Extracting frames from a BMP

Hey everyone, I am working on a 2d game engine in DirectX. Everything that moves and animates in my game is based off of objects. The part I am having trouble with at this point is the loading of individual frames. I am using a function that has no problem loading in the file. My problem is that I am having a hard time extracting the frame that I want. The function will open the BMP to load from, create a surface, and copy the frame in. The problem is that it creates a surface the size of the BMP and copies the frame to the location it was in the BMP. When I tried to set the surface width/height to the obj->width/height, the frame didn''t even display on the screen...What is the best way to do this/ What am I doing wrong? Thanks a million

  

//-----------------------------------------------------------------//

//-----------------------------------------------------------------//

//------ bitmap_surface()-function loads a BMP into a DD surface --//

//-----------------------------------------------------------------//

//-----------------------------------------------------------------//


//this function loads a frame from a bitmap into a LPDIRECTDRAWSURFACE4


LPDIRECTDRAWSURFACE4 bitmap_surface(OBJECT_PTR obj, LPCTSTR file_name, LPDIRECTDRAW4 lpDD,
									LPDIRECTDRAWSURFACE4 lpDDSPrimary, 
									int cx, int cy)//the cell coordinates (based off of the obj->width/height)

									
{
	HDC hdc;
	HBITMAP bit;
	LPDIRECTDRAWSURFACE4 surf;

	ShowCursor(FALSE); // Hide the cursor



	// load the interface bitmap


	bit=(HBITMAP) LoadImage(NULL,file_name,IMAGE_BITMAP,0,0,
								LR_DEFAULTSIZE|LR_LOADFROMFILE);
	if (!bit) 

		// failed to load, return failure to caller


		return NULL;

	// get bitmap dimensions


	BITMAP bitmap;
    GetObject( bit, sizeof(BITMAP), &bitmap );
	int surf_width=bitmap.bmWidth;
	int surf_height=bitmap.bmHeight;

	// create surface


	HRESULT ddrval;
	DDSURFACEDESC2 ddsd;
	ZeroMemory(&ddsd,sizeof(ddsd));
	ddsd.dwSize = sizeof(DDSURFACEDESC2);
	ddsd.dwFlags = DDSD_CAPS | DDSD_WIDTH | DDSD_HEIGHT ;
	ddsd.ddsCaps.dwCaps = DDSCAPS_OFFSCREENPLAIN|DDSCAPS_SYSTEMMEMORY; 
	ddsd.dwWidth = surf_width;
	ddsd.dwHeight = surf_height; 

	// attempt to create surface


	ddrval=lpDD->CreateSurface(&ddsd,&surf,NULL);

	// created ok?


	if (ddrval!=DD_OK) {

		// no, release the bitmap and return failure to caller


		DeleteObject(bit);
		return NULL;

	} else {

		// yes, get a DC for the surface


		surf->GetDC(&hdc);

		// generate a compatible DC


		HDC bit_dc=CreateCompatibleDC(hdc);

		// blit the interface to the surface


		SelectObject(bit_dc,bit);
		BitBlt(hdc,cx*(obj->width+1)+1,
			cy*(obj->height+1)+1,
			cx*(obj->width+1)+1+obj->width,
			cy*(obj->height+1)+1+obj->width,
			bit_dc,0,0,SRCCOPY);

		// release the DCs


		surf->ReleaseDC(hdc);
		DeleteDC(bit_dc);
	}

	// clear bitmap 


	DeleteObject(bit);

	//set color key as pure green


	DDPIXELFORMAT ddpf;
	ddpf.dwSize=sizeof(ddpf);
	lpDDSPrimary->GetPixelFormat(&ddpf);
	DWORD KeyColor = ddpf.dwGBitMask;
	DDCOLORKEY key;
	key.dwColorSpaceLowValue= KeyColor;
	key.dwColorSpaceHighValue = KeyColor;

    // now set the color key pure green for source blitting

    surf->SetColorKey(DDCKEY_SRCBLT, &key);
    
	// return pointer to caller


	return surf;
}

- Jesse

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