我们到底能走多远系列（34）

扯淡：

　　送给各位一段话：

人生是一个不断做加法的过程

从赤条条无牵无挂的来

到学会荣辱羞耻礼仪规范

再到赚取世间的名声财富地位

但是人生还要学会做减法

财富名声这些身外之物有一天会失去

朋友亲人终有一天会离你而去

我们自己会衰老迟钝

最后赤条条的离开这个世界

我们都不太擅长做人生的减法

很难学会放下

放不下面子所以要打肿脸充胖子

放不下逝去的情感就会沉溺其中痛苦不堪

放不下输赢所以总是如履薄冰心惊胆战

佛说我执是痛苦的根源

人生要学会断舍离

断绝不需要的东西

舍弃多余的废物

脱离对物品的执念

所以想幸福请先放下

主题：

　　最近想用html5来话图表，就接触了下，发现html5 是一个总称而已，进去后里面分成各种标签比如：HTML5 Video，HTML5 Audio，HTML5 Canvas等等，各不相关，所以学习起来也不复杂，比如我想画图表就先学习下Canvas就好了。

　　所以，我感觉这东西也就是调下api，没什么太大的难度，难得地方是要实现一个东西还需要学习css，javascript这些东西才行。

　　自己画的线图: 用一个function包起来，是为了简单的封装一下内部的变量。

　　需要注意的是代码依赖jquery。

　　这是一个比较初步的实现，对于canvas上画图，其实直接理解成现实中那笔在话就可以了，像下面的线图，先画好x y 轴，然后再话线，再来画事件现实文字。画面变化的产生目前我发现的是用clearRect方法先清空画面，然后重画....

function lineChart(data){
    var xPadding = 60;//x轴离边框的距离
    var yPadding = 50;//y轴离边框的距离
    var canvasWidth;
    var canvasHeight;
    var xAxisLength; //x轴长度
    var yAxisLength; //y轴长度
    var xTextColour = "#000000";   // x轴字体颜色
    var yTextColour = "#000000";  // y轴字体颜色
    var dotsColour = "#183487";  // 图标点的颜色
    var lineWidth = 2 //线宽度
    var lineColour = "#194E9C";  // 线颜色
    var lineShadowColour = "rgba( 0, 0, 0, .5 )"; // 线阴影颜色
    var lineShadowBlur = 15;
    var lineShadowOffsetX = 3;
    var lineShadowOffsetY = 3;
    var xyColour = "#4B0082";   //xy轴颜色
    var xToTextlength = 20; //x轴和文字的间距
    var yToTextlength = 10; //y轴和文字的间距
    var yTextNum = 6;  //y轴和文字数量
    var chartLineFont = "bold 16px 'Trebuchet MS', Verdana, sans-serif";// xy轴字体
    var chooseDotTextFont = "bold 16px 'Trebuchet MS', Verdana, sans-serif";//显示提示字体
    var dotsToDotsXLength; //x轴间距
    var dotsXArray = [];
    var divideXArray = [];  //分割每个点的竖切线的x坐标
    var lineChart;                       // The canvas element in the page
    init(data);

    function init(data){
        lineChart =  document.getElementById('lineChart');
        // Initialise some properties of the canvas and chart
        canvasWidth = lineChart.width;
        canvasHeight = lineChart.height;
        xAxisLength = canvasWidth - 2*xPadding;
        yAxisLength = canvasHeight - 2*yPadding;
        dotsToDotsXLength = xAxisLength / data.length;
        drawLineChart();
        // 添加事件
        $('#lineChart').mousemove(handleDotsMousemoveEvent);
    }

    function drawLineChart(index){
        var c = lineChart.getContext('2d');
        // Clear the canvas, ready for the new frame
        c.clearRect ( 0, 0, canvasWidth, canvasHeight );
        
        c.lineWidth = lineWidth;
        c.strokeStyle = xyColour;
        
