[Qgis-developer] Rejigging raster layer drawing
Peter Ersts
ersts at amnh.org
Fri Apr 27 12:46:09 EDT 2007
Barry,
There is a separate branch on the SVN where a couple of people have been
working on some raster issues (raster_transparency_branch)
http://wiki.qgis.org/qgiswiki/RasterTransparencyBranch,
Thing specifically being addressed at this time are:
Stretching
Transparency
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correct me if I am wrong or out-of-date, is to get the raster methods a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.
-pete
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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