275 lines
8.6 KiB
Python
275 lines
8.6 KiB
Python
import curses
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import praw.errors
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from .helpers import clean
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from .curses_helpers import Color, show_notification
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__all__ = ['Navigator']
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class Navigator(object):
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"""
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Handles math behind cursor movement and screen paging.
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"""
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def __init__(
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self,
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valid_page_cb,
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page_index=0,
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cursor_index=0,
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inverted=False):
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self.page_index = page_index
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self.cursor_index = cursor_index
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self.inverted = inverted
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self._page_cb = valid_page_cb
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self._header_window = None
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self._content_window = None
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@property
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def step(self):
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return 1 if not self.inverted else -1
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@property
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def position(self):
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return (self.page_index, self.cursor_index, self.inverted)
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@property
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def absolute_index(self):
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return self.page_index + (self.step * self.cursor_index)
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def move(self, direction, n_windows):
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"Move the cursor down (positive direction) or up (negative direction)"
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valid, redraw = True, False
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forward = ((direction*self.step) > 0)
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if forward:
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if self.page_index < 0:
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if self._is_valid(0):
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# Special case - advance the page index if less than zero
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self.page_index = 0
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self.cursor_index = 0
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redraw = True
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else:
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valid = False
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else:
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self.cursor_index += 1
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if not self._is_valid(self.absolute_index):
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# Move would take us out of bounds
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self.cursor_index -= 1
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valid = False
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elif self.cursor_index >= (n_windows - 1):
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# Flip the orientation and reset the cursor
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self.flip(self.cursor_index)
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self.cursor_index = 0
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redraw = True
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else:
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if self.cursor_index > 0:
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self.cursor_index -= 1
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else:
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self.page_index -= self.step
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if self._is_valid(self.absolute_index):
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# We have reached the beginning of the page - move the index
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redraw = True
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else:
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self.page_index += self.step
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valid = False # Revert
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return valid, redraw
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def flip(self, n_windows):
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"Flip the orientation of the page"
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self.page_index += (self.step * n_windows)
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self.cursor_index = n_windows
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self.inverted = not self.inverted
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def _is_valid(self, page_index):
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"Check if a page index will cause entries to fall outside valid range"
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try:
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self._page_cb(page_index)
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except IndexError:
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return False
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else:
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return True
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class BasePage(object):
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"""
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Base terminal viewer incorperates a cursor to navigate content
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"""
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MIN_HEIGHT = 10
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MIN_WIDTH = 20
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def __init__(self, stdscr, reddit, content, **kwargs):
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self.stdscr = stdscr
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self.reddit = reddit
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self.content = content
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self.nav = Navigator(self.content.get, **kwargs)
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self._header_window = None
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self._content_window = None
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self._subwindows = None
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def move_cursor_up(self):
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self._move_cursor(-1)
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def move_cursor_down(self):
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self._move_cursor(1)
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def clear_input_queue(self):
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"Clear excessive input caused by the scroll wheel or holding down a key"
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self.stdscr.nodelay(1)
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while self.stdscr.getch() != -1:
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continue
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self.stdscr.nodelay(0)
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def upvote(self):
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data = self.content.get(self.nav.absolute_index)
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try:
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if 'likes' not in data:
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pass
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elif data['likes']:
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data['object'].clear_vote()
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data['likes'] = None
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else:
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data['object'].upvote()
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data['likes'] = True
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except praw.errors.LoginOrScopeRequired:
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show_notification(self.stdscr, ['Login to vote'])
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def downvote(self):
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data = self.content.get(self.nav.absolute_index)
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try:
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if 'likes' not in data:
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pass
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if data['likes'] is False:
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data['object'].clear_vote()
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data['likes'] = None
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else:
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data['object'].downvote()
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data['likes'] = False
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except praw.errors.LoginOrScopeRequired:
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show_notification(self.stdscr, ['Login to vote'])
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def draw(self):
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n_rows, n_cols = self.stdscr.getmaxyx()
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if n_rows < self.MIN_HEIGHT or n_cols < self.MIN_WIDTH:
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return
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# Note: 2 argument form of derwin breaks PDcurses on Windows 7!
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self._header_window = self.stdscr.derwin(1, n_cols, 0, 0)
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self._content_window = self.stdscr.derwin(n_rows-1, n_cols, 1, 0)
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self.stdscr.erase()
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self._draw_header()
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self._draw_content()
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self._add_cursor()
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@staticmethod
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def draw_item(window, data, inverted):
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raise NotImplementedError
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def _draw_header(self):
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n_rows, n_cols = self._header_window.getmaxyx()
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self._header_window.erase()
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attr = curses.A_REVERSE | curses.A_BOLD | Color.CYAN
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self._header_window.bkgd(' ', attr)
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sub_name = self.content.name.replace('/r/front', 'Front Page ')
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self._header_window.addnstr(0, 0, clean(sub_name), n_cols-1)
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if self.reddit.user is not None:
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username = self.reddit.user.name
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s_col = (n_cols - len(username) - 1)
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# Only print the username if it fits in the empty space on the right
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if (s_col - 1) >= len(sub_name):
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n = (n_cols - s_col - 1)
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self._header_window.addnstr(0, s_col, clean(username), n)
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self._header_window.refresh()
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def _draw_content(self):
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"""
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Loop through submissions and fill up the content page.
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"""
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n_rows, n_cols = self._content_window.getmaxyx()
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self._content_window.erase()
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self._subwindows = []
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page_index, cursor_index, inverted = self.nav.position
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step = self.nav.step
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# If not inverted, align the first submission with the top and draw
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# downwards. If inverted, align the first submission with the bottom
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# and draw upwards.
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current_row = (n_rows - 1) if inverted else 0
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available_rows = (n_rows - 1) if inverted else n_rows
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for data in self.content.iterate(page_index, step, n_cols-2):
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window_rows = min(available_rows, data['n_rows'])
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window_cols = n_cols - data['offset']
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start = current_row - window_rows if inverted else current_row
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subwindow = self._content_window.derwin(
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window_rows, window_cols, start, data['offset'])
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attr = self.draw_item(subwindow, data, inverted)
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self._subwindows.append((subwindow, attr))
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available_rows -= (window_rows + 1) # Add one for the blank line
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current_row += step * (window_rows + 1)
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if available_rows <= 0:
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break
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else:
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# If the page is not full we need to make sure that it is NOT
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# inverted. Unfortunately, this currently means drawing the whole
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# page over again. Could not think of a better way to pre-determine
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# if the content will fill up the page, given that it is dependent
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# on the size of the terminal.
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if self.nav.inverted:
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self.nav.flip((len(self._subwindows) - 1))
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self._draw_content()
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self._content_window.refresh()
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def _add_cursor(self):
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self._edit_cursor(curses.A_REVERSE)
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def _remove_cursor(self):
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self._edit_cursor(curses.A_NORMAL)
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def _move_cursor(self, direction):
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self._remove_cursor()
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valid, redraw = self.nav.move(direction, len(self._subwindows))
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if not valid: curses.flash()
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# Note: ACS_VLINE doesn't like changing the attribute, so always redraw.
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# if redraw: self._draw_content()
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self._draw_content()
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self._add_cursor()
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def _edit_cursor(self, attribute=None):
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# Don't allow the cursor to go below page index 0
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if self.nav.absolute_index < 0:
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return
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window, attr = self._subwindows[self.nav.cursor_index]
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if attr is not None:
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attribute |= attr
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n_rows, _ = window.getmaxyx()
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for row in range(n_rows):
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window.chgat(row, 0, 1, attribute)
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window.refresh()
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