Ftxui: C++ Functional Terminal User Interface
github.com
github.com
> Cross platform (mostly). Linux (main target), Windows (experimental), Mac.
So, it is not targeting _terminals_ (like traditional libraries do, including ncurses), it is targeting entire operating systems. That suggests it might be relying on things it shouldn't be relying on, and possibly making a bunch of simplifying assumptions. Given that it also says:
> No dependencies
I'm even more worried.
On Windows, writing to a terminal window has different effects depending on the type of terminal. The classic Windows Console doesn't understand VT codes but there are API calls to do the same things (position cursor, change attributes etc). Recent versions of Windows Console can be told to understand VT codes, but require an API call to enable VT interpretation, then they understand a subset. Windows Terminal isn't the same as Windows Console. Then there's running things under Mintty, or Cygwin Terminal. Control+C behaves differently under those than under the Windows Console. Then there's running things under "winpty" in a Cygwin Terminal, which uses a hidden Windows Console and translates the resulting character matrix as best it can to terminal codes. There are other terminal emulators too.
Linux terminals have a lot of diversity regarding which VT codes they interpret, but at least there's a common subset for most of them. There's also some variation about codes for keypress, such as modifiers with function keys.
If it uses terminfo or termcap to work with various terminals, there are some OS dependencies regarding what capabilities are likely to be indicated.
The color capability varies. Sending 24-bit color to some terminals will not have the desired effect on others.
Unicode support varies among terminals, and this toolkit uses plenty of Unicode in the demos: Radio buttons, check boxes, box drawing characters, and the bar graph demo. What counts as a wide character (two cells) also varies.
Every terminal compatible with the main subset of the various VT specifications should be compatible with FTXUI. If someone can prove this wrong, I must fix this ;-)
I own a Linux machine so this is the "main" target. Support is quite strong. However, I don't own a Windows machine and it's quite painful for me to test on it. Windows support has been added by contributors mostly. That's the reason I say it is still "experimental". The various Windows terminal requires some Windows specific calls to enable VT interpretation, as explained above.
FTXUI can be compiled toward WebAssembly and executed against xterm.js terminal. This proves you can use FTXUI against a compliant terminal and not really depends on OS calls. https://arthursonzogni.com/FTXUI/examples/
There are some function depending on the systems:
- Windows diverges a bit (see above)
- Getting terminal dimensions.
- Getting terminal support for colors.
Second, I suggest you get in contact with Thomas E. Dickey, the maintainer of libncurses and terminfo, to see how he tests that library - on something like 15 different platforms.
Finally, over time, consider relaxing your set of terminal requirements - either with workarounds or with limitation of functionality for less-capable terminals.
why ? If I have a choice between using a software that works on mac / win / linux, and one that works on those three + a ton of obscure architectures / old systems I'd definitely choose the first one - every additional platform supported invariably means that :
- you have to give up some features or reimplement them yourself (because you want that feature anyways) thus more possibilities of bugs, e.g. the amount of times I've seen people reimplementing badly some POSIX functions or stuff like clock_gettime on windows
- you have to duplicate code, say DLL / so loading if you have some plugin system (plus a mess of #ifdefs because of shit like macOS having a non-functional pthread_cancel, etc...)
- in some cases this may mean that the program author needs to add some run-time indirections, e.g. to call platform functions, which may have a performance cost.
- most likely the build system will be some terrible autotools mess which has not been updated in 15 years and does need 50 changes before working on a modern linux distro (had that merely a week ago) + a batch script for windows
- maybe some performance / technical improvements / simplifications would not be available because they would break compatibility with whatever EBCDIC IBM platform with two users, thus making the software worse, condemning us to the "state of the art" of the oldest supported platform
etc etc...
The first option probably means they are assuming the terminal behavior of the common terminal apps desktop users on one of the two/three main platforms are using. But if they're making that assumption, they might as well assume they can use a proper GUI and go with that.
The whole point of terminal programming is that you live within the abstraction which is the terminal. The fact that you're thinking about _systems_ rather than _terminals_ is the problem.
It's perfectly ok to have your app refuse to run on a terminal which lacks certain capabilities (annoying, but ok): You check for whatever you need from the terminal using Terminfo(https://en.wikipedia.org/wiki/Terminfo), and die gracefully if necessary. What's not ok is saying "Oh, I'm running on Windows, so XYZ must be true about the terminal I'm in, I'll just go ahead and assume that's the case".
Also - what you consider "obscure and esoteric systems", for many other people is just "systems".
