2; // Width (in pixels) of the pull-out slice border var pullOutBorderStyle = "#333"; // Colour of the pull-out slice border var chartStartAngle = -.5 * Math.PI; // Start the chart at 12 o'clock instead of 3 o'clock // Declare some variables for the chart var canvas; // The canvas element in the page var currentPullOutSlice = -1; // The slice currently pulled out (-1 = no slice) var currentPullOutDistance = 0; // How many pixels the pulled-out slice is currently pulled out in the animation var animationId = 0; // Tracks the interval ID for the animation created by setInterval() var chartData = []; // Chart data (labels, values, and angles) var chartColours = []; // Chart colours (pulled from the HTML table) var totalValue = 0; // Total of all the values in the chart var canvasWidth; // Width of the canvas, in pixels var canvasHeight; // Height of the canvas, in pixels var centreX; // X-coordinate of centre of the canvas/chart var centreY; // Y-coordinate of centre of the canvas/chart var chartRadius; // Radius of the pie chart, in pixels // Set things up and draw the chart init();
初始化图表
/** * Set up the chart data and colours, as well as the chart and table click handlers, * and draw the initial pie chart */ function init() { // Get the canvas element in the page canvas = document.getElementById('chart'); // Exit if the browser isn't canvas-capable if ( typeof canvas.getContext === 'undefined' ) return; // Initialise some properties of the canvas and chart canvasWidth = canvas.width; canvasHeight = canvas.height; centreX = canvasWidth / 2; centreY = canvasHeight / 2; chartRadius = Math.min( canvasWidth, canvasHeight ) / 2 * ( chartSizePercent / 100 ); // Grab the data from the table, // and assign click handlers to the table data cells var currentRow = -1; var currentCell = 0; $('#chartData td').each( function() { currentCell++; if ( currentCell % 2 != 0 ) { currentRow++; chartData[currentRow] = []; chartData[currentRow]['label'] = $(this).text(); } else { var value = parseFloat($(this).text()); totalValue += value; value = value.toFixed(2); chartData[currentRow]['value'] = value; } // Store the slice index in this cell, and attach a click handler to it $(this).data( 'slice', currentRow ); $(this).click( handleTableClick ); // Extract and store the cell colour if ( rgb = $(this).css('color').match( /rgb\((\d+), (\d+), (\d+)/) ) { chartColours[currentRow] = [ rgb[1], rgb[2], rgb[3] ]; } else if ( hex = $(this).css('color').match(/#([a-fA-F0-9]{2})([a-fA-F0-9]{2})([a-fA-F0-9]{2})/) ) { chartColours[currentRow] = [ parseInt(hex[1],16) ,parseInt(hex[2],16), parseInt(hex[3], 16) ]; } else { alert( "Error: Colour could not be determined! Please specify table colours using the format '#xxxxxx'" ); return; } } ); // Now compute and store the start and end angles of each slice in the chart data var currentPos = 0; // The current position of the slice in the pie (from 0 to 1) for ( var slice in chartData ) { chartData[slice]['startAngle'] = 2 * Math.PI * currentPos; chartData[slice]['endAngle'] = 2 * Math.PI * ( currentPos + ( chartData[slice]['value'] / totalValue ) ); currentPos += chartData[slice]['value'] / totalValue; } // All ready! Now draw the pie chart, and add the click handler to it drawChart(); $('#chart').click ( handleChartClick ); }
更多详细信息请查看:http://www.elated.com/articles/snazzy-animated-pie-chart-html5-jquery/
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