On Fri, Oct 23, 2009 at 05:16:14AM +0200, Kris Geusebroek wrote: > Hi All, > > > > As a result of the BOF session @foss4g in Sydney I wrote up some > thoughts on my companie sblog > > http://blog.xebia.com/2009/10/23/taking-openlayers-to-the-next-level/ > > > > Please feel free to contact me especially for the HTML5 related stuff. > > When I'm back in Holland I want to make a start in trying out the HTML5 > canvas for drawing tiles, wms and vectorlayers so if anybody has > attempted before or has any ideas about architectural stuff and how to > fit it in OL please tell.
Point by point response: 1. "There are a lot of examples on how to use OpenLayers. The only problem is that these are not all written with the same style. Some of them are still using some old school way of dealing with the OpenLayers code." This is simply the result of when the examples were written. In almost all cases, the examples were written at the same time the code was, and use the style that was appropriate at the time. Since things change -- especially over the lifetime of approximately 3 years, which is the current age of the OpenLayers 2.x series -- the examples have various vintages, and unlike a fine wine, documentation does not get better with age. If there was a substantial investment -- cash or effort from a highly knowledgable source -- this could easily be solved. There's nothing particularly complex about writing an example, but it requires someone who knows the 'current best practices', has an eye for addressing the needs of users -- despite them never having been stated, and doing it in a way that is helpful. This is a substantial effort. I have no doubt that someone could spend dozens of hours on building a good set of examples. Generally, we focus more on the code, and the examples are a best effort that points motivated people in the right direction. 2. "Separation of UI look and feel" Sure. Many people in the community would agree with that. It comes down to effort, time, investment of energy into the problem. Solving these things in a simple way is not trivial. Note that controls are *not* complex; you can build OpenLayers without support for any controls, and build all of your controls externally. GeoExt *does* this, demonstrating that it's possible. There are some things that could maek this easier, but it's not really neccesary to 'clean up' the existing code to fix this problem. If you think that there is some kind of 'core functionality' to a control that is detached from the UI and isn't available as API functionality, I'd be somewhat surprised; can you think of something? 3. "With the new html5 functionality around the corner..." Anything that starts like this is likely doomed to failure :) "it would be great if we can start using the geolocation api to for example center the map on your current position" Trivial. Been done in many OpenLayers apps; requires no OpenLayers library level functionality. "use a canvas for the map and its layers to minimize the dom manipulation" Using the Canvas to draw vector features is already supported. http://crschmidt.net/mapping/choropleth-canvas.html is an example I wrote more than 18 months ago to do exactly that; the code is all in the OpenLayers library at this point. It has some benefits -- drawing is faster when zooming, etc. However, there are downsides; when you give up the DOM, for feature interaction, you have to switch to doing all of your intersection detection in Javascript, which is slow. You also mention that this will somehow speed up IE, which has no native Canvas support; only a translation through VML (and therefore, DOM manipulation). I don't see how this is supposed to help improve performance for IE. Canvas is great for some things, but not for everything; the DOM is pretty good at what it does, and for things other than vector features, is rarely (though not never) the performance bottleneck. For vector features, Canvas has some benefit for large numbers of features when you don't need interactivity, but has the same *lack* of benefit in cases where you do. " since i imagine the Map to be a 3d (or 2d) canvas where you can add your image tiles and features from different layers." I don't see what you see here as being different than what OpenLayers is. There are many things that OpenLayers does well, and many things it could do better. For the sake of the project community, I think the biggest thing to do would be to expand http://docs.openlayers.org/ to be a fully fledged resource, incorporating a full explanation, enough to cover what goes into the building of every one of the current examples. If that was really the case -- if the documentation covered enough information to make it possible for anyone to read the documentation, then build a complete example -- then I think that the community would be much better served. There are also many features or other things which could be built upon to improve OpenLayers which are not documentation. These things may be neat and fun, though I tend to think they're not going to help the community as much. Some of them may even speak towards drastically reevaluation what OpenLayers should do and should be -- the UI vs. not-UI controls stuff certainly falls into that role. I tend to think those things are probably less important to the overall success of the project, and I think many of them can be developed without changing a single piece of the existing API -- simply using it in new ways. Best Regards, -- Christopher Schmidt MetaCarta _______________________________________________ Dev mailing list Dev@openlayers.org http://openlayers.org/mailman/listinfo/dev
