Custom __rich_console__ method - only the first line of output is being displayed

Read the docs I have checked the documentation for __rich_console__ - I couldn’t find much, so I may have missed something.

Describe the bug I have a class that wraps a renderable, with a custom __rich_console__ method which yields only the last N lines of the rendered representation of the wrapped renderable. However, when I use it, only the first of the yielded lines is displayed.

To Reproduce

import rich

class Latest:
  def __init__(self, n, renderable):
    self.n = n
    self.renderable = renderable
  def __rich_console__(self, console, options):
    for line in console.render_lines(self.renderable)[-self.n:]:
        for seg in line:
            print(repr(seg))
            yield seg

rich.print(Latest(3, "\n".join(f"Line {i}" for i in range(10))))

Output from this is:

Segment('Line ', Style())
Segment('7', Style(color=Color('cyan', ColorType.STANDARD, number=6), bold=True, italic=False))
Segment('
   ', Style())
Segment('Line ', Style())
Segment('8', Style(color=Color('cyan', ColorType.STANDARD, number=6), bold=True, italic=False))
Segment('
   ', Style())
Segment('Line ', Style())
Segment('9', Style(color=Color('cyan', ColorType.STANDARD, number=6), bold=True, italic=False))
Segment('
   ')
Line 7

It shows all of the segments, but the rendered output is only “Line 7” - the following lines appear to have been discarded.

Platform What platform (Win/Linux/Mac) are you running on? Windows 10 What terminal software are you using? Windows Terminal

Diagnose I may ask you to cut and paste the output of the following commands. It may save some time if you do it now.

python -m rich.diagnose
python -m rich._windows
pip freeze | grep rich

❯ python -m rich.diagnose
╭───────────────────────── <class 'rich.console.Console'> ─────────────────────────╮
│ A high level console interface.                                                  │
│                                                                                  │
│ ╭──────────────────────────────────────────────────────────────────────────────╮ │
│ │ <console width=120 ColorSystem.TRUECOLOR>                                    │ │
│ ╰──────────────────────────────────────────────────────────────────────────────╯ │
│                                                                                  │
│     color_system = 'truecolor'                                                   │
│         encoding = 'utf-8'                                                       │
│             file = <_io.TextIOWrapper name='<stdout>' mode='w' encoding='utf-8'> │
│           height = 30                                                            │
│    is_alt_screen = False                                                         │
│ is_dumb_terminal = False                                                         │
│   is_interactive = True                                                          │
│       is_jupyter = False                                                         │
│      is_terminal = True                                                          │
│   legacy_windows = False                                                         │
│         no_color = False                                                         │
│          options = ConsoleOptions(                                               │
│                        size=ConsoleDimensions(width=120, height=30),             │
│                        legacy_windows=False,                                     │
│                        min_width=1,                                              │
│                        max_width=120,                                            │
│                        is_terminal=True,                                         │
│                        encoding='utf-8',                                         │
│                        max_height=30,                                            │
│                        justify=None,                                             │
│                        overflow=None,                                            │
│                        no_wrap=False,                                            │
│                        highlight=None,                                           │
│                        markup=None,                                              │
│                        height=None                                               │
│                    )                                                             │
│            quiet = False                                                         │
│           record = False                                                         │
│         safe_box = True                                                          │
│             size = ConsoleDimensions(width=120, height=30)                       │
│        soft_wrap = False                                                         │
│           stderr = False                                                         │
│            style = None                                                          │
│         tab_size = 8                                                             │
│            width = 120                                                           │
╰──────────────────────────────────────────────────────────────────────────────────╯
PS 16:55 (.venv) 00:00.461 C:\Work\Scratch\threadprog
❯ python -m rich._windows
platform="Windows"
WindowsConsoleFeatures(vt=True, truecolor=True)
PS 16:56 (.venv) 00:00.449 C:\Work\Scratch\threadprog
❯ pip freeze | grep rich
rich==10.10.0

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[pfmoore]

Ah! They are probably long stretches of spaces to fill the line. It’s the terminal wrapping them that confused me. That makes sense (I’m sort of abusing the machinery here, so getting something weird isn’t entirely unexpected).

Thanks for the very fast and useful help.

[willmcgugan]

You’ll need new lines (“\n”) in the output. Easiest way to do that would be to set new_lines=True on the render_lines call.