I’ve been trying to figure this one out for several weeks. I need a way to draw lines & rects onto a custom slate widget, in order to visualize some internal data. And although I can’t seem to figure out where, I believe that somewhere, UE4 is doing this internally for things like SGraphEditor.
So is there any way to actually draw lines in an SWindow, or any other slate widget?
Where in code I should be looking?
Ok, so I was under the impression that you couldn’t actually override OnPaint in 4.17+, but I guess that’s not the case after all. The solution to anyone trying to do so and getting compiler errors is to NOT copy/paste function definitions from the API docs, but instead, copy them from the engine source whenever possible.
In this particular case, the SCanvas::OnPaint definition from the docs is actually missing it’s const qualifier at the end, forcing the compiler to throw C3668.
The actual definition in code is:
virtual int32 OnPaint( const FPaintArgs& Args, const FGeometry& AllottedGeometry, const FSlateRect& MyCullingRect, FSlateWindowElementList& OutDrawElements, int32 LayerId, const FWidgetStyle& InWidgetStyle, bool bParentEnabled ) const override;
After fixing my custom widget class’s definition to match this, I got it to compile and was able to use the typical FSlateDrawElement::* methods to paint onto the canvas.