[issue33289] tkinter askcolor returning floats for r, g, b values instead of ints

[Serhiy Storchaka]

Change by Serhiy Storchaka :


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resolution:  -> fixed
stage: patch review -> resolved
status: open -> closed

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[issue33289] tkinter askcolor returning floats for r, g, b values instead of ints

[miss-islington]

miss-islington  added the comment:


New changeset 96bcf6f4d4bed1cdf97883eb43e872ff1a92013d by Miss Islington (bot) 
in branch '3.8':
[3.9] bpo-33289: Return RGB triplet of ints instead of floats from 
tkinter.colorchooser (GH-6578). (GH-24318)
https://github.com/python/cpython/commit/96bcf6f4d4bed1cdf97883eb43e872ff1a92013d


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[issue33289] tkinter askcolor returning floats for r, g, b values instead of ints

[Serhiy Storchaka]

Serhiy Storchaka  added the comment:


New changeset 3d5434d5cbc945c58be663e3dbd5ef4875677b7a by Serhiy Storchaka in 
branch '3.9':
[3.9] bpo-33289: Return RGB triplet of ints instead of floats from 
tkinter.colorchooser (GH-6578). (GH-24318)
https://github.com/python/cpython/commit/3d5434d5cbc945c58be663e3dbd5ef4875677b7a


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[issue33289] tkinter askcolor returning floats for r, g, b values instead of ints

[miss-islington]

Change by miss-islington :


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nosy: +miss-islington
nosy_count: 5.0 -> 6.0
pull_requests: +23144
pull_request: https://github.com/python/cpython/pull/24325

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[issue33289] tkinter askcolor returning floats for r, g, b values instead of ints

[Serhiy Storchaka]

Change by Serhiy Storchaka :


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pull_requests: +23137
pull_request: https://github.com/python/cpython/pull/24318

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[issue33289] tkinter askcolor returning floats for r, g, b values instead of ints

[Serhiy Storchaka]

Serhiy Storchaka  added the comment:


New changeset 6713e869c4989c04318158b406c30a147ea52904 by Cheryl Sabella in 
branch 'master':
bpo-33289: Return RGB triplet of ints instead of floats from 
tkinter.colorchooser (GH-6578)
https://github.com/python/cpython/commit/6713e869c4989c04318158b406c30a147ea52904


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[issue33289] tkinter askcolor returning floats for r, g, b values instead of ints

[Terry J. Reedy]

Terry J. Reedy  added the comment:

Your Linux result is the same as on Windows. Given strings 'abc' or 'abcd', 
ignore 'c' or 'cd' and expand 'ab' to 'abab', making value 0xabab.  Is your 
computer Ubuntu (implying that personal Ubuntu != CI Ubuntu) or a different 
Linux?  Are there tk/tcl compilation flags or X window options that could 
affect stored color values?

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[issue33289] tkinter askcolor returning floats for r, g, b values instead of ints

[Serhiy Storchaka]

Serhiy Storchaka  added the comment:

I do not understand why #abc00 and #abcd give 0xabab on my computer 
(Linux) and even weirder result on Ubuntu on CI. Reading the code I expected 
the same behavior as on macOS.

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[issue33289] tkinter askcolor returning floats for r, g, b values instead of ints

[Terry J. Reedy]

Terry J. Reedy  added the comment:

65535 = 35536 - 1 = 256 * 256 - 1 == 255 * 257

On Windows, each r, g, b value is n * 257 for n in range(256) (see attached 
file).  The precision loss happens when colors are stored, before the division 
in winfo_rgb.  Perhaps 8 bits/channel (including alpha) is baked in.

Since divmod(n * 257, 257) = (n, 0) and divmod(n * 257, 256) = (n, n),
(n*257) // m = divmod(n*257, m)[0] = n whether m is 256 or 257.
---

macOS appears (from limited experiments) to handle 1 and 2 digits the same as 
Windows (repeat 4 or 2 times): val('#a00') = val('#') = 0x, 
val('#ab') = val('#abab') = 0xabab.  4 digits are left alone while 
3 digits use the 1st as the 4th val('#abc00') = val('#abca') = 
0xabca.

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Added file: https://bugs.python.org/file49756/tk_rgb.py

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[issue33289] tkinter askcolor returning floats for r, g, b values instead of ints

[Terry J. Reedy]

Terry J. Reedy  added the comment:

https://www.tcl.tk/man/tcl8.6/TkCmd/winfo.htm says
"winfo rgb window color
Returns a list containing three decimal values in the range 0 to 65535, 
which are the red, green, and blue intensities that correspond to color in the 
window given by window. Color may be specified in any of the forms acceptable 
for a color option."

Since tk represents data as strings, 'decimal value in [0, 65535)' means 
'integer value represented by decimal digits'.  'correspond to color in the 
window' implies that the mapping from color to decimal value could depend on 
the window.  The mapping *does* differ between systems (see below).

https://www.tcl.tk/man/tcl8.6/TkLib/GetColor.htm
Lists possible return values, hence acceptible forms, as name or '#' followed 
by 1 to 4 hex digits.  It continues with "Each R, G, or B represents a single 
hexadecimal digit. The four forms permit colors to be specified with 4-bit, 
8-bit, 12-bit or 16-bit values. When fewer than 16 bits are provided for each 
color, they represent the most significant bits of the color, while the lower 
unfilled bits will be repeatedly replicated from the available higher bits. For 
example, #3a7 is the same as #."

This omits to say what happens when there are 2 or 3 hex digits.  Windows 
ignores 3rd and 4th hex digits.  On Windows, dividing by 257 instead of 256 
would be correct.  However, 256 works because the 'error', represented by the 
remainder, is always in [0, 256).  MacOS does not ignore digits.

https://www.tcl.tk/man/tcl8.6/TkCmd/colors.htm
Lists current color names and their values as 16 bit decimals.

