drawline

[Ben Bush]

I had the following code and when I clicked the left mouse button one
time. I got green line and the second click got a purple line and the
green disappeared.
I was confused by two questions:
First, Clicknum increases when every time I click the button. Is it
possible to reset Clicknum to 0?
Second, how to do something like: I click the left button the first
time, the green line appear then disappear, the purple line
appear(just as the code has done but become a loop; if a second-time
click is implied, the loop stops.
from Tkinter import *

ClickNum = 0

def drawline(event) :
global ClickNum
if ClickNum == 0:
canvas.create_l ine(100, 0, 100, 200, arrow=FIRST,fil l="green",tag=" a")
elif ClickNum == 1:
canvas.delete(" a")
canvas.create_l ine(100, 50, 60, 300, arrow=FIRST,fil l="purple")
ClickNum += 1

tk = Tk()
canvas = Canvas(tk, bg="white", bd=0, highlightthickn ess=0)
canvas.pack(fil l=BOTH, expand=YES)
canvas.create_l ine(100, 200, 350, 200, arrow=LAST,fill ='red')
canvas.bind("<1 >", drawline)
tk.mainloop()

[Eugene Druker]

Hi Ben,
if I understood your questions properly, this code gives some answers (on
XP):

from Tkinter import *

lines = [
[ (100, 200, 350, 200), LAST, "red", '' ],
[ (100, 0, 100, 200), FIRST, "green", 'a' ],
[ (100, 200, 300, 100), LAST, "purple", 'b' ],
]

ClickMax = len(lines)
ClickNum = 0
lasttag = ''

def drawline(event) :
global ClickNum,lastta g
canvas.delete(l asttag)
line = lines[ClickNum]
canvas.create_l ine(line[0], arrow=line[1], fill=line[2],tag=line[3])
lasttag = line[3]
ClickNum = (ClickNum+1) % ClickMax
ClickNum = ClickNum or 1

canvas = Canvas(Tk(), bg="white", bd=0, highlightthickn ess=0)
canvas.pack(fil l=BOTH, expand=YES)
drawline(0)
canvas.bind("<1 >", drawline)
canvas.mainloop ()

Eugene
"Ben Bush" <py*******@gmai l.com> wrote in message
news:ma******** *************** *************** *@python.org...
I had the following code and when I clicked the left mouse button one
time. I got green line and the second click got a purple line and the
green disappeared.
I was confused by two questions:
First, Clicknum increases when every time I click the button. Is it
possible to reset Clicknum to 0?
Second, how to do something like: I click the left button the first
time, the green line appear then disappear, the purple line
appear(just as the code has done but become a loop; if a second-time
click is implied, the loop stops.
from Tkinter import *

ClickNum = 0

def drawline(event) :
global ClickNum
if ClickNum == 0:
canvas.create_l ine(100, 0, 100, 200,
arrow=FIRST,fil l="green",tag=" a")
elif ClickNum == 1:
canvas.delete(" a")
canvas.create_l ine(100, 50, 60, 300, arrow=FIRST,fil l="purple")
ClickNum += 1

tk = Tk()
canvas = Canvas(tk, bg="white", bd=0, highlightthickn ess=0)
canvas.pack(fil l=BOTH, expand=YES)
canvas.create_l ine(100, 200, 350, 200, arrow=LAST,fill ='red')
canvas.bind("<1 >", drawline)
tk.mainloop()

[Magnus Lycka]

Ben Bush wrote:

I had the following code and when I clicked the left mouse button one
time. I got green line and the second click got a purple line and the
green disappeared.
I was confused by two questions:

It's good that these postings are archived, so that teachers can
check them before grading their students. After all, the grades
belong to those who solved the problems, not to those who handed
them in...

[Ben Bush]

On 11/23/05, Magnus Lycka <ly***@carmen.s e> wrote:

Ben Bush wrote:

I had the following code and when I clicked the left mouse button one
time. I got green line and the second click got a purple line and the
green disappeared.
I was confused by two questions:

It's good that these postings are archived, so that teachers can
check them before grading their students. After all, the grades
belong to those who solved the problems, not to those who handed
them in...

I learned Python by myself and not seeking to hand in these results
for anyone. All the questions are not from any textbook. Please be
polite and do not assume something just in your mind.