Cetting lpVtbl of COM

SuperStrict

Framework PUB.DirectX

' Don't remove this main function!
Function DllMain:Int(hinstDLL:Byte Ptr,fdwReason:Int,lpvReserved:Byte Ptr)"win32"
	Select fdwReason
		Case 1 ' DLL_PROCESS_ATTACH
		Case 2 ' DLL_THREAD_ATTACH
		Case 3 ' DLL_THREAD_DETACH
		Case 0 ' DLL_PROCESS_DETACH
	End Select

	Return True
End Function

' Don't remove the EXPORT comment!
Function ChangeShading:Int(Device:IDirect3DDevice7, Mode:Int) "win32" 'EXPORT
	Local VirtualTable:Int Ptr
	Local SetRenderState:Int(This:IDirect3DDevice7, RenderStateType:Int, ..
	      RenderState:Int) "win32"

	VirtualTable = Int Ptr(Int Ptr(Byte Ptr(Device))[0])
	SetRenderState = Byte Ptr(VirtualTable[20])
	Return SetRenderState(Device, D3DRS_SHADEMODE, Mode)
End Function

Function ChangeShading2:Int(Device:IDirect3DDevice7, Mode:Int) "win32" 'EXPORT
	Device.SetRenderState(D3DRS_SHADEMODE, Mode)
End Function

MakeDLL renderstate.bmx D:\BlitzMax

.lib "renderstate.dll"
ChangeShading%(D3DDevice%, Mode%) : "ChangeShading"

Const D3DSHADE_FLAT    = 1
Const D3DSHADE_GOURAUD = 2
Const D3DSHADE_PHONG   = 3

Graphics3D 800,600,32,2

Global Device = Int(SystemProperty("Direct3DDevice7"))

Camera = CreateCamera()
PositionEntity Camera, 0, 0, -4.0

Light = CreateLight()
RotateEntity Light, 60, 30, 0
Sphere = CreateSphere()

While Not KeyHit(1)
   If KeyHit(2) ChangeShading Device, D3DSHADE_FLAT
   If KeyHit(3) ChangeShading Device, D3DSHADE_GOURAUD
   If KeyHit(4) ChangeShading Device, D3DSHADE_PHONG
   
   RenderWorld()
   Text 0, 0, "Press 1,2 or 3 to change the Render Style"
   Flip()
Wend

End

SuperStrict

Framework PUB.DirectX

Const MB_OK              : Int   = $0
Const MB_ICONEXCLAMATION : Int   = $30

Extern "win32"
	Function MessageBoxA:Int(hWnd:Int, lpText$z, lpCaption$z, uType:Int)
End Extern

Const VTBL_SETRENDERSTATE : Int = 20

Global VirtualTable      : Int Ptr
Global OrgSetRenderState : Int(This:IDirect3DDevice7, RenderStateType:Int, RenderState:Int)

Function DllMain:Int(hinstDLL:Byte Ptr, fdwReason:Int, lpvReserved:Byte Ptr) "win32"
	Select fdwReason
		Case 1 ' DLL_PROCESS_ATTACH
		Case 2 ' DLL_THREAD_ATTACH
		Case 3 ' DLL_THREAD_DETACH
		Case 0 ' DLL_PROCESS_DETACH
	End Select

	Return True
End Function

Function StartRecording(Device:IDirect3DDevice7) "win32" 'EXPORT
	' Get virtual table from interface/instance
	VirtualTable = Int Ptr(Int Ptr(Byte Ptr(Device))[0])
	
	' Get original method
	OrgSetRenderState = Byte Ptr(VirtualTable[VTBL_SETRENDERSTATE])
	
	' Overload with own method
	VirtualTable[VTBL_SETRENDERSTATE] = Int(Byte Ptr(SetRenderState))
End Function

Function StopRecording:Int() "win32" 'EXPORT
	' Rewrite original method
	VirtualTable[VTBL_SETRENDERSTATE] = Int(Byte Ptr(OrgSetRenderState))
End Function

