Control: terminal emulator

[migueldeicaza]

Can use the work-in-progress XtermSharp and mono/pty-sharp

[migueldeicaza]

Someone at Build told me about a full VT emulator they were about to open source, it is here:

darrenstarr/VtNetCore#4

Need to wait for the license to be official, then we can use it.

[migueldeicaza]

Working on one as part of XtermSharp: https://github.com/migueldeicaza/XtermSharp the GuiCsConsole has it, will split it out later.

[SpocWeb]

Hi, it seems @darrenstarr has updated the License to MIT.
I'm currently looking to add Escape-Sequence Support to the .NET Core Console and wonder whether to choose XtermSharp or VtNetCore. Can you provide advice?

[darrenstarr]

It depends what you’re looking for. I was going for compatibility. So if you look at the UWP example, you’ll find it’s pretty complete.

Since I went for maximum compatibility and support all scrolling modes as well as protected areas and characters, it might not be as fast as some other libraries.

Once I start my new job at the university, I’ll have time to support it better and if it’s possible to do so, I’ll move to a no-copy model as well as switching to a hierarchal state machine for parsing. This might be an issue since I found a lot of cases (beyond standard VT320) which breaks state machine and cause artifacts.

I’m also planning on supporting sixel graphics which may seem silly, but is great for things like math.

The greatest weakness in the implementation currently is that I’m not invalidating with time enough control. This is because UWP tends to handle redraws coarsely.

I’ll finish ISO2022 (if I remember the number) encoding support as well as X-JIS as soon as I get a chance.

Let me know if there’s anything I can do to help. No exaggeration, I wrote most of VtNetCore in a weekend. The rest has been adding more and more features.

[SpocWeb]

@darrenstarr thank you, currently I only want basic foreground/background colors. Actually I was about to write a simple parser myself and translate the Codes into the corresponding System.Console Commands, but it would be better to re-use a parser done properly ;-)

I don't see any Adapter to Console Functionality in your Code though. Do you think I am on the right track using your code for what I want to achieve? Could you give me a Code-hint to start with?
Best regards...

PS: to clarify, I know I can enable all this on the Windows10 Console and many Unix Terminals, but I would like to stick with the standard .NET Core Console.

[darrenstarr]

The XtermParser component of my code isn’t too hard to use for that. It parses everything, but if you implement a controller (inherit it) and implement the functions you want, it should do what you’re looking for.

I am on my phone now, but I can talk more intelligently about it when I’m in front of a keyboard. :)

I warn against making an oversimplified parser... it’s absolutely amazing how many crazy cases there are. But if you have a controlled data set... it might not be an issue.

[darrenstarr]

Sorry... responded before reading the whole thing.
I didn’t do a System.Console view. But it wouldn’t take long to do it I think. If I can get 20 minutes tomorrow, I’ll see what I can get up and running. It is abstracted.

[SpocWeb]

@darrenstarr That's why I'm asking, no worries, I won't, although it seems tempting.
You don't really have to program it though. I would rather 'use' than 'subclass'. I see that VirtualTerminalController is not abstract, but it has many events. I suppose one could subscribe to these and to the proper handling?

[darrenstarr]

Look at IVirtualTerminalController. Subclass it, then implement the interesting features. Pass your instance to the DataConsumer class. The DataConsumer is the parser and the IVirtualTerminalController is what it calls as it parses. You just need to push data to the consumer.

[SpocWeb]

Ah, I see, a very broad Interface, but quite specific and I can leave Methods empty if they don't interest me. Just out of curiosity, what does the concrete VirtualTerminalController do? What is its purpose? Is it the "model" for the Terminal GUI?

[darrenstarr]

It is the model... but to use the term loosely, it's an observable model. If you look at https://github.com/darrenstarr/VtNetCore.UWP you'll see there's an implementation for UWP and I also had Cocoa working at one point, but I haven't followed up on it. There's also an AvaloniaUI version which is used by AvaloniaStudio.

