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

[Bernhard Herzog]

Jonathan Coles <jonathan at jpcoles.com> writes:

>> Jonathan Coles <jonathan at jpcoles.com> writes:
>> > by
>> > default, it is off because it requires more memory and using a mask
>> > could take a little longer to draw.

It shouldn't require much more memory.  Just about 1 byte per pixel of
the canvas window.  That's almost negligible considering that several
bytes per pixel are already required without the alpha channel.

How much slower is the rendering with the alpha channel?  My impression
with the iceland data is that the difference isn't much.  It takes maybe
25% longer (tested with a session with several instances of the image).
I'd say, the mask should always be on without a way of switching it off.
The little speed gain isn't worth the complication in the code and the
file format.

> either way, if the user changes the setting to differ from the default,
> then the flag must be saved. if i'm a user, i expect the session to be
> the same every time i load it. i shouldn't have to select not to use the
> mask (should i desire that) every time i open up thuban.

If we save it into the .thuban file, we have to support it in future
versions of Thuban.  I don't want that to happen for settings that
aren't really necessary.

   Bernhard

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