Fix #13652: Show opacity control in color picker where appropriate

[octopols]

Resolves: #13652
Color picker now have alpha value. If the alpha value is 0 and the color picker is launched the value is changed to 255 automatically.

Sorry I had to close the last PR fixing this issue because of me deleting my original fork.
This PR is a replacement for #16103 .

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[octopols]

issue_13652_fix.mp4

[octopols]

Is there a way for me to add a checkbox to QColorDialog to enable or disable checkbox? When I first tackled this issue I couldn't find the qml for QColorDialog and soon realized it's an inbuit component and never really looked into editing the dialog's UI.

[cbjeukendrup]

@octopols What do you mean? The color dialog is platform-dependent, i.e. Qt just calls the OS's color dialog. That means that you don't have any possibilities to customise it, beyond the options offered by Qt.

[cbjeukendrup]

I see one issue with this PR: probably not every color picker should have an alpha channel. For example, I think the color pickers in Preferences > Appearance should not have an alpha channel, because that may cause strange results.

So I think you need to add a property to the ColorPicker component in QML to enable/disable the alpha channel per instance of ColorPicker. Then, you need to propagate the value of that property via ColorPickerModel to Interactive::selectColor, which should get a new parameter for that. Then, based on that parameter, you should pass QColorDialog::ShowAlphaChannel or QColorDialog::ColorDialogOptions() to the QColorDialog.

[octopols]

I was discussing this issue with @VanSHOE recently, and he suggested editing it through Qt Quick components. However, I'm not entirely sure if I conveyed my problem correctly to him.
I will implement the fix you mentioned. However, if we do decide to add a checkbox to enable the alpha channel, is our only option to design a completely new component?

[cbjeukendrup]

I'm afraid yes...

I would prefer to use the platform dialogs as much as we can, because they "just work" and people already know them from other apps.

[octopols]

@cbjeukendrup I'm having a really hard time propagating a bool I created showAlpha to Interactive::selectColor. I think I need to make some changes in src\framework\uicomponents\view\colorpickermodel.cpp but I don't even know where to start. Should I commit the changes I made so far?

[octopols]

[cbjeukendrup]

That list of files looks good. The "missing link" will indeed be in colorpickermodel.h/cpp. I think the easiest way is to add a showAlpha bool parameter the method Q_INVOKABLE QColor selectColor(const QColor& currentColor);.

[octopols]

I made some changes in the colorpickermodel.h/cpp files but I'm still getting an error in the ColorPicker.qml file.

These are the changes I made in colorpickermodel.h

And these are the changes I made in colorpickermodel.cpp

[cbjeukendrup]

Ah, the problem is that showAlpha is not a property of the ColorPickerModel class, but a parameter of the selectColor method.

That method is called here:

    QtObject {
        id: prv

        function selectColor() {
            var selectedColor = colorPickerModel.selectColor(root.color) // <-- here
            root.newColorSelected(selectedColor)
        }
    }

So in that place, you need to pass the showAlpha parameter.

[octopols]

I have this one last problem (hopefully), how do I set the value of showAlpha from TextSettings.qml.

[cbjeukendrup]

There are two solutions:

1. setting the property of the color picker inside ColorSection.qml (but that means that it will be enabled for all color pickers that are created using ColorSection; not sure if that's desired
2. create a showAlpha property alias in ColorSection.qml: inside the root item of the file, you would add property alias showAlpha: colorPicker.showAlpha.
   After giving ColorSection this property, you can go to TextSettings.qml and use it like just showAlpha: true.

[octopols]

Thank you very much for your help. The issue has been resolved now.

[MarcSabatella]

Sorry if this was already obvious to everyone else, but in case it's useful or relevant - I just realized, the alpha channel control already is present if you involve the color picker from the Format / Style / Text Styles. Which is great, because that's where it is actually needed most. But of course, it would be great to have in Properties as well

[Jojo-Schmitz]

Rebase needed

[octopols]

Rebase needed

I'll rebase it today, sorry for replying late

[cbjeukendrup]

@zacjansheski please check that the colour pickers in the properties panel now have a (working) alpha channel, i.e. the one inside the Appearance popup, and the ones for text border / fill.

[zacjansheski]

I'm unable to open these builds, tried on both MacOS and Windows. Splash screen and then MSS crashes.

@cbjeukendrup please advise

[cbjeukendrup]

It turns out I had not properly removed a change from an old version of this PR... should be fixed now!

[zacjansheski]

Tested on MacOS 15, Windows 11. Approved
#13652 FIXED

[Jojo-Schmitz]

Backporting to 4.6.4?

[cbjeukendrup]

Hm... yeah, I'm not against.

[Jojo-Schmitz]

Done, see #30918