scrollable window ncurses ruby - ruby

Question

I created a class that I am trying to make to simulate richtextbox, sort of, on windows forms. this means when you add new data to the form/richtextbox it is added to the bottom of the box/window and the rest is scrolled up one line.
ive tried to enable scrollok(), but it does not seem to want to scroll. i am not sure if it's bugged or my way of implementing it is wrong.
class Textpad
attr_accessor :data, :name, :window
def initialize(name, height, width, startx, starty)
#data = []
#name = name
#height = height
#width = width
#startx = startx
#starty = starty
Ncurses.refresh
#window = Ncurses.newwin(height, width, starty, startx)
#window.scrollok true
#window.wrefresh
end
def add(packetid, username, message)
#data.push [Time.new.strftime('[%T]'), packetid, username, message]
#data.shift if #data.length > 500
end
def draw
Ncurses.init_pair(1, Ncurses::COLOR_YELLOW, Ncurses::COLOR_BLACK)
Ncurses.init_pair(2, Ncurses::COLOR_CYAN, Ncurses::COLOR_BLACK)
Ncurses.init_pair(3, Ncurses::COLOR_RED, Ncurses::COLOR_BLACK)
Ncurses.init_pair(4, Ncurses::COLOR_WHITE, Ncurses::COLOR_BLACK)
#window.wclear
position = 0
#data.each do |timestamp, packetid, username, message|
case packetid
when '1005'
#window.mvwprintw(1*position, 1, "#{timestamp} «#{username}» #{message}")
#window.mvchgat(1*position, timestamp.length+2, 1, Ncurses::A_NORMAL, 3, NIL)
#window.mvchgat(1*position, timestamp.length+3+username.length, 1, Ncurses::A_NORMAL, 3, NIL) #colorize the symboles around the username
end
position += 1
end
#window.wrefresh
end
end
the problem would be inside my draw method of the Textpad class. i can fill the data array for the Textpad class with hundreds of entries but only the very top of the array gets written (until it reaches the bottom of the window) with no scrolling. Do i manually have to scroll the screen or something? from the documentation it says it should automatically scroll when the cursor reaches the bottom and another line is added.

Answer 1

To quote the man page:
The scrollok option controls what happens when the cursor of a window is moved off the edge of the window or scrolling region, either as a result of a newline action on the bottom line, or typing the last character of the last line. If disabled, (bf is FALSE), the cursor is left on the bottom line. If enabled, (bf is TRUE), the window is scrolled up one line...
What is happening in your code is that you are attempting to print outside the window which is an error, but an error that curses handles by not printing anything.
You can either print an new line when you get to the bottom of the window or once your reach the bottom of the window you can call #window.scroll.
Either way you will need to keep printing on the last line if you are explicitly setting the position.