Location¶
If you just want to move the location of the cursor before writing text, and aren’t worried about returning, do something like this:
>>> print(term.home + term.clear)
>>> print(term.down(2) + term.move_right(20) + term.bright_red('fire!'))
>>> print(term.move_xy(20, 7) + term.bold('Direct hit!'))
>>> print(term.move_y(term.height - 3))
There are four direct movement capabilities:
move_xy(x, y)
- Position cursor at given x, y.
move_x(x)
- Position cursor at column x.
move_y(y)
- Position cursor at row y.
home
- Position cursor at (0, 0).
And four relative capabilities:
move_up
ormove_up(y)
- Position cursor 1 or y cells above the current position.
move_down
ormove_down(y)
- Position cursor 1 or y cells below the current position.
move_left
ormove_left(x)
- Position cursor 1 or x cells left of the current position.
move_right
ormove_right(x)
- Position cursor 1 or x cells right of the current position.
Note
move_down
, if printed directly, is often valued as \n, which additionally returns
the carriage to column 0, and, depending on your terminal emulator, may also destroy any
characters to end of line. move_down(1)
is always a safe non-destructive one-notch movement
in the downward direction.
Example¶
The source code of bounce.py combines a small bit of Keyboard input with many of the
Terminal location capabilities, home
, width
, height
, and move_xy
are used to create
a classic game of tennis:
# std imports
from math import floor
# local
from blessed import Terminal
def roundxy(x, y):
return int(floor(x)), int(floor(y))
term = Terminal()
x, y, xs, ys = 2, 2, 0.4, 0.3
with term.cbreak(), term.hidden_cursor():
# clear the screen
print(term.home + term.black_on_olivedrab4 + term.clear)
# loop every 20ms
while term.inkey(timeout=0.02) != 'q':
# erase,
txt_erase = term.move_xy(*roundxy(x, y)) + ' '
# bounce,
if x >= (term.width - 1) or x <= 0:
xs *= -1
if y >= term.height or y <= 0:
ys *= -1
# move,
x, y = x + xs, y + ys
# draw !
txt_ball = term.move_xy(*roundxy(x, y)) + '█'
print(txt_erase + txt_ball, end='', flush=True)
Context Manager¶
A contextlib.contextmanager()
, location()
is provided to move the cursor to
an (x, y) screen position and restore the previous position on exit:
with term.location(0, term.height - 1):
print('Here is the bottom.')
print('This is back where I came from.')
All parameters to location()
are optional, we can use
it without any arguments at all to restore the cursor location:
with term.location():
print(term.move_xy(1, 1) + 'Hi Mom!' + term.clear_eol)
Note
calls to location()
may not be nested.
Finding The Cursor¶
We can determine the cursor’s current position at anytime using get_location()
.
This uses a kind of “answer back” sequence that your terminal emulator responds to. Because the
terminal may not respond, or may take some time to respond, the timeout
keyword argument can be specified to return coordinates (-1, -1) after a blocking timeout:
>>> term.get_location(timeout=5)
(32, 0)
The return value of get_location()
mirrors the arguments of
location()
:
with term.location(12, 12):
val = term.get_location()
print(val)
Produces output, (12, 12)
Although this wouldn’t be suggested in most applications because of its latency, it certainly simplifies many applications, and, can also be timed, to make a determination of the round-trip time, perhaps even the bandwidth constraints, of a remote terminal!