FTXUI/doc/module-dom.md

@page module-dom ftxui / dom @tableofcontents

This module defines a hierarchical set of ftxui::Element. An element manages the layout and can be responsive to the terminal dimension changes. Note the following example where this module is used to create a simple layout with a number of operators:

The @subpage module-dom-examples section provides a collection of examples.

Example:

namespace ftxui {
    ...

// Define the document
Element document = vbox({
  text("The window") | bold | color(Color::Blue),
  gauge(0.5)
  text("The footer")
});

// Add a border, by calling the `ftxui::border` decorator function.
document = border(document);

// Add another border, using the pipe operator.
document = document | border.

// Add another border, using the |= operator.
document |= border

...
}

List of elements

The list of all elements are included and can be accessed by including the corresponding header file:

#include <ftxui/dom/elements.hpp>

\include{strip} "ftxui/dom/elements.hpp"

text

The most simple widget. It displays a text.

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

I am a piece of text.

vtext

Identical to ftxui::text, but displayed vertically.

Code:

vtext("HELLO");

Terminal output:

H
E
L
L
O

paragraph 

Similar to ftxui::text, but the individual word are wrapped along multiple lines, depending on the width of its container.

Sample Code:

paragraph("A very long text")

For a more detailed example refer to detailed example. Paragraph also includes a number of other variants as shown below:

namespace ftxui {
    Element paragraph(std::string text);
    Element paragraphAlignLeft(std::string text);
    Element paragraphAlignRight(std::string text);
    Element paragraphAlignCenter(std::string text);
    Element paragraphAlignJustify(std::string text);
}

border

Adds a border around an element.

Code:

border(text("The element"))

Terminal output:

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

Note

You can achieve the same behavior by using the pipe operator.

Code:

text("The element") | border

Border also comes in a variety of styles as shown below:

namespace ftxui {
    Element border(Element);
    Element borderLight(Element);
    Element borderHeavy(Element);
    Element borderDouble(Element);
    Element borderRounded(Element);
    Element borderEmpty(Element);
    Decorator borderStyled(BorderStyle);
    Decorator borderWith(Pixel);
}

window

A ftxui::window is a ftxui::border, but with an additional header. To add a window around an element, wrap it and specify a string as the header. Code:

window("The window", text("The element"))

Terminal output:

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

separator

Displays a vertical/horizontal line to visually split the content of a container in two.

Code:

border(
  hbox({
    text("Left"), 
    separator(),
    text("Right")
  })
)

Terminal output:

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

Separators come in a variety of flavors as shown below:

namespace ftxui {
    Element separator(void);
    Element separatorLight();
    Element separatorHeavy();
    Element separatorDouble();
    Element separatorEmpty();
    Element separatorStyled(BorderStyle);
    Element separator(Pixel);
    Element separatorCharacter(std::string);
    Element separatorHSelector(float left,
                               float right,
                               Color background,
                               Color foreground);
    Element separatorVSelector(float up,
                               float down,
                               Color background,
                               Color foreground);
}

gauge

This is a visual element that represents a ratio of progress.

Code:

border(gauge(0.5))

Terminal output:

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

Gauges can be displayed in many orientations as shown below:

namespace {
    Element gauge(float ratio);
    Element gaugeLeft(float ratio);
    Element gaugeRight(float ratio);
    Element gaugeUp(float ratio);
    Element gaugeDown(float ratio);
    Element gaugeDirection(float ratio, GaugeDirection);
}

graph

@htmlonly

@endhtmlonly

See:

Element graph(GraphFunction);

Colors

Most terminal consoles can display colored text and colored backgrounds. FTXUI supports every color palette:

Decorator color(Color);
Decorator bgcolor(Color);

Color gallery:

Palette16 #

On most terminals the following colors are supported:

• Default

• Black

• GrayDark

• GrayLight

• White

• Blue

• BlueLight

• Cyan

• CyanLight

• Green

• GreenLight

• Magenta

• MagentaLight

• Red

• RedLight

• Yellow

• YellowLight

Example use of the above colors using the pipe operator:

text("Blue foreground") | color(Color::Blue);
text("Blue background") | bgcolor(Color::Blue);
text("Black on white") | color(Color::Black) | bgcolor(Color::White);

Palette256 #

On terminal supporting 256 colors. @htmlonly

@endhtmlonly

text("HotPink") | color(Color::HotPink);

TrueColor

On terminal supporting trueColor, you can directly use the 24bit RGB color space:

Use the constructors below to specify the RGB or HSV values for your color:

There are two constructors:

ftxui::Color::RGB(uint8_t red, uint8_t green, uint8_t blue);
ftxui::Color::HSV(uint8_t hue, uint8_t saturation, uint8_t value);

@htmlonly

@endhtmlonly

LinearGradient

FTXUI supports linear gradient. Either on the foreground or the background.

Decorator color(const LinearGradient&);
Decorator bgcolor(const LinearGradient&);

A ftxui::LinearGradient is defined by an angle in degree, and a list of color stops.

auto gradient = LinearGradient()
  .Angle(45)
  .AddStop(0.0, Color::Red)
  .AddStop(0.5, Color::Green)
  .AddStop(1.0, Color::Blue);

You can also use simplified constructors:

LinearGradient(Color::Red, Color::Blue);

LinearGradient(45, Color::Red, Color::Blue);

See demo.

Style

In addition to colored text and colored backgrounds. Many terminals support text effects such as: bold, italic, dim, underlined, inverted, blink.

Element bold(Element);
Element italic(Element);
Element dim(Element);
Element inverted(Element);
Element underlined(Element);
Element underlinedDouble(Element);
Element strikethrough(Element);
Element blink(Element);
Decorator color(Color);
Decorator bgcolor(Color);
Decorator colorgrad(LinearGradient);
Decorator bgcolorgrad(LinearGradient);

Example

To use these effects, simply wrap your elements with your desired effect:

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

Alternatively, use the pipe operator to chain it on your element:

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

Layout

Enables elements to be arranged in the following ways:

• Horizontally with ftxui::hbox
• Vertically with ftxui::vbox
• Inside a grid with ftxui::gridbox
• Wrapped along one direction using the ftxui::flexbox.

Example using ftxui::hbox, ftxui::vbox and ftxui::filler.

Example using ftxui::gridbox:

Example using flexbox:

Checkout this example and the associated demo.

Element can also become flexible using the ftxui::flex decorator.

Code:

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

Terminal output:

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

Code:

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

Terminal output:

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

Table

Enables easy formatting of data into a neat table like visual form.

Code example:

Canvas

See the API <ftxui/dom/canvas.hpp>

  auto c = Canvas(100, 100);
  c.DrawPointLine(10, 10, 80, 10, Color::Red);
  auto element = canvas(c);

Drawing can be performed on a ftxui::Canvas, using braille, block, or simple characters:

Simple example:

Complex example: