[IAEP] Paint and Transparent Backgrounds

[Albert Cahalan]

Tim McNamara writes:
> 2009/10/5 Caroline Meeks <caroline at solutiongrove.com>

>> Could we set Paint to have a transparent background on images
>> as a default rather then white? That would make it easier to
>> layer different drawings and have them interact. Is that
>> difficult programatically?  Can people think of places where
>> having a transparent background will be a problem?

It's trivial programatically, but a problem for a kid's GUI.
This adds all sorts of complexity. If you want that, use GIMP.

Other things to NOT ask for: layers, channels, physical resolution,
non-square pixels, zoom, painting bounded by selection, scrolling,
user-defined canvas sizes, and maybe even cut-and-paste!

On the other hand, you should expect stereo sound. :-)

> What format does Tux Paint save in? If it can save in PNG, then
> setting the alpha layer to #000000 (or is it #ffffff - must check!)
> should be fairly straight forward. If we wanted this functionality
> by default, it may need cooperation from the upstream developers.

For drawings, Tux Paint normally uses PNG without an alpha layer.
The stamps (clip art) are normally PNG with alpha, meaning that
you currently need something like the GIMP to create a stamp.

There has been talk of changing things for the specific case of
stamp creation. Tux Paint remembers the initial background image.
This could allow the background image to be subtracted out, even
with the anti-aliasing that Tux Paint uses for everything. The
result would then be made available as a stamp.

There are problems, some of which could perhaps be mostly solved
by having more than one stamp creation button. Consider the case
of a simple unfilled circle. Do you want the middle opaque?
Now suppose the user draws a gray object on a white background.
Is that to be opaque gray, or partially transparant black?