python - 如何使用 python-xlib 读取 X 属性？

Question

我在 Python Xlib 中找不到类似 XGetWindowProperty 的东西...

Answer 1

不要使用 get_property，而是使用 get_full_property。它隐藏了 XGetWindowProperty API 的奇怪方面。

我必须 grep 遍历 python-xlib 源代码才能找到它的使用示例，但这里是我最终编写的使用它的简化版本。

_NET_CLIENT_LIST 的定义来自 this spec :

_NET_CLIENT_LIST, WINDOW[]/32

...以及来自 this spec 的 _NET_WM_STRUT_PARTIAL 的定义:

_NET_WM_STRUT_PARTIAL, left, right, top, bottom, left_start_y, left_end_y,
right_start_y, right_end_y, top_start_x, top_end_x, bottom_start_x,
bottom_end_x,CARDINAL[12]/32

...转换成这段 Python 代码:

from collections import namedtuple

from Xlib.display import Display
from Xlib import Xatom

display = Display()
root = display.screen(0)['root']

StrutPartial = namedtuple('StrutPartial', 'left right top bottom'
    ' left_start_y left_end_y right_start_y right_end_y'
    ' top_start_x, top_end_x, bottom_start_x bottom_end_x')


def query_property(win, name, prop_type, format_size, empty=None):
    if isinstance(win, int):
        # Create a Window object for the Window ID
        win = display.create_resource_object('window', win)
    if isinstance(name, str):
        # Create/retrieve the X11 Atom for the property name
        name = display.get_atom(name)

    result = win.get_full_property(name, prop_type)
    if result and result.format == format_size:
        return result.value
    return empty

window_ids = ([root.id] +
    list(query_property(root, '_NET_CLIENT_LIST', Xatom.WINDOW, 32, [])))

for wid in window_ids:
    result = query_property(wid, '_NET_WM_STRUT_PARTIAL', Xatom.CARDINAL, 32)

    if result:
        # Toss it in a namedtuple to avoid needing opaque numeric indexes
        strut = StrutPartial(*result)
        print(strut)

...打印此示例输出:

StrutPartial(left=0, right=0, top=0, bottom=30, left_start_y=0, left_end_y=0, right_start_y=0, right_end_y=0, top_start_x=0, top_end_x=0, bottom_start_x=3200, bottom_end_x=4479)
StrutPartial(left=0, right=0, top=0, bottom=30, left_start_y=0, left_end_y=0, right_start_y=0, right_end_y=0, top_start_x=0, top_end_x=0, bottom_start_x=1280, bottom_end_x=3199)
StrutPartial(left=0, right=0, top=0, bottom=0, left_start_y=0, left_end_y=0, right_start_y=0, right_end_y=0, top_start_x=0, top_end_x=0, bottom_start_x=0, bottom_end_x=0)
StrutPartial(left=0, right=0, top=0, bottom=30, left_start_y=0, left_end_y=0, right_start_y=0, right_end_y=0, top_start_x=0, top_end_x=0, bottom_start_x=0, bottom_end_x=1279)

(result.value 是 12 个 32 位整数的 array.array，因为规范要求将 _NET_WM_STRUT_PARTIAL 设置为CARDINAL[12]/32。您可以像处理普通 list 或 tuple 一样迭代或索引 array.array ，但是 namedtuple 是一种使用命名属性的简单、舒适的方式。)