zterm Terminal User Interface Library

zterm is a terminal user interface library to implement terminal (fullscreen or inline) applications.

Note

Only builds using the master version are tested to work.

Usage

To add or update zterm as a dependency in your project run the following command:

zig fetch --save git+https://gitea.yves-biener.de/yves-biener/zterm

Add the dependency to your module as follows in your build.zig:

const zterm: *Dependency = b.dependency("zterm", .{
    .target = target,
    .optimize = optimize,
});
// ...
exe.root_module.addImport("zterm", zterm.module("zterm"));

For an example you can take a look at build.zig for an example.

Design Goals

This project draws heavy inspiration from clay in the way the layout is declared by the user. As terminal applications usually are rendered in intermediate mode, the rendering is also part of the event loop. Such that every time an event happens a render call will usually be done as well. However this is not strickly necessary and can be separated to have a fixed rendering of every 16ms (i.e. for 60 fps), etc.

There is only one generic container which contains properties and elements (or children) which can also be containers, such that each layout in the end is a tree.

The library is designed to be very basic and not to provide any more complex elements such as input fields, drop-down menu's, buttons, etc. Some of them are either easy to implement yourself, specific for you needs or a too complex to be provided by the library effectively. For these use-cases there may be other libraries that build on top of this one to provide the complex elements as some sort of pre-built elements for you to use in your application (or you create them yourself).

There are only very few system events, that are used by the built-in containers and properties accordingly. For you own widgets (i.e. a collection of elements) you can extend the events to include your own events to communicate between elements, effect the control flow and the corresponding generated layouts and much more.

As this is a terminal based layout library it also provides a rendering pipeline alongside the event loop implementation. Usually the event loop is waiting blocking and will only cause a re-draw (intermediate mode) after each event. Even though the each frame is regenerated from scratch each render loop, the corresponding application is still pretty performant as the renderer uses a double buffered intermediate mode implementation to only apply the changes from each frame to the next to the terminal.

This library is also designed to work accordingly in ssh hosted environments, such that an application created using this library can be accessed directly via ssh. This provides security through the ssh protocol and can defer the synchronization process, as users may access the same running instance. Which is the primary use-case for myself to create this library in the first place.

Roadmap

Container rendering
- Layout
  - direction
    - vertical
    - horizontal
  - padding
  - gap
  - alignment
    - center
    - left
    - right
  - sizing
    - width
    - height
    - options
      - fit
      - grow
      - fixed
      - percent
- Border
  - sides
  - corners
  - separators
- Rectangle
- Scroll
  - vertical
  - horizontal
  - scroll bar(s)

For the correct rendering of the corresponding layout's that extend the view port I need to figure out a way to render what would be visible at a given frame. I would need to separate the between the Layout size -> i.e. the size the container uses in virtual space and the real screen!

Here the sizing options are relevant!

fit: adjust virtual space of container by the size of its children (i.e. a container needs to be able to get the necessary size of its children)
grow: use as much space as available (what exactly would be the difference between this option and fit?)
fixed: use exactly as much cells (in the specified direction)