need an event to know when overlays finish loading

Note Trac only shows the first part of the patch, so you need to download it in its raw format.

I like the idea behind this patch very much, but I think the right way to do this is not to tag the event to the Map but rather to give the OpenLayers.Layer class its own Events object, and make "onload" the name of the event.

If anyone wants to re-write this patch, then I think it will be a great addition to the code base. Who knows what other events we might want to add to Layer!?

If noone volunteers, I'll re-write it myself... just as soon as I have a spare minute... ;-)

Here is a new patch which implements Erik's suggestions. I've also added a better patch than window.settimeout to the problem I described on the dev list when images come from cache.

Erik, I tried logging in with my bartvde account, but I had no privileges on the ticket. Is something wrong with the permissions of my user account?

patch to implement an onload event for WMS.Untiled

Test comment.

After some discussion with Erik we decided its best to have a loadstart and loadend event on the Layer instead.

I've implemented this in two new patches: -layer.patch -untiled.patch

Erik, another question, do we not also need an error event when the image fails to load, so the counter can be decreased by one in that case. This is especially the case if the somebody has set the IMAGE_RELOAD_ATTEMPTS parameter.

Something like:

OpenLayers.Event.observe(this.tile.imgDiv, 'error', function() { this.events.triggerEvent("loaderror"); }.bindAsEventListener(this));

?

Another concern with this approach: if I use the mousewheel very fast, so requesting the second image before the first one comes in, there is also a problem since not enough loadend events will come in.

Here my OpenLayers internals knowledge is too limited to think of a solution, do you have any hints/pointers?

Okay, I fixed the last-mentioned issue in Untiled.js, and will attach new patches incorporating also this change. I added an event called loadcancel, which is issued when the src of the image is set before the previous one has finished loading.

patch for Layer.js

patch for Untiled.js

Bart, these new patches look great! I've made a few small stylistic changes and am re-adding them smooshed together as one file ( svn diff > diff.js from trunk). Thanks a bunch for your work on this patch! This is a great addition to OpenLayers :-)

Replying to euzuro:

( svn diff > diff.js from trunk)

actually svn diff > layer_loading.patch

:-)

combination of bart's two patches with some very small stylistic changes

committed with r2200