Resize Font in All Sessions in Window

This script registers a function that resizes the font of all sessions in a window. To use it, place it in ~/Library/Application Support/iTerm2/Scripts/AutoLaunch. Then restart iTerm2 or launch it manually. Then add keybindings with the action Invoke Script Function… and use a command of change_font_size(session_id:id,delta:1) for the keystroke that will make the font bigger and change_font_size(session_id:id,delta:-1) for the keystroke that will make the font smaller.

#!/usr/bin/env python3.7

import asyncio
import iterm2
import re

async def main(connection):
    app = await iterm2.async_get_app(connection)
    # This regex splits the font into its name and size. Fonts always end with
    # their size in points, preceded by a space.
    r = re.compile(r'^(.* )(\d*)$')

    async def change_font_size_session(session, delta):
        """Change the size of the font in a session by `delta` points."""
        # Get the session's profile because we need to know its font.
        profile = await session.async_get_profile()

        # Extract the name and point size of the font using a regex.
        font = profile.normal_font
        match = r.search(font)
        if not match:
            return
        groups = match.groups()
        name = groups[0]
        size = int(groups[1])

        # Prepare an update to the profile that increases the font size
        # by 6 points.
        replacement = name + str(size + delta)
        change = iterm2.LocalWriteOnlyProfile()
        change.set_normal_font(replacement)

        # Update the session's copy of its profile without updating the
        # underlying profile.
        await session.async_set_profile_properties(change)

    @iterm2.RPC
    async def change_font_size(session_id, delta):
        """Change the font size of all sessions in the window containing the
        session whose ID is `session_id` by `delta` points."""
        session = app.get_session_by_id(session_id)
        if not session:
            return
        tasks = []
        for tab in session.tab.window.tabs:
            for s in tab.sessions:
                tasks.append(change_font_size_session(s, delta))
        await asyncio.gather(*tasks)
    await change_font_size.async_register(connection)

iterm2.run_forever(main)

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