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Canvas scale- 缩放

可以进行坐标缩放，设为负值可以翻转图片；

<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <title>scale</title>
</head>

<body>
    <canvas id='myCanvas' width='800' height='600'>
        your browser does not support canvas
    </canvas>
    <script type="text/javascript">
    var c = document.getElementById('myCanvas');
    var ctx = c.getContext('2d');
    ctx.beginPath();
    ctx.strokeStyle = '#000000';
    ctx.strokeRect(10, 10, 150, 100);
    ctx.scale(3, 3);
    ctx.beginPath();
    ctx.strokeStyle = '#cccccc';
    ctx.strokeRect(10, 10, 150, 100);
    ctx.scale(0.15,0.15);
    ctx.beginPath();
    ctx.strokeStyle = '#ff0000';
    ctx.strokeRect(10,10,150,100);

    </script>
</body>

</html>
<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <title>scale</title>
</head>

<body>
    <canvas id='myCanvas' width='800' height='600'>
        your browser does not support canvas
    </canvas>
    <script type="text/javascript">
    var c = document.getElementById('myCanvas');
    var ctx = c.getContext('2d');
    var img = new Image();
    img.src = 'face.jpg';
    img.onload = function() {
        ctx.drawImage(img, 10, 10);
        ctx.scale(1, -1);
        ctx.drawImage(img, 250, -250);
        ctx.arc(250, -250, 20, 0, 2 * Math.PI, true);
        ctx.stroke();
    };
    </script>
</body>

</html>

 

posted @ 2015-07-23 14:06  stono  阅读(1504)  评论(0)  编辑  收藏  举报