[mapguide-trac] #1910: Quick Plot: "Print" button never enables after the first launch up on IE 8

[MapGuide Open Source]

#1910: Quick Plot: "Print" button never enables after the first launch up on IE 8
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   Reporter:  wuma        |       Owner:  Mars Wu
       Type:  defect      |      Status:  new    
   Priority:  medium      |   Milestone:  2.4    
  Component:  General     |     Version:         
   Severity:  major       |    Keywords:         
External_id:  1440635.01  |  
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 The steps to reproduce the problem are:

  1. Using the Sheboygan dataset, add the Quick Plot widget to a Basic Web
 Layout.
  2. Open the map in the Browser (IE) and click the Quick Plot button.
  3. In the Quick Plot pane, set Advanced options and then click Generate.
 The preview window shows up with print preview. So everything is ok.
  4. After this, click the Cancel button in the preview dialog and without
 touching anything in the map click again the Generate button in the Quick
 Plot panel.

 Result: the print preview won't load and the loading process will hang.
 You will have to close the browser window.

 The problem occurs with Internet Explorer 8 and earlier version only. It
 happens with both Basic and Flexible web layout.

 It's because the cache mechanism of IE before 9.0.
 If the second request image src is the same as the first one, IE will not
 send out the request but direclty fires the "ImageLoaded" event which
 messes up the logic of quick plot - because something supposed to happen
 later happens earlier.
 The solution is: append a timestamp to the image src url which makes the
 url different for each request. Then IE will not cache the image and the
 events will fire in the expected order.

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Ticket URL: <http://trac.osgeo.org/mapguide/ticket/1910>
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