208 lines
7.3 KiB
Python
208 lines
7.3 KiB
Python
# ----------------------------------------------------------------------------
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# pyglet
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# Copyright (c) 2006-2008 Alex Holkner
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# Copyright (c) 2008-2021 pyglet contributors
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# All rights reserved.
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#
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# Redistribution and use in source and binary forms, with or without
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# modification, are permitted provided that the following conditions
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# are met:
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#
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# * Redistributions of source code must retain the above copyright
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# notice, this list of conditions and the following disclaimer.
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# * Redistributions in binary form must reproduce the above copyright
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# notice, this list of conditions and the following disclaimer in
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# the documentation and/or other materials provided with the
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# distribution.
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# * Neither the name of pyglet nor the names of its
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# contributors may be used to endorse or promote products
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# derived from this software without specific prior written
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# permission.
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#
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# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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# FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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# COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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# INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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# BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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# LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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# CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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# ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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# POSSIBILITY OF SUCH DAMAGE.
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# ----------------------------------------------------------------------------
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"""Fork a child process and inform it of mode changes to each screen. The
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child waits until the parent process dies, and then connects to each X server
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with a mode change and restores the mode.
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This emulates the behaviour of Windows and Mac, so that resolution changes
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made by an application are not permanent after the program exits, even if
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the process is terminated uncleanly.
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The child process is communicated to via a pipe, and watches for parent
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death with a Linux extension signal handler.
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"""
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import ctypes
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import os
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import signal
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import struct
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import threading
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from pyglet.libs.x11 import xlib
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from pyglet.util import asbytes
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try:
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from pyglet.libs.x11 import xf86vmode
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except:
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# No xf86vmode... should not be switching modes.
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pass
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_restore_mode_child_installed = False
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_restorable_screens = set()
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_mode_write_pipe = None
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# Mode packets tell the child process how to restore a given display and
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# screen. Only one packet should be sent per display/screen (more would
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# indicate redundancy or incorrect restoration). Packet format is:
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# display (max 256 chars),
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# screen
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# width
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# height
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# rate
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class ModePacket:
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format = '256siHHI'
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size = struct.calcsize(format)
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def __init__(self, display, screen, width, height, rate):
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self.display = display
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self.screen = screen
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self.width = width
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self.height = height
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self.rate = rate
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def encode(self):
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return struct.pack(self.format, self.display, self.screen, self.width, self.height, self.rate)
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@classmethod
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def decode(cls, data):
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display, screen, width, height, rate = struct.unpack(cls.format, data)
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return cls(display.strip(asbytes('\0')), screen, width, height, rate)
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def __repr__(self):
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return '%s(%r, %r, %r, %r, %r)' % (
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self.__class__.__name__, self.display, self.screen,
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self.width, self.height, self.rate)
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def set(self):
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display = xlib.XOpenDisplay(self.display)
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modes, n_modes = get_modes_array(display, self.screen)
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mode = get_matching_mode(modes, n_modes, self.width, self.height, self.rate)
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if mode is not None:
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xf86vmode.XF86VidModeSwitchToMode(display, self.screen, mode)
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free_modes_array(modes, n_modes)
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xlib.XCloseDisplay(display)
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def get_modes_array(display, screen):
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count = ctypes.c_int()
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modes = ctypes.POINTER(ctypes.POINTER(xf86vmode.XF86VidModeModeInfo))()
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xf86vmode.XF86VidModeGetAllModeLines(display, screen, count, modes)
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return modes, count.value
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def get_matching_mode(modes, n_modes, width, height, rate):
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# Copy modes out of list and free list
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for i in range(n_modes):
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mode = modes.contents[i]
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if (mode.hdisplay == width and
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mode.vdisplay == height and
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mode.dotclock == rate):
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return mode
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return None
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def free_modes_array(modes, n_modes):
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for i in range(n_modes):
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mode = modes.contents[i]
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if mode.privsize:
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xlib.XFree(mode.private)
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xlib.XFree(modes)
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def _install_restore_mode_child():
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global _mode_write_pipe
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global _restore_mode_child_installed
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if _restore_mode_child_installed:
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return
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# Parent communicates to child by sending "mode packets" through a pipe:
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mode_read_pipe, _mode_write_pipe = os.pipe()
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if os.fork() == 0:
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# Child process (watches for parent to die then restores video mode(s).
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os.close(_mode_write_pipe)
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# Set up SIGHUP to be the signal for when the parent dies.
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PR_SET_PDEATHSIG = 1
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libc = ctypes.cdll.LoadLibrary('libc.so.6')
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libc.prctl.argtypes = (ctypes.c_int, ctypes.c_ulong, ctypes.c_ulong,
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ctypes.c_ulong, ctypes.c_ulong)
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libc.prctl(PR_SET_PDEATHSIG, signal.SIGHUP, 0, 0, 0)
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# SIGHUP indicates the parent has died. The child lock is unlocked, it
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# stops reading from the mode packet pipe and restores video modes on
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# all displays/screens it knows about.
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def _sighup(signum, frame):
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parent_wait_lock.release()
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parent_wait_lock = threading.Lock()
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parent_wait_lock.acquire()
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signal.signal(signal.SIGHUP, _sighup)
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# Wait for parent to die and read packets from parent pipe
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packets = []
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buffer = asbytes('')
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while parent_wait_lock.locked():
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try:
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data = os.read(mode_read_pipe, ModePacket.size)
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buffer += data
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# Decode packets
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while len(buffer) >= ModePacket.size:
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packet = ModePacket.decode(buffer[:ModePacket.size])
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packets.append(packet)
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buffer = buffer[ModePacket.size:]
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except OSError:
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pass # Interrupted system call
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for packet in packets:
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packet.set()
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os._exit(0)
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else:
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# Parent process. Clean up pipe then continue running program as
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# normal. Send mode packets through pipe as additional
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# displays/screens are mode switched.
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os.close(mode_read_pipe)
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_restore_mode_child_installed = True
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def set_initial_mode(mode):
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_install_restore_mode_child()
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display = xlib.XDisplayString(mode.screen.display._display)
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screen = mode.screen.display.x_screen
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# Only store one mode per screen.
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if (display, screen) in _restorable_screens:
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return
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packet = ModePacket(display, screen, mode.width, mode.height, mode.rate)
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os.write(_mode_write_pipe, packet.encode())
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_restorable_screens.add((display, screen))
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