        // Draw the axises
        c.beginPath();
        c.moveTo(xPadding, yPadding);
        // y轴
        c.lineTo(xPadding, lineChart.height - yPadding);
        // x轴
        c.lineTo(lineChart.width - yPadding, lineChart.height - yPadding);
        c.stroke();
        
        // Draw the the background line
        c.beginPath();
        c.strokeStyle = '#D9D6D6';
        for(var i = 0; i <= getMaxYPoint(getMaxY()); i += getYSpace()) {
            if(i != 0){
                c.moveTo(xPadding + 2, getYPixel(i));
                c.lineTo(xPadding + xAxisLength + 2, getYPixel(i));
            }
        }
        c.stroke();
        
        // Draw the X value texts
        c.font = chartLineFont;
        c.fillStyle = xTextColour;
        c.textAlign = "center";
        var step = parseInt(data.length/yTextNum);
        for(var i = 0; i < data.length; i =i + step) {
            c.fillText(data[i].X, getXPixel(i), lineChart.height - yPadding + xToTextlength);
        }
        
        // Draw the Y value texts
        c.textAlign = "right";
        c.textBaseline = "middle";
        c.fillStyle = yTextColour;
        for(var i = 0; i <= getMaxYPoint(getMaxY()); i += getYSpace()) {
            c.fillText(formatNum(i), xPadding - yToTextlength, getYPixel(i));
        }
        
        // Draw the line graph
        drawLineAndDots(c, index);
    }

    /**
     * 画线
     * @param c
     * @param index
     */
    function drawLineAndDots(c, index){
        c.beginPath();
        c.strokeStyle = lineColour;
        c.moveTo(getXPixel(0), getYPixel(data[0].value));
        for(var i = 1; i < data.length; i ++) {
            // 使用直线
            //c.lineTo(getXPixel(i), getYPixel(data[i].value));
            //var cps = getControlPoints(getXPixel(i-1),getYPixel(data[i-1].value),getXPixel(i),getYPixel(data[i].value));
            //为了更美观一点 使用了弯曲的线 
            c.bezierCurveTo(getXPixel(i-1)+9,getYPixel(data[i-1].value)+9,getXPixel(i)-9,getYPixel(data[i].value)-9,getXPixel(i), getYPixel(data[i].value))
            
            /**
            // 线的阴影部分
            c.shadowBlur = lineShadowBlur;
            c.shadowOffsetX = lineShadowOffsetX;
            c.shadowOffsetY = lineShadowOffsetY;
            c.shadowColor = lineShadowColour;
            **/
            
        }

        c.stroke();
        c.shadowColor = "rgba( 0, 0, 0, 0 )";
        c.closePath();
        // Draw the dots
        c.fillStyle = dotsColour;

        for(var i = 0; i < data.length; i ++) {
            // 有点中的节点
            if(i == index){
                c.beginPath();
                c.arc(getXPixel(i), getYPixel(data[i].value), 8, 0, Math.PI * 2, true);
                c.fill();
                c.textAlign = "center";
                c.font = chooseDotTextFont;
                c.fillText(data[i].X, xAxisLength + xPadding + 5 , 20 )
                c.fillText(data[i].value, xAxisLength + xPadding + 5 , 40 )
            }else{
                c.beginPath();
                c.arc(getXPixel(i), getYPixel(data[i].value), 4, 0, Math.PI * 2, true);
                c.fill();
            }
            divideXArray[i] = getXPixel(i) + dotsToDotsXLength/2;
        }
    }

    function getMaxY() {
        var max = 0;
        for(var i = 0; i < data.length; i ++) {
            if(data[i].value > max) {
                max = data[i].value;
            }
        }
        max += 10 - max % 10;
        return max;
    }

    /**
     * 计算x轴间距
     * @param val
     * @returns {number}
     */
    function getXPixel(val) {
        return (dotsToDotsXLength) * val + (xPadding * 1.5);
    }

    /**
     * 计算y轴间距
     * @param val
     * @returns {number}
     */
    function getYPixel(val) {
        return lineChart.height - ((yAxisLength / getMaxYPoint(getMaxY())) * val) - yPadding;
    }

