guess_protocol() falls back to Halfblocks on Windows Terminal (Preview)

[matthias-buttgereit]

Windows Terminal (Preview) supports Sixel as of 1.22 (https://github.com/microsoft/terminal/releases).

When running code inside WSL it does actually display images using Sixel but outside of WSL it falls back to Halfblocks.

Windows Terminal (Preview) without WSL	Windows Terminal (Preview) with WSL

My guess is that the guess_protocol() function is not testing for Sixel support under Windows. Not sure if there is a way to do it yet but would be great if it could be added.

[j4james]

FYI, there is a bug in the latest Windows Terminal preview that affects VT reports in applications that don't enable VT input mode (see microsoft/terminal#17813). It's possible that might be why it's not working outside WSL. VT input mode is set automatically in WSL, but that isn't the case for regular Windows console applications, unless they set the mode themselves, and I don't think the crossterm library does that.

[matthias-buttgereit]

Seems like Sixel is working in Windows Terminal (Preview) even without WSL when you manually cycle through the protocols (like in the demo example).

Just showing some weird behaviour when resizing (not fully clearing the area) but that might be a problem on the Windows Terminal part.