[OpenLayers-Dev] Towards slick panning and animated zooming

Andreas Hocevar ahocevar at opengeo.org
Fri Dec 21 03:46:30 PST 2012

I added another pull request that is used in my mobile-wmts-vienna
branch and in the live exymple now:

Use transitionend listeners where available. Should be easy to review.


On Wed, Dec 19, 2012 at 9:41 AM, Andreas Hocevar <ahocevar at opengeo.org> wrote:
> Hey fellow developers,
> I don't know if you saw the enthusiastic tweets (e.g.
> https://twitter.com/19_norte/status/281134258725199875), but
> http://ahocevar.github.com/openlayers/mobile-wmts-vienna/examples/mobile-wmts-vienna.html
> shows the improvements in tile rendering we can get with four pull
> requests. All these pull requests have been thoroughly tested, and are
> the result of client work at OpenGeo. To bring these improvements into
> master, I am asking for reviews:
> http://github.com/openlayers/openlayers/pull/702
> New tile image cache and tile queue improvements. This pull request
> gets rid of the current tile queue, which I know many people were
> unhappy with. It adds a new TileManager class, which delays tile
> loading for panning (replacement for previous tileLoadingDelay in
> Layer.Grid) and zooming to avoid unnecessary tile image requests. It
> also keeps references to image elements, so they can be reused when
> the user pans or zooms back to regions or zoom levels that were
> already visited.
> http://github.com/openlayers/openlayers/pull/800
> Use translate3d to enable GPU support where available. This introduces
> an applyTransform method on the map, which will use an appropriate
> positioning method for the layerContainerDiv. Without any transform3d
> styles on the layerContainerDiv, style.left and style.top will be used
> just like we currently do, and scale transforms will be used for
> scaling. But with a translate3d style on the layerContainerDiv, all
> positioning is made with translate3d, and scaling is done with
> scale3d. By doing so, the GPU kicks in and brings greatly improved
> dragging and pinch-zooming performance.
> http://github.com/openlayers/openlayers/pull/503
> Animated zooming. This depends on #800, and I will rebase it when #800
> is in. For now, it is best to look at the three commits mentioned in
> https://github.com/openlayers/openlayers/pull/503#issuecomment-11495176.
> This change includes some improvements to the MouseWheel handler, and
> better mousewheel defaults for the Navigation control, to allow for
> usable and predictable wheel zooming on touch pads.
> http://github.com/openlayers/openlayers/pull/803
> Tween: skip frames when minimum frame rate is not reached. We use
> requestAnimationFrame for tween already, but we have no control over
> the frame rate. This change introduces a new minFrameRate option. When
> set, frames will be skipped if the animation gets too slow. The effect
> of this can best be seen when zooming with #503 applied in Firefox:
> instead of the 20 frames (which work fine in Chrome), about half of
> the frames will be skipped because Firefox can not scale the
> layerContainer fast enough. The visual effect of animated zooming
> still works fine, and users do not have to wait too long for the zoom
> to finish.
> Thanks for any reviews! With these changes in, the visual appearance
> and performance of OpenLayers will be on par with Leaflet.
> Andreas.
> --
> Andreas Hocevar
> OpenGeo - http://opengeo.org/
> Expert service straight from the developers.

Andreas Hocevar
OpenGeo - http://opengeo.org/
Expert service straight from the developers.

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