Function SetRenderState:Int(This:IDirect3DDevice7, RenderStateType:Int, RenderState:Int)
	' Display some information
	MessageBoxA(0, "RSType: "+RenderStateType+"; RS: "+RenderState, ..
	            "Overloaded method", MB_OK | MB_ICONEXCLAMATION)
	
	' Use original method
	Return OrgSetRenderState(This, RenderStateType, RenderState)
End Function

MakeDLL DX7Overloader.bmx D:\BlitzMax
Pause

.lib "DX7Overload.dll"
StartRecording(Device%)
StopRecording()

Graphics3D 640, 480, 0, 2

Global Device = Int(SystemProperty("Direct3DDevice7"))

Camera = CreateCamera()
PositionEntity(Camera, 0.0, 0.0, -4.0)

Light = CreateLight(2, Camera)

Cube = CreateCube()
RotateEntity Cube, 0.0, 45.0, 0.0

StartRecording(Device)
RenderWorld()
StopRecording()
Flip()

WaitKey()
End

Global OrgSetRenderState : Int(This:IDirect3DDevice7, RenderStateType:Int, RenderState:Int)

Global OrgSetRenderState : Int(This:IDirect3DDevice7, RenderStateType:Int, RenderState:Int) "win32"

SuperStrict

Framework PUB.DirectX

Const MB_OK              : Int   = $0
Const MB_ICONEXCLAMATION : Int   = $30

Extern "win32"
	Function MessageBoxA:Int(hWnd:Int, lpText$z, lpCaption$z, uType:Int)
End Extern

Const VTBL_SETRENDERSTATE : Int = 20

Global VirtualTable      : Int Ptr
Global OrgSetRenderState : Int(This:IDirect3DDevice7, RenderStateType:Int, RenderState:Int) "win32"

Function DllMain:Int(hinstDLL:Byte Ptr, fdwReason:Int, lpvReserved:Byte Ptr) "win32"
	Select fdwReason
		Case 1 ' DLL_PROCESS_ATTACH
		Case 2 ' DLL_THREAD_ATTACH
		Case 3 ' DLL_THREAD_DETACH
		Case 0 ' DLL_PROCESS_DETACH
	End Select

	Return True
End Function

Function StartRecording(Device:IDirect3DDevice7) "win32" 'EXPORT
	' Get virtual table from interface/instance
	VirtualTable = Int Ptr(Int Ptr(Byte Ptr(Device))[0])
	
	' Get original method
	OrgSetRenderState = Byte Ptr(VirtualTable[VTBL_SETRENDERSTATE])
	
	' Overload with own method
	VirtualTable[VTBL_SETRENDERSTATE] = Int(Byte Ptr(SetRenderState))
End Function

Function StopRecording:Int() "win32" 'EXPORT
	' Rewrite original method
	VirtualTable[VTBL_SETRENDERSTATE] = Int(Byte Ptr(OrgSetRenderState))
End Function

Function SetRenderState:Int(This:IDirect3DDevice7, RenderStateType:Int, RenderState:Int)
	' Display some information
	MessageBoxA(0, "RSType: "+RenderStateType+"; RS: "+RenderState, ..
	            "Overloaded method", MB_OK | MB_ICONEXCLAMATION)
	
	' Use original method
	Return OrgSetRenderState(This, RenderStateType, RenderState)
End Function

#include <stdio.h>
// Sample interfaced class  cppobject.cpp
// Delecare an Interface for class
// note we using reference counting to implement cleanup
class IObject 
{
	public:
	    virtual int  _AddRef()=0;
	    virtual int  _Release()=0;
		virtual int  Add(int X,int Y)=0;  // This is important to be pure interface
};


// Class that implements the interface

class TestObject: public IObject
{
  private: 
	int refCount;
  public:
    TestObject() 
    { 
      refCount=1; 
      printf("Created TestObject\n");
	  fflush(stdout );
    }
    ~TestObject() 
    {
    	printf("Destroyed TestObject\n");
 	    fflush(stdout );
    }
    virtual int  _AddRef() { refCount++; return refCount; }
    virtual int  _Release() 
    { 
	  refCount--;
      if (refCount==0) delete this;
      return refCount;        
    
