MarkupExtension for multiple styles in C++

arjunc007 · 14 Dec 2021, 13:37

Hi,

I'm trying to implement a MultiStyle MarkupExtension that allows me to merge multiple Styles like

<Style x:key="Combined" BasedOn="{local:MultiStyle A B}">
      ... other properties.
</Style>

I'm, following
https://stackoverflow.com/questions/574 ... nd-basedon

The code works on the C# side but I'm having trouble using the StaticResourceExtension class to find the Style Resources in the ProvideValue function in C++.

I have this in C++ right now with a bunch of errors

Noesis::Ptr<BaseComponent> ProvideValue(const Noesis::ValueTargetProvider* provider) override {
			  Noesis::Ptr<Noesis::Style> resultStyle = *new Noesis::Style();
			  for (std::string currentResourceKey : resourceKeys)
			  {
				  Noesis::TypeClass key = Noesis::TypeClass(Noesis::Symbol(currentResourceKey.c_str()), false);
				  if (currentResourceKey == ".")
				  {
					  key = *(provider->GetTargetObject()->GetClassType());
				  }
				  Noesis::Ptr<Noesis::MarkupExtension> ext = Noesis::MakePtr<Noesis::MarkupExtension>();
				  Noesis::Style* currentStyle = Noesis::DynamicCast<Noesis::Style*>(ext->FindNodeResource(key.c_str(), true));
				  if (currentStyle == nullptr) 
					  throw std::runtime_error("Invalid Style resource specified");
				  
				  MultiStyleMethods::Merge(resultStyle, currentStyle);
			  }

			  return Noesis::Ptr<Noesis::Style>(resultStyle);
		  }

What is the right way to get resources in C++ using a string? And is making 'key' a TypeClass from a string the right approach or should it be something else?

16 Dec 2021, 14:32

Hi,

The resource keys are simple strings, you don't have to create a TypeClass for that.

Regarding the StaticResourceExtension, I see we don't have that class in the public API, could you report this in our bugtracker?
In the meantime you can just search for the resource in the target object and application resources:

Noesis::Ptr<BaseComponent> ProvideValue(const Noesis::ValueTargetProvider* provider) override {
    Noesis::Ptr<Noesis::Style> resultStyle = *new Noesis::Style();
    Noesis::ResourceDictionary* app = Noesis::GUI::GetApplicationResources();
    Noesis::IUITreeNode* node = Noesis::DynamicCast<Noesis::IUITreeNode*>(provider->GetTargetObject());
    if (node != nullptr) {
        for (std::string currentResourceKey : resourceKeys) {
            const char* key = currentResourceKey == "." ? node->GetClassType()->GetName() : currentResourceKey.c_str();
            // try find resource in the UI tree first
            Noesis::Style* currentStyle = Noesis::DynamicCast<Noesis::Style*>(node->FindNodeResource(key, false));
            if (currentStyle == nullptr) {
                // try find in application resources
                Noesis::Ptr<Noesis::BaseComponent> resource;
                if (app->Find(key, resource)) {
                    currentStyle = Noesis::DynamicCast<Noesis::Style*>(resource.GetPtr());
                    if (currentStyle == nullptr) {
                        throw std::runtime_error("Invalid Style resource specified");
                    }
                }
            }
            MultiStyleMethods::Merge(resultStyle, currentStyle);
        }
    }
    return Noesis::Ptr<Noesis::Style>(resultStyle);
}

arjunc007 · 16 Dec 2021, 20:57

Thanks for the code. This plus viewtopic.php?t=1150 worked well!

Created a bug for StaticResourceExtension here https://www.noesisengine.com/bugs/view.php?id=2216

17 Dec 2021, 12:02

Thank you!

MarkupExtension for multiple styles in C++ Topic is solved

MarkupExtension for multiple styles in C++

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