<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<title>绘制折线图</title>
<style type="text/css">
canvas {
border: 1px solid black;
}
</style>
</head>
<body>
<canvas width="600" height="400"></canvas>
<script type="text/javascript">
var myline = document.querySelector("canvas");
var ctx = myline.getContext("2d");
var griadSize = 10;
var canvasW = ctx.canvas.width;
var canvasH = ctx.canvas.height;
var xNum = parseInt(canvasH/griadSize);
var yNum = parseInt(canvasW/griadSize);
//背景网格
for(var i = 0 ;i < xNum;i++){
ctx.moveTo(0,griadSize*i-0.5);
ctx.lineTo(canvasW,griadSize*i-0.5);
ctx.strokeStyle = "#eee";
ctx.stroke();
}
for(var j = 0 ;j < yNum;j++){
ctx.moveTo(griadSize*j-0.5,0);
ctx.lineTo(griadSize*j-0.5,canvasW);
ctx.strokeStyle = "#eee";
ctx.stroke();
}
//坐标X轴
ctx.beginPath();
var grad = 20;
var x0 = grad;
var y0 = canvasH-grad;
var tra = 10;
ctx.moveTo(x0,y0);
ctx.lineTo(canvasW-2*grad,y0);
ctx.lineTo(canvasW-2*grad-tra,y0-tra/2);
ctx.lineTo(canvasW-2*grad-tra,y0+tra/2);
ctx.lineTo(canvasW-2*grad,y0);
ctx.strokeStyle = "#000000";
ctx.fillStyle = "#000000";
ctx.fill();
ctx.stroke();
ctx.font = "20px 微软雅黑";
ctx.textBaseline = "middle";
ctx.fillText("X",canvasW-2*grad,canvasH-grad);
//坐标Y轴
ctx.moveTo(x0,y0);
ctx.lineTo(x0,2*grad);
ctx.lineTo(x0-tra/2,2*grad+tra);
ctx.lineTo(x0+tra/2,2*grad+tra);
ctx.lineTo(x0,2*grad);
ctx.strokeStyle = "#000000";
ctx.fillStyle = "#000000";
ctx.fill();
ctx.stroke();
ctx.font = "20px 微软雅黑";
ctx.textAlign="center";
ctx.fillText("Y",x0,2*grad-tra);
//数据包传入的数据
var arr = [
{
x:0,
y:0
},
{
x:50,
y:80
},
{
x:100,
y:140
},
{
x:200,
y:120
},
{
x:250,
y:200
},
{
x:300,
y:180
},
{
x:450,
y:200
},
{
x:480,
y:300
},
];
ctx.beginPath();
for(var k = 0;k < arr.length;k++){
ctx.lineTo(x0+arr[k].x-0.5,y0-arr[k].y-0.5);
ctx.fillRect(x0+arr[k].x-2,y0-arr[k].y-2,4,4);
ctx.strokeStyle = "#00f";
ctx.stroke();
ctx.font = "15px 微软雅黑";
ctx.textAlign="center";
ctx.textBaseline = "middle";
if(arr[k].x == 0 && arr[k].y == 0){
ctx.fillText("",0,0);
}else{
ctx.fillText(("("+arr[k].x+","+arr[k].y+")"),x0+arr[k].x+17,y0-arr[k].y+15);
}
ctx.fillStyle="#00f";
}
</script>
</body>
</html>
效果图：