    }
	virtual int Add(int X,int Y)
	{
		return (X+Y);
	}

};

extern "C" {
  IObject* CreateTestObject() { return new TestObject(); }
}

Superstrict
Import "cppobject.cpp"


Extern "C"
  Type IObject 
    Method _AddRef:int()
	Method _Release:Int()
	Method Add:Int(X:Int,Y:Int)
  End Type	  
  Function CreateTestObject:IObject()
End Extern

Function MyAdd:Int(obj:IObject , X:Int,Y:Int)
    Print "Subclassed-Subtracting"
	return X-Y
End Function


local _saveAdd:Int(obj:IObject , X:Int,Y:Int)
Print "Testing Interfaced C++ Object"
local obj:IObject= CreateTestObject()
print "1. Adding 1+2="+obj.Add(1,2)
local vtable:Int Ptr= Int Ptr(Int Ptr(Byte Ptr(obj))[0])
_saveAdd=Byte Ptr(vtable[2])
vtable[2]=Int(Byte Ptr(MyAdd))
print "2. Adding 1+2="+Obj.Add(1,2)
obj._Release()
obj:IObject= CreateTestObject()
print "3. Adding 1+2="+Obj.Add(1,2)
vtable[2]=Int(Byte Ptr(_saveAdd))
print "4. Adding 1+2="+Obj.Add(1,2)
obj._Release()
obj=null
print "Done"

vtable[2]=Int(Byte Ptr(MyAdd))

#include <stdio.h>

extern "C" {
/* Simple Functions to get Object from Pointer and Back */                        
void* ObjectFrompVtbl(void* Vtbl) { return (void*)(*(((int*)Vtbl)+1));}
}


// Sample interfaced class  cppobject.cpp
// Delecare an Interface for class
// note we using reference counting to implement cleanup
class IObject 
{
	public:
	    virtual int  _AddRef()=0;
	    virtual int  _Release()=0;
		virtual int  Add(int X,int Y)=0;  // This is important to be pure interface
};

// Some Test functions to pass our BMAX interfaced object too
static IObject* instance=0;

extern "C" {
	void SetInstance(IObject* io) 
	{ 
		if (instance) instance->_Release();
		instance=0;
		if (io)
		{
			instance=io; 
			instance->_AddRef(); 
		}	
	}
	int AddInstance(int X,int Y)
	{
		if (instance)
		{
			return instance->Add(X,Y);
		}
		else return 0;
	}	

}

Superstrict
Import "cppobject.cpp"


Rem 
  Help Function to Tranlate VPtr to Object Handle
  This can be changed around to play with TMAP Handles but that is too slow
  This works and is based upon the structure of the Object in BMAX,  has been this way 
  since version 1.  Use to be able to do with Object Ptr but removed
end Rem

Extern "C"
  Function ObjectFrompVtbl:Object(pVtbl: Byte Ptr)
End Extern


Rem
	This is Blitz Max interface definition corrosponding to C++ Interface Definition
	
End Rem

Extern "C"
  Type IObject 
    Method _AddRef:int()
	Method _Release:Int()
	Method Add:Int(X:Int,Y:Int)
  End Type	  
End Extern

Rem
   This is our definitoon of the VTable
   Since I cant test this on machine with DEP, might need to implment differently
   not a big deal to change to work with DEP just need to make OS Specific calls to allocate 
   executeable chunk of memory   
End Rem

Type TIObjectVTable
 	Field _AddRef:Int(pVtbl:Byte Ptr)=vAddRef
	Field _Release:Int(pVtbl:Byte Ptr)=vRelease
	Field Add:Int(pVtbl:Byte Ptr,x:Int,Y:Int)=vAdd
End Type

