Setting callback for SEditableText widget to save text - unreal-engine4

Question

I have implemented an SEditableText widget in my editor plugin but I can't figure out a reasonable way of accessing the value in the widget. I know there is an SEditableText.OnTextChanged() function but I don't see anyway to override it or set a callback of my own. Is there a standard way to save the content of an SEditableText to a variable?
I am working in the context of FModeToolKit, not sure if that makes a difference.

Answer 1

When you instantiate the slate widget, you should already be making a call to SNew. As part of the property initialiser chain list, initialise SEditableText::OnTextChanged and bind to your container UObject, using BIND_UOBJECT_DELEGATE. The delegate signature should be FOnTextChanged. Your handler will receive an FText which may be stored in a variable as required.
Example:
SEditableText EditableText = SNew(SEditableText)
.OnTextChanged(BIND_UOBJECT_DELEGATE(FOnTextChanged, OnTextChanged);
then:
void UMyUObject::HandleOnTextChanged(const FText& InText)
{
// Do something with text
}
Take a look at it in action in UEditableText::RebuildWidget (EditableText.cpp:50, v4.22.1).
NB. I know you specifically asked about OnTextChanged, but also consider OnTextComitted; this is only fired when the slate widget loses focus.
Ah; BIND_UOBJECT_DELEGATE is in UMG. The macro is however just a helper to create a UObject to which you may bind:
#define BIND_UOBJECT_DELEGATE(Type, Function) \
Type::CreateUObject( this, &ThisClass::Function )
So there's two options, either use <my type>::CreateUObject, or you could bind via a shared pointer. Off the top of my head, SP method should look something like:
Edit (based on comments):
If you're not linked against UMG, you could try manually creating the UObject based on the macro defined in SlateWrapperTypes in UMG:
#define BIND_UOBJECT_DELEGATE(Type, Function) \
Type::CreateUObject( this, &ThisClass::Function )
To instead use a shared pointer, the syntax should be along the following lines:
auto OnTextChangedSP = FOnTextChanged::CreateSP(this, &MyClass::MyOnTextChangedHandler);
SEditableText EditableText = SNew(SEditableText)
.OnTextChanged(OnTextChangedSP);