    /**
     * 计算Y轴显示最大值
     * 输入1234 输出2000
     * @param maxY
     */
    function getMaxYPoint(maxY){
        var firstDigit  =  parseInt((maxY + '').substring(0,1)) + 1;
        var digitNum =  parseInt((maxY+"").length);
        for(var i = 1; i<digitNum; i++){
            firstDigit = firstDigit *10
        }
        return firstDigit;
    }

    /**
     * 计算Y轴坐标增加数量
     * @returns {number}
     */
    function getYSpace(){
        return getMaxYPoint(getMaxY())/5;
    }

    /**
     * 格式化:三位数字加逗号
     * @param num
     * @returns {*}
     */
    function formatNum(num){
        if(!/^(\+|-)?\d+(\.\d+)?$/.test(num)){
            alert("wrong!");
            return num;
        }
        var re = new RegExp();
        re.compile("(\\d)(\\d{3})(,|\\.|$)");
        num += "";
        while(re.test(num)){
            num = num.replace(re, "$1,$2$3")
        }    
        return num;
    }

    //鼠标事件
    function handleDotsMousemoveEvent(mousemoveEvent){
        //取得鼠标位置
        var mouseX = mousemoveEvent.pageX - this.offsetLeft;
        var dot = 0;
        if(0 < mouseX && mouseX< xPadding){
            return;
        }
        if((xPadding + xAxisLength) < mouseX){
            return;
        }
        for(var i=0; i<divideXArray.length; i++){
            
            if(mouseX < divideXArray[i]){
                dot = i;
                break;
            }
        }
        drawLineChart(dot);
    }
}

效果：

饼图：

这个代码是来自于网上：http://www.elated.com/articles/snazzy-animated-pie-chart-html5-jquery/

里面有详细的解释。

注意以上网站上的源码无法直接使用所以本人进行了部分的修改，以实现能够动态的处理后台传输的数据，并增加一个栏目，使功能完整。可以直接作为插件放入项目。

修改后的代码：（直接保存html文件即可）

<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>Pie Chart with HTML5 and jQuery - 1.0</title>
<meta http-equiv="Content-Type" content="text/html;charset=utf-8" >

<style>

body {
  background: #fff;
  color: #333;
  font-family: "Trebuchet MS", Verdana, Arial, Helvetica, sans-serif;
  font-size: 0.9em;
  padding: 40px;
}

#container {
  width: 900px;
  margin: 0 auto;
}

.chart, .chartData {
  border: 1px solid #333;
  background: #ebedf2 url("images/gradient.png") repeat-x 0 0;
}

.chart {
  display: block;
  margin: 0 0 50px 0;
  float: left;
  cursor: pointer;
}

.chartData {
  width: 200px;
  margin: 0 40px 0 0;
  float: right;
  border-collapse: collapse;
  box-shadow: 0 0 1em rgba(0, 0, 0, 0.5);
  -moz-box-shadow: 0 0 1em rgba(0, 0, 0, 0.5);
  -webkit-box-shadow: 0 0 1em rgba(0, 0, 0, 0.5);
  background-position: 0 -100px;
}

.chartData th, .chartData td {
  padding: 0.5em;
  border: 1px dotted #666;
  text-align: left;
}

.chartData th {
  border-bottom: 2px solid #333;
  text-transform: uppercase;
}

.chartData td {
  cursor: pointer;
}

.chartData td.highlight {
  background: #e8e8e8;
}

.chartData tr:hover td {
  background: #f0f0f0;
}

</style>

<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.4.2/jquery.min.js"></script>
<!--[if IE]>
<script src="http://explorercanvas.googlecode.com/svn/trunk/excanvas.js"></script>
<![endif]-->
</head>
<body>

<div id="container">

  <canvas id="chart" width="600" height="500" class="chart"></canvas>

  <table id="chartData" class="chartData">
    <tr><th>Widget</th><th>Sales ($)</th><th>prcent (%)</th></tr>
  </table>

