canvas实现图片根据滑块放大缩小效果
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2022-04-12 11:01:36
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本文主要介绍了canvas实现图片根据滑块放大缩小效果的实例,具有很好的参考价值,下面跟着小编一起来看下吧
效果图:
图(1) 原始图
图(2) 缩小后
图(3) 放大后
代码如下:
<!DOCTYPE html> <html> <head> <meta charset="utf-8" /> <title></title> <style type="text/css"> #canvas1{ box-shadow: 3px 3px 10px black; } </style> </head> <body> <canvas id="canvas1" width="500" height="500"></canvas> <input type="range" name="slider" id="silder" value="0.5" max="1" min="0" step="0.01"/> </body> <script type="text/javascript"> var canvas = document.getElementById("canvas1"); var context = canvas.getContext("2d"); var slider = document.getElementById("silder"); var scale = slider.value; creatImg(scale); slider.onmousedown = function() { slider.onmousemove = function () { scale = slider.value; creatImg(scale); } } function creatImg (scale) { var myImg = new Image(); myImg.src = "https://gss0.baidu.com/-vo3dSag_xI4khGko9WTAnF6hhy/zhidao/pic/item/902397dda144ad34ac75c376d7a20cf430ad857d.jpg" var imgh = canvas.height * scale; var imgw = canvas.width * scale; var x = canvas.width / 2 - imgw / 2; var y = canvas.height / 2 - imgh / 2 myImg.onload = function () { context.clearRect(0 , 0 , canvas.width , canvas.height); context.drawImage(myImg , x , y ,imgw , imgh) } } </script> </html>
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