dotfiles/sway/window_dimensions.py

#!/usr/bin/env python3
# Return the dimensions of the current window[s] as selected in sway.
#
# Non-zero exitcode if something unexpected comes up.
#
# The printed dimensions will match the slup regex below:
#   /[0-9]+,[0-9]+ [0-9]+x[0-9]+/
import json
import os
from subprocess import run, PIPE
from typing import Optional


def get_sway_tree() -> dict:
    swaymsg = run([MSG_COMMAND, "-t", "get_tree"], stdout=PIPE)
    swaymsg.check_returncode()
    return json.loads(swaymsg.stdout)


def format_window_coords(window: dict, rect: dict) -> str:
    if sum(window.values()) == 0:  # Multiple windows selected
        x = rect["x"]
        y = rect["y"]
        w = rect["width"]
        h = rect["height"]
    elif window["y"] + window["height"] == rect["height"]:  # Account for border
        x = rect["x"] + window["x"]
        y = rect["y"]
        w = window["width"]
        h = window["height"] - window["y"]
    else:
        x = rect["x"] + window["x"]
        y = rect["y"] + window["y"]
        w = window["width"]
        h = window["height"]

    return f"{x},{y} {w}x{h}"


# Return dict indexing path to the first entry with "key" matching "val"
# For example, it may return
#   ['nodes', 1, 'nodes', 1, 'nodes', 0, 'nodes', 0]
# Which can then be used to index the original js:
#   js['nodes'][1]['nodes'][1]['nodes'][0]['nodes'][0][find_key] == find_val
def trace_json_path(js, find_key, find_val) -> Optional[list]:
    if isinstance(js, dict):
        for key, val in js.items():
            if key == find_key and val == find_val:
                return []  # Base case

            elif isinstance(val, list):
                trace = trace_json_path(val, find_key, find_val)
                if trace is not None:
                    return [key] + trace

    elif isinstance(js, list):
        for i, item in enumerate(js):
            trace = trace_json_path(item, find_key, find_val)
            if trace is not None:
                return [i] + trace

    return None


def focused_sway_area():
    tree = get_sway_tree()
    trace = trace_json_path(tree, "focused", True)

    if trace is None:
        print("No focused window was found")
        exit(1)

    for i in trace:
        tree = tree[i]
    return format_window_coords(tree["window_rect"], tree["rect"])


if __name__ == "__main__":
    try:
        if "wayland" in os.environ["XDG_SESSION_TYPE"]:
            MSG_COMMAND = "swaymsg"
        else:
            MSG_COMMAND = "i3-msg"
    except KeyError:
        MSG_COMMAND = "i3-msg"

    print(focused_sway_area())