[Qgis-developer] Rejigging raster layer drawing

Peter Ersts ersts at amnh.org
Fri Apr 27 12:46:09 EDT 2007


There is a separate branch on the SVN where a couple of people have been 
working on some raster issues (raster_transparency_branch)  

Thing specifically being addressed at this time are:
Color maps

I have been very delinquent on working on this  over the last month but 
hope to get back to it very soon.  The current line of thinking, Tim 
correct me if I am wrong or out-of-date, is to get the raster methods a 
bit more robust and filled out then at a later time split the different 
rendering routines for each layer type into their own classes and 
finally, eventually , integrate OSSIM into QGIS.


Barry Rowlingson wrote:
> I've been digging deep into the raster layer draw code, and it seems 
> to have a lot of cruft lying around. Exhibit A is the unused method, 
> QgsRasterLayer::drawPalettedSingleBandColor, which I guess is related 
> to the unused drawing style of 'PALETTED_COLOR' - these things are 
> defined but not referenced anywhere...
> The pseudo-color stuff is a bit crocky too, with colouring techniques 
> hard coded into the draw methods. Pseudo-color just seems to be a 
> modification of the paletted drawing methods.
> I think this code could all be simplified into a more unified set of 
> drawing methods, using user-defined colour palettes to produce colour 
> or grayscale renderings based on single or multi-layers, or using 
> palettes from the layer data itself, with optional 
> scaling/stretching/clipping.
> I am prepared to put some time into this since its a feature I dearly 
> want in QGis, in fact I pretty much need it for a current project, and 
> attempts to bodge it into shape have failed! What I think I need is 
> some help from the more competent to make sure my plans are good plans 
> (and not evil plans), and to see any other ramifications they may have 
> - for example it will probably imply changes to the 'properties' 
> dialog in the Qgis App code...
> Anyone on board with this? I'd chat on #qgis but you lot are only 
> there at 3am my time!
> Barry
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