The PR is blocked because the new colorchooser tests pass on Windows and macOS 
but fail on Ubuntu.  Cheryl speculated that the color names values vary across 
systems.  I think that it might instead be a coding issue, but I want to 
understand coding on Windows and Mac better before looking into Linux.

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versions: +Python 3.10 -Python 3.6, Python 3.7, Python 3.8

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[issue33289] tkinter askcolor returning floats for r, g, b values instead of ints

[Steve Dower]

Change by Steve Dower :


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keywords:  -easy

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[issue33289] tkinter askcolor returning floats for r, g, b values instead of ints

[Bryan Oakley]

Bryan Oakley  added the comment:

yes, this is a well known backwards incompatibility. In python 2, the
division operator returns an integer if both operands are integers. In
python 3 it returns a float.

https://www.python.org/dev/peps/pep-0238/

On Thu, Jul 12, 2018 at 8:48 AM STINNER Victor 
wrote:

>
> STINNER Victor  added the comment:
>
> Is this issue a regression of Python 3? red/256 gave an integer on Python
> 2?
>
> --
> nosy: +vstinner
>
> ___
> Python tracker 
> 
> ___
>

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title: tkinter askcolor returning floats for r,g,b values instead of ints -> 
tkinter askcolor returning floats for r, g, b values instead of ints

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[issue33289] tkinter askcolor returning floats for r, g, b values instead of ints

[Terry J. Reedy]

Terry J. Reedy  added the comment:

It appears so.

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[issue33289] tkinter askcolor returning floats for r, g, b values instead of ints

[STINNER Victor]

STINNER Victor  added the comment:

Is this issue a regression of Python 3? red/256 gave an integer on Python 2?

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[issue33289] tkinter askcolor returning floats for r, g, b values instead of ints

[Cheryl Sabella]

Change by Cheryl Sabella :


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keywords: +patch
pull_requests: +6278
stage: needs patch -> patch review

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[issue33289] tkinter askcolor returning floats for r, g, b values instead of ints

[Cheryl Sabella]

Cheryl Sabella  added the comment:

Adding to what Serhiy said about the askcolor() return value is an issue that 
also affects input:


>>> cc.askcolor('red')
((255, 0, 0), '#ff')
>>> cc.askcolor((255, 0, 0))
((255, 0, 0), '#ff')
>>> cc.askcolor((65535, 0, 0))
Traceback (most recent call last):
  File "", line 1, in 
  File "/home/cheryl/cpython/Lib/tkinter/colorchooser.py", line 75, in askcolor
return Chooser(**options).show()
  File "/home/cheryl/cpython/Lib/tkinter/commondialog.py", line 43, in show
s = w.tk.call(self.command, *w._options(self.options))
_tkinter.TclError: invalid color name "#"


Changing _fixoptions to format initialcolor using "#%04x%04x%04x" % color.

allows for 16-bit hex values, but it's not the same as 8-bit.

>>> cc.askcolor('red')
((255, 0, 0), '#ff')
>>> cc.askcolor((255, 0, 0))
((0, 0, 0), '#00')
>>> cc.askcolor((65535, 0, 0))
((255, 0, 0), '#ff')

(255, 0, 0) in the second call is black and not red.

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nosy: +csabella

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[issue33289] tkinter askcolor returning floats for r, g, b values instead of ints

[Serhiy Storchaka]

Change by Serhiy Storchaka :


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stage:  -> needs patch

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[issue33289] tkinter askcolor returning floats for r, g, b values instead of ints

[Serhiy Storchaka]

Serhiy Storchaka  added the comment:

Good catch! A color tuple will likely be used in '#%02x%02x%02x' % color, and 
this will fail because %x works only with integers (in general sense). 
Therefore returning a tuple of floats is a bug.

The downside is that we loss some information. Tk supports up to 16 bit per 
color component, and askcolor() keeps only higher 8 of them. This can't be 
changed for backward compatibility, but it may be worth to add an option for 
control the representation of the result. winfo_rgb() returns 16-bit color 
components. This is a separate issue.

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keywords: +easy

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[issue33289] tkinter askcolor returning floats for r, g, b values instead of ints

[Terry J. Reedy]

Terry J. Reedy  added the comment:

For future reference, 3.4 and 3.5 only get security fixes.

The quoted line of code is from the main part of 
tkinter.colorchooser,Chooser._fixresult:
r, g, b = widget.winfo_rgb(result)
return (r/256, g/256, b/256), str(result)

where tkinter.Misc defines
def winfo_rgb(self, color):
"""Return tuple of decimal values for red, green, blue for
COLOR in this widget."""
return self._getints(
self.tk.call('winfo', 'rgb', self._w, color))

The code in tkColorChooser and Tkinter in 2.x is the same.

The docstring for winfo_rgb is wrong as it returns a tuple of ints in 
range(2**16256).  For red, the results are
>>> Tk().winfo_rgb('red')
(65535, 0, 0)  # 2.x and 3.x
>>> cc.askcolor('red')
((255, 0, 0), '#ff')  # 2.7
>>> cc.askcolor('red')
((255.99609375, 0.0, 0.0), '#ff')  # 3.8

In addition to fixing the winfo_rgb docstring (in all versions), and adding doc 
strings to colorchooser, it seems that '/' should be '//' in 3.x.  I don't know 
if I would fix this in 3.6.

--
nosy: +serhiy.storchaka, terry.reedy
title: askcolor is returning floats for r,g,b values instead of ints -> tkinter 
askcolor returning floats for r,g,b values instead of ints
type:  -> behavior
versions:  -Python 3.4, Python 3.5

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