Tkinter Does Not Suck

Tkinter doesn’t suck!
Honest!

Saturday, 7 November 2009

“What GUI toolkit
should I use?”

– random poster in random forum

wxWindows!


import wx

class Application(wx.Frame):
def __init__(self, parent):
wx.Frame.__init__(self, parent, -1, 'My GUI', size=(300, 200))
panel = wx.Panel(self)
sizer = wx.BoxSizer(wx.VERTICAL)
panel.SetSizer(sizer)
txt = wx.StaticText(panel, -1, 'Hello, world')
sizer.Add(txt, 0, wx.TOP|wx.LEFT, 20)
self.Centre()
self.Show(True)

app = wx.App(0)
Application(None)
app.MainLoop()


pyGTK


import gtk

window = gtk.Window()
label = gtk.Label("Hello, world")
window.add(label)
window.show_all()
gtk.main()


PyQt!


import sys
import PyQt4.Qt as qt

a=qt.QApplication(sys.argv)
w=qt.QLabel("Hello, world")
w.show()
a.exec_()


“whatever you do...


...don’t use Tkinter!”


“Tkinter sucks!”


import Tkinter as tk

root = tk.Tk()
tk.Label(root, text="Hello, world").pack()
root.mainloop()


“yeah, OMG, Tkinter
sucks!”


I disagree


1. it’s simple to use
- rich base widget set
- which is not verbose
- automatic packing


2. it’s always there

on Windows & OS X

-- on Linuxes you might
need to install an
optional package


3. it’s mature

first release 1991
8.0 released August 1999
8.5 released December 2007


how I discovered this
I had this project that I wanted to be click-to-run, but needed to select a file

Looked for a cross-platform “file dialog” solution and found some hacks

Then I noticed a reference to Tkinter, and lo and behold...


filename = tkFileDialog.askopenfilename(parent=root,
filetypes=[('ReStructuredText Files', '.rst .txt'),
('All Files', '.*')],
title='Select your presentation file')


well, if it can do that...

what about the program’s command-line options?


self.root = tk.Tk()
frame = Tk.Frame(self.root)
frame.pack()

Tk.Label(frame, text='Bruce, the Presentation Tool!').pack()

self.fullscreen = Tk.IntVar()
Tk.Checkbutton(frame, text='Fullscreen?', variable=self.fullscreen).pack()

# screen selection
display = pyglet.window.get_platform().get_default_display()
N = len(display.get_screens())
self.screen = Tk.IntVar(0)
if N > 1:
for n in range(N):
Tk.Radiobutton(frame, text="Display on screen %d"%(n+1),
variable=self.screen, value=n).pack()

self.timer = Tk.IntVar()
Tk.Checkbutton(frame, text='Show Timer?', variable=self.timer).pack()
self.page_count = Tk.IntVar()
Tk.Checkbutton(frame, text='Show Page Count?', variable=self.page_count).pack()
self.bullet_mode = Tk.IntVar()
Tk.Checkbutton(frame, text='Run in Bullet Mode?', variable=self.bullet_mode).pack()
self.source = Tk.IntVar()
Tk.Checkbutton(frame, text='Display source in console?', variable=self.source).pack()

Tk.Button(frame, text='Play Presentation', command=self.go).pack()


speciﬁc Tkinter gripes


1. it’s not pretty


1. it’s not pretty
1. it doesn’t look native,
2. fonts are not anti-aliased


2. extending is tricky


native look and feel
(since Tk 8.0, 1999)


(since Tk 8.0, 1999)
(much improved in Tk 8.5, 2008)


(since Tk 8.0, 1999)
(much improved in Tk 8.5, 2008)
(“less ugly but not perfect”)


truetype / opentype
fonts
(since Tk 8.5)


1. Simple to use


Widgets



root = tk.Tk()
root.mainloop()

demo image display

label properties:
foreground, background,
font, ???



root = tk.Tk()
root.mainloop()

No point showing the
other three lines in other
examples


from PIL import Image, ImageTk
image = ImageTk.PhotoImage(Image.open('kitten.jpg'))
tk.Label(root, image=image).pack()


def pressed():
print 'You pressed me!'

tk.Button(root, text='Press me!',
command=pressed).pack()


entry = tk.Entry(root)
entry.pack()
entry.insert(0, 'some text')


value = tk.IntVar()
tk.Checkbutton(root, text='Checked?',
variable=value).pack()


value = tk.IntVar()
for n in range(4):
tk.Radiobutton(root, value=n
text="Selection %d"%(n+1),
variable=value).pack()


value = tk.StringVar(value='One')
tk.OptionMenu(root, value, 'One', 'Two',
'Three').pack()

10 minutes


listbox = tk.Listbox(root)
listbox.pack()
listbox.insert(tk.END, "a list entry")
for item in ‘one two three four’.split():
listbox.insert(tk.END, item)


text = tk.Text(root)
text.pack()
text.insert(tk.END, '''some text
more text''')

also allows:
- embedding of images
and widgets
- searching
- tagging (identification,
useful for properties)
- styles


scale = tk.Scale(root, from_=0, to=100)
scale.pack()


w = tk.Canvas(root, width=200, height=100)
w.pack()
w.create_line(0, 0, 200, 100)
w.create_line(0, 100, 200, 0,
fill="red", dash=(4, 4))
w.create_rectangle(50, 25, 150, 75,
fill="blue")

- line (with arrows), arc,
image, oval, polygon,
rectangle, text, widgets
- outline, fill
- scrollable (limitable)
- picking (with closest)


Packing


rows or columns
the pack manager packs
into rows or columns

the default is column,
centered.


