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The pure virtual factory function CAnimDll::CreateInstanceL()
must be provided in the derived class to create new instances of animation objects of type CAnim
contained in the DLL
Declare your CAnimDll
derived class in a header file as follows:
class CExampleAnimDll : public CAnimDll
{
public:
virtual CAnim* CreateInstanceL(TInt aType);
};
A convenient way to implement CreateInstanceL()
is to switch on the TInt aType
argument, with each switch constructing a different CAnim
derived animation class identified by an aType
enum, for example if CShapesAnims
is one of those classes:
switch(aType)
{
// cases
case EShapesAnims:
return new(ELeave) CShapesAnims;
...
default:
iFunctions -> Panic();
return NULL; // dummy return to prevent compiler error
}
}
It is up to the implementer to decide whether receiving a bad parameter should cause a panic, as here, or a leave. The approach shown is recommended.
The Panic()
function is an MAnimGeneralFunctions
helper function, to which CAnim
provides the iFunctions
pointer. These functions are implemented by the window server and are available to any CAnim
derived class.
The animation class's ConstructL()
function is called after CreateInstanceL()
.