如何使用图像DOM元素作为jCanvas中source属性的值？

Question

I want to test this example : http://calebevans.me/projects/jcanvas/sandbox.php#%24%28%22canvas%22%29.drawImage%28%7B%0A%20%20source%3A%20%24%28%27%23image-fish%27%29%5B0%5D%2C%0A%20%20x%3A%2050%2C%20y%3A%2050%2C%0A%20%20width%3A%20100%2C%0A%20%20fromCenter%3A%20false%0A%7D%29%3B 我想测试这个例子： http ： //calebevans.me/projects/jcanvas/sandbox.php#%24%28%22canvas%22%29.drawImage%28%7B%0A%20%20source%3A%20% 24％28％27％23image鱼％27％29％5B0％5D％2C％0A％20％20×％3A％2050％2C％20Y％3A％2050％2C％0A％20％20width％3A％20100％ 2C％0A％20％20fromCenter％3A％20false％0A％7D％29％3B

But I don't see any result in the browser except image by default "img src". 但我没有在浏览器中看到任何结果，默认情况下为“img src”。 Please someone help me. 请有人帮助我。 How can I use this function? 我该如何使用此功能？

  <!doctype html>
    <html>
      <head>
        <meta charset="utf-8">
        <title>Demo</title> 
        <canvas width="500" height="250"></canvas> 
      </head>
        <script src="jquery.js"></script>
        <script src="jcanvas.js"></script>
        <script>

        $("canvas").drawImage({
        source: $('#draggable')[0],
        x: 50, y: 50,
        width: 60,
        fromCenter: false
        });

        </script>            
         <body>
            <img src="../image/0.jpg" class="drag-image" id="draggable"/>
        </div>
      </body>
    </html>

Thanks. 谢谢。

Answer 1

image tag is not fully loaded when source for the canvas tag is set. 设置canvas标记的source时，image标记未完全加载。 As a result, $('#draggable')[0] is returning undefined. 结果，$（'＃draggable'）[0]返回undefined。 try calling drawImage on load of the document. 尝试在加载文档时调用drawImage。 The following should fix your problem. 以下应该可以解决您的问题。

 <!doctype html>
    <html>
      <head>
        <meta charset="utf-8">
        <title>Demo</title> 
        <canvas width="500" height="250"></canvas> 
      </head>
        <script src="jquery.js"></script>
        <script src="jcanvas.js"></script>
        <script>

        $(document).ready(function(){
            $("canvas").drawImage({
                 source: $('#draggable')[0],
                 x: 50, y: 50,
                 width: 60,
                 fromCenter: false
              });
         });

        </script>            
         <body>
            <img src="../image/0.jpg" class="drag-image" id="draggable"/>
        </div>
      </body>
    </html>

如何使用图像DOM元素作为jCanvas中source属性的值？

问题描述

1 个解决方案

解决方案1
2 2012-06-04 18:34:41

如何使用图像DOM元素作为jCanvas中source属性的值？

问题描述

1 个解决方案

解决方案1 2 2012-06-04 18:34:41

解决方案1
2 2012-06-04 18:34:41