te')); return $arr; } /* 遍历用户所有主题 * @param $uid 用户ID * @param int $page 页数 * @param int $pagesize 每页记录条数 * @param bool $desc 排序方式 TRUE降序 FALSE升序 * @param string $key 返回的数组用那一列的值作为 key * @param array $col 查询哪些列 */ function thread_tid_find_by_uid($uid, $page = 1, $pagesize = 1000, $desc = TRUE, $key = 'tid', $col = array()) { if (empty($uid)) return array(); $orderby = TRUE == $desc ? -1 : 1; $arr = thread_tid__find($cond = array('uid' => $uid), array('tid' => $orderby), $page, $pagesize, $key, $col); return $arr; } // 遍历栏目下tid 支持数组 $fid = array(1,2,3) function thread_tid_find_by_fid($fid, $page = 1, $pagesize = 1000, $desc = TRUE) { if (empty($fid)) return array(); $orderby = TRUE == $desc ? -1 : 1; $arr = thread_tid__find($cond = array('fid' => $fid), array('tid' => $orderby), $page, $pagesize, 'tid', array('tid', 'verify_date')); return $arr; } function thread_tid_delete($tid) { if (empty($tid)) return FALSE; $r = thread_tid__delete(array('tid' => $tid)); return $r; } function thread_tid_count() { $n = thread_tid__count(); return $n; } // 统计用户主题数 大数量下严谨使用非主键统计 function thread_uid_count($uid) { $n = thread_tid__count(array('uid' => $uid)); return $n; } // 统计栏目主题数 大数量下严谨使用非主键统计 function thread_fid_count($fid) { $n = thread_tid__count(array('fid' => $fid)); return $n; } ?>Create HTML image from data in Javascript variable - Stack Overflow

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    I have image data (either JPEG or PNG) in a Javascript variable. How do I display the image in an HTML document? These are very large images and code like this doesn't work because the URI is too long:

    // doesn't work because the URI is too long
$('img#target').attr('src', 'data:...');

    Using canvas is probably the answer but I cannot figure out how to load it with the image data.

    In case you are wondering: no, I cannot just download the image data directly to the img tag. It came from the server encrypted and was decrypted within the browser using Javascript.

    Thanks,
    -- Art Z.

    I have image data (either JPEG or PNG) in a Javascript variable. How do I display the image in an HTML document? These are very large images and code like this doesn't work because the URI is too long:

    // doesn't work because the URI is too long
$('img#target').attr('src', 'data:...');

    Using canvas is probably the answer but I cannot figure out how to load it with the image data.

    In case you are wondering: no, I cannot just download the image data directly to the img tag. It came from the server encrypted and was decrypted within the browser using Javascript.

    Thanks,
    -- Art Z.

    • javascript
    • html
    • canvas
    • image
    Share Improve this question asked Jan 31, 2011 at 4:52 Art Z.Art Z. 1531 silver badge7 bronze badges 1
    • 3 Both data URIs and canvas aren't pletely supported everywhere. What about proxying the image through a server that does the encryption and serves it as a normal image? – deceze ♦ Commented Jan 31, 2011 at 4:55
    Add a ment  | 

    2 Answers 2

    Reset to default 9

    To use a data URL to draw on a canvas:

    var img = new Image;
img.onload = function(){
  myCanvasContext.drawImage(img,0,0);
};
img.src = "data:...";

    Per this question/answer be sure that you set the onload before the src.

    You say that "the URI is too long", but it is not clear what you mean by this. Only IE8 has a 32kB limit on the data URI; for other browsers it should work fine. If you are experiencing an error, please describe it.

    It turns out that 

    $('img#target').attr('src', 'data:...');

    does work in all except IE. My problem originated elsewhere.

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