file iTexture.h (for the final user)
class iTexture
{
virtual bool IsTextureValid(void) = 0;
};
file cTexture.h (internal to the dll)
class cTexture : public iTexture
{
bool IsTextureValid(void);
};
file iStreamTexture.h (for the final user)
#include "iTexture.h"
class iStreamTexture : public iTexture
{
virtual bool LoadAVIStream(const char *filename) = 0;
};
file cStreamTexture.h (internal to the dll)
#include "cTexture.h"
class cStreamTexture : public cTexture
{
bool LoadAVIStream(const char *filename);
};
class inheritance within dll (c++)
Author
Hi
I'm building a dll and I export class to the final user
My new created functions in cStreamTexture are all invalid (0x00000000 in vtable). Does someone have an idea ?
Quote:Original post by iliak
Hi
I'm building a dll and I export class to the final user
*** Source Snippet Removed ***
My new created functions in cStreamTexture are all invalid (0x00000000 in vtable). Does someone have an idea ?
You need to declare the linkage type for the classes that reside in the dll....
when compiling the dll each class that is exported must have:
__declspec(dllexport)
and while compiling the user application it should be:
__declspec(dllimport)
As in:
__declspec(dllexport) class someclass { .....};
Author
It only breaks when I try to call any new function in iStreamTexture. An example :
//Create a cStreamTexture in my dll and give back a iStreamTextureiStreamTexture *stream = (iStreamTexture *)Texture->CreateTexture(256, 256, false, PF_RGB, Video);if (stream){ stream->GetHeight(); <= Good stream->LoadAVIStream("data/face2.avi"); <= Fail}
Your vtables do not match up. iStreamTexture is-a iTexture and has two virtual functions: bool IsTextureValid() and bool LoadAVIStream(const char *). cStreamTexture on the other hand is-a cTexture (and therefore also is-a iTexture. It therefore has only one virtual function: bool IsTextureValid(), inherited from iTexture.
What you need to do is this:
Now cStreamTexture is-a iStreamTexture and the vtables match up. As an added bonus the vtables will always match up even if you use different compilers for the source and dll, provided both compilers are COM-compliant. To use it you also need to swap your unsafe C-style cast for a C++ dynamic_cast:
Enigma
What you need to do is this:
// iTexture.hclass iTexture{ public: virtual bool isTextureValid() = 0;};// cTexture.hclass cTexture : public virtual iTexture{ public: virtual bool isTextureValid(void);};// iStreamTexture.hclass iStreamTexture : public virtual iTexture{ public: virtual bool loadAviStream(char const * filename) = 0;};// cStreamTexture.hclass cStreamTexture : public virtual cTexture, public virtual iStreamTexture{ public: virtual bool loadAviStream(char const * filename);};Now cStreamTexture is-a iStreamTexture and the vtables match up. As an added bonus the vtables will always match up even if you use different compilers for the source and dll, provided both compilers are COM-compliant. To use it you also need to swap your unsafe C-style cast for a C++ dynamic_cast:
iStreamTexture * stream = dynamic_cast< iStreamTexture * >(Texture->CreateTexture(256, 256, false, PF_RGB, Video));if (stream){ stream->getHeight(); stream->loadAviStream("data/face2.avi");}Enigma
Author
Nice shot Cap'tain ! Now the project compile right, but I have a a C4250 warning for each function as below :
Compilation...cStreamTexture.cppd:\Dev\BradockEngine\Bradock\src\cStreamTexture.h(40) : warning C4250: 'bradock::cStreamTexture' : hérite de 'bradock::cTexture::bradock::cTexture::GetType' via la dominance d:\Dev\BradockEngine\Bradock\src\cTexture.h(267) : voir la déclaration de 'bradock::cTexture::GetType'd:\Dev\BradockEngine\Bradock\src\cStreamTexture.h(40) : warning C4250: 'bradock::cStreamTexture' : hérite de 'bradock::cTexture::bradock::cTexture::Save' via la dominance d:\Dev\BradockEngine\Bradock\src\cTexture.h(271) : voir la déclaration de 'bradock::cTexture::Save'd:\Dev\BradockEngine\Bradock\src\cStreamTexture.h(40) : warning C4250: 'bradock::cStreamTexture' : hérite de 'bradock::cTexture::bradock::cTexture::IsTextureValid' via la dominance d:\Dev\BradockEngine\Bradock\src\cTexture.h(283) : voir la déclaration de 'bradock::cTexture::IsTextureValid'd:\Dev\BradockEngine\Bradock\src\cStreamTexture.h(40) : warning C4250: 'bradock::cStreamTexture' : hérite de 'bradock::cTexture::bradock::cTexture::SetWrapClamp' via la dominance d:\Dev\BradockEngine\Bradock\src\cTexture.h(275) : voir la déclaration de 'bradock::cTexture::SetWrapClamp'd:\Dev\BradockEngine\Bradock\src\cStreamTexture.h(40) : warning C4250: 'bradock::cStreamTexture' : hérite de 'bradock::cTexture::bradock::cTexture::SetWrapRepeat' via la dominance d:\Dev\BradockEngine\Bradock\src\cTexture.h(276) : voir la déclaration de 'bradock::cTexture::SetWrapRepeat'd:\Dev\BradockEngine\Bradock\src\cStreamTexture.h(40) : warning C4250: 'bradock::cStreamTexture' : hérite de 'bradock::cTexture::bradock::cTexture::GetHeight' via la dominance d:\Dev\BradockEngine\Bradock\src\cTexture.h(281) : voir la déclaration de 'bradock::cTexture::GetHeight'd:\Dev\BradockEngine\Bradock\src\cStreamTexture.h(40) : warning C4250: 'bradock::cStreamTexture' : hérite de 'bradock::cTexture::bradock::cTexture::GetWidth' via la dominance d:\Dev\BradockEngine\Bradock\src\cTexture.h(282) : voir la déclaration de 'bradock::cTexture::GetWidth'd:\Dev\BradockEngine\Bradock\src\cStreamTexture.h(40) : warning C4250: 'bradock::cStreamTexture' : hérite de 'bradock::cTexture::bradock::cTexture::GetPixelFormat' via la dominance d:\Dev\BradockEngine\Bradock\src\cTexture.h(280) : voir la déclaration de 'bradock::cTexture::GetPixelFormat'd:\Dev\BradockEngine\Bradock\src\cStreamTexture.h(40) : warning C4250: 'bradock::cStreamTexture' : hérite de 'bradock::cTexture::bradock::cTexture::Lock' via la dominance d:\Dev\BradockEngine\Bradock\src\cTexture.h(294) : voir la déclaration de 'bradock::cTexture::Lock'd:\Dev\BradockEngine\Bradock\src\cStreamTexture.h(40) : warning C4250: 'bradock::cStreamTexture' : hérite de 'bradock::cTexture::bradock::cTexture::Unlock' via la dominance d:\Dev\BradockEngine\Bradock\src\cTexture.h(295) : voir la déclaration de 'bradock::cTexture::Unlock'd:\Dev\BradockEngine\Bradock\src\cStreamTexture.h(40) : warning C4250: 'bradock::cStreamTexture' : hérite de 'bradock::cTexture::bradock::cTexture::AutoMipMapGenerate' via la dominance d:\Dev\BradockEngine\Bradock\src\cTexture.h(288) : voir la déclaration de 'bradock::cTexture::AutoMipMapGenerate'Édition des liens en cours...
That warning is informational only and can be safely ignored (or better yet, disabled with #pragma warning(disable: 4250)).
Enigma
Enigma
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