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HTML5 Canvas ( 图形变换矩阵 ) transform, setTransform

2024-09-10 20:24:07   215人阅读

 

<!DOCTYPE html>
<html>
<head>
    <meta charset="UTF-8">
    <title>canvas</title>
    <script type="text/javascript" src="../js/jQuery.js"></script>
    <style type="text/css">
        *{
            margin: 0;
            padding: 0;
            outline: none;
            border: none;
        }
        #canvas{
            width: 7rem;
            margin: .25rem 0 0 1.5rem;
            border: 1px solid black;
        }
    </style>
</head>
<body> 
    <canvas id="canvas" width="1000" height="600"></canvas>
</body>
</html>
<script type="text/javascript">
    /**
     * rem 布局初始化
     */
    $(‘html‘).css(‘font-size‘, $(window).width()/10);
    /**
     * 获取 canvas 画布
     * 获取 canvas 绘图上下文环境
     */
    var canvas = $(‘#canvas‘)[0];
    var cxt = canvas.getContext(‘2d‘);
    
    /**
     * 图形变换矩阵( 默认情况下是一个单位举证 )
     * 一个三维正矩阵  transform 的效果会累计, 直到遇到 setTransform
     *  a, c, e  |  1, 0, 0 
     *  b, d, f  |  0, 1, 0
     *  0, 0, 1  |  0, 0, 1
     * transform(水平缩放a, 水平倾斜b, 垂直倾斜c, 垂直缩放d, 水平位移e, 垂直位移f)
     */
    cxt.fillStyle = ‘red‘;
    cxt.strokeStyle = ‘#058‘;
    cxt.lineWidth = 5;
    
    cxt.save();
    cxt.transform(1, 0, 0, 1, 100, 100);
    cxt.transform(1.5, 0, 0, 1.5, 0, 0);
    cxt.transform(1, 0.2, 0.2, 1, 0, 0);
    //cxt.setTransform(1, 0, 0, 1, 0, 0);
    cxt.fillRect(50, 50, 100, 100);
    cxt.strokeRect(50, 50, 100, 100);
    cxt.restore();
</script>

 

HTML5 Canvas ( 图形变换矩阵 ) transform, setTransform


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