下面小编就为大家带来一篇用html5绘制折线图的实例代码。小编觉得挺不错的,现在分享给大家。也给大家一个参考。
XML/HTML Code
(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 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); })(); 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