Status: Layer organisation

[Bernhard Herzog]

Martin Schulze <joey at infodrom.org> writes:

>  1. I guess that we should see if we can support more graphics
>     formats.  That's easily doable, but there may be a good reason for
>     limiting support to BMP and JPEG.

There's no particular reason for the limitation, IIRC.  We simply didn't
need something else yet.  Which formats Thuban can support depends on
what the underlying the wxWidgets library supports, so I don't think we
should can guarantte much about the availability of support for formats
that are optional in wx.  I'm not sure which are optional, ATM.

>  2. If 1. we should see why transparency is currently not supported by
>     Thuban

The reason is simple: It's not easy to do with a wxDC.  It would be
possible and probably not even difficult to do a gif-like transparency
(effecively one bit alpha channel, every pixel is either drawn or not).
Full blown translucency (where the underlying pixels shine through)
can't be done unless all rendering is done with some other library and
only a complete raster image with the entire map is drawn by the DC, or
we switch to OpenGL.

For the one-bit transparency, we'd need to extend the draw_raster_data
method so that it either accepts an additional one-bit image with a
clip-mask and/or accepts image format with equivalent transparency
information.

   Bernhard

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