in the beginning there is
a container, and it is
empty

we’re going to pack this
container at the default
tk.TOP


tk.Button(root, text='Press me!').pack()

pack a button


tk.Button(root, text='Press me too!').pack()

pack a button


tk.Button(root, text='Press me too!').pack()
tk.Button(root, text='And me!').pack()

pack a button


tk.Button(root, text='Press me!').pack(side=tk.LEFT)
tk.Button(root, text='Press me too!').pack(side=tk.LEFT)
tk.Button(root, text='And me!').pack(side=tk.LEFT)

pack on tk.LEFT instead


tk.Button(root, text='Press me!').pack(side=tk.RIGHT)
tk.Button(root, text='Press me too!').pack(side=tk.RIGHT)
tk.Button(root, text='And me!').pack(side=tk.RIGHT)

pack on tk.RIGHT instead


more complex packing?


horizontal = tk.Frame(root)
horizontal.pack()
tk.Button(horizontal, text='Press me too!').pack(side=tk.LEFT)
tk.Button(horizontal, text='Press me too!').pack(side=tk.LEFT)


grids


tk.Button(root, text='Press me!').grid(row=0, column=0)
tk.Message(root, text='Pressnmentoo!').grid(row=1, column=0)
tk.Button(root, text='And me!').grid(row=1, column=1)

those are tk.CENTER “sticky”

other options are the 9 points of the compass

pack() also allows the sticky side to be specified

see I snuck in the multiline “Message” widget
there?


... or place


Widget values


widgets with a variable
variable = tk.IntVar()
value = variable.get()
variable.set(value)


text widgets
entry = tk.Entry()
value = entry.get()
entry.delete(0, tk.END)
entry.insert(0, value)


list boxes
listbox = tk.Listbox(root)
listbox.pack()
for item in ‘one two three four’.split():
listbox.insert(tk.END, item)
selected = list.curselection()


Styling


2 methods:
1. direct
2. themed (py2.6+, py3k+)


tk.Label(root, text="Hello, world!",
background='black',
foreground='white',
font='Courier').pack()


tk.Button(root, text="Hello, world!",
background='black',
foreground='white',
font='Courier').pack()

some limitations
(sometimes depending on
your theme)


Option 2: Themed


from [tT]kinter import ttk
lower-case “t” in py3k+

If you want it earlier you
can install the tile
extension


complementary
Though the themed widget commands work similarly to the originals,
there are important differences.
Themed widgets are not a drop-in replacement.
In particular, themed widgets generally provide less options for
customizing their appearance than regular Tk widgets (e.g. they will
often not have options like "-background").
Such changes, if needed (and they should be needed much less often)
must be done by defining new widget styles, using the facilities offered
by the themed widget package.


Implements
button, checkbutton, entry, label,
menubutton, radiobutton, scale,
scrollbar, frame, labelframe,
panedwindow


Added
combobox, notebook,
progressbar, separator,
sizegrip


Not present
canvas, listbox,
menu, spinbox, text

these aren’t really
needed


“classes” and “styles”
>>> from tkinter import ttk
>>> l = ttk.Label('hello, world!')
>>> l.winfo_class()
'TLabel'
>>> l['style']
''


layout example (button)


>>> style = ttk.Style()
>>> style.layout('TButton')
[("Button.border", {"children": [("Button.focus", {"children":
[("Button.spacing", {"children": [("Button.label", {"sticky":
"nswe"})], "sticky": "nswe"})], "sticky": "nswe"})], "sticky":
"nswe", "border": "1"})]


element options
>>> style = ttk.Style()
>>> style.element_options('Button.label')
('-compound', '-space', '-text', '-font', '-foreground', '-underline',
'-width', '-anchor', '-justify', '-wraplength', '-embossed', '-image',
'-stipple', '-background')


style = ttk.Style()
style.configure("Red.TLabel", foreground="red", font="Courier 32")
ttk.Label(text="Test Styled", style="Red.TLabel").pack()
ttk.Label(text="Test Unstyled").pack()


switching themes
style = ttk.Style()
current_theme = style.theme_use()
new_theme = style.theme_create(...)
style.theme_use(new_theme)


Events


bind(), unbind()
def callback(event):
print "clicked at", event.x, event.y

frame = Frame(root, width=100, height=100)
frame.bind("<Button-1>", callback)


<modiﬁer-type-detail>


mouse event types
mouse button <Button-1>, <Button-2>, <Button-3>

mouse drag <B1-Motion>

mouse release <ButtonRelease-1>, ...

double click <Double-Button-1>, ...

triple click <Triple-Button-1>, ...

mouse entered <Enter>

mouse left <Leave>


keyboard event types
focus <FocusIn>, <FocusOut>

<Enter>, <Delete>, <Left>,
speciﬁc keys <Right>, ...

any key <Key>

any text a, b, 1, 2, ...

<Shift-Up>, <Alt-Enter>,
modiﬁed keys <Control-Tab>, ...


special event types
conﬁguration <Configure>

The widget changed size (or location, on some
platforms). The new size is provided in the width
and height attributes of the event object passed to
the callback.


Canvas
w = tk.Canvas(root, width=400, height=300)
w.pack()


w.create_line(0, 0, 400, 300)


w.create_line(0, 300, 400, 0,fill="red", dash=(4, 4))


w.create_rectangle(150, 125, 250, 175, outline="green", fill="blue")

specify corders, outline and fill colors


w.create_arc(50, 50, 200, 200, outline="blue", fill="green")


w.create_oval(200, 200, 250, 250, outline="blue", fill="green")


from PIL import Image, ImageTk
image = ImageTk.PhotoImage(Image.open('kitten.jpg'))
w.create_image((0, 0), image=image, anchor=tk.NW)


Tips


self.attributes('-topmost', True)


Tkinter Does Not Suck

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