canvas__2 饼状图
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2022-07-07 15:37:58
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<!DOCTYPE html>
<html>
<head lang="en">
<meta charset="GBK">
<title></title>
<style>
canvas{
border: 1px solid #A4E2F9;
}
</style>
</head>
<body>
<div height="400" width="600" style="margin:50px">
<canvas id="chart"> 你的浏览器不支持HTML5 canvas </canvas>
</div>
<script type="text/javascript">
function goChart(dataArr){
// 声明所需变量
var canvas,ctx;
// 图表属性
var cWidth, cHeight, cMargin, cSpace;
// 饼状图属性
var radius,ox,oy;//半径 圆心
var tWidth, tHeight;//图例宽高
var posX, posY, textX, textY;
var startAngle, endAngle;
var totleNb;
// 运动相关变量
var ctr, numctr, speed;
//鼠标移动
var mousePosition = {};
//线条和文字
var lineStartAngle,line,textPadding,textMoveDis;
// 获得canvas上下文
canvas = document.getElementById("chart");
if(canvas && canvas.getContext){
ctx = canvas.getContext("2d");
}
initChart();
// 图表初始化
function initChart(){
// 图表信息
cMargin = 20;
cSpace = 40;
canvas.width = canvas.parentNode.getAttribute("width")* 2 ;
canvas.height = canvas.parentNode.getAttribute("height")* 2;
canvas.style.height = canvas.height/2 + "px";
canvas.style.width = canvas.width/2 + "px";
cHeight = canvas.height - cMargin*2;
cWidth = canvas.width - cMargin*2;
//饼状图信息
radius = cHeight*2/6; //半径 高度的2/6
ox = canvas.width/2 + cSpace; //圆心
oy = canvas.height/2;
tWidth = 60; //图例宽和高
tHeight = 20;
posX = cMargin;
posY = cMargin; //
textX = posX + tWidth + 15
textY = posY + 18;
startAngle = endAngle = 90*Math.PI/180; //起始弧度 结束弧度
rotateAngle = 0; //整体旋转的弧度
//将传入的数据转化百分比
totleNb = 0;
new_data_arr = [];
for (var i = 0; i < dataArr.length; i++){
totleNb += dataArr[i][0];
}
for (var i = 0; i < dataArr.length; i++){
new_data_arr.push( dataArr[i][0]/totleNb );
}
totalYNomber = 10;
// 运动相关
ctr = 1;//初始步骤
numctr = 50;//步骤
speed = 1.2; //毫秒 timer速度
//指示线 和 文字
lineStartAngle = -startAngle;
line=40; //画线的时候超出半径的一段线长
textPadding=10; //文字与线之间的间距
textMoveDis = 200; //文字运动开始的间距
}
drawMarkers();
//绘制比例图及文字
function drawMarkers(){
ctx.textAlign="left";
for (var i = 0; i < dataArr.length; i++){
//绘制比例图及文字
ctx.fillStyle = dataArr[i][1];
ctx.fillRect(posX, posY + 40 * i, tWidth, tHeight);
ctx.moveTo(posX, posY + 40 * i);
ctx.font = 'normal 24px 微软雅黑'; //斜体 30像素 微软雅黑字体
ctx.fillStyle = dataArr[i][1]; //"#000000";
var percent = dataArr[i][2] + "：" + parseInt(100 * new_data_arr[i]) + "%";
ctx.fillText(percent, textX, textY + 40 * i);
}
};
//绘制动画
pieDraw();
function pieDraw(mouseMove){
for (var n = 0; n < dataArr.length; n++){
ctx.fillStyle = ctx.strokeStyle = dataArr[n][1];
ctx.lineWidth=1;