</div>

</body>
</html>
<script>
var data=[{label:"SuperWidget",value:1862.12},{label:"MegaWidget1",value:1316.00},{label:"redasd",value:1300.00},{label:"hope",value:300.00},{label:"hack",value:300.00},{label:"MegaWidget",value:1316.00},{label:"redasd",value:1300.00},{label:"hope",value:300.00},{label:"hack",value:300.00}];
// Run the code when the DOM is ready
//$( pieChart );
pieChart(data, 'chart', 'chartData');

function pieChart(data, chartElementId, chartTableElementId) {

  // 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 = data;               // 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
  
  var chartElementId = chartElementId; // 圆饼元素id
  var chartTableElementId = chartTableElementId; // 数据表格元素id
  
  // Set things up and draw the chart
  init();


  /**
   * Set up the chart data and colours, as well as the chart and table click handlers,
   * and draw the initial pie chart
   */

  function init() {
    var colors=['#FF4500','#0DA068','#194E9C','#ED9C13','#ED5713','#CD00CD','#7A378B','#B8860B','#8B2500','#9932CC','#5F91DC','#F88E5D','#0000FF','#B3EE3A','#7A378B','#FF1493','#F5DA81','#80FF00','#173B0B','#0B3B39','#0B0B3B','#A901DB','#6E6E6E','#5F04B4','#01DFD7','#A31A1A','#1A653C','#A49D0C','#790CA4','#CA80E8','#6E87D7','#D76ED2','#D7B86E','#49543B','#9EEBE8','#9ED9EB','#549B21']
    // Get the canvas element in the page
    canvas = document.getElementById(chartElementId);

    // 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 = 0;
    var currentCell = 0;
    //$('#chartData').append('<tr><th>Widget</th><th>Sales ($)</th><th>prcent (%)</th></tr>')
    $.each(chartData, function(index,value){
        totalValue += value.value;
    });
    $.each(chartData, function(index,value){
        $('#'+chartTableElementId).append('<tr style="color: '+colors[index]+'"><td>'+value.label+'</td><td>'+value.value+'</td><td>'+ ( value.value / totalValue * 100 + .5 ).toFixed(2) +  '%'+'</td></tr>')
        
    });

    $('#'+chartTableElementId+' td').each( function() {
      currentCell++;
      // 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;
      }
      if(currentCell % 3 == 0){
        currentRow++;
      }
    } );

    // 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();
    $('#'+chartElementId).click ( handleChartClick );
  }


  /**
   * Process mouse clicks in the chart area.
   *
   * If a slice was clicked, toggle it in or out.
   * If the user clicked outside the pie, push any slices back in.
   *
   * @param Event The click event
   */

  function handleChartClick ( clickEvent ) {

    // Get the mouse cursor position at the time of the click, relative to the canvas
    var mouseX = clickEvent.pageX - this.offsetLeft;
    var mouseY = clickEvent.pageY - this.offsetTop;

    // Was the click inside the pie chart?
    var xFromCentre = mouseX - centreX;
    var yFromCentre = mouseY - centreY;
    var distanceFromCentre = Math.sqrt( Math.pow( Math.abs( xFromCentre ), 2 ) + Math.pow( Math.abs( yFromCentre ), 2 ) );

    if ( distanceFromCentre <= chartRadius ) {

      // Yes, the click was inside the chart.
      // Find the slice that was clicked by comparing angles relative to the chart centre.

      var clickAngle = Math.atan2( yFromCentre, xFromCentre ) - chartStartAngle;
      if ( clickAngle < 0 ) clickAngle = 2 * Math.PI + clickAngle;
                  
      for ( var slice in chartData ) {
        if ( clickAngle >= chartData[slice]['startAngle'] && clickAngle <= chartData[slice]['endAngle'] ) {

          // Slice found. Pull it out or push it in, as required.
          toggleSlice ( slice );
          return;
        }
      }
    }

