[OpenLayers-Users] intercepting mouse events that are too rapid in succession

[Tim Schaub]

Hey-

Michael Quentel wrote:
> Via OpenLayers (or other javascript means), any ideas on how to
> intercept mouse events that are "too rapid" in succession?  

You'd have to customize the event handling code to set timers 
(window.setTimeout) and only respond to a limited set of events.

> 
> For example, if someone uses a mouse wheel too fast, it would be nice to
> intercept the movements, then submit the net result to the server,
> rather than submitting each event that has occurred.  Reason why this is
> of concern is that some server-side mapping applications are prone to
> fail if too many requests are made in rapid succession.

Yeah, we'd be better off if mouse wheeling just did a "transition 
effect" or "animated zooming" on the client side - not issuing requests 
until after scrolling finished (after some delay with no more wheel events).

The easiest way to modify this behavior right now would be to override 
this function:

OpenLayers.Handler.MouseWheel.prototype.onWheelEvent

Basically, you'd want to duplicate the existing code, but execute it 
with a window.setTimeout, accruing the wheel delta somewhere (on the 
handler) and canceling previous timers when you got a new event.

All this is a bit ugly - and without animated zooming the user will get 
no response until they stop scrolling - but it will give your server a 
break.

Good luck,
Tim

> I am not using a popular off-the-shelf map server; nor am I using an
> open source map server.  Please, any advice on intercepting the net
> result of mouse events is appreciated.
> 
> Many thanks.
> 
> Mike Quentel
> 
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