Any way to stop curses from crashing on resize?

[pepperphd]

Hi. I've been using the curses library with python for a few projects. It is a little frustrating that something as simple as resizing the terminal can easily crash curses, and google is failing me for answers. If anyone here has good experience with curses, how do you prevent silly crashes like this?

[johnl]

Hi,

When the terminal window size changes your application should receive a SIGWINCH signal. You should catch this signal and perform any resizing logic when you receive it.

this site (http://invisible-island.net/ncurses/ncurses.faq.html#handle_resize) has a pair of suggestions on how to respond to this signal.

Hope this helps.

[geirha]

Would be very helpful if you provided some code that has this problem. Preferably as small as possible.

[pepperphd]

Would be very helpful if you provided some code that has this problem. Preferably as small as possible.

Okay. Here are 3 functions that I use to put information on the screen. Resizing the playlist window causes curses to crash.



def make_playlist_window():
254
255 """
256 i believe this speaks for itself, but pylint complains about
257 even the simplest undocumented function ;)
258 """
259
260 SPACE_FOR_FILLER = 5
261 begin_x = 5
262 begin_y = 2
263 height = len(displayed_songs) + 2
264 width = find_longest_song() + SPACE_FOR_FILLER
265 playlist_window = curses.newwin(height, width, begin_y, begin_x)
266 playlist_window.box()
267 return playlist_window



def make_display_list(cursor, current_song):
210
211 """
212 attempts to create a list of songs for the playlist window
213 based on the cursor position and/or the song being played
214 for small playlists (index error) it just returns the playlist
215 """
216
217 displayed_songs = []
218 begin = -9
219 end = 11
220 if cursor != current_song:
221 center = cursor
222 else:
223 center = current_song
224 if len(playlist) -1 < -begin + end:
225 end = len(playlist) -1 + begin
226 i = begin
227 try:
228 while i < end:
229 if i + center > len(playlist) -1:
230 for x in range(end - i):
231 displayed_songs.append(playlist[x])
232 return displayed_songs
233 displayed_songs.append(playlist[center + i])
234 i += 1
235 return displayed_songs
236 except IndexError:
237 return playlist




Here, the songs that make_display_list determines will be shown are put on the screen. Resizing the terminal window to a size smaller than needed to complete this function throws an error.


def show_playlist(cursor, current_song):
271
272 """
273 here the songs obtained from make_display_list() are shown
274 in one of three ways. the current song is always highlighted in white.
275 the song the cursor is over, if it isnt the current song, is highlighted
276 in red. and all other songs are simple white on black
277 """
278
279 displayed_songs = make_display_list(cursor, current_song)
280 i = 0
281 for song in displayed_songs:
282 if song == playlist[current_song]:
283 playlist_window.addstr(i + 1, 2, song[song.rfind("/") + 1:], curses.color_pair(1))
284 elif cursor != current_song and song == playlist[cursor]:
285 playlist_window.addstr(i + 1, 2, song[song.rfind("/") + 1:], curses.color_pair(2))
286 else:
287 playlist_window.addstr(i + 1, 2, song[song.rfind("/") + 1:])
288 i += 1