Directly in CVS? (Re: raster layer properties and mask patches)

[Jonathan Coles]

Am Donnerstag, den 27.01.2005, 20:13 +0100 schrieb Bernhard Herzog:
> I think it's fine to raise the requirement to 1.2.4 or 1.2.5 even.  This
> is a development version after all, and the alpha channel support will
> make raster image rendering better.

ok, now i have another question :)

if we support gdal 1.2.5 we have two options with regard to how we
handle masking:

1) we can support only a true mask (either a pixel is there or it
isn't). this is supported with the current stable version of wxWidgets. 

2) we can also support alpha blending. gdal 1.2.5 will generate the
correct values for this, but only the development version of wxWidgets
supports alpha blending (and even then, its not natively supported on
all platforms).

i've looked at the rendering code and it would be pretty easy to support
both. 

in case 1, ProjectRasterFile can return a bit array and use
wxBitmapFromBits (bernhard h. just sent a mail about this). this saves a
lot of memory.

in case 2, ProjectRasterFile can return a byte array which wxImage
supports in version >=2.5 for the alpha channel. this also saves memory
and can result in some interesting effects.

anyone in opposition to implementing 1 and 2? 2 would only be available
if the version of wxWidgets supports it. i'm not going to get too
involved with it. i'll only add support for returning the alpha data if
the correct option is passed to ProjectRasterFile. i'll leave the python
implementation until later.

--jonathan

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 Jonathan Coles                               http://www.jpcoles.com
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