> In addition, I'd like to add support for highlighting regions in the grid. I've got a plan for doing this, and while I don't want to hold up inclusion of the existing functionality, I do think the highlight functionality might inform a bit more how things could be structured.
Highlighting is a bit of an unusual question with UTFGrid. It's a tiles-only format - original geometries are never sent over in their full form. I've written a quick proof of concept, glower: http://mapbox.com/glower/# which does an overlay of canvas tiles over normal tiles and implements some simple edge-squaring, anti-aliasing (by hand :/ ), and such. The OpenLayers implementation - I'm not sure if I've seen whether it loads all tiles by default or lazy-loads (as the other implementations do), but basically you need to resolve tile boundaries and do a bit of odd logic for figuring out which features are equal. On Sat, Feb 25, 2012 at 6:35 PM, Tim Schaub <[email protected]> wrote: > Hey Matt, > > Thanks for this great contribution. It's been high on my list of > desires to get UTFGrid support into OpenLayers, and it looks like you > have done a nice job of it. > > After a quick preliminary review, I do have a few comments. First, > we'll need some tests to go along with this addition. Beyond that, > I've got some suggestions about the layer API that I hope you'll be > amenable to. I think it would make sense to provide a method on the > layer to get attribute data for a map location. This functionality is > currently in the control, but can see situations where it would be > useful to access this and awkward to have to add a control. I'll > provide a pull request for this and some additional tweaks. Note that > my pull request will look a lot smaller if you merge the latest master > into your utfgrid branch. > > In addition, I'd like to add support for highlighting regions in the > grid. I've got a plan for doing this, and while I don't want to hold > up inclusion of the existing functionality, I do think the highlight > functionality might inform a bit more how things could be structured. > > I'll leave more comments on your pull request. > > Tim > > On Thu, Feb 16, 2012 at 12:08 PM, Matt Perry <[email protected]> wrote: > > Hey all - I'm excited to share my implementation of OpenLayers support > > for UTFGrids. I wanted to get some feedback before doing a pull > > request. > > > > Just a little background: UTFGrids are json "hit grids" used to > > provide a high degree of interactivity. For example, you can have > > mouseover events that display the attributes of the features *without* > > fetching additional data from the server. The best demo of the concept > > is probably http://mapbox.com/demo/visiblemap/. > > > > This functionality exists in the wax library and is largely deployed > > with ModestMaps. I've ported it to native OpenLayers code to better > > integrate with OL event handlers and such. There are three additional > > components: a UTFGrid Layer, Control and Tile. It has both ajax and > > jsonp loading protocols, tries to keep a clear separation between the > > grid layers, the grid controls and callbacks which allows things like > > multiple handlers and multiple hit grids per map. > > > > Some example code: > > var world_utfgrid = new OpenLayers.Layer.UTFGrid( > > 'UTFGrid Layer', > > "http://tiles.example.com/world_utfgrid/${z}/${x}/${y}.json"; > > ); > > map.addLayer(world_utfgrid); > > > > var control = new OpenLayers.Control.UTFGrid({ > > 'div': 'attrsdiv', > > 'layers': [world_utfgrid], > > 'handlerMode': 'move' > > }) > > map.addControl(control); > > > > > > Some demos: > > http://labs.ecotrust.org/utfgrid/events.html > > http://labs.ecotrust.org/utfgrid/multi.html > > > > and source: > > https://github.com/perrygeo/openlayers/tree/utfgrid > > > > Any thoughts on getting this into 2.12? This is my first substantial > > effort in extending OpenLayers so if you have any critiques or > > concerns that need to be addressed before a pull request would be > > considered, let me know. > > -- > > ·´¯`·.¸. , . .·´¯`·.. ><((((º>`·.¸¸.·´¯`·.¸.·´¯`·...¸><((((º> > > "The best way to predict the future is to invent it." -- Alan Kay > > Matthew T. Perry > > http://www.perrygeo.net > > http://viedevelo.wordpress.com > > _______________________________________________ > > Dev mailing list > > [email protected] > > http://lists.osgeo.org/mailman/listinfo/openlayers-dev > > > > -- > Tim Schaub > OpenGeo http://opengeo.org/ > Expert service straight from the developers. > _______________________________________________ > Dev mailing list > [email protected] > http://lists.osgeo.org/mailman/listinfo/openlayers-dev >
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