溫馨提示×
您好，登錄后才能下訂單哦！
點(diǎn)擊 登錄注冊 即表示同意《億速云用戶服務(wù)條款》
您好，登錄后才能下訂單哦！
這篇文章給大家分享的是有關(guān)JavaScript canvas怎么繪制折線圖的內(nèi)容。小編覺得挺實(shí)用的，因此分享給大家做個(gè)參考，一起跟隨小編過來看看吧。
具體內(nèi)容如下
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
<style>
canvas {
border: 1px solid #ccc;
}
</style>
</head>
<body>
<canvas width="600" height="400"></canvas>
<script>
/*1.構(gòu)造函數(shù)*/
var LineChart = function (ctx) {
/*獲取繪圖工具*/
this.ctx = ctx || document.querySelector('canvas').getContext('2d');
/*畫布的大小*/
this.canvasWidth = this.ctx.canvas.width;
this.canvasHeight = this.ctx.canvas.height;
/*網(wǎng)格的大小*/
this.gridSize = 10;
/*坐標(biāo)系的間距*/
this.space = 20;
/*坐標(biāo)原點(diǎn)*/
this.x0 = this.space;
this.y0 = this.canvasHeight - this.space;
/*箭頭的大小*/
this.arrowSize = 10;
/*繪制點(diǎn)*/
this.dottedSize = 6;
/*點(diǎn)的坐標(biāo) 和數(shù)據(jù)有關(guān)系 數(shù)據(jù)可視化*/
}
/*2.行為方法*/
LineChart.prototype.init = function (data) {
this.drawGrid();
this.drawAxis();
this.drawDotted(data);
};
/*繪制網(wǎng)格*/
LineChart.prototype.drawGrid = function () {
/*x方向的線*/
var xLineTotal = Math.floor(this.canvasHeight / this.gridSize);
this.ctx.strokeStyle = '#eee';
for (var i = 0; i <= xLineTotal; i++) {
this.ctx.beginPath();
this.ctx.moveTo(0, i * this.gridSize - 0.5);
this.ctx.lineTo(this.canvasWidth, i * this.gridSize - 0.5);
this.ctx.stroke();
}
/*y方向的線*/
var yLineTotal = Math.floor(this.canvasWidth / this.gridSize);
for (var i = 0; i <= yLineTotal; i++) {
this.ctx.beginPath();
this.ctx.moveTo(i * this.gridSize - 0.5, 0);
this.ctx.lineTo(i * this.gridSize - 0.5, this.canvasHeight);
this.ctx.stroke();
}
};
/*繪制坐標(biāo)系*/
LineChart.prototype.drawAxis = function () {
/*X軸*/
this.ctx.beginPath();
this.ctx.strokeStyle = '#000';
this.ctx.moveTo(this.x0, this.y0);
this.ctx.lineTo(this.canvasWidth - this.space, this.y0);
this.ctx.lineTo(this.canvasWidth - this.space - this.arrowSize, this.y0 + this.arrowSize / 2);
this.ctx.lineTo(this.canvasWidth - this.space - this.arrowSize, this.y0 - this.arrowSize / 2);
this.ctx.lineTo(this.canvasWidth - this.space, this.y0);
this.ctx.stroke();
this.ctx.fill();
/*Y軸*/
this.ctx.beginPath();
this.ctx.strokeStyle = '#000';
this.ctx.moveTo(this.x0, this.y0);
this.ctx.lineTo(this.space, this.space);
this.ctx.lineTo(this.space + this.arrowSize / 2, this.space + this.arrowSize);
this.ctx.lineTo(this.space - this.arrowSize / 2, this.space + this.arrowSize);
this.ctx.lineTo(this.space, this.space);
this.ctx.stroke();
this.ctx.fill();
};
/*繪制所有點(diǎn)*/
LineChart.prototype.drawDotted = function (data) {
/*1.數(shù)據(jù)的坐標(biāo) 需要轉(zhuǎn)換 canvas坐標(biāo)*/
/*2.再進(jìn)行點(diǎn)的繪制*/
/*3.把線連起來*/
var that = this;
/*記錄當(dāng)前坐標(biāo)*/
var prevCanvasX = 0;
var prevCanvasY = 0;
data.forEach(function (item, i) {
/* x = 原點(diǎn)的坐標(biāo) + 數(shù)據(jù)的坐標(biāo) */
/* y = 原點(diǎn)的坐標(biāo) - 數(shù)據(jù)的坐標(biāo) */
var canvasX = that.x0 + item.x;
var canvasY = that.y0 - item.y;
/*繪制點(diǎn)*/
that.ctx.beginPath();
that.ctx.moveTo(canvasX - that.dottedSize / 2, canvasY - that.dottedSize / 2);
that.ctx.lineTo(canvasX + that.dottedSize / 2, canvasY - that.dottedSize / 2);
that.ctx.lineTo(canvasX + that.dottedSize / 2, canvasY + that.dottedSize / 2);
that.ctx.lineTo(canvasX - that.dottedSize / 2, canvasY + that.dottedSize / 2);
that.ctx.closePath();
that.ctx.fill();
/*點(diǎn)的連線*/
/*當(dāng)時(shí)第一個(gè)點(diǎn)的時(shí)候 起點(diǎn)是 x0 y0*/
/*當(dāng)時(shí)不是第一個(gè)點(diǎn)的時(shí)候 起點(diǎn)是 上一個(gè)點(diǎn)*/
if(i == 0){
that.ctx.beginPath();
that.ctx.moveTo(that.x0,that.y0);
that.ctx.lineTo(canvasX,canvasY);
that.ctx.stroke();
}else{
/*上一個(gè)點(diǎn)*/
that.ctx.beginPath();
that.ctx.moveTo(prevCanvasX,prevCanvasY);
that.ctx.lineTo(canvasX,canvasY);
that.ctx.stroke();
}
/*記錄當(dāng)前的坐標(biāo)，下一次要用*/
prevCanvasX = canvasX;
prevCanvasY = canvasY;
});
};
/*3.初始化*/
var data = [
{
x: 100,
y: 120
},
{
x: 200,
y: 160
},
{
x: 300,
y: 240
},
{
x: 400,
y: 120
},
{
x: 500,
y: 80
}
];
var lineChart = new LineChart();
lineChart.init(data);
</script>
</body>
</html>運(yùn)行結(jié)果如下：
1.JavaScript主要用來向HTML頁面添加交互行為。 2.JavaScript可以直接嵌入到HTML頁面，但寫成單獨(dú)的js文件有利于結(jié)構(gòu)和行為的分離。 3.JavaScript具有跨平臺(tái)特性，在絕大多數(shù)瀏覽器的支持下，可以在多種平臺(tái)下運(yùn)行。
感謝各位的閱讀！關(guān)于“JavaScript canvas怎么繪制折線圖”這篇文章就分享到這里了，希望以上內(nèi)容可以對大家有一定的幫助，讓大家可以學(xué)到更多知識(shí)，如果覺得文章不錯(cuò)，可以把它分享出去讓更多的人看到吧！
免責(zé)聲明：本站發(fā)布的內(nèi)容（圖片、視頻和文字）以原創(chuàng)、轉(zhuǎn)載和分享為主，文章觀點(diǎn)不代表本網(wǎng)站立場，如果涉及侵權(quán)請聯(lián)系站長郵箱：is@yisu.com進(jìn)行舉報(bào)，并提供相關(guān)證據(jù)，一經(jīng)查實(shí)，將立刻刪除涉嫌侵權(quán)內(nèi)容。
億速云公眾號(hào)
手機(jī)網(wǎng)站二維碼