You can leave empty as much as you want. The definitions for some of the items are pretty specific. INCITS 4-1986[R2012] (or ISO6429 C0 & C1 codes) ... Wikipedia does a great job describing them https://en.wikipedia.org/wiki/C0_and_C1_control_codes

This is pretty important for how you'll handle backspace, and tabs and such. I doubt you'll need to be concerned with it, but shift in and shift out are pretty confusing,

Be mindful of "SetUtf8()", the parser will take care of this itself, but it could be useful to make sure that it's sent at the start of a session. By default, 8-bit values mean ASCII-extended (if I recall correctly).

I should probably provide header documentation in IVirtualTerminalController now that I'm pretty sure it's there to stay :)

[darrenstarr]

public void SetCharacterAttribute(int parameter)

This is the function I think you're most interested in. It's the most common method of setting the text color.

[SpocWeb]

@darrenstarr thanks again, would you care for a pull request with my implementation of a ConsoleTerminal.cs when I'm ready?

I have to sort it out with a change I did: I switched to System.ConsoleKey and ConsoleModifiers modifiers. Would you object to that?

[darrenstarr]

I had no idea there was a .NET Core solution to that... I'm concerned that it will have an issue with IMEs... if I understand correctly, there is no .NET Core mapper for ConsoleKey/ConsoleModifiers and unicode.

I'll look into what's being done on Windows Terminal. I am guessing they have a solution for that :)

In the meantime, I don't see any drawback to having an alternative.

I'm always interested in pull requests. :)

[SpocWeb]

I created a Core 1.1 Solution and ConsoleKey/ConsoleModifiers were available. What are IMEs?

[darrenstarr]

Input method editors. If you were to watch a person type in Korean for example, they have the same key codes as we have, but each key has a different meaning than ours do. As they type more, the characters combine to create more complex characters.

Of course at this time, I don't have support for complex scripts, but I write in Norwegian, Danish, Swedish and Spanish quite often. When I switch between keyboard layouts the key codes for each button don't change, but they need to be interpretted differently. For example ';' and 'ø' are the same key code using ConsoleKey on my keyboard depending on which IME I'm using.

Handwriting and voice input should also be considered.

Surprisingly, at Opera (back when I was a developer there), I think we used 2000+ hours to get basic support for keyboard input as such. Windows has translation tools built in to deal with that issue though. I'll have to read more on ECMA-48 to better understand how to support internationalization. But for now, the method I'm using works for latin scripts.

[darrenstarr]

ping... @SpocWeb is there anything I can help you with? Or did you decide my code was so horrible you abandoned it? :)

[SpocWeb]

No, sorry, I was busy. Now I'm fighting conflicting private and business git credentials...
I prepared a pull-Request, please have a look at it.
I wasn't aware of Windows Terminal either.
But it's in C++ anyway.

[migueldeicaza]

Well, I am biased, so I would recommend my terminal and will eventually bundle it here, but it is really up to you.

[SpocWeb]

I thought so ;-) would do the same, but Darren's solution seemed much more complete, so I adapted it.
BTW I would like to express my admiration for the hard work you've been doing for ages on Mono, Xamarin and open source projects like your Excel Clone...

[darrenstarr]

I’m teaching all week (and next) so I’ll handle the day pull request after :) Thanks!

And Miguel, I am biased too :) But, if you started before me, I would have extended yours instead.

As for Microsoft Terminal... it is beautiful and those guys are really working wonders. It was a real shame they chose to kill portability by making it C++. I plan to port their DirectX view when I can find the time. I am a little concerned that they are basing their state machine on an antiquated VT520 doc. And I’m a little worried that their line wrapping logic could keep them from implementing protected regions without some considerable refactoring.