I really fundamentally disagree that there is a "whole point" to terminals (or any other kind of things we use when we use computers). They are just tools which are able to perform things and one should really not ascribe any kind of semantic layer to them, as this is always a very very brittle abstraction. Just look at things in terms of what they are able to do, not what they are called.
Yes, that's correct. The whole frame is printed. As said above, as long as you are careful about flickering, this is fine.
This runs very smoothly. So I would say "premature optimization is the root of all evil" for now.
Note that in case of many events sent in a row, we don't render a new frame after every events. We first empty the list of pending events and only render once when it is empty. This ensure there are no lags.
If there is a need, this can be added easily. We just need to ensure this doesn't regress performance. Sending a single chunk representing the whole frame can sometimes be cheaper than sending several diffs at various locations of the screen.
Also, FTXUI support not only rendering to the alternate buffer (fullscreen mode), but it can also render inline. In case of terminal window resize, printing the whole frame avoids garbages to remain, which is nice.
Overuse of shared_ptr (what we call "Java Disease") is probably forgiveable in a UI toolkit. Even protected data members, often frowned upon in O-O circles, are probably OK, here. A note to the author (and, you know, everybody): the "#ifndef xxxx/#define xxxx" two-step is no longer necessary or useful; "#pragma once" is supported everywhere now.
https://stackoverflow.com/a/34884735
> (Historical note: The only reason I didn't rip #pragma once and #import out of GCC when I had the authority to do so, ~12 years ago, was Apple's system headers relying on them. In retrospect, that shouldn't have stopped me.)
I find the argument unpersuasive for the same reasons commenters there did. The case for C++ is stronger because the set of current C++ compilers (which nowadays have integrated pre-processor) is much smaller than of C compilers that could be encountered in the wild.
Doing complicated things with header files and paths is inherently fragile, pragma or no pragma. So, don't do them. Absent fragile header file or include-path games, there is no problem.
In the foreseeable future, #include will begin to fade from C++ code, and with it #pragma once, include guards, and any sort of worries about them. (Then we might start to worry about module name collisions, instead.)
Wish we have some nice cross-platform GUI with modern c++ works across linux/windows/macos too, the only choice used to be Qt. Nowadays imgui seems a good alternative.
Looks like a nice alternative indeed. it uses MSYS2 for windows native build.
Not modern c++ last time I checked but active development for sure.
[0]: https://github.com/willmcgugan/rich
[1]: https://www.willmcgugan.com/blog/tech/post/building-rich-ter...
https://arthursonzogni.com/FTXUI/examples/?file=./component/...
Mouse support was introduced only 30 days ago: https://github.com/ArthurSonzogni/FTXUI/pull/85 The combinaison of:
- The "frame" element - allowing you to draw inside a virtual area potentially larger than the real one.
- The "select"/"focus" element - to scroll the content of the "frame" toward the selected element.
- The "Menu" component.
isn't currently working satisfyingly. I should work on this.
There are two approaches there. One is to project abstract UI onto platform controls (React Native), the other is to use “drawing” (Flutter). Both have their pros and cons.
The main drawback of abstracting over controls is that each platform works very differently and the abstraction quickly starts leaking. Also some of the targets don’t have any controls like the terminal. All you can do in a terminal is draw text in rows and columns.
That is why most (not all) cross platform frameworks abstract on the drawing level. Gtk, Qt, Flutter, Druid, Dear ImGui and many more.
I think that is the distinction that parent is making.
In a TUI environment (ignoring mouse support) traditional GUI elements and layouts often don’t make sense. Like one of the examples with all the radio buttons in small boxes.
The good TUI apps like htop, newsboat, mutt, vim/emacs, tmux all have mostly line-and-column oriented simple layout primitives.
Notcurses' principal author aspires for it to provide a widget toolkit for TUIs[1], but much of the demo and much of the commit log to date is heavily focused on graphical capabilities and lower-level details.
It may be that one day it ships with a robust widget toolkit; or perhaps someone else will build another library on top of notcurses with that as the principal focus.
I'm also impressed with the effort put into FinalCut[2], but notcurses seems to me to be paving a more interesting path forward for TUI development.
[1] https://nick-black.com/htp-notcurses.pdf, see e.g. page 3
VS Code shows how utterly difficult it is to get a GUI working well in that scenario.
My first experience with remote XWindows was using IBM X Windows terminals in 1994.
Did you mean running VS Code on a remote server and forwarding it to the local machine? X11 based forwarding?