How do you convert a WinDef.POINT to a WinDef.POINT.ByValue?

Question

Say I receive a WinDef.POINT using User32.INSTANCE.GetCursorPos. How can pass this WinDef.POINT to a function that requires a WinDef.POINT.ByValue?

Answer 1

The WinDef.POINT.ByValue class includes a Pointer constructor.

You can retrieve the Pointer to the POINT structure you received using the Structure class method getPointer().

So a type safe way of doing it that I'd probably do:

WinDef.POINT thePoint = new WinDef.POINT();
User32.INSTANCE.GetCursorPos(thePoint);
WinDef.POINT.ByValue thePointByVal = new WinDef.POINT.ByValue(thePoint.getPointer());
passThePointToTheOtherFunction(thePointByVal);

Knowing the inner workings of the class, I can see the nested ByValue class extends the POINT class without changing anything about its fields, so simple typecasting would work here, although may be considered a code smell:

WinDef.POINT thePoint = new WinDef.POINT();
User32.INSTANCE.GetCursorPos(thePoint);
passThePointToTheOtherFunction((WinDef.POINT.ByValue) thePoint);

Upcasting would work as well is probably "safer" but since we're still intentionally causing different behavior it's relying on implementation details and may also be a code smell:

WinDef.POINT.ByValue thePoint = new WinDef.POINT.ByValue();
// Explicitly upcast to trigger default ByReference behavior
User32.INSTANCE.GetCursorPos((WinDef.POINT) thePoint);
passThePointToTheOtherFunction(thePoint);