supercanvas 0.2.0

tkinter simplified (and augmented) canvas

This package provides a supercanvas widget based on the original tkinter canvas. It provides a quickly useable canvas with a usual cartesian coordinate system.

If you just want to have this supercanvas alone with no other widget, see magicTk section at the end.

class object

>>> from supercanvas import *

Once package importation completed, you have to create a supercanvas the usual way.

r = tkinter.Tk()
c = supercanvas(r, bg="white", width=800, height=600)

origin and units

By default, origin is located at supercanvas's center and units are both 1 pixel (and axes are drawn in french style with arrows). You can change this with setOrigin and setUnit methods:

c.setUnit(80, 100)
c.setOrigin(50, 200)

axes and ticks

By default, axes and ticks are shown/drawn. If you want them not to appear, you pass options axes and/or ticks to False in the supercanvas command.

Or you can these variables to False into your script.

setTicks method allow you to set distance between ticks.

c.axes = False
c.setTicks(1, .5)

For the moment, ticks come with texts.

supercanvas items

supercanvas provides four drawing methods drawPoint, drawLine, drawFunction and drawParam.

• drawPoint method create a point at the desired coords.

f = lambda x:x**2
x = 3
c.drawPoint(x, f(x), fill="red", outline="red")

It's based on create_oval so you can pass each option related to Oval object.

• drawLine method create a line with a list of coords.

c.drawLine([(-2, 2), (-1, 0), (0, 3)], fill="blue", width=3)

drawLine also supports a flat list of coords:

c.drawLine([-2, 2, -1, 0, 0, 3], fill="blue", width=3)

gives the same line.

• drawFunction methode create a line representing a function passed.

f = lambda x: 3 * x ** 1.2 + 2 
c.drawLine(f, -2, 7, fill="green")

-2 and 7 are the lower and upper values of argumentt's function.

You can use step method to specify difference between two consecutive argguments, default is 1.

f = lambda x: 3 * x ** 1.2 + 2
c.step = .1
c.drawLine(f, -2, 7, fill="green")

• drawParam methode create a line representing a parametric curve.

this code create a unit circle:

f = lambda x: math.cos(x)
g = lambda x: math.sin(x)
c.step = .01
c.drawParam(f, g, 0, 2 * math.pi)

grab/release background

You can move the whole supercanvas content in grabing / realeasing the background. It will refresh coords.

supercanvas options

• axes

passing axes=False to supercanvas options disable axes, default is True. For the moment, you cannot change axes style...

• ticks

passing ticks=False to supercanvas options disable ticks, default is True.

• follow

passing follow=False to supercanvas options disable cursor follow with coords, default is True.

full examples

• example 1

Points and functions using drawPoint and drawLine.

from supercanvas import *
import math
r = tkinter.Tk()

c = supercanvas(r, bg="white", width=800, height=600, ticks=False)
c.setUnit(100, 100)

f=lambda x:math.cos(x)
g=lambda x:math.sin(x)

p = .1
a, b = -3, 3
x = a
listePointsF = []
listePointsG = []
for i in range(int(1 + (b - a) / p)):
    # creating points 
    c.drawPoint(x, f(x), fill="red", outline="red")
    # two lists
    # function f with tuples
    listePointsF += (x, f(x))
    # function g with flat list
    listePointsG += [x]+[g(x)]
    x += p

# drawings of the two curves
c.drawLine(listePointsF, fill="green")
c.drawLine(listePointsG, fill="blue", width=3)

# balancing canvas on the root
c.pack(expand=True)

# q to quit
r.bind("<q>", quit)
tkinter.mainloop()

• example 2

Function using drawFunction.

from supercanvas import *
import math
r = tkinter.Tk()

c = supercanvas(r, bg="#00964a")
c.setOrigin(30, 150)
c.setUnit(10, 80)

f = lambda x: math.sin(x) / x
c.step=.1
c.drawFunction(f, c.step, 10*math.pi, width=3, fill="white")

c.pack()
r.bind("<q>", quit)
tkinter.mainloop()

• example 3

Cardioid curve using drawParam

from supercanvas import *
import math
r = tkinter.Tk()

c = supercanvas(r, bg="red", width=500, height=500)
c.setOrigin(100, 250)
c.setUnit(150, 150)

x = lambda t: 2 * (1 - t ** 2) / (1 + t ** 2) ** 2
y = lambda t: 4 * t / (1 + t ** 2) ** 2
c.step=.001
c.drawParam(x, y, -10, 10, width=3, fill="white")

c.pack()
r.bind("<q>", quit)
tkinter.mainloop()

magicTk

Because remembering tkinter commands for just one widget is awful, supercanvas provides two commands beginMagicTk and endMagicTk.

Key q is bind to close/exit event.

Here's how to use them in a standalone example file:

from supercanvas import *
w = beginMagicTk()

c = supercanvas(w, bg="white")
c.setUnit(100, 20)
c.setTicks(.5, 2)

f = lambda x: x ** 3
c.step=.1
c.drawFunction(f, -3, 3)

endMagicTk(w)

Assign first command output, use it in supercanvas and endMagicTk commands.

further

Much much more!

about

supercanvas is rather an attempt to publish on the PyPi packages index than a fully completed python project, I do not recommend supercanvas usage for professionnal use. You have to consider this package as an experiment.