[OpenLayers-Dev] Empty geometries causing errors in IE
cameron.shorter at gmail.com
Tue Oct 30 01:34:35 EDT 2007
Roald de Wit wrote:
> On Fri, 2007-10-26 at 09:52 -0600, Tim Schaub wrote:
>> I'm entirely in favor of this. I don't think the renderer is the right
>> place to bomb (or hey maybe even throw an exception!) on an empty geometry.
>> I think it makes sense to have our format classes throw exceptions on
>> empty geometries. They could even have an option to allow empty
>> geometry. In any case, it should be up to the application designer to
>> decide what to do with empty geometry. As library developers, I don't
>> think we should impose our beliefs about empty geometries on all others.
>> Breaking in only one browser, and only when rendering, is a bit late and
>> a bit inconsistent.
>>> See ticket #1111 for a simple 'fix'.
>> See also http://trac.openlayers.org/ticket/968
>> I'd like to see some tests for the renderers really. I haven't looked
>> closely at your patch, but it would be nice to make sure we don't slip
>> once we decide to make a change (like make browser behavior consistent).
> That fix in the patch I mentioned is probably not the best solution
> (although it worked for us).
> A few places where I can imagine we could prevent the renderer from
> trying to render the empty geometry is:
> - Renderer/Elements.js: drawGeometryNode()
> - Renderer.js: drawFeature()
> - Format/*.js: parseGeometry()
> It would be nice if we can come up with a clean solution for this.
Chris has noted on IRC that he doesn't think VML.setNodeDimension() is
the right place to catch this error and after digging around I agree.
The problem is that a point geometry is created which has an x,y point
of (null, null). This eventually causes an exception in the VML renderer.
I propose we fix in Geometry/Point.initialize(x,y) where we should throw
an exception if x or y is null.
1. Exceptions are already raised by Format/KML.js if it needs to create
a (null,null) point, so I believe we have a precedence for handling
errors by raising exceptions.
2. Our error was caused because Format/GML.js allows the creation of
(null,null) points, probably from an empty <Point></Point> tag.
3. I don't expect to break any legacy code by forcing Geometry to have
valid values because old code would have caused exceptions in VML.js as
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