# Rich

Rich is a Python library for _rich_ text and advanced formatting to the terminal. Rich provided an easy to use API for colored text (up to 16.7million colors) with bold / italic / underline etc. and a number of more sophisticated formatting options, such as syntax / regex highlighting, emoji, tables, and markdown rendering.

Rich is also a _framework_ in that it implements a simple protocol which you may use to make custom objects renderable with advanced terminal formatting.

## Installing

Rich may be installed with pip or your favorite PyPi package manager.

```
pip install rich
```

## Console Printing

The first step to using the rich console is to import and construct the `Console` object.

```python
from rich.console import Console

console = Console()
```

Most applications will require one `Console` instance. The easiest way to manage your console instance would be to construct an instance at the module level and import it where needed.

The Console object has a `print` method which has an intentionally similar interface to the builtin `print` function. Here's an example of use:

```
console.print("Hello", "World!")
```

As you might expect, this will print `"Hello World!"` to the terminal. The only difference from the `print` function is that the output is word-wrapped by default (Rich auto-detects the width of the terminal).

There are a few ways of adding color and style to your output. You can set a style for the entire output, by adding a `style` keyword argument. Here's an example:

```
console.print("Hello", "World!", style="bold red")
```

The output will be something like the following:

![Hello World](./imgs/hello_world.png)

That's fine for styling a line of text at a time. For more finely grained styling, Rich renders a special markup which is similar in syntax to [bbcode](https://en.wikipedia.org/wiki/BBCode). Here's an example:

![Console Markup](./imgs/where_there_is_a_will.png)

<code>
        <pre style="font-family:Menlo,'DejaVu Sans Mono',consolas,'Courier New',monospace">
Where there is a <span style="font-weight: bold">Will</span> there is a <span style="font-style: italic">way</span>. 
</pre>
    </code>

### Style definitions

Rich expects styles to be specified with a _style definition_ string, which is a intuitive syntax that reads almost like English.

There are a few ways of specifying colors:

- The name of the color (one of 256 possible constants) e.g. `"magenta"`. To see the full range of colors run `python -m rich.color` from the console.
- A number between 0 and 255 (inclusive) which corresponds to one of the 256 possible constants above.
- A CSS hex style color, e.g. `#ff0000` or `#d75faf`
- A CSS rbg style color, e.g. `rgb(215,95,175)`

By itself, a color will set the _foreground_ color. To set a _background_ color, precede the color with the word `"on"`. For example `"red on white"`.

Not that the CSS hex and RGB style of color lets you chose one of 16.7 million colors, but some terminals (notably OSX terminal) only support 256 colors. If Rich detects that only 256 colors are supported it will pick the closest color available.

To set a style or attribute add one or more of the following words:

- `"bold"` for bold text.
- `"dim"` for dim text.
- `"italic"` for italic text.
- `"underline"` for underlined text.
- `"blink"` for text that blinks.
- `"reverse"` to swap foreground and background text.
- `"conceal"` for concealed text (not supported on most terminals).
- `"strike"` for text with a line through it (bit supported on all terminals).

Style attributes and colors may appear in any order, so `"bold underline magenta on yellow"` has the same effect as `"on yellow magenta underline bold"`.

## Console Logging

## Emoji

Rich supports a simple way of inserting emoji in to terminal output, by using the name of the emoji between two colons. Here's an example:

```python
>>> console.print(":smiley: :vampire: :pile_of_poo: :thumbs_up: :raccoon:")
😃 🧛 💩 👍 🦝
```

Please use this feature wisely.

## Markdown

Rich can render markdown, and does a reasonable job of translating the formatting to the terminal.

To render markdown import the `Markdown` class and construct it with a string containing markdown. Then print it to the console.

```python
from rich.console import Console
from rich.markdown import Markdown

console = Console()
with open("README.md") as readme:
    markdown = Markdown(readme.read())
console.print(markdown)
```

This will produce output something like the following:

![markdown](./imgs/markdown.png)

## Syntax Highlighting

Rich uses the [pygments](https://pygments.org/) library to implement syntax highlighting. Usage is similar to rendering markdown; construct a `Syntax` object and print it to the console. Here's an example:

```python
from rich.console import Console
from rich.syntax import Syntax

my_code = '''
def iter_first_last(values: Iterable[T]) -> Iterable[Tuple[bool, bool, T]]:
    """Iterate and generate a tuple with a flag for first and last value."""
    iter_values = iter(values)
    try:
        previous_value = next(iter_values)
    except StopIteration:
        return
    first = True
    for value in iter_values:
        yield first, False, previous_value
        first = False
        previous_value = value
    yield first, True, previous_value
'''
syntax = Syntax(my_code, "python", theme="monokai", line_numbers=True)
console = Console()
console.print(syntax)
```

This will produce the following output:

![syntax](./imgs/syntax.png)