The new dedicated getfeatureinfo example shows how to combine
feature info from a WMS and a vector layer. The other examples
that previously used getFeatureInfo from vector layers now use
the more appropriate getFeatures.
To avoid surprises for application developers, this change
creates a new getFeatures method. So it is clear now beforehand
whether features or feature info markup is returned. The result
is now also grouped by layer, so application developers always
have a link between a layer and the feature info it returns.
To make getFeatureInfo return markup for vector layers, this
change also adds a featureInfoFunction property to the vector
layer, which gives developers full control over how features are
rendered to feature info markup.
This method is an entry point for getting feature information.
Renderers can use a hit canvas or defer to a layer (source) to
get matching features for a pixel.
For now this is only implemented for vector layers, and it uses
a bbox query because we cannot refine the result because of
missing geometry intersection functions yet.
This is a workaround for our check-example.js PhantomJS script to work with this example. Without this check-example.js fails because xhr.status is 0. I tried to give the explicit file:/// scheme as indicated in https://groups.google.com/d/msg/phantomjs/wFGme0pE-Tk/WUjU5s-27NwJ, but that didn't work for me.
The first set geometry is considered the default. As an added bonus, we're back to a single argument constructor. Later, we could allow a schema to be set. This would be done before setting values (calling constructor with no args).
It looks like this approach will work well for panning (as anticipated). For animated zooming, it is not going to work as is. It looks like the canvas tile generation is too much for this type of animation loop. Though there are clearly still areas for optimization:
* Don't create new tiles while animating between zoom levels. Using existing tiles only while animating should bring a significant performance gain.
* Simple spatial index for tiles - each tile coord in the matrix could have a feature lookup object (keyed by id). This needs to account for rendered dimension (as witnessed by the point being cut by a tile). Given that the current example uses only three features, adding the spatial index should only be a minor improvement.
* Reuse a fixed set of canvas tiles that are generated at construction (and increased/decreased with view size changes).
* If a fixed set of tiles is not used, at least new ones could be cloned from existing ones (minor).
* Do some profiling to look for more ideas.
In addition, world-wrapping needs addressed. I don't think this renderer is the right (or at least the only) place to address this. And the cache of tiles needs to be managed for real. But hey, at least we've got a working tiled vector renderer now.
There is a ton of room for optimization here. The vector layer renderer should only render dirty areas and could maintain a cache of rendered canvas tiles. The vector source could have a simple spatial index for features (by tile coord). Need to also discuss how to work with this animation framework (to avoid the excess work while waiting for tiles to load on every other layer).
