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 chartcanvasWidth = 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 framec.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 textsc.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 textsc.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 dotsc.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：

<!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 settingsvar chartSizePercent = 55;                        // The chart radius relative to the canvas width/height (in percent)var sliceBorderWidth = 1;                         // Width (in pixels) of the border around each slicevar sliceBorderStyle = "#fff";                    // Colour of the border around each slicevar sliceGradientColour = "#ddd";                 // Colour to use for one end of the chart gradientvar maxPullOutDistance = 25;                      // How far, in pixels, to pull slices out when clickedvar pullOutFrameStep = 4;                         // How many pixels to move a slice with each animation framevar pullOutFrameInterval = 40;                    // How long (in ms) between each animation framevar pullOutLabelPadding = 65;                     // Padding between pulled-out slice and its label  var pullOutLabelFont = "bold 16px 'Trebuchet MS', Verdana, sans-serif";  // Pull-out slice label fontvar pullOutValueFont = "bold 12px 'Trebuchet MS', Verdana, sans-serif";  // Pull-out slice value fontvar pullOutValuePrefix = "";                     // Pull-out slice value prefixvar pullOutShadowColour = "rgba( 0, 0, 0, .5 )";  // Colour to use for the pull-out slice shadowvar pullOutShadowOffsetX = 5;                     // X-offset (in pixels) of the pull-out slice shadowvar pullOutShadowOffsetY = 5;                     // Y-offset (in pixels) of the pull-out slice shadowvar pullOutShadowBlur = 5;                        // How much to blur the pull-out slice shadowvar pullOutBorderWidth = 2;                       // Width (in pixels) of the pull-out slice bordervar pullOutBorderStyle = "#333";                  // Colour of the pull-out slice bordervar chartStartAngle = -.5 * Math.PI;              // Start the chart at 12 o'clock instead of 3 o'clock// Declare some variables for the chartvar canvas;                       // The canvas element in the pagevar 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 animationvar 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 chartvar canvasWidth;                  // Width of the canvas, in pixelsvar canvasHeight;                 // Height of the canvas, in pixelsvar centreX;                      // X-coordinate of centre of the canvas/chartvar centreY;                      // Y-coordinate of centre of the canvas/chartvar chartRadius;                  // Radius of the pie chart, in pixelsvar chartElementId = chartElementId; // 圆饼元素idvar 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 pagecanvas = document.getElementById(chartElementId);// Exit if the browser isn't canvas-capableif ( typeof canvas.getContext === 'undefined' ) return;// Initialise some properties of the canvas and chartcanvasWidth = 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 cellsvar 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 colourif ( rgb = $(this).css('color').match( /rgb\((\d+), (\d+), (\d+)/) ) {chartColours[currentRow] = [ rgb[1], rgb[2], rgb[3] ];} else if ( hex = $(this).css('color').match(/#([a-fA-F0-9]{2})([a-fA-F0-9]{2})([a-fA-F0-9]{2})/) ) {chartColours[currentRow] = [ parseInt(hex[1],16) ,parseInt(hex[2],16), parseInt(hex[3], 16) ];} else {alert( "Error: Colour could not be determined! Please specify table colours using the format '#xxxxxx'" );return;}if(currentCell % 3 == 0){currentRow++;}} );// Now compute and store the start and end angles of each slice in the chart datavar currentPos = 0; // The current position of the slice in the pie (from 0 to 1)for ( var slice in chartData ) {chartData[slice]['startAngle'] = 2 * Math.PI * currentPos;chartData[slice]['endAngle'] = 2 * Math.PI * ( currentPos + ( chartData[slice]['value'] / totalValue ) );currentPos += chartData[slice]['value'] / totalValue;}// All ready! Now draw the pie chart, and add the click handler to it
    drawChart();$('#'+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 canvasvar 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 = $(this).data('slice');toggleSlice ( slice );}/*** Push a slice in or out.** If it's already pulled out, push it in. Otherwise, pull it out.** @param Number The slice index (between 0 and the number of slices - 1)*/function toggleSlice ( slice ) {if ( slice == currentPullOutSlice ) {pushIn();} else {startPullOut ( slice );}}/*** Start pulling a slice out from the pie.** @param Number The slice index (between 0 and the number of slices - 1)*/function startPullOut ( slice ) {// Exit if we're already pulling out this sliceif ( currentPullOutSlice == slice ) return;// Record the slice that we're pulling out, clear any previous animation, then start the animationcurrentPullOutSlice = slice;currentPullOutDistance = 0;clearInterval( animationId );animationId = setInterval( function() { animatePullOut( slice ); }, pullOutFrameInterval );// Highlight the corresponding row in the key table$('#'+chartTableElementId+' td').removeClass('highlight');var labelCell = $('#'+chartTableElementId+' td:eq(' + (slice*3) + ')');var valueCell = $('#'+chartTableElementId+' td:eq(' + (slice*3+1) + ')');var prcentCell = $('#'+chartTableElementId+' td:eq(' + (slice*3+2) + ')');labelCell.addClass('highlight');valueCell.addClass('highlight');prcentCell.addClass('highlight');}/*** Draw a frame of the pull-out animation.** @param Number The index of the slice being pulled out*/function animatePullOut ( slice ) {// Pull the slice out some morecurrentPullOutDistance += pullOutFrameStep;// If we've pulled it right out, stop animatingif ( currentPullOutDistance >= maxPullOutDistance ) {clearInterval( animationId );return;}// Draw the frame
    drawChart();}/*** Push any pulled-out slice back in.** Resets the animation variables and redraws the chart.* Also un-highlights all rows in the table.*/function pushIn() {currentPullOutSlice = -1;currentPullOutDistance = 0;clearInterval( animationId );drawChart();$('#'+chartTableElementId+' td').removeClass('highlight');}/*** Draw the chart.** Loop through each slice of the pie, and draw it.*/function drawChart() {// Get a drawing contextvar context = canvas.getContext('2d');// Clear the canvas, ready for the new framecontext.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 slicevar 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 centrestartX = centreX;startY = centreY;}// Set up the gradient fill for the slicevar 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 appropriatelyif ( 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>