[OpenLayers-Dev] Exception in OpenLayers.Layer.Grid.removeBackBuffer

Tim-Hinnerk Heuer th.heuer at gmail.com
Wed Mar 14 00:57:52 EDT 2012

Hi Eric,

I couldn't reproduce the problem in any simple example. However, I did fix
it within OpenLayers. Basically, I changed a couple of lines:

     * Method: removeBackBuffer
     * Remove back buffer from DOM.
    removeBackBuffer: function() {
        if(this.backBuffer) {
            if (this.div.hasChildNodes(this.backBuffer)) { // ADDED THIS
            } // AND OF COURSE THIS
            this.backBuffer = null;
            this.backBufferResolution = null;
            if(this.backBufferTimerId !== null) {
                this.backBufferTimerId = null;

It's in my public repo. Should I make a pull request? I know it's yet
another check and might slow down things, but stability seems more
important. What do you think?


Twitter: @timhheuer
Blog: http://www.thheuer.com

On Wed, Mar 14, 2012 at 2:03 PM, Tim-Hinnerk Heuer <th.heuer at gmail.com>wrote:

> Cool, I was sure it would be interesting for some.
> What it does is simply replace the <img/> elements in the Grid of
> OpenLayers with <video/> elements. So, it works only with HTML5 support. We
> have a use case here with density data and I have implemented it as an
> extension to OpenLayers as mentioned. Unfortunately, it's still in
> alpha/beta, so it's not public yet. And also (surprisingly) it does not
> work correctly in Google Chrome but in Firefox.
> You can pull from the mentioned repo to test it out.
> Basically on the WMS side I simply cached the n layers (one for each
> frame) and then wrote a shell script to append those images to a video with
> ffmpeg. On the mapcache side I used a trick to fool it the correct mime
> type. So, it only works with a full cache. We used MapServer and MapCache
> for this.
> We are thinking of presenting this with our use case at one of the
> upcoming conferences. Interested? Please reply here.
> Thanks,
> Tim
> Twitter: @timhheuer
> Blog: http://www.thheuer.com
> On Wed, Mar 14, 2012 at 12:04 PM, Phil Scadden <p.scadden at gns.cri.nz>wrote:
>> I'm working for GNS but based down in Landcare in NZ. VideoWMS sounds
>> very much like something I have down my to-do list. Could you explain a
>> bit more about what it does?
>> Thanks.
>> --
>> Phil Scadden, Senior Scientist GNS Science Ltd 764 Cumberland St,
>> Private Bag 1930, Dunedin, New Zealand Ph +64 3 4799663, fax +64 3 477
>> 5232
>> Notice: This email and any attachments are confidential. If received in
>> error please destroy and immediately notify us. Do not copy or disclose the
>> contents.
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