javascript - Problems with asynchrony of loading images (using a canvas and timer) -


enter link description herei have seen derivatives of question ask here not think addresses problem.

i have canvas object , refreshing need be. many frames second.

to these new frames call web api within recurring timer latest time stamp of image on server , if different loads hidden canvas object data.

when loaded 'refreshes' visible canvas.

on observation have seen images can load out of sync. have tested order images sent server , have tested order images 'grabbed' server , displayed in client browser.

how can ensure initial image has finished loading before loading or skipping next image?

should use queue of canvas images , 'read' top 1? cause memory spike have read using queue in javascript can cause memory leak?

thanks

this javascript code:

i have misnised not inclduing html5 , error handling.

if not enough post rest...

<script type="text/javascript">     var j1 = new jpegimage();      j1.onload = function () {         var d1 = ctx1.getimagedata(0, 0, 360, 238);         j1.copytoimagedata(d1);         //brightenandcontrastimage(d1, contrastby, brightenby);         csingle.putimagedata(d1, 0, 0)     };      var tmrfeeder;     function startfeedup() {         try {             var throttled = _.delay(startnonhtml5feed, 100);         }         catch (err) {             document.getelementbyid("divmode2").innerhtml = err;         }     }       function startnonhtml5feed() {         jquery(function ($) {             jquery.support.cors = true;             $.ajax({                 crossdomain: true,                 type: "post",                 url: "feed.aspx/getnextframes",                 data: json.stringify({                     alias: alias,                     guidlogon: guidlogon                 }),                 timeout: 10000,                 contenttype: "application/json; charset=utf-8",                 datatype: "json",                 success: function (msg) {                     var ts1 = msg.d['ts1'];                                 if (ts1 == "") {                         ts1 = "0";                     }                      if (t1 != ts1) {                         t1 = ts1;                         j1.load('/cloud/livexp.ashx?alias=' + alias + '&camindex=0&guid=' + ts1);                     }                 });         });         var throttled = _.delay(startnonhtml5feed, 100);     } </script>


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