今天算是第一天学习canvas,学习了一个通过滑动滑块改变图片大小比例e
html部分
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
<style>
.root {
width: 100%;
height: 100%;
display: flex;
justify-content: center;
align-items: center;
flex-direction: column;
background-color: black;
}
</style>
</head>
<body>
<div class="root">
<canvas id="dome1" width="800" height="500"></canvas>
<div class="input">
<input type="range" style="display: block; width: 800px;" id="scroll_range" min="0.5" max="3.0" step="0.01"
value="1.0">
</div>
</div>
// 引入js文件
<script src="./canvas_1.js"></script>
</body>
</html>
js代码
class Img {
constructor(cid, sid) {
this.cid = cid
this.sid = sid
this.canvas = document.getElementById(cid)
this.slider = document.getElementById(sid)
this.ctx = this.canvas.getContext('2d')
this._init_()
}
_init_() {
const image = new Image()
image.src = '../img/《Fate Grand Order》游戏美女4k壁纸_彼岸图网.jpg'
window.onload = () => {
this.drawImg(image)
}
}
drawImg(image) {
this.slider.onmousemove = () => {
const imageWidth = this.canvas.width * this.slider.value
const imageHeight = this.canvas.height * this.slider.value
const dx = this.canvas.width / 2 - imageWidth / 2
const dy = this.canvas.height / 2 - imageHeight / 2
this.ctx.clearRect(0, 0, this.canvas.width, this.canvas.height)
this.ctx.drawImage(image, dx, dy, imageWidth, imageHeight)
}
this.ctx.drawImage(image, 0, 0, this.canvas.width, this.canvas.height)
}
}
const img = new Img('dome1', 'scroll_range')
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