Transparency support for PNG

[tryadelion]

there seems to be no support for alpha channel on PNG's / Gifs, is that a possibility? atleast on fully transparent rgba(0,0,0,0) pixels.

[aaronliu0130]

I don't think that is as this project uses unicode half-block characters, and I don't think there is a transparent half block character. If we use unicode invisible characters, we can't really promise on the spacing.

[tryadelion]

how about U+2591 for 0-alpha? it wouldnt look solid, atleast

[stefanhaustein]

We can't access / preserve the terminal background. We could add support for a user-specified "background" color though.... Perhaps default to the common gray/gray checkerboard pattern?

[aaronliu0130]

how about U+2591 for 0-alpha? it wouldnt look solid, atleast

Yes, that Unicode character sure doesn't work well on my terminal emulator. See the screenshot below.

[tryadelion]

@stefanhaustein maybe sth like this? https://stackoverflow.com/questions/43931304/is-it-possible-to-determine-the-background-color-of-the-terminal-in-a-linux-mach

[stefanhaustein]

Not sure how accessible the shell variable would be from cross-platform c++... if not, an explicit command line parameter would still help to pass it over... So I think it makes sense to start with that and then take it from there....

[aaronliu0130]

Well, usage of system() is considered to be not good, but since we don't have any other options lets just take it from here. I'm not sure if that shell script is cross-terminal though...

[tryadelion]

I can test on some terminals mac and debian, mint and a couple more if necessary