xnano.output

The frames a canvas has drawn, and the text printed while it was on the screen.

Get it from canvas.output. To print the current frame, use Canvas.render.

Attributes:

• is_captured (bool) –

  Whether a canvas on the screen is holding back what is printed, so it cannot corrupt the screen.

Examples:

import xnano

with xnano.new(width=12, height=2) as canvas:
    canvas.write('hello', x=1, y=1)
    canvas.output.render()
    assert canvas.output.snapshot().lines()[1] == ' hello'

Create the output's view of a canvas. Use canvas.output instead of calling this.

Parameters:

• canvas (Canvas[object, object]) –

  The canvas whose frames and held-back text this reads.

Methods:

• render –

  Draw a frame now and return it.

• snapshot –

  Return the last frame that was drawn, without drawing.

• take_captured –

  Return the text printed or logged since the last call, from a canvas on the screen.

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def __init__(self, canvas: Canvas[object, object]) -> None:
    """
    Create the output's view of a canvas. Use ``canvas.output`` instead of calling this.

    Args:
        canvas: The canvas whose frames and held-back text this reads.
    """
    self._canvas = canvas

is_captured: bool

render() -> FrameSnapshot

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def render(self) -> _core.FrameSnapshot:
    """Draw a frame now and return it."""
    canvas = self._canvas
    canvas._require_open()
    return canvas._host.call(lambda: canvas._runtime.render())

snapshot() -> FrameSnapshot

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def snapshot(self) -> _core.FrameSnapshot:
    """Return the last frame that was drawn, without drawing."""
    canvas = self._canvas
    canvas._require_open()
    return canvas._host.call(lambda: canvas._runtime.snapshot())

take_captured() -> str

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def take_captured(self) -> str:
    """
    Return the text printed or logged since the last call, from a canvas on the screen.

    A canvas on the screen holds back anything written to standard output or standard
    error so it cannot corrupt the screen. Text you do not take is printed when the
    canvas closes.
    """
    canvas = self._canvas
    canvas._require_open()
    return canvas._host.call(lambda: canvas._runtime.take_captured_output())