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# Copyright 2014 Open Source Robotics Foundation, Inc.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
"""
This module has a miscellaneous set of functions for working with terminals.
You can use the :py:func:`get_terminal_dimensions` to get the width and
height of the terminal as a tuple.
You can also use the :py:func:`is_tty` function to determine if a given object
is a tty.
"""
import os
import struct
import subprocess
__all__ = ['GetTerminalDimensionsError', 'get_terminal_dimensions', 'is_tty']
class GetTerminalDimensionsError(Exception):
"""Raised when the terminal dimensions cannot be determined."""
pass
def _get_terminal_dimensions_windows():
try:
from ctypes import create_string_buffer
from ctypes import windll
except ImportError as exc:
raise GetTerminalDimensionsError("Failed to get dimensions: {0}"
.format(exc))
STDOUT = -11
h = windll.kernel32.GetStdHandle(STDOUT)
buffer_info = create_string_buffer(22)
if not windll.kernel32.GetConsoleScreenBufferInfo(h, buffer_info):
raise GetTerminalDimensionsError(
"Call to windll.kernel32.GetConsoleScreenBufferInfo failed")
try:
(_, _, _, _, _, left, top, right, bottom, _, _) \
= struct.unpack("hhhhHhhhhhh", buffer_info.raw)
except struct.error as exc:
raise GetTerminalDimensionsError("Failed to unpack data: {0}"
.format(exc))
width = right - left + 1
height = bottom - top + 1
return width, height
def _get_terminal_dimensions_unix():
# This function uses `tput` and should work on any Unix system
# See: http://en.wikipedia.org/wiki/Tput
try:
width = subprocess.check_output(['tput', 'cols'])
width = int(width.strip())
except (subprocess.CalledProcessError, ValueError) as exc:
raise GetTerminalDimensionsError("Failed to get width: {0}"
.format(exc))
try:
height = subprocess.check_output(['tput', 'lines'])
height = int(height.strip())
except (subprocess.CalledProcessError, ValueError) as exc:
raise GetTerminalDimensionsError("Failed to get height: {0}"
.format(exc))
return width, height
def get_terminal_dimensions():
"""Returns the width and height of the terminal.
:returns: width and height in that order as a tuple
:rtype: tuple
:raises: GetTerminalDimensionsError when the terminal dimensions
cannot be determined
"""
if os.name in ['nt']:
return _get_terminal_dimensions_windows()
return _get_terminal_dimensions_unix()
def is_tty(stream):
"""Returns True if the given stream is a tty, else False
:param stream: object to be checked for being a tty
:returns: True if the given object is a tty, otherwise False
:rtype: bool
"""
return hasattr(stream, 'isatty') and stream.isatty()
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