- <html>
- <canvas id="a_canvas" width="1000" height="700"></canvas>
- <script>
- (function (){
- window.addEventListener("load", function(){
- var data = [100,-1000,0,700];
- // 获取上下文
- var a_canvas = document.getElementById('a_canvas');
- var context = a_canvas.getContext("2d");
- // 绘制背景
- var gradient = context.createLinearGradient(0,0,0,300);
- // gradient.addColorStop(0,"#e0e0e0");
- //gradient.addColorStop(1,"#ffffff");
- context.fillStyle = gradient;
- context.fillRect(0,0,a_canvas.width,a_canvas.height);
- // 描绘边框
- var grid_cols = data.length + 1;
- var grid_rows = 4;
- var cell_height = a_canvas.height / grid_rows;
- var cell_width = a_canvas.width / grid_cols;
- context.lineWidth = 1;
- context.strokeStyle = "#a0a0a0";
- // 结束边框描绘
- context.beginPath();
- // 准备画横线
- /*for (var col = 0; col <= grid_cols; col++) {
- var x = col * cell_width;
- context.moveTo(x,0);
- context.lineTo(x,a_canvas.height);
- }
- // 准备画竖线
- for(var row = 0; row <= grid_rows; row++){
- var y = row * cell_height;
- context.moveTo(0,y);
- context.lineTo(a_canvas.width, y);
- }*/
- //划横线
- context.moveTo(0,a_canvas.height/2);
- context.lineTo(a_canvas.width,a_canvas.height/2);
- //画竖线
- context.moveTo(0,0);
- context.lineTo(0,a_canvas.height);
- context.lineWidth = 1;
- context.strokeStyle = "#c0c0c0";
- context.stroke();
- var max_v =0;
- for(var i = 0; i<data.length; i++){
- var d=0;
- if(data[i]<0)
- {dd=d-data[i];
- }
- else{d=data[i];};
- if (d > max_v) { max_v =d};
- }
- max_vmax_v = max_v * 1.1;
- // 将数据换算为坐标
- var points = [];
- for( var i=0; i < data.length; i++){
- var v= data[i];
- var px = cell_width * (i +1);
- var py = a_canvas.height/2 - a_canvas.height*(v / max_v)/2;
- points.push({"x":px,"y":py});
- }
- // 绘制折现
- context.beginPath();
- context.moveTo(points[0].x, points[0].y);
- for(var i= 1; i< points.length; i++){
- context.lineTo(points[i].x,points[i].y);
- }
- context.lineWidth = 2;
- context.strokeStyle = "#8BA9FF";
- context.stroke();
- //绘制坐标图形
- for(var i in points){
- var p = points[i];
- context.beginPath();
- context.arc(p.x,p.y,4,0,2*Math.PI);
- //实心圆
- /*
- context.fillStyle = "#000";*/
- //空心圆
- context.strokeStyle = "#000";
- context.stroke();
- context.fillStyle="white";
- context.fill();
- }
- //添加文字
- for(var i in points)
- { var p = points[i];
- context.beginPath();
- context.fillStyle="black";
- context.fillText(data[i], p.x + 1, p.y - 15);
- }
- },false);
- })();
- </script>
- </html>
运行结果如下：
以上这篇用html5绘制折线图的实例代码就是小编分享给大家的全部内容了，希望能给大家一个参考，也希望大家多多支持脚本之家。
原文地址：http://www.cnblogs.com/shuniuniu/archive/2016/03/25/5318717.html
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