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This module can move the cursor around in the terminal, change the text color, highlighting color, et cetera, bold, underlined, flashing (if supported). It also has a word wrap function, and can center text.

Python, 247 lines
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#!/usr/bin/python

import sys,os

hist=[]

def actually_write():
	global hist
	sys.stdout.write("\x1b[%sm"%(";".join(hist)))

def o(msg):
	global hist
	msg="%02i"%msg
	hist.append(msg)
	actually_write()

def undo():
	global hist
	hist.pop()
	actually_write()

def reset():
	global hist
	hist=[]
	sys.stdout.write("\x1bc\x1b[!p\x1b[?3;4l\x1b[4l\x1b>")
	default()

def default():
	o(10) # in case someone called o(12) by mistake :P
	o(0)

def clear():
	sys.stdout.write("\x1b[H\x1b[2J")

def move(y,x):
	sys.stdout.write("\x1b[%i;%iH"%(y+1,x+1))

def up():
	sys.stdout.write("\x1b[A")

def down():
	sys.stdout.write("\x1b[B")

def right():
	sys.stdout.write("\x1b[C")

def left():
	sys.stdout.write("\x1b[D")

def endline():
	sys.stdout.write("\x1b[K")

def cursorinvisible():
	sys.stdout.write("\x1b[?25l")

def cursornormal():
	sys.stdout.write("\x1b[?12l\x1b[?25h")

def cursorveryvisible():
	sys.stdout.write("\x1b[?12;25h")

def deletelines(lines=1):
	sys.stdout.write("'\x1b[%iM"%lines)

def scrolldown():
	sys.stdout.write("\x1bM")

def cols():
	return int(os.popen("tput cols").read().strip())

def lines():
	return int(os.popen("tput lines").read().strip())

def savecursor():
	sys.stdout.write("\x1b7")

def restorecursor():
	sys.stdout.write("\x1b8")

def bold():
	o(1)

def hidden():
	o(2)

def underline():
	o(4)

def blink():
	o(5)

def reverse():
	o(7)

def formatting():
	o(12)

def black():
	o(30)

def red():
	o(31)

def green():
	o(32)

def orange():
	o(33)

def blue():
	o(34)

def magenta():
	o(35)

def cyan():
	o(36)

def white():
	o(37)

def bgred():
	o(41)

def bggreen():
	o(42)

def bgorange():
	o(43)

def bgblue():
	o(44)

def bgmagenta():
	o(45)

def bgcyan():
	o(46)

def bgwhite():
	o(47)

def put(line,indent,msg):
	move(line,indent)
	sys.stdout.write(msg)

def center(line,msg):
	columns=cols()
	indent=(columns-len(msg))/2
	put(line,indent,msg)
	return line,indent+len(msg)

def wrap(*args):
	"wrap(line, [[lmargin,] rmargin,] msg)"
	if len(args)==4:
		line,lmargin,rmargin,msg=args
	elif len(args)==3:
		line,rmargin,msg=args
		lmargin=0
	elif len(args)==2:
		line,msg=args
		lmargin,rmargin=0,0
	elif len(args)<2:
		raise TypeError,"wrap() takes at least two arguments"
	else:
		raise TypeError,"wrap() takes at most four arguments"
	line_length=cols()-lmargin-rmargin
	msg=list(msg)
	curr_indent=0
	curr_line=line
	char=msg.pop(0)
	while 1:
		if line_length-curr_indent<1:
			put(curr_line,lmargin+curr_indent,'\n')
			curr_line+=1
			curr_indent=0
			put(curr_line,lmargin,char)
		else:
			put(curr_line,lmargin+curr_indent,char)
			curr_indent+=1
			if len(msg)==0:
				break
			char=msg.pop(0)
	return curr_line,lmargin+curr_indent

def wordwrap(*args):
	"wordwrap(line, [[lmargin,] rmargin,] msg)"
	if len(args)==4:
		line,lmargin,rmargin,msg=args
	elif len(args)==3:
		line,rmargin,msg=args
		lmargin=0
	elif len(args)==2:
		line,msg=args
		lmargin,rmargin=0,0
	elif len(args)<2:
		raise TypeError,"wordwrap() takes at least two arguments"
	else:
		raise TypeError,"wordwrap() takes at most four arguments"
	line_length=cols()-lmargin-rmargin
	msg=msg.split()
	curr_indent=0
	curr_line=line
	word=msg.pop(0)
	while 1:
		if line_length<len(word): # word is longer than allowed line
			put(curr_line,lmargin,word[:line_length]) # wrap by letter
			word=word[line_length:]
			put(curr_line,lmargin+curr_indent,'\n')
			curr_line+=1
			curr_indent=0
		elif line_length-curr_indent<len(word): # word cannot fit on remainder
			put(curr_line,lmargin+curr_indent,'\n') # of line -- wrap by word
			curr_line+=1
			curr_indent=0
			put(curr_line,lmargin,word)
		else: # word fits on line
			put(curr_line,lmargin+curr_indent,word)
			curr_indent+=len(word)+1
			if len(msg)==0:
				break
			word=msg.pop(0)
	return curr_line,lmargin+curr_indent

def main():
	reset()
	bgblue()
	white()
	bold()
	clear()
	reverse()
	center(5,' Windows ')
	undo()
	line,col=wordwrap(7,7,8,"Windows crashed again. I am the Blue Screen of Death. No one hears your screams.")
	print
	put(line+2,11,"*")
	line,col=wordwrap(line+2,14,8,"Press any key to terminate the application.")
	put(line+1,11,"*")
	line,col=wordwrap(line+1,14,8,"Press CTRL+ALT+DEL again to restart your computer. You will lose any unsaved data in all applications.")
	line,col=center(line+3,"Press any key to continue")
	move(line,col+1)
	endline()
	raw_input()
	reset()

if __name__=="__main__":
	main()

I wrote this program a while ago just for fun. It has the ability to change text and background color in the terminal, move the cursor, word-wrap, center text, et cetera. Also, if you run it in a virtual terminal as the main application, you get a rather convincing (and comical, if you read the text) rendition of the BSOD with a nice haiku at the beginning of it. Oh, and it also has an "undo()" function, so you don't have to keep track of the stack of things that you've done that messed up the screen :-P

Enjoy :)

4 comments

Dinu Gherman 15 years, 7 months ago  # | flag

Nice. And seems to run nicely on OS X, too. The code would be more reusable as a class, though.

Collin Stocks (author) 15 years, 6 months ago  # | flag

Thanks :)

Feel free to change it and email me the edited code at [my first name][my last name] at gmail dot com.

David Lambert 15 years, 5 months ago  # | flag

The stack is a nice feature.

Use the curses module, it handles a lot more terminal types.

Collin Stocks (author) 15 years, 4 months ago  # | flag

Yeah, I wrote this because I actually needed a quick and dirty hack to do something with terminal colors and I couldn't be bothered learning how to use curses. It was actually more of a learning experience related to how the linux terminal works behind the scenes. I couldn't be bothered turning it into a class, either, because in my case there was only one terminal that it could print to.

I know that what I did was equivalent as far as good form goes to writing raw X code to create my windows where I should be using a cross-platform library. So be it. I learned how the terminal works.

I expect that others can learn the same from this code, since it is simple enough to understand without knowing too much Python.