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最新推荐文章于 2025-04-29 19:47:04 发布

原创最新推荐文章于 2025-04-29 19:47:04 发布 · 359 阅读

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<!DOCTYPE html>

<html>

<head>

<meta charset="UTF-8">

<title></title>

</head>

<body>

<canvas id="canvas" width="750" height="420"></canvas></br>

<input type="range" name="" id="slider" min="0.5" max="3.0" step="0.01" value="1.0" /></br>

<canvas id="watermark-canvas" display = "none" width="750" height="420"></canvas></br>

<script type="text/javascript">

var canvas = document.getElementById("canvas");

var ctx = canvas.getContext("2d");

var slider = document.getElementById("slider");

var watermarkCanvas = document.getElementById("watermark-canvas");

var watermarkCtx = watermarkCanvas.getContext("2d");

var img = new Image();

window.onload = function(){

var scale = slider.value;

img.src = "img/a11.jpg";

img.onload = function(){

// ctx.drawImage(img,0,0,canvas.width,canvas.height);

drawImageByScale(scale);

slider.onmousemove = function(){

scale = slider.value;

drawImageByScale(scale);

}

}

// 水印设置

watermarkCanvas.width = 600;

watermarkCanvas.height = 100;

watermarkCtx.font = "bold 50px Arial";

watermarkCtx.fillStyle = "rgba(255,255,255,0.5)";

watermarkCtx.textBaseline = "middle";

watermarkCtx.fillText("== shuang.com ==",20,50);

}

function drawImageByScale(scale){

var imgWidth = 750 * scale;

var imgHeight = 420 * scale;

// var sx = imgWidth / 2 - canvas.width / 2;

// var sx = imgHeight / 2 - canvas.height / 2;

// ctx.drawImage(img,sx,sy,canvas.width,canvas.height,0,0,canvas.width,canvas.height);

var dx = canvas.width / 2 - imgWidth / 2;

var dy = canvas.height / 2 - imgHeight / 2;

ctx.clearRect(0,0,canvas.width,canvas.height);

ctx.drawImage(img,dx,dy,imgWidth,imgHeight);

ctx.drawImage(watermarkCanvas,canvas.width - watermarkCanvas.width,canvas.height - watermarkCanvas.height);

}

</script>

</body>

</html>

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