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这篇文章主要介绍了关于用html5绘制折线图的实例代码,有着一定的参考价值,现在分享给大家,有需要的朋友可以参考一下XML/HTML Code复制内容到剪贴板
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<
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:
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