Support for Symbol libraries

[ksgeograf]

The only support there is for symbols, are the built in (ea. triangle, square, etc).

The MapGuide also supports some advanced symbols, it would be nice to have an editor for those.

[ksgeograf]

The symbol libraries are implemented in a slightly complicated way. Instead of merely adding images to the resource, in form of resource data, a DWF file is used. As I understand, this was done to support some transformation features avalible in DWF, and it probably plugs into the render quite well.

The DWF format is actually a Zip file with a few magic header bytes added. Removing the bytes, makes it possible to read the zip file with standard zip tools.

Inside the zip file there is a dictionary xml file of sorts, that explain what items are found in the file. This file is pretty straightforward, and can easily be created based on a template.

For each resource inside the DWF, there is also a descriptor xml file, that indicates what images are used, and has transformation, clipping and other information. For a simple implementation, this part could be fixed to some standard values.

The real problem with this format is the images. They are in a format called w2d, and I cannot find a .Net library that is capable of reading and writing those files.

The DWF toolkit is open source (not sure what license it is though), but in C++, meaning that there would have to be a port avalible for all possible platforms. This price is a bit too step for this single feature.

If anyone wants to look into w2d or the DWF stuff, here are some pointers from Traian: ​http://lists.osgeo.org/pipermail/mapguide-internals/2009-May/003870.html

[jbirch]

My preference on this would be to completely ignore the w2d/dwf pointers and just support the part of symbol libraries that point to the new style xml symbol definitions. Not sure how this would work when accessing existing symbol libraries tho.

[ksgeograf]

I have not seen such a symbol library. The ones in the sample packages are either DWF based or SymbolDefinition based. Do you have a sample?

[jbirch]

Apparently I was hallucinating. For some reason I thought that the SymbolInstance allowed specification of a LibraryItemName as well as the ResourceId, but apparently not. Sorry for the confusion.

[jng]

3.0 has browse support for Symbol Libraries, but the effort to implement actual editor support is just too much for too little gain, when Symbol Definitions offer much more!