It is certainly an interesting method of bypass and rerouting a method.
Reminds me of heart surgery triple bypass performed by an icing chef ;)
Ross Levis wrote:
I just noticed a bug which I'll
await Rob to fix it. The Result value of any functions being called is
not being returned to the caller (DLL). Perhaps this is due to the
parameters being shifted one position.
Ross.
-----
Original Message -----
Sent:
Monday, July 11, 2005 11:31 PM
Subject:
Re: [DUG] call a method function from outside object
It's attached. Below are Rob's
instructions for use. I found I had to add a dummy parameter in the
method declarations otherwise the parameter values were shifted one to
the right.
To use it, start by declaring data types for your function and
method
pointers:
type
TConfigFunction = procedure(ParentWindow: HWnd); cdecl;
TConfigMethod = procedure(ParentWindow: HWnd) of object; stdcall;
TCanWriteFunction = function: Integer; cdecl;
TCanWriteMethod = function: Integer of object; stdcall;
The calling conventions differ on purpose. It just makes things a lot
easier that way.
When you instantiate your object, call my MakeCdeclInstance function to
create a wrapper for your method.
type
TWinampPlugIn = class
private
FConfig: TConfigFunction;
FCanWrite: TCanWriteFunction;
procedure Config(ParentWindow: HWnd); stdcall;
function CanWrite: Integer; stdcall;
public
constructor Create;
destructor Destroy; override;
end;
constructor TWinampPlugIn.Create;
var
Method: TMethod;
ConfigMethod: TConfigMethod;
CanWriteMethod: TCanWriteMethod;
begin
inherited;
ConfigMethod := Config;
Method := TMethod(ConfigMethod);
FConfig := MakeCdeclInstance(Method, SizeOf(HWnd));
CanWriteMethod := CanWrite;
Method := TMethod(CanWriteMethod);
FCanWrite := MakeCdeclInstance(Method, 0);
end;
destructor TWinampPlugIn.Destroy;
begin
FreeCdeclInstance(@FCanWrite);
FreeCdeclInstance(@FConfig);
inherited;
end;
After that, FConfig and FCanWrite are regular standalone-function
pointers. When you or the DLL call them, though, they will call the
corresponding method on a specific instance of the TWinampPlugIn class.
_______________________________________________
Delphi mailing list
[email protected]
http://ns3.123.co.nz/mailman/listinfo/delphi
|
_______________________________________________
Delphi mailing list
[email protected]
http://ns3.123.co.nz/mailman/listinfo/delphi
