Change theme dynamically on the fly

[firedm]

Type of Issues (Enhancement, Error, Bug, Question): Enhancement

Operating System: windows

Python version: 3.6

PySimpleGUI Port and Version: tkinter

Hello Mike,
This is not an urgent request, I know you are busy so you can delay it when you have time.

Is it possible to change theme while window is running? i.e. without the need for restarting the window?

my current theme implementation is to
1 - close active window
2- call ChangeLookAndFeel('new_theme_name')
3- recreate window
4 - start window read

sometimes restarting the window consume time plus it would be more elegant to change theme and see the results instantly

i was playing with pysimplegui and tkinter code, and i came up with this result so far, it is horrible because i never used tkinter before

below is an example, where you can select theme and it will iterate over all window elements and change colors according to the selected theme, however it doesn't work as expected
the window background doesn't fill completely around other elements, i think i am missing something,

please have a look, as you are the expert here who can come up with an acceptable implementation

import PySimpleGUI as sg

themes = sg.ListOfLookAndFeelValues()
selected_theme = 'Reds'
current_them = sg.LOOK_AND_FEEL_TABLE[selected_theme]
sg.ChangeLookAndFeel(selected_theme)

layout = [
        [sg.T('User Setting:')],
        [sg.Text('Select Theme:'), 
        sg.Combo(values=themes, default_value=selected_theme, size=(15, 1), enable_events=True, key='select_theme')],
        [sg.I('this is input')], 
        [sg.B('Hello'), sg.Button(' about ', key='about')]
]

window = sg.Window('', layout=layout)

while True:
    e, v= window()
    if e is None:
        break
       
    elif e == 'select_theme':
        
            selected_theme = v['select_theme']
            print(selected_theme)
            current_them = sg.LOOK_AND_FEEL_TABLE[selected_theme]

            try:
                window_bkg = current_them.get('BACKGROUND')
                window.TKroot.config(background=window_bkg)
            except Exception as e:
                    print(e)

             # iterate over all widgets:
            for v, element in window.AllKeysDict.items():
            # for child in window.TKroot.frame.children.values():
                
                try:
                    color = current_them.get(element.Type.upper())
                    if color:
                        if element.Type == 'button':
                            element.Widget.config(foreground=color[0], background=color[1])
                        else:
                            element.Widget.config(background=color)

                        element.update()
                except Exception as e:
                    print(e)

[PySimpleGUI]

The only way to change a window is to call each of the update methods for the elements. I am unsure if you can change the colors on them all.

You're correct in your tkinter specific implementation. But, of course it's not portable.

[PySimpleGUI]

You should change over to the new theme calls instead of the older change_look_and_feel. It provides access to the colors easier theme_background_color() will both get and change the color in the theme.

[firedm]

theme_background_color() is this changing the whole theme?

[PySimpleGUI]

https://pysimplegui.readthedocs.io/en/latest/#themes_1

[firedm]

ok will have a look to the docs

[PySimpleGUI]

Yea, there's also a new Theme section that lists all of the theme_ functions available.

https://pysimplegui.readthedocs.io/en/latest/#themes-automatic-coloring-of-your-windows

[definite-d]

Hello!

Sorry if I'm intruding, but this issue caught my attention.
The presence of these phrases...:

The only way to change a window is to call each of the update methods for the elements. I am unsure if you can change the colors on them all.

# iterate over all widgets: for v, element in window.AllKeysDict.items():

...made me want to experiment with this. I'm thinking of a solution whose end-result will be a function like this:
realtime_theme_change(theme, init_window)
...where theme could be any existing theme, built-in or custom generated, to change to, and init_window stands for the latest window opened. If there's a way to obtain the names of all windows via a PySimpleGUI function, then that would be really cool too.

[firedm]

Sorry if I'm intruding, but this issue caught my attention.

I believe people feedback is what makes any library grow, so thanks for sharing, for me as a PySimpleGUI user, my responsibility is to report bugs and ideas to help the author make more improvements.

realtime_theme_change(theme, init_window)

nice name, it also could be an extra code under theme() or ChangeLookAndFeel() or a method for Window itself,

from my understanding, to add a feature for PySimpleGUIxx it should works also on other ports i.e. wx and Qt, to be portal.

My above "horrible" code did get a close result or show case for tkinter, still need a working code for both wxpython and Qt.

if you come up with something, please share :)

[PySimpleGUI]

I like ideas 😃

Hooking it into the PySimpleGUI APIs isn't difficult. If something were hooked into PySimpleGUI's existing APIs then it would belong in the main theme function call.

def theme(new_theme=None, window=None)

If window is specified then the theme would be applied to the window instead of the system.

[firedm]

I agree theme() is the right place for this
i suggest an extra parameter, something like

def theme(new_theme=None, window=None, system_wide=True) 

The default should be changing theme on both window 'if specified' and the system in same time, and if user want theme applied to window only, he should modify parameter system_wide=False

[PySimpleGUI]

I don't think the 3rd is needed.

Not sure if this belongs inside PySimpleGUI yet. It sounds doable by applications. There are some applications that want to do real-time skinning type operations, but it's not what I would consider to be a critical feature.

It's adding complexity. theme went from a simple 1 parameter call to now one with 3 variables and multiple states.

[definite-d]

The complexity aspect could be solved if the proposed solution is created as an extension module for PySimpleGUI. Like Colorpiq.

That way, only those who need the feature specifically can have it, and theme() can always be simple as usual.

I didn't see a way to know the names of all PySimpleGUI windows running, so I guess I'll have to use a good old file search using open(), regex and operands.

By the way, I forked this repo yesterday to make a minor fix (the theme preview window is a behemoth that needs to be trimmed by a scrollable Column), but I couldn't even locate the theme() function by a browser search. I'm confused about that.

[PySimpleGUI]

Exactly!

The ANSI text viewer is another example. One could argue that displaying a string with ANSI color codes embedded is something that should be added to PySimpleGUI. I instead opted to create a separate little Python file / code snippet that does the processing for the user and provides code that will update their Multiline or other element with the correct calls to display the string in color.

There is a count of the number of open windows, but there is not a list of them saved anywhere. That can be added however. It's a reasonable thing to want to know if you're working on extending PySimpleGUI, which is what's happening here. I've no problem with opening an enhancement to keep that information around. It's something I should be doing anyway. It would be portable code across the other ports so I'm not worried about the rippling impact.

The theme function should be in the code. It uses change_look_and_feel just like before.

BTW, I published code for making your own previewer that's based off the built-in one if you have trouble messing around with it. Seems like a reasonable thing to add. Even with a low number of columns, it will be quite tall. I've got an enormous monitor which is why I let it float to be so large. I'll look at how to add the ability to control the display more.

[definite-d]

That's cool to see. Since you've already put in measures to control the theme preview window, I guess I've got no use for a fork anymore 😆. For now.

So, I started off with the ext-module. I called it 'realtime_theme', then added the major function as 'change'. That function has two params (currently). Theme and client. Theme is, well, a theme, while client is the name of the script the extension will work on (like a target for all its queries), which the user should always name after their script. I had to use the 'client' approach after failing at getting it automatically with name and friends.

That approach works as expected, but if there's a workaround for 'client', please let me know.

Anyway, I currently have a list of all window names at my disposal from a loop operation through 'client'. The main challenge would be obtaining all layouts, but I guess two loops could take care of it.