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Trouble loading bitmaps

Started by ComputrJam Sep 4, 2000 at 6:38 PM 2 replies 600+ views

Original Post

Sep 4, 2000 at 6:38 PM

I really don''t know what''s wrong with my code, I''m getting very frustrated with directx. OpenGL is so easy to use compared to directx its almost funny. But for some reason I want to continue torturing myself by trying to learn it. My "LoadBitmap" function is below, please help: ///////////////////////////////////////////////////////////////// // // Func: LoadBitmap // Desc: loads bitmap from file // ///////////////////////////////////////////////////////////////// IDirectDrawSurface7 *LoadBitmap() { HBITMAP hbm = NULL; BITMAP bm; HDC hdcImage = NULL; HDC hdc = NULL; DDSURFACEDESC2 ddsd; IDirectDrawSurface7 *pdds; // // Try to load the bitmap as a file // hbm = (HBITMAP) LoadImage(NULL, "test.bmp", IMAGE_BITMAP, 0, 0,LR_LOADFROMFILE); if(hbm == NULL) { MessageBox(NULL,"Loading Image Failed.","SHUTDOWN ERROR",MB_OK | MB_ICONINFORMATION); } // // Get size of the bitmap // GetObject(hbm, sizeof(bm), &bm); // // Create a DirectDrawSurface for this bitmap // ZeroMemory(&ddsd, sizeof(ddsd)); ddsd.dwSize = sizeof(ddsd); ddsd.dwFlags = DDSD_CAPS | DDSD_HEIGHT | DDSD_WIDTH; ddsd.ddsCaps.dwCaps = DDSCAPS_OFFSCREENPLAIN; ddsd.dwWidth = bm.bmWidth; ddsd.dwHeight = bm.bmHeight; if (DirectDraw7->CreateSurface(&ddsd, &pdds, NULL) != DD_OK) { // Failed return NULL; } // // Select bitmap into a memoryDC so it can be used // hdcImage = CreateCompatibleDC(NULL); if (pdds->GetDC(&hdc) == DD_OK) { BitBlt(hdc, 0, 0, ddsd.dwWidth, ddsd.dwHeight, hdcImage, 0, 0, SRCCOPY); pdds->ReleaseDC(hdc); } DeleteObject(hbm); DeleteDC(hdcImage); return pdds; }

dj9781

Sep 4, 2000 at 9:39 PM

Heres my loadbitmap function:

    
LoadBitmap(LPDIRECTDRAW7 lpDD, RECT *dims)
{
        HDC hdc;
	HBITMAP bit;
	LPDIRECTDRAWSURFACE7 surf=NULL;
	
	// load the 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 0;
	
	// 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; 
	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 0;
	} 
	
	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,0,0,surf_width,surf_height,bit_dc,0,0,SRCCOPY);
		
		// release the DCs

		surf->ReleaseDC(hdc);
		DeleteDC(bit_dc);
		
		// save the dimensions if rectangle pointer provided

		if (dims) 
		{
			dims->left=0;
			dims->top=0;
			dims->right=surf_width;
			dims->bottom=surf_height;
		}
	}
	
	// clear bitmap 

	DeleteObject(bit);
	

	//return succes

	return 1;
}

and now surf has the bitmap loaded into it.

Ironblayde

Sep 5, 2000 at 2:07 AM

ComputrJam: Your function creates a device context for the bitmap, but never selects the bitmap into the device context, thus your call to BitBlt() is not copying anything. After the call to CreateCompatibleDC(), be sure to use SelectObject() to select the bitmap into the DC.

-Ironblayde
Aeon Software

ComputrJam

Author

ComputrJam

Sep 5, 2000 at 11:17 AM

You''re right, that''s what I was doing wrong. It works now...thanks for your input guys.

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