277 lines
8.0 KiB
Python
277 lines
8.0 KiB
Python
import os
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import time
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import threading
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import curses
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from curses import textpad, ascii
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from contextlib import contextmanager
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from .docs import HELP
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from .helpers import strip_textpad
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__all__ = ['ESCAPE', 'UARROW', 'DARROW', 'BULLET', 'show_notification',
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'show_help', 'LoadScreen', 'Color', 'text_input', 'curses_session']
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ESCAPE = 27
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# Curses does define constants for these (e.g. curses.ACS_BULLET)
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# However, they rely on using the curses.addch() function, which has been
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# found to be buggy and a PITA to work with. By defining them as unicode
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# points they can be added via the more reliable curses.addstr().
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# http://bugs.python.org/issue21088
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UARROW = u'\u25b2'.encode('utf-8')
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DARROW = u'\u25bc'.encode('utf-8')
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BULLET = u'\u2022'.encode('utf-8')
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def show_notification(stdscr, message):
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"""
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Overlay a message box on the center of the screen and wait for user input.
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Params:
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message (list): List of strings, one per line.
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"""
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n_rows, n_cols = stdscr.getmaxyx()
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box_width = max(map(len, message)) + 2
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box_height = len(message) + 2
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# Make sure the window is large enough to fit the message
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if (box_width > n_cols) or (box_height > n_rows):
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curses.flash()
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return
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s_row = (n_rows - box_height) // 2
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s_col = (n_cols - box_width) // 2
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window = stdscr.derwin(box_height, box_width, s_row, s_col)
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window.erase()
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window.border()
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for index, line in enumerate(message, start=1):
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window.addstr(index, 1, line)
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window.refresh()
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stdscr.getch()
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window.clear()
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window = None
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stdscr.refresh()
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def show_help(stdscr):
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"""
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Overlay a message box with the help screen.
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"""
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show_notification(stdscr, docs.HELP.split("\n"))
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class LoadScreen(object):
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"""
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Display a loading dialog while waiting for a blocking action to complete.
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This class spins off a seperate thread to animate the loading screen in the
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background.
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Usage:
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#>>> loader = LoadScreen(stdscr)
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#>>> with loader(...):
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#>>> blocking_request(...)
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"""
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def __init__(self, stdscr):
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self._stdscr = stdscr
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self._args = None
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self._animator = None
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self._is_running = None
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def __call__(
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self,
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delay=0.5,
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interval=0.4,
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message='Downloading',
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trail='...'):
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"""
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Params:
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delay (float): Length of time that the loader will wait before
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printing on the screen. Used to prevent flicker on pages that
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load very fast.
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interval (float): Length of time between each animation frame.
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message (str): Message to display
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trail (str): Trail of characters that will be animated by the
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loading screen.
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"""
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self._args = (delay, interval, message, trail)
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return self
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def __enter__(self):
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self._animator = threading.Thread(target=self.animate, args=self._args)
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self._animator.daemon = True
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self._is_running = True
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self._animator.start()
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def __exit__(self, exc_type, exc_val, exc_tb):
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self._is_running = False
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self._animator.join()
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def animate(self, delay, interval, message, trail):
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start = time.time()
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while (time.time() - start) < delay:
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if not self._is_running:
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return
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message_len = len(message) + len(trail)
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n_rows, n_cols = self._stdscr.getmaxyx()
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s_row = (n_rows - 3) // 2
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s_col = (n_cols - message_len - 1) // 2
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window = self._stdscr.derwin(3, message_len+2, s_row, s_col)
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while True:
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for i in range(len(trail)+1):
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if not self._is_running:
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window.clear()
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window = None
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self._stdscr.refresh()
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return
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window.erase()
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window.border()
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window.addstr(1, 1, message + trail[:i])
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window.refresh()
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time.sleep(interval)
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class Color(object):
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"""
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Color attributes for curses.
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"""
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_colors = {
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'RED': (curses.COLOR_RED, -1),
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'GREEN': (curses.COLOR_GREEN, -1),
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'YELLOW': (curses.COLOR_YELLOW, -1),
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'BLUE': (curses.COLOR_BLUE, -1),
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'MAGENTA': (curses.COLOR_MAGENTA, -1),
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'CYAN': (curses.COLOR_CYAN, -1),
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'WHITE': (curses.COLOR_WHITE, -1),
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}
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@classmethod
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def init(cls):
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"""
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Initialize color pairs inside of curses using the default background.
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This should be called once during the curses initial setup. Afterwards,
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curses color pairs can be accessed directly through class attributes.
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"""
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# Assign the terminal's default (background) color to code -1
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curses.use_default_colors()
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for index, (attr, code) in enumerate(cls._colors.items(), start=1):
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curses.init_pair(index, code[0], code[1])
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setattr(cls, attr, curses.color_pair(index))
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@classmethod
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def get_level(cls, level):
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levels = [cls.MAGENTA, cls.CYAN, cls.GREEN, cls.YELLOW]
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return levels[level % len(levels)]
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def text_input(window, allow_resize=True):
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"""
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Transform a window into a text box that will accept user input and loop
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until an escape sequence is entered.
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If enter is pressed, return the input text as a string.
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If escape is pressed, return None.
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"""
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window.clear()
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# Set cursor mode to 1 because 2 doesn't display on some terminals
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curses.curs_set(1)
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# Turn insert_mode off to avoid the recursion error described here
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# http://bugs.python.org/issue13051
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textbox = textpad.Textbox(window, insert_mode=False)
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textbox.stripspaces = 0
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def validate(ch):
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"Filters characters for special key sequences"
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if ch == ESCAPE:
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raise EscapeInterrupt
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if (not allow_resize) and (ch == curses.KEY_RESIZE):
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raise EscapeInterrupt
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# Fix backspace for iterm
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if ch == ascii.DEL:
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ch = curses.KEY_BACKSPACE
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return ch
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# Wrapping in an exception block so that we can distinguish when the user
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# hits the return character from when the user tries to back out of the
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# input.
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try:
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out = textbox.edit(validate=validate)
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except EscapeInterrupt:
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out = None
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curses.curs_set(0)
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return strip_textpad(out)
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@contextmanager
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def curses_session():
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"""
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Setup terminal and initialize curses.
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"""
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try:
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# Curses must wait for some time after the Escape key is pressed to
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# check if it is the beginning of an escape sequence indicating a
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# special key. The default wait time is 1 second, which means that
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# getch() will not return the escape key (27) until a full second
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# after it has been pressed.
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# Turn this down to 25 ms, which is close to what VIM uses.
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# http://stackoverflow.com/questions/27372068
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os.environ['ESCDELAY'] = '25'
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# Initialize curses
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stdscr = curses.initscr()
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# Turn off echoing of keys, and enter cbreak mode,
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# where no buffering is performed on keyboard input
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curses.noecho()
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curses.cbreak()
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# In keypad mode, escape sequences for special keys
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# (like the cursor keys) will be interpreted and
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# a special value like curses.KEY_LEFT will be returned
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stdscr.keypad(1)
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# Start color, too. Harmless if the terminal doesn't have
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# color; user can test with has_color() later on. The try/catch
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# works around a minor bit of over-conscientiousness in the curses
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# module -- the error return from C start_color() is ignorable.
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try:
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curses.start_color()
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except:
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pass
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Color.init()
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# Hide blinking cursor
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curses.curs_set(0)
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yield stdscr
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finally:
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if stdscr is not None:
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stdscr.keypad(0)
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curses.echo()
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curses.nocbreak()
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curses.endwin()
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