var step = new_data_arr[n]* Math.PI * 2; //旋转弧度
var lineAngle = lineStartAngle+step/2; //计算线的角度
lineStartAngle += step;//结束弧度
ctx.beginPath();
var x0=ox+radius*Math.cos(lineAngle),//圆弧上线与圆相交点的x坐标
y0=oy+radius*Math.sin(lineAngle),//圆弧上线与圆相交点的y坐标
x1=ox+(radius+line)*Math.cos(lineAngle),//圆弧上线与圆相交点的x坐标
y1=oy+(radius+line)*Math.sin(lineAngle),//圆弧上线与圆相交点的y坐标
x2=x1,//转折点的x坐标
y2=y1,
linePadding=ctx.measureText(dataArr[n][2]).width+10; //获取文本长度来确定折线的长度
ctx.moveTo(x0,y0);
//对x1/y1进行处理，来实现折线的运动
yMove = y0+(y1-y0)*ctr/numctr;
ctx.lineTo(x1,yMove);
if(x1<=x0){
x2 -= line;
ctx.textAlign="right";
ctx.lineTo(x2-linePadding,yMove);
ctx.fillText(dataArr[n][2],x2-textPadding-textMoveDis*(numctr-ctr)/numctr,y2-textPadding);
}else{
x2 += line;
ctx.textAlign="left";
ctx.lineTo(x2+linePadding,yMove);
ctx.fillText(dataArr[n][2],x2+textPadding+textMoveDis*(numctr-ctr)/numctr,y2-textPadding);
}
ctx.stroke();
}
//设置旋转
ctx.save();
ctx.translate(ox, oy);
ctx.rotate((Math.PI*2/numctr)*ctr/2);
//绘制一个圆圈
ctx.strokeStyle = "rgba(0,0,0,"+ 0.5*ctr/numctr +")"
ctx.beginPath();
ctx.arc(0, 0 ,(radius+20)*ctr/numctr, 0, Math.PI*2, false);
ctx.stroke();
for (var j = 0; j < dataArr.length; j++){
//绘制饼图
endAngle = endAngle + new_data_arr[j]* ctr/numctr * Math.PI * 2; //结束弧度
ctx.beginPath();
ctx.moveTo(0,0); //移动到到圆心
ctx.arc(0, 0, radius*ctr/numctr, startAngle, endAngle, false); //绘制圆弧
ctx.fillStyle = dataArr[j][1];
if(mouseMove && ctx.isPointInPath(mousePosition.x*2, mousePosition.y*2)){
ctx.globalAlpha = 0.8;
}
ctx.closePath();
ctx.fill();
ctx.globalAlpha = 1;
startAngle = endAngle; //设置起始弧度
if( j == dataArr.length-1 ){
startAngle = endAngle = 90*Math.PI/180; //起始弧度 结束弧度
}
}
ctx.restore();
if(ctr<numctr){
ctr++;
setTimeout(function(){
//ctx.clearRect(-canvas.width,-canvas.width,canvas.width*2, canvas.height*2);
ctx.clearRect(-canvas.width, -canvas.height,canvas.width*2, canvas.height*2);
drawMarkers();
pieDraw();
}, speed*=1.085);
}
}
//监听鼠标移动
var mouseTimer = null;
canvas.addEventListener("mousemove",function(e){
e = e || window.event;
if( e.offsetX || e.offsetX==0 ){
mousePosition.x = e.offsetX;
mousePosition.y = e.offsetY;
}else if( e.layerX || e.layerX==0 ){
mousePosition.x = e.layerX;
mousePosition.y = e.layerY;
}
clearTimeout(mouseTimer);
mouseTimer = setTimeout(function(){
ctx.clearRect(0,0,canvas.width, canvas.height);
drawMarkers();
pieDraw(true);
},10);
});
}
var chartData = [[50,"#2dc6c8","瓜子"], [100,"#b6a2dd", "花生"], [200,"#5ab1ee","土豆"], [700,"#d7797f","南瓜四号"]];
goChart(chartData);
</script>
</body>
</html>
参考：https://www.cnblogs.com/chengduxiaoc/p/7688794.html