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#!/usr/bin/env python3
"""
Example program that can view a body of text and scroll.
This is meant to be a test for writing termdiff using curses.
"""
import sys
import urwid
import urwid.command_map
import urwid.curses_display
urwid.command_map['ctrl v'] = urwid.CURSOR_PAGE_DOWN
urwid.command_map['meta v'] = urwid.CURSOR_PAGE_UP
FTEST = open('/tmp/input.log', 'w')
def debug_input_filter(keys, raw):
FTEST.write('{} ({})\n'.format(keys, raw))
FTEST.flush()
return keys
class LineWalker(urwid.ListWalker):
"""ListWalker-compatible class for lazily reading file contents."""
def __init__(self, name):
self.file = open(name)
self.lines = []
self.focus = 0
def get_focus(self):
return self._get_at_pos(self.focus)
def set_focus(self, focus):
self.focus = focus
self._modified()
def get_next(self, start_from):
return self._get_at_pos(start_from + 1)
def get_prev(self, start_from):
return self._get_at_pos(start_from - 1)
def __read_next_line(self):
"""Read another line from the file."""
next_line = self.file.readline()
if not next_line or next_line[-1:] != '\n':
# no newline on last line of file
self.file = None
else:
# trim newline characters
next_line = next_line[:-1]
expanded = next_line.expandtabs()
edit = urwid.Edit("", expanded, allow_tab=True)
edit.set_edit_pos(0)
edit.original_text = next_line
self.lines.append(edit)
return next_line
def _get_at_pos(self, pos):
"""Return a widget for the line number passed."""
if pos < 0:
# line 0 is the start of the file, no more above
return None, None
if len(self.lines) > pos:
# we have that line so return it
return self.lines[pos], pos
if self.file is None:
# file is closed, so there are no more lines
return None, None
assert pos == len(self.lines), "out of order request?"
self.__read_next_line()
return self.lines[-1], pos
class EditDisplay:
palette = [
('body','default', 'default'),
('foot','dark cyan', 'dark blue', 'bold'),
('key','light cyan', 'dark blue', 'underline'),
]
footer_text = ('foot', [
"Text Viewer ",
('key', "meta q"), " quit",
])
def __init__(self, name):
self.save_name = name
self.walker = LineWalker(name)
self.listbox = urwid.ListBox(self.walker)
self.footer = urwid.AttrWrap(urwid.Text(self.footer_text),
"foot")
self.view = urwid.Frame(urwid.AttrWrap(self.listbox, 'body'),
footer=self.footer)
def main(self):
self.loop = urwid.MainLoop(self.view, self.palette,
unhandled_input=self.unhandled_keypress,
input_filter=debug_input_filter)
##screen=urwid.curses_display.Screen())
self.loop.run()
def unhandled_keypress(self, k):
"""Last resort for keypresses."""
if k == "meta q":
raise urwid.ExitMainLoop()
elif k == "right":
w, pos = self.walker.get_focus()
w, pos = self.walker.get_next(pos)
if w:
self.listbox.set_focus(pos, 'above')
self.loop.process_input(["home"])
elif k == "left":
w, pos = self.walker.get_focus()
w, pos = self.walker.get_prev(pos)
if w:
self.listbox.set_focus(pos, 'below')
self.loop.process_input(["end"])
else:
return
return True
def main():
try:
name = sys.argv[1]
assert open(name, "a")
except Exception:
sys.stderr.write(__doc__)
return
EditDisplay(name).main()
if __name__=="__main__":
main()
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