How should I dynamically position strings?

Question

Here is a program that shows a simple animation to show the user that the program is waiting for input, or is doing something, and it hasn't crashed:

    require "curses"
        include Curses

        chars = ["   ","*  ","** ","***","***","** ","*  ","   "]

          four = Window.new(3,20,10,30)
          four.box('|', '-')
          four.setpos 1, 1
          four.addstr "Hello"
          while ( true )
            four.setpos 1, 6
            four.addstr chars[0]
            four.refresh
            sleep 0.1
            chars.push chars.shift
          end

Inside the while loop, the cursor is repositioned to line 1, column 6 every turn of the loop. This is so that stars are overwritten with blank spaces and it all works perfectly.

However, try changing the "Hello" string to "Hello Everyone"

As you can see, the star animation now occurs in the middle of this string. The animation hasn't been 'shunted along'. Is there a way to automatically append the animation to the end of a string?

Or would I need to programatically position it? Find the length of the hello string and add 1 to it, and use this to position the col coordinate?

Seems like you already know the answer— have you tried implementing the idea in your last paragraph? — Zach Kemp, Oct 15 '13 at 03:48

falsetru · Answer 1 · 2013-10-15T03:54:13.973

Ruby Curses module does not provide getyx. So you should calculate the position yourself.

Another option is writing "Hello" or "Hello Everyone" followed by chars[0] inside loop.

require "curses"
include Curses

chars = ["   ","*  ","** ","***","***","** ","*  ","   "]
four = Window.new(3,20,10,30)
four.box('|', '-')

loop do
  four.setpos 1, 1
  four.addstr 'Hello'
  four.addstr chars[0]
  four.refresh
  sleep 0.1
  chars.push chars.shift
end

Reference: Following is Python version that use getyx.

import curses
import itertools
import time

chars = itertools.cycle(["   ", "*  ", "** ", "***", "***", "** ", "*  ", "   "])
curses.initscr()
four = curses.newwin(3, 20, 10, 30)
four.box()
four.addstr(1, 1, 'Hello Everyone')
y, x = four.getyx()
while True:
    four.addstr(1, x, next(chars))
    four.refresh()
    time.sleep(0.1)

How should I dynamically position strings?

1 Answers1