    // User must have clicked outside the pie. Push any pulled-out slice back in.
    pushIn();
  }


  /**
   * Process mouse clicks in the table area.
   *
   * Retrieve the slice number from the jQuery data stored in the
   * clicked table cell, then toggle the slice
   *
   * @param Event The click event
   */

  function handleTableClick ( clickEvent ) {
    var slice = $(this).data('slice');
    toggleSlice ( slice );
  }


  /**
   * Push a slice in or out.
   *
   * If it's already pulled out, push it in. Otherwise, pull it out.
   *
   * @param Number The slice index (between 0 and the number of slices - 1)
   */

  function toggleSlice ( slice ) {
    if ( slice == currentPullOutSlice ) {
      pushIn();
    } else {
      startPullOut ( slice );
    }
  }

 
  /**
   * Start pulling a slice out from the pie.
   *
   * @param Number The slice index (between 0 and the number of slices - 1)
   */

  function startPullOut ( slice ) {

    // Exit if we're already pulling out this slice
    if ( currentPullOutSlice == slice ) return;

    // Record the slice that we're pulling out, clear any previous animation, then start the animation
    currentPullOutSlice = slice;
    currentPullOutDistance = 0;
    clearInterval( animationId );
    animationId = setInterval( function() { animatePullOut( slice ); }, pullOutFrameInterval );

    // Highlight the corresponding row in the key table
            $('#'+chartTableElementId+' td').removeClass('highlight');
    var labelCell = $('#'+chartTableElementId+' td:eq(' + (slice*3) + ')');
    var valueCell = $('#'+chartTableElementId+' td:eq(' + (slice*3+1) + ')');
    var prcentCell = $('#'+chartTableElementId+' td:eq(' + (slice*3+2) + ')');
    labelCell.addClass('highlight');
    valueCell.addClass('highlight');
    prcentCell.addClass('highlight');
  }

 
  /**
   * Draw a frame of the pull-out animation.
   *
   * @param Number The index of the slice being pulled out
   */

  function animatePullOut ( slice ) {

    // Pull the slice out some more
    currentPullOutDistance += pullOutFrameStep;

    // If we've pulled it right out, stop animating
    if ( currentPullOutDistance >= maxPullOutDistance ) {
      clearInterval( animationId );
      return;
    }

    // Draw the frame
    drawChart();
  }

 
  /**
   * Push any pulled-out slice back in.
   *
   * Resets the animation variables and redraws the chart.
   * Also un-highlights all rows in the table.
   */

  function pushIn() {
    currentPullOutSlice = -1;
    currentPullOutDistance = 0;
    clearInterval( animationId );
    drawChart();
    $('#'+chartTableElementId+' td').removeClass('highlight');
  }
 
 
  /**
   * Draw the chart.
   *
   * Loop through each slice of the pie, and draw it.
   */

  function drawChart() {

    // Get a drawing context
    var context = canvas.getContext('2d');
        
    // Clear the canvas, ready for the new frame
    context.clearRect ( 0, 0, canvasWidth, canvasHeight );

    // Draw each slice of the chart, skipping the pull-out slice (if any)
    for ( var slice in chartData ) {
      if ( slice != currentPullOutSlice ) drawSlice( context, slice );
    }

    // If there's a pull-out slice in effect, draw it.
    // (We draw the pull-out slice last so its drop shadow doesn't get painted over.)
    if ( currentPullOutSlice != -1 ) drawSlice( context, currentPullOutSlice );
  }


  /**
   * Draw an individual slice in the chart.
   *
   * @param Context A canvas context to draw on  
   * @param Number The index of the slice to draw
   */

  function drawSlice ( context, slice ) {

    // Compute the adjusted start and end angles for the slice
    var startAngle = chartData[slice]['startAngle']  + chartStartAngle;
    var endAngle = chartData[slice]['endAngle']  + chartStartAngle;
      
    if ( slice == currentPullOutSlice ) {

      // We're pulling (or have pulled) this slice out.
      // Offset it from the pie centre, draw the text label,
      // and add a drop shadow.

