From: Hidetoshi NAGAI <nagai@...>
Date: 2007-10-12T13:42:49+09:00
Subject: Re: ruby tk drawing a line

From: Ed Redman <redman@accesswave.ca>
Subject: ruby tk drawing a line
Date: Fri, 12 Oct 2007 12:50:10 +0900
Message-ID: <k7CPi.10981$G25.2545@edtnps89>
> canvas.bind('B1-Motion', proc { |e| 
>       $endx = e.x
>       $endy = e.y
>                         
>       $a  = TkcLine.new(canvas, $startx, $starty, $endx, $endy)

You write so many new lines at here.
Each short line is made at each 'B1-Motion' callback.

The following may be an example which you want.
-----------------------------------------------------------------
require 'tk'

line = nil
first = nil
last = nil

canvas = TkCanvas.new(:relief=>:ridge, :borderwidth=>3).pack

f = TkFrame.new.pack(:fill=>:x)

color = 'black'
TkButton.new(f, :text=>'color', :command=>proc{
               color = Tk.chooseColor(:initialcolor=>color)
             }).pack(:side=>:right, :padx=>[10,3])

option = TkSpinbox.new(f, :from=>1, :to=>1000, 
                       :width=>4).pack(:side=>:right, :padx=>0)
TkLabel.new(f, :text=>'width').pack(:side=>:right, :padx=>[10,0])

canvas.bind('1', '%x', '%y'){|*first|
  line = TkcLine.new(canvas, first, first, 
                     :width=>option.value, :fill=>color)
}

canvas.bind('B1-Motion', '%x', '%y'){|*last| line.coords(first, last)}

Tk.mainloop
-----------------------------------------------------------------

Ruby/Tk accepts all of the following coords pattern for a canvas item.

 (1) x1, y1, x2, y2, x3, y3, ...

 (2) [x1, y1], [x2, y2], [x3, y3], ...

 (3) [ [x1, y1], [x2, y2], [x3, y3], ... ]

In my example, I use the pattern (2).
-- 
Hidetoshi NAGAI (nagai@ai.kyutech.ac.jp)