FTXUI/tutorial/tutorial.md

Table of content:

• Introduction
• DOM
  • Widget.
    • text
    • border
    • separator gauge
  • Style
  • Layout
    • Examples
• Components.
  • Input
  • Menu
  • Toggle.

Introduction

I recommand not to take too much time reading the tutorial. Instead, you should try to read the examples (in ./examples/).

The library is split in 3 parts:

• ftxui/screen/

  It defines a ftxui::Screen. A Screen is a grid of ftxui::Pixel. A Pixel contains a character and its associated style. Once the screen is ready, you can display it on the terminal.

• ftuix/dom/

  These are a set of hierachical ftxui::Element declared in ftxui/dom/elements.hpp. An element can render itself on the the Screen. It manage layout and is responsive to the Screen dimensions.

• ftuix/component/ The part is only needed if you need to respond to the User input. It defines a set of ftxui::Component. The use can navigates using the arrow keys and interact with widgets like checkbox/inputbox/... You can make you own components.

DOM

All the dom element are declared in one header:

#include <ftxui/dom/elements.hpp>

It declares the following set of elements:

// --- Widget ---
Element text(std::wstring text);
Element separator();
Element separator(Pixel);
Element gauge(float ratio);
Element border(Element);
Decorator borderWith(Pixel);
Element window(Element title, Element content);
Element spinner(int charset_index, size_t image_index);
Elements paragraph(std::wstring text); // Use inside hflow(). Split by space.
Element graph(GraphFunction);

// -- Decorator ---
Element bold(Element);
Element dim(Element);
Element inverted(Element);
Element underlined(Element);
Element blink(Element);
Decorator color(Color);
Decorator bgcolor(Color);
Element color(Color, Element);
Element bgcolor(Color, Element);

// --- Layout ---
// Horizontal, Vertical or stacked set of elements.
Element hbox(Elements);
Element vbox(Elements);
Element dbox(Elements);
Element hflow(Elements);

// -- Flexibility ---
// Define how to share the remaining space when not all of it is used inside a
// container.
Element filler();
Element flex(Element);
Element notflex(Element);

// -- Size override;
enum Direction { WIDTH, HEIGHT };
enum Constraint { LESS_THAN, EQUAL, GREATER_THAN };
Decorator size(Direction, Constraint, int value);

// --- Frame ---
// A frame is a scrollable area. The internal area is potentially larger than
// the external one. The internal area is scrolled in order to make visible the
// focused element.
Element frame(Element);
Element focus(Element);
Element select(Element);

// --- Util --------------------------------------------------------------------
Element hcenter(Element);
Element vcenter(Element);
Element center(Element);
Element align_right(Element);
Element nothing(Element element);

Widget.

text

The most simple widget. It displays a text.

  text(L"I am a piece of text");

I am a piece of text.

border

Add a border around an element

border(text(L"The element"))

┌───────────┐
│The element│
└───────────┘

separator

Display a vertical or horizontal line to visually split the content of a container in two.

border(
  hbox({
    vbox({
      text(L"left top"),
      text(L"left bottom"),
    }),
    separator(),
    vbox({
      text(L"right top"),
      text(L"right bottom"),
    }),
  })
);

┌───────────┬────────────┐
│left top   │right top   │
│left bottom│right bottom│
└───────────┴────────────┘

gauge

A gauge. It can be used to represent a progress bar.

border(gauge(0.5))

┌────────────────────────────────────────────────────────────────────────────┐
│██████████████████████████████████████                                      │
└────────────────────────────────────────────────────────────────────────────┘

graph

Style

A terminal console can usually display colored text and colored background. The text can also have different effects: bold, dim, underlined, inverted, blink.

Element bold(Element);
Element dim(Element);
Element inverted(Element);
Element underlined(Element);
Element blink(Element);
Decorator color(Color);
Decorator bgcolor(Color);

Example:

underlined(bold(text(L"This text is bold and underlined")))

Tips: The pipe operator can be used to chain Decorator:

text(L"This text is bold")) | bold | underlined

Layout

These layout are similar to the HTML flexbox:

• vbox (Vertical-box)
• hbox (Horizontal-box)
• dbox (Z-axis-box) They are used to compose all the elements together. Each children are put side by side. If the container is flexible, the extra space available will be shared among the remaining flexible children.

flex(element) can be used to make a non-flexible element flexible. filler() is a flexible empty element. You can use it align children on one side of the container.

An horizontal flow layout is implemented by:

• hflow (Horizontal flow)

Examples

  hbox({
    text(L"left") | border ,
    text(L"middle") | border | flex,
    text(L"right") | border,
    });

┌────┐┌─────────────────────────────────────────────────────────────────┐┌─────┐
│left││middle                                                           ││right│
└────┘└─────────────────────────────────────────────────────────────────┘└─────┘

  hbox({
    text(L"left") | border ,
    text(L"middle") | border | flex,
    text(L"right") | border | flex,
    });

┌────┐┌───────────────────────────────────┐┌───────────────────────────────────┐
│left││middle                             ││right                              │
└────┘└───────────────────────────────────┘└───────────────────────────────────┘

Components.

Element are stateless object. On the other side, components are used when an internal state is needed. Components are used to interact with the user with its keyboard. They handle keyboard navigation, including component focus.

Input

Menu

Toggle.

CheckBox

RadioBox