      var midAngle = (startAngle + endAngle) / 2;
      var actualPullOutDistance = currentPullOutDistance * easeOut( currentPullOutDistance/maxPullOutDistance, .8 );
      startX = centreX + Math.cos(midAngle) * actualPullOutDistance;
      startY = centreY + Math.sin(midAngle) * actualPullOutDistance;
      context.fillStyle = 'rgb(' + chartColours[slice].join(',') + ')';
      context.textAlign = "center";
      context.font = pullOutLabelFont;
      context.fillText( chartData[slice]['label'], centreX + Math.cos(midAngle) * ( chartRadius + maxPullOutDistance + pullOutLabelPadding ), centreY + Math.sin(midAngle) * ( chartRadius + maxPullOutDistance + pullOutLabelPadding ) );
      context.font = pullOutValueFont;
      context.fillText( pullOutValuePrefix + chartData[slice]['value'] + " (" + (  chartData[slice]['value'] / totalValue * 100 + .5 ).toFixed(2) +  "%)", centreX + Math.cos(midAngle) * ( chartRadius + maxPullOutDistance + pullOutLabelPadding ), centreY + Math.sin(midAngle) * ( chartRadius + maxPullOutDistance + pullOutLabelPadding ) + 20 );
      context.shadowOffsetX = pullOutShadowOffsetX;
      context.shadowOffsetY = pullOutShadowOffsetY;
      context.shadowBlur = pullOutShadowBlur;

    } else {

      // This slice isn't pulled out, so draw it from the pie centre
      startX = centreX;
      startY = centreY;
    }

    // Set up the gradient fill for the slice
    var sliceGradient = context.createLinearGradient( 0, 0, canvasWidth*.75, canvasHeight*.75 );
    sliceGradient.addColorStop( 0, sliceGradientColour );
    sliceGradient.addColorStop( 1, 'rgb(' + chartColours[slice].join(',') + ')' );

    // Draw the slice
    context.beginPath();
    context.moveTo( startX, startY );
    context.arc( startX, startY, chartRadius, startAngle, endAngle, false );
    context.lineTo( startX, startY );
    context.closePath();
    context.fillStyle = sliceGradient;
    context.shadowColor = ( slice == currentPullOutSlice ) ? pullOutShadowColour : "rgba( 0, 0, 0, 0 )";
    context.fill();
    context.shadowColor = "rgba( 0, 0, 0, 0 )";

    // Style the slice border appropriately
    if ( slice == currentPullOutSlice ) {
      context.lineWidth = pullOutBorderWidth;
      context.strokeStyle = pullOutBorderStyle;
    } else {
      context.lineWidth = sliceBorderWidth;
      context.strokeStyle = sliceBorderStyle;
    }

    // Draw the slice border
    context.stroke();
  }


  /**
   * Easing function.
   *
   *
   * @param Number The ratio of the current distance travelled to the maximum distance
   * @param Number The power (higher numbers = more gradual easing)
   * @return Number The new ratio
   */

  function easeOut( ratio, power ) {
    return ( Math.pow ( 1 - ratio, power ) + 1 );
  }
};

</script>

View Code

总结：

1,我们完全可以只利用API画出自己想要的东西：API

2，关于html5图表的插件有很多比如：国内的国外的 

3，阅读网站：http://diveintohtml5.info/

4，不管html5以后发不发展，学点然后做个比较复杂的动画玩玩，也不错

补充：

　　鉴于项目压力，为了竟可能满足需求，可能最终我们不得不选择网上更加成熟的框架，但无论如何，本人还是希望能够完善出一个比较好的图表框架出来。

让我们继续前行

----------------------------------------------------------------------

努力不一定成功，但不努力肯定不会成功。
共勉。

爱程序网

html5实现饼图和线图-我们到底能走多远系列（34）

我们到底能走多远系列（34）

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