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Date: Thu, 12 Jun 2014 13:17:48 -0700 (PDT)
From: Pedro Izecksohn <izecksohn@yahoo.com>
Subject: Re: Lines on a tkinter.Canvas
To: "python-list@python.org" <python-list@python.org>
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Reply-To: Pedro Izecksohn <izecksohn@yahoo.com>
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Xref: csiph.com comp.lang.python:73237

=A0 As Peter Otten did not see the same result that I saw, I prepared an im=
age that shows the result on my notebook:=0Ahttp://izecksohn.com/pedro/pyth=
on/canvas/tk_window.xcf=0A=A0 For those that might not know: xcf is the Gim=
p's file format.=0A=0A=0A----- Original Message -----=0A> From: Peter Otten=
=0A> To: python-list@python.org=0A> Sent: Thursday, June 12, 2014 4:02 AM=
=0A> Subject: Re: Lines on a tkinter.Canvas=0A> =0A> Pedro Izecksohn wrote:=
=0A> =0A>>  The code available from:=0A>>  http://izecksohn.com/pedro/pytho=
n/canvas/testing.py=0A>>  draws 2 horizontal lines on a Canvas. Why the 2 l=
ines differ on thickness=0A>>  and length?=0A>> =0A>>  The Canvas' method c=
reate_line turns on at least 2 pixels. But I want =0A> to=0A>>  turn on man=
y single pixels on a Canvas. How should I do this? Canvas has=0A>>  no meth=
od create_pixel or create_point.=0A> =0A>>  #!/usr/bin/python3=0A>> =0A>>  =
import tkinter as tk=0A>> =0A>>  class Point ():=0A>> =A0  def __init__ (se=
lf, x, y):=0A>> =A0 =A0  self.x =3D x=0A>> =A0 =A0  self.y =3D y=0A>> =0A>>=
  class Board (tk.Frame):=0A>> =A0  def __init__ (self, bg, dimensions):=0A=
>> =A0 =A0  tk.Frame.__init__ (self, tk.Tk())=0A>> =A0 =A0  self.pack()=0A>=
> =A0 =A0  self.canvas =3D tk.Canvas (self, bd =3D 0, bg =3D bg, width =3D =
dimensions.x, =0A> height =3D dimensions.y)=0A>> =A0 =A0  self.canvas.pack =
(side =3D "top")=0A>> =A0  def drawLine (self, pa, pb, color):=0A>> =A0 =A0=
  self.canvas.create_line (pa.x, pa.y, pb.x, pb.y, fill =3D color)=0A>> =A0=
  def drawPoint (self, p, color):=0A>> =A0 =A0  self.canvas.create_line (p.=
x, p.y, p.x, p.y, fill =3D color)=0A>> =0A>>  dimensions =3D Point (500, 50=
0)=0A>>  board =3D Board ('black', dimensions)=0A>>  color =3D 'red'=0A>>  =
p =3D Point (0, 250)=0A>>  while (p.x < dimensions.x):=0A>> =A0  board.draw=
Point (p, color)=0A>> =A0  p.x +=3D 1=0A>>  pa =3D Point (0, 350)=0A>>  pb =
=3D Point (499, 350)=0A>>  board.drawLine (pa, pb, color)=0A>>  board.mainl=
oop()=0A> =0A> I just tried your script, and over here the line drawn with=
=0A> =0A>> =A0  def drawLine (self, pa, pb, color):=0A>> =A0 =A0  self.canv=
as.create_line (pa.x, pa.y, pb.x, pb.y, fill =3D color)=0A> =0A> has a widt=
h of 1 pixel and does not include the end point. Therefore the =0A> "line" =
drawn with=0A> =0A>> =A0  def drawPoint (self, p, color):=0A>> =A0 =A0  sel=
f.canvas.create_line (p.x, p.y, p.x, p.y, fill =3D color)=0A> =0A> does not=
 show up at all. You could try to specify the line width explicitly:=0A> =
=0A> =A0  def drawPoint (self, p, color):=0A> =A0 =A0  self.canvas.create_l=
ine (p.x, p.y, p.x+1, p.y, fill=3Dcolor, width=3D1)=0A> =0A> If that doesn'=
t work (or there's too much overhead) use pillow to =0A> prepare an =0A> im=
age and show that.=0A> =0A> Another random idea: if you have a high resolut=
ion display your OS might =0A> blow up everything. In that case there would=
 be no fix on the application =0A> level.=0A>