[Interest] Creating a custom QML style with Material as a fallback, but with a dark theme

[Matthew Fincham]

Hi Mitch

Thanks for the reply. That is effectively what I have resorted to doing: 
setting the attached properties for the root window item:

Material.theme: Material.Dark
Material.primary: ...
Material.accent: ...
Material.foreground: ...
Material.background: ...

One problem with this approach is the 'Variant' property can't be set 
(Dense/Normal). Looking in the source code, that can only be set from 
the environment variable, which is done in 
QQuickMaterialStyle::initGlobals()

Just to complete the picture, I have tried with the import in qmldir:

import QtQuick.Controls.Material auto

and setting the fallback style in C++:

QQuickStyle::setFallbackStyle("Material");

I would imagine 'initiGlobals' should be called, even when it is the 
fallback style. But I don't know the infrastructure for the style 
plugins and the theme initialisation, so not sure how that should be 
accomplished.

Kind regards
Matthew

On 2023/09/20 03:44, EXT Mitch Curtis wrote:
> Hi Matthew,
>
>> -----Original Message-----
>> From: Interest <interest-bounces at qt-project.org> On Behalf Of Matthew
>> Fincham via Interest
>> Sent: Tuesday, September 19, 2023 1:13 PM
>> To: interest at qt-project.org
>> Subject: Re: [Interest] Creating a custom QML style with Material as a fallback,
>> but with a dark theme
>>
>> Hi
>>
>> Following up on my own post.
>>
>> QQuickMaterialStyle logs a warning if an invalid theme is used (not 'Light' or
>> 'Dark'). This is in the function that initialises the style's global variables. (in
>> qquickmaterialstyle.cpp)
>>
>> When the 'Material' style is used as the fallback style, this log is not seen. This
>> initialisation function is called from the 'Material' plugin (
>> qtquickcontrols2materialstyleplugin.cpp), which seems to indicate the plugin's
>> initialisation is not run when it is the fallback theme.
>>
>> Does this make sense, and is there a way to force the initialisation?
> I'm looking into it, but as a workaround, assuming your style imports the Material style as a fallback in its qmldir (or IMPORTS in qt_add_qml_module):
>
>      import QtQuick.Controls.Material auto
>
> you can then use the attached API to set the theme:
>
>      Material.theme: Material.Dark
>
>> Thanks again.
>> Matthew Fincham
>>
>> On 2023/09/18 12:52, Matthew Fincham via Interest wrote:
>>> Hi
>>>
>>> I am attempting to create a custom QML style using this documentation:
>>>
>> https://doc/.
>>> qt.io%2Fqt-6%2Fqtquickcontrols-customize.html%23definition-of-a-style&
>>>
>> data=05%7C01%7Cmitch.curtis%40qt.io%7C4e7b0a9253b649740eed08dbb
>> 8cf6fb0
>> %7C20d0b167794d448a9d01aaeccc1124ac%7C0%7C0%7C638306973314
>> 152407%7CUnk
>> nown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6I
>> k1haWw
>> iLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=V2b3M0MBvsarYVwtDQd
>> aF3kwWtc2xurp
>>> AuA%2F10IABak%3D&reserved=0
>>>
>>> I won't provide sample code because it is close to line-for-line. The
>>> custom style works - there is a custom button and the other controls
>>> use the Material style. However, I can't get the Material style to run
>>> with the Dark theme.
>>>
>>> The theme is set with an environment variable:
>>>
>>> QT_QUICK_CONTROLS_MATERIAL_THEME=Dark
>>>
>>> The style is set in C++:
>>>
>>> QQuickStyle::setStyle("MyStyle");
>>>
>>> If the style is "Material" this works as expected. With 'MyStyle',
>>> that falls back to Material, a Light theme is used. Is there any was
>>> to force the fallback style to use the Dark theme?
>>>
>>> Many thanks
>>> Matthew Fincham
>>> _______________________________________________
>>> Interest mailing list
>>> Interest at qt-project.org
>>> https://list/
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