Either way, my code, Miguel’s and Richard’s team’s are all really good and it’s fantastic that we’re finally getting proper terminal support on Windows in the open source :)

[migueldeicaza]

XtermSharp now contains a gui.cs terminal emulator:

https://github.com/migueldeicaza/XtermSharp/tree/master/GuiCsHost

[ghost]

@darrenstarr

I’m also planning on supporting sixel graphics which may seem silly, but is great for things like math.

Did you implement sixel? If so I would love to give it a spin. :)

[darrenstarr]

Hey Miguel, Long time, no hear (I abandoned twitter), I hope all is well. I did start working towards implementing it, but was side tracked because I needed something to accurately verify against and xterm seemed to discontinue support for it and frankly, I didn’t have much luck getting it working on vtstar. I now have a Dec VT320 on my desk which I haven’t had a chance to mess around with. If you’re up for implementing it on your side, I’m certainly interested in assisting even if only to write unit tests for it. I’ve been through the docs and it seems pretty straight forward. The main concern is that handling scroll-back gracefully looks challenging and making the graphics ephemeral is less than interesting. If only for math purposes, you don’t want the buffer the be dropped just because you scroll. If you come up with a reasonable solution for how to support a frame buffer (architecturally) which addresses those issues, I haven’t invested the time in it and I have some hairbrained ideas, I’d love to hear what you come up with. Also, I think the biggest concern I had with doing it was that I wanted to make sure that it supported high-DPI gracefully. I don’t know if you have a proper DEC terminal to test against, but if you want, I can aim a webcam at the VT320, plug it into a Raspberry Pi and you can have a shell account to push to /dev/ttySx on. Let me know if any of this would help 😊 * Darren

…

________________________________ From: Autumn Lamonte ***@***.***> Sent: Thursday, February 3, 2022 5:15:43 PM To: migueldeicaza/gui.cs ***@***.***> Cc: Darren Starr ***@***.***>; Mention ***@***.***> Subject: Re: [migueldeicaza/gui.cs] Control: terminal emulator (#21) @darrenstarr<https://github.com/darrenstarr> I’m also planning on supporting sixel graphics which may seem silly, but is great for things like math. Did you implement sixel? If so I would love to give it a spin. :) — Reply to this email directly, view it on GitHub<#21 (comment)>, or unsubscribe<https://github.com/notifications/unsubscribe-auth/ACQKO3WSYCDDN6VP4GSHPO3UZKS27ANCNFSM4ELJGAGQ>. Triage notifications on the go with GitHub Mobile for iOS<https://apps.apple.com/app/apple-store/id1477376905?ct=notification-email&mt=8&pt=524675> or Android<https://play.google.com/store/apps/details?id=com.github.android&referrer=utm_campaign%3Dnotification-email%26utm_medium%3Demail%26utm_source%3Dgithub>. You are receiving this because you were mentioned.Message ID: ***@***.***>

[migueldeicaza]

I did an implementation using XtermSharp, which could use an update:

https://github.com/migueldeicaza/XtermSharp/tree/master/GuiCsHost

I think the major issue is whether the code above gets merged into gui.cs (and thus takes a dependency on XtermSharp), or if XtermSharp takes a dependency on gui.cs, or if I split this out so neither gui.cs or XtermSharp take dependencies, and the terminal emulator is standalone.

[migueldeicaza]

As for Sixel support:

I implemented Sixel support (and a bunch of other graphic APIs) in my Swift version of the terminal emulator, and it could be easily backported to XtermSharp.

XtermSharp could get a big boost by bringing all the changes I did to SwiftTerm, I kept an issue to track those here:

migueldeicaza/XtermSharp#79

[ghost]

Would there be a way to test sixel at this time?

I have an interest in image-supporting terminals, and if another embeddable terminal widget can now do it I would love to advertise it. :)

[migueldeicaza]

Someone would need to port the code from Swift to C#, I do not currently have much time to devote to that backport.

That said, you could try SwiftTerm which supports assorted image formats (including sixel)