html5生成柱状图(条形图)效果的实例代码

admin html5 2022-02-06 02:18:54 html5 柱状图条形图"

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<html>
<canvas id="a_canvas" width="1000" height="700">canvas>
<script>
(function (){
window.addEventListener("load", function(){
var data = [1000,1300,2000,3000,2000,2000,1000,1500,2000,5000,1000,1000];
var xinforma = ['1月','2月','3月','4月','5月','6月','7月','8月','9月','10月','11月','12月'];
// 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);
var realheight = a_canvas.height-15;
var realwidth = a_canvas.width-40;
// 描绘边框
var grid_cols = data.length + 1;
var grid_rows = 4;
var cell_height = realheight / grid_rows;
var cell_width = realwidth / grid_cols;
context.lineWidth = 1;
context.strokeStyle = "#a0a0a0";
// 结束边框描绘
context.beginPath();
// 准备画横线
/*for(var row = 1; 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,realheight);
context.lineTo(realwidth,realheight);
//画竖线
context.moveTo(0,20);
context.lineTo(0,realheight);
context.lineWidth = 1;
context.strokeStyle = "black";
context.stroke();
var max_v =0;
for(var i = 0; i<data.length; i++){
if (data[i] > max_v) { max_v =data[i]};
}
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 = realheight - realheight*(v / max_v);
//alert(py);
points.push({"x":px,"y":py});
}
//绘制坐标图形
for(var i in points){
var p = points[i];
context.beginPath();
context.fillStyle="green";
context.fillRect(p.x,p.y,15,realheight-p.y);
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);
context.fillText(xinforma[i],p.x + 1,realheight+12);
context.fillText('月份',realwidth,realheight+12);
context.fillText('资金量',0,10);
}
},false);
})();
script>
html>