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.
This commit adds several features:
- rename of class to better reflect its behaviour
- full ol.Object support
- integration with postrender event for integration with animations and
render loop
- minimised DOM modifications
- more precise positioning
- element placed in DIV to avoid modifications to user-supplied element
- correctly handle changes to the positioning property
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).
Previously, the TiledWMS source generated a resolutions array
derived from the world extent in meters, to match the default
Web Mercator resolutions of the map. This wouldn't work for
projections with distance units different than meters. It is
better to commit to a default resolutions array where zoom level
0 is the validity extent of the projection (not the Web Mercator
world extent!) at a 256 pixel tile size.
This commit is a cherry-pick of 19f7778.
The current draft of the [filter spec](https://dvcs.w3.org/hg/FXTF/raw-file/tip/filters/index.html)
describes brightness, contrast, hue-rotate, and saturate functions that
roughly match our layer's setBrightness, setContrast, setHue, and
setSaturation methods. These changes make the range of our methods match
the corresponding functions in the spec. The one exception is the
brightness function. The spec says it has a range of 0 to positive infinity.
The WebKit implementation accepts a range of -1 to 1 (as of
https://github.com/WebKit/webkit/commit/8f4765e569). There's an open
(ticket)[https://www.w3.org/Bugs/Public/show_bug.cgi?id=15647] recommending
that the spec be changed to match.
I'm not stuck on having our methods match those of the filter spec, but the
parity would be nice.
These changes leave the WebGL map renderer "broken" (whacky colors). It would
be straightforward to update the current fragment shader to handle the new
range of hue, but the brightness, contrast, and saturation handling will
need to be reworked.
For inspiration, here are the color transformation
matrix calculations the WebKit filters:
8f4765e569/Source/WebCore/platform/graphics/chromium/cc/CCRenderSurfaceFilters.cpp (L64-80)
Conflicts:
src/ol/renderer/dom/domlayerrenderer.js
* The Map's private createProjection_ method is now a public
method of the Projection. It is also used by TiledWMSSource
to calculate the appropriate projection from the user
configuration.
* ol.Projection.addProjection now adds the transformation for
the source == target case. This makes it easy for the user
to create custom projection maps without including proj4js and
without adding a custom transformation, as long as the
userProjection equals the projection.
* The TiledWMSSource now uses the same default resolutions as
the map (i.e. the OSM resolutions)
* The modulo calculation for wrapping extents now works for all
grid configurations, by not calculating the number of columns
based on an assumption about the way the zoom levels relate to
resolutions.
* The wms-custom-proj example now shows how to properly
configure a custom resolution, i.e. by using the validity
extent of the projection as its extent.
The server does not send CORS headers, so we cannot use the
WebGL renderer. Since the layers use the projection's extent,
it is not necessary to specify the extent.
Setting the extent on a tile source now only means that tiles
won't be drawn outside that extent. Now the only way to specify
the origin of the tile grid is to provide a custom tileGrid. By
default, the grid origin is the top left corner of the
projection's extent.
The WMS used in the example does not send CORS headers (I think
not many WMS services do). It seems that the WebGL renderer
needs script access to the image data, so the example only works
with the DOM renderer in Firefox.
