[settings] support direct connection from widget value change to upda…

[3nids]

…te setting value

This is useful to remember last used values for instance.

There is an API break in QgsSettingsEditorWidgetWrapper. I would prefer to make the method pure virtual from the beginning. Considering the recently solved ticket of settings unregistration from plugin (#58595), it is pretty sure no one ever implemented a custom QgsSettingsEditorWidgetWrapper in python.

For instance, this code will set a combobox to display options from an enum with translations and auto save the last used option:

const auto *QgsVectorTileConnectionDialog::settingsLastLoadingMode = new QgsSettingsEntryEnumFlag<QgsVectorTileConnectionDialog::LoadingMode>( QStringLiteral( "vector-tile-loading-mode" ), QgsGui::sTtreeWidgetLastUsedValues, QgsVectorTileConnectionDialog::LoadingMode::Url, QString() ) ;

…

auto *settingsWidgetWrapper = new QgsSettingsEnumEditorWidgetWrapper<QgsVectorTileConnectionDialog::LoadingMode>( this );
settingsWidgetWrapper->setDisplayStrings(
{
  {LoadingMode::Style, tr( "Load from style" )},
  {LoadingMode::Url, tr( "Load from URL" )},
} );
settingsWidgetWrapper->configureEditor( mModeComboBox, settingsLastLoadingMode );
settingsWidgetWrapper->enableAutomaticUpdate();

[github-actions]

🪟 Windows builds ready!

Windows builds of this PR are available for testing here. Debug symbols for this build are available here.

(Built from commit 8ded78f)

[3nids]

@nyalldawson now, you can give a dialog, so it saves on accept.

[nirvn]

Sorry, I think this would be a bit better in my humble opinion :)

(also, you'll need a sip update, so good reason to do a final name tweak ;) )

Suggested change

	void configureAutomaticUpdate( QDialog *dialog = nullptr );
	void configureUpdateBehavior( QDialog *dialog = nullptr );

[3nids]

I prefer configureAutomaticUpdate because it actually enables the auto update (not direct if dialog, direct if no dialog)

[nirvn]

@3nids , I guess yeah automatic update in that it'll automatically take care of updates (live update vs dialog close update). OK.