mirror of https://github.com/Textualize/rich.git
168 lines
5.6 KiB
ReStructuredText
168 lines
5.6 KiB
ReStructuredText
.. _live:
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Live Display
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============
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Rich can display continiuously updated information for any renderable.
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To see some live display examples, try this from the command line::
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python -m rich.live
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.. note::
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Make sure your terminal is tall enough or you may see it print "Terminal too small"
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Basic Usage
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-----------
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The basic usage can be split into two use cases.
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1. Same Renderable
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~~~~~~~~~~~~~~~~~~
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When keeping the same renderable, you simply pass the :class:`~rich.console.RenderableType` you would like to see updating and provide
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a ``refresh_per_second`` parameter. The Live :class:`~rich.live.Live` will automatically update the console at the provided refresh rate.
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**Example**::
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import time
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from rich.live import Live
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from rich.table import Table
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table = Table()
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table.add_column("Row ID")
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table.add_column("Description")
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table.add_column("Level")
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with Live(table, refresh_per_second=4): # update 4 times a second to feel fluid
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for row in range(12):
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time.sleep(0.4) # arbitrary delay
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# update the renderable internally
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table.add_row(f"{row}", f"description {row}", "[red]ERROR")
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2. New Renderable
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~~~~~~~~~~~~~~~~~
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You can also provide constant new renderable to :class:`~rich.live.Live` using the :meth:`~rich.live.Live.update` function. This allows you to
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completely change what is rendered live.
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**Example**::
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import random
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import time
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from rich.live import Live
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from rich.table import Table
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def generate_table() -> Table:
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table = Table()
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table.add_column("ID")
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table.add_column("Value")
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table.add_column("Status")
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for row in range(random.randint(2, 6)):
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value = random.random() * 100
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table.add_row(
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f"{row}", f"{value:3.2f}", "[red]ERROR" if value < 50 else "[green]SUCCESS"
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)
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return table
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with Live(refresh_per_second=4) as live:
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for _ in range(40):
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time.sleep(0.4)
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live.update(generate_table())
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Advanced Usage
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--------------
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Transient Display
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~~~~~~~~~~~~~~~~~
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Normally when you exit live context manager (or call :meth:`~rich.live.Live.stop`) the last refreshed item remains in the terminal with the cursor on the following line.
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You can also make the live display disappear on exit by setting ``transient=True`` on the Live constructor. Here's an example::
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with Live(transient=True) as live:
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...
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Auto refresh
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~~~~~~~~~~~~
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By default, the live display will refresh 4 times a second. You can set the refresh rate with the ``refresh_per_second`` argument on the :class:`~rich.live.Live` constructor.
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You should set this to something lower than 4 if you know your updates will not be that frequent or higher for a smoother feeling.
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You might want to disable auto-refresh entirely if your updates are not very frequent, which you can do by setting ``auto_refresh=False`` on the constructor.
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If you disable auto-refresh you will need to call :meth:`~rich.live.Live.refresh` manually or :meth:`~rich.live.Live.update` with ``refresh=True``.
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Hide "Terminal Too Small" Warning
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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By default, the live display will not render if the renderable is too tall for the console and instead will render a warning line "Terminal Too Small".
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This is because the console cannot properly clear a renderable if it is too large (limitation on terminals). You can disable this by setting ``hide_overflow=False`` on the constructor.
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You may want to disable this feature if:
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1. You want to always see the live display and also do not mind that it will fill-up with previous renderings.
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2. If you need the display to render as fast as possible. (This check performs a pre-rendering of the renderable which may be costly)
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.. note::
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Once the live display stops, even if the display is too small it will render the last frame since it doesn't have to clear it.
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Complex Renders
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~~~~~~~~~~~~~~~
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Refer to the :ref:`Render Groups` about combining multiple :class:`RenderableType` together so that it may be passed into the :class:`~rich.live.Live` constructor
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or :meth:`~rich.live.Live.update` method.
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For more powerful structuring it is also possible to use nested tables.
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Print / log
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~~~~~~~~~~~
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The Live class will create an internal Console object which you can access via ``live.console``. If you print or log to this console, the output will be displayed *above* the live display. Here's an example::
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import time
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from rich.live import Live
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from rich.table import Table
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table = Table()
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table.add_column("Row ID")
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table.add_column("Description")
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table.add_column("Level")
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with Live(table, refresh_per_second=4): # update 4 times a second to feel fluid
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for row in range(12):
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live.console.print("Working on row #{row}")
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time.sleep(0.4)
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table.add_row(f"{row}", f"description {row}", "[red]ERROR")
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If you have another Console object you want to use, pass it in to the :class:`~rich.live.Live` constructor. Here's an example::
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from my_project import my_console
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with Live(console=my_console) as live:
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my_console.print("[bold blue]Starting work!")
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...
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.. note::
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If you are passing in a file console, the live display only show the last item once the live context is left.
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Redirecting stdout / stderr
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~~~~~~~~~~~~~~~~~~~~~~~~~~~
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To avoid breaking the progress display visuals, Rich will redirect ``stdout`` and ``stderr`` so that you can use the builtin ``print`` statement. This feature is enabled by default, but you can disable by setting ``redirect_stdout`` or ``redirect_stderr`` to ``False``
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