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POMVC4 Ajax wait before executing the next process
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  1. POMVC4 Ajax wait before executing the next process
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    copied!<p>In my MVC project I generate an array of images and store the array as a session variable, I animate the images using slidebar and by detecting mouse movement while mouse button is down by calculating the distance between the first click and x position while the mouse is moving on a canvas.</p> <p>In the controller I use:</p> <pre><code>public ActionResult Animate(int slice = 0, int udm = 0) { FileContentResult data; Image objImage = null; Bitmap im = null; try { im = MySession.Current.imageArray[slice]; .... MySession.Current.image = im; } else { return RedirectToAction("Index",new {.... }); } } catch { } return null; } </code></pre> <p>and</p> <pre><code> public ActionResult ImageOut(int udm = 0) { FileContentResult data; Image objImage = null; Bitmap im = null; im = MySession.Current.image; ... objImage = im.Bitmap(outputSize, PixelFormat.Format24bppRgb, m); MemoryStream ms1 = new MemoryStream(); using (var memStream = new MemoryStream()) { objImage.Save(memStream, ImageFormat.Png); data = this.File(memStream.GetBuffer(), "image/png"); } objImage.Dispose(); return data; } </code></pre> <p>From the view I use Ajax:</p> <pre><code> $.ajax({ url: '/Home/Animate', type: 'POST', async: false, data: { slice: ((lastX - firstX) + nSlice), udm: ++udm }, success: function(data) { if (data.udm) { nSlice = (data.slice); image.src = '/Home/ImageOut?' + $.param({ udm: data.udm }); } }, error: function() { } }); </code></pre> <p>I have two problems, first it takes time to update the view and skips a number of images, the second is it open many threads and if a number of users accessing the same page it slows down. I thought of using async but I am still using c# 4 and this may requires lots of changes to my code. I was reading about SignalR, my question is can this be done (providing I just update the user screen not all users) or is there a better solution. </p> <p>The sequence of events I would like to achieve is:</p> <ol> <li>Ajax send to the first action a request or generate the first image and wait </li> <li>When the image is generated, Ajax receive success, then display the image on the screen using the second action</li> <li>Then the first action generate the second image </li> </ol> <p>The challenge I see is the first image keep generating the images without waiting, so my question is how I make the first action wait, and how to send to it a message to generate the following image.</p> <p>I just installed VS2012 c#5, is there any example that can help me!! Would appreciate your suggestions, thanks in advance.</p>
 

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