Rem
	These functions implment the VTable and fixup the calls to the 
	Objects,  ideally this would be inline ASM to use a JMP instead of CALL but 
	here we are SOL so we need to deal with overhead of CALL 
End Rem

Function vAddRef:int(pVtbl:Byte Ptr)
	Return TIObject(ObjectFrompVtbl(pVtbl))._AddRef()
End Function
Function vRelease:Int(pVtbl:Byte Ptr)
	Return TIObject(ObjectFrompVtbl(pVtbl))._Release()
End Function
Function vAdd:Int(pVtbl:Byte Ptr,X:Int,Y:Int)
	Return TIObject(ObjectFrompVtbl(pVtbl)).Add(x,y)
End Function

Rem
   Only need one instance of VTABLE for all instances of Object 
End Rem
Global IObjectVTableVtblInstance:TIObjectVTable=New TIObjectVTable


Rem 
  Here is our base definition of the object that implments the VTABLE
End Rem

Type TIObject
    Field _Vtable: Byte Ptr ' these two variables must be in sequence
    Field _Handle: TIObject ' this allows us to implment multiple interfaces the fixup code gets the instance handle 
	Field _RefCount: Int    ' since we are interfaced _Ref counting is good idea to track our external allocations
	Method New()
	  Print "Created"
		 _Vtable= Byte Ptr(IObjectVTableVtblInstance)
	End Method
	Method Delete()
	  Print "Deleted"
	End Method
	Method IObject:IObject() Final
	    ' this code looks tricky but not too bad  IObject is not Blitz Object its a pointer
	    ' we are stuffing the VTable value into it and returning it
		Local u:IObject 
		Local b:Byte Ptr=Varptr(u)
		Int Ptr(b)[0]=Int(Varptr(_Vtable))
		' Add Ref since we gave out our VTable Ref we should add one to it
		' careful use here required since as soon as we give out object it sets count to 1
		_AddRef()
		Return u		
	End Method

	
	Method _AddRef:Int()  Final	
	    ' if we are giving out externa ref set our handle
	    ' this prevents GC as well as allows interface to be cracked
		If _RefCount=0 Then _Handle=Self
		_RefCount:+1	
		Print "RefCount"+_RefCount		
		Return _RefCount
	End Method
	Method _Release:Int() Final
		_RefCount:-1	
		' No more external references then we set handle to null for clean up
		If _RefCount=0 Then _Handle=Null
		Print "RefCount"+_RefCount
		Return _RefCount
	End Method
	Method Add:Int(x:Int,Y:Int)
		Return X+Y
	End Method
End Type


Type TIObjectSubtract extends TIObject
    Method Add:Int(X:Int,Y:Int)
		return X-Y
	End Method
End Type

' Test it
Extern "C"
	Function SetInstance(io:IObject) 
	Function AddInstance:Int(X:Int,Y:Int)
end Extern


Print "Test One"
Print "We play with interface locally in BMAX"
Print "Note: we dont have variable of TIObject but the interface"
global obj : IObject= (new TIObject).IObject()
Print "1+2="+obj.Add(1,2)
Print "Try to collect it"
GCCollect()
Print "Nope!"
Print "Release our Interface"
obj._Release()
Print "Released it so now should collect"
GCCollect()
Print "Success"
Print ""
Print "Test Two" 
Print "Externally with C"
obj =(new TIObject).IObject()
Print "Setting to external C Variable"
SetInstance(obj)
Print "3+4="+AddInstance(3,4)
Print "Release External Ref"
SetInstance(null)
Print "Release our local ref"
obj._Release()
GCCollect()
Print "Success"

Print "Test Three"
Print "Extending BMAX Object"
obj= (new TIObjectSubtract).IObject()
SetInstance(obj)
Print "Release our local we dont need anymore"
obj._Release()
GCCollect()
Print "Still alive since external reference valid"
Print "5+4="+AddInstance(3,4)
Print "Release our external Ref"
SetInstance(null)
GCCollect()
Print "Success"