<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title></title>
</head>
<body style="padding: 100px;">
<canvas id="canvas" width="900" height="600" style="border:1px solid #000"></canvas>
<!--<img id="icon" src="images/img_01.jpg" alt="狗狗">-->
<script>
// 1. 获取标签
var canvas = document.getElementById("canvas");
var ctx = canvas.getContext("2d");
// 2. 绘制图片 - 方式一
/*
var icon = document.getElementById('icon');
// 当图片加载完毕 (重点)
icon.onload = function () {
// 等比
var w = 200, h = w * (icon.height / icon.width);
ctx.drawImage(icon, 100, 100, w, h);
};
console.log(icon);
*/
// 3. 绘制图片 - 方式二
var image = new Image();
image.src = 'images/img_02.jpg';
image.onload = function () {
// 等比公式： toH = Height * toW / Width;
// 设置的高度 = 原高度 * 设置的宽度 / 原宽度;
var w = 200, h = w * (this.height / this.width);
ctx.drawImage(this, 100, 100, w, h);
};
// 4. 裁剪图片显示
var image1 = new Image();
image1.src = 'images/img_01.jpg';
image1.addEventListener('load', function () {
// 裁剪的x,y,width,height 50, 50, 120, 120, 放置的位置x,y,width,height: 350, 100, 120, 120
ctx.drawImage(this, 50, 50, 120, 120, 350, 100, 120, 120);
});
</script>
</body>
</html>
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