BitBlt in MFC - can someone assist please?
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Linux L drive
#1 / 4
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 BitBlt in MFC - can someone assist please? Folks, I have got the BitBlt to work in a non-MFC prog using HDCs but can't get an MFC version to work. I think it's the SelectObject that is thr problem. Coded as below I get an Access violation and when I code it as CBitmap* pOldBitmap = srcDC.SelectObject((CBitmap *)&pBitmap); /* this works */ it "works" but I get 0 in pOldBitmap. Obviously there is an incompatibility with the way I'm using LoadImage??? CBitmap * pBitmap;
CBitmap cBitmap;
BITMAP bm;
int ret;
bool bret;
LPCTSTR lpszImg = "D:\\Chip16.bmp";
pBitmap = (CBitmap *)LoadImage (0, lpszImg, IMAGE_BITMAP, 0, 0,
LR_CREATEDIBSECTION | LR_LOADFROMFILE | LR_DEFAULTSIZE );
// create an in-memory DC
CDC srcDC;
int inta = srcDC.CreateCompatibleDC(pDC);
// select bitmap into in-memory DC
CBitmap* pOldBitmap = srcDC.SelectObject((CBitmap *)pBitmap);
/* this fails */
int intb = GetObject(pBitmap, sizeof(BITMAP), &bm );
// CBitmap* pOldBitmap = dc.SelectObject((CBitmap* )&pBitmap);
ret = pDC->BitBlt( 50, 30, bm.bmWidth, bm.bmHeight,
&srcDC, 0, 0, BLACKNESS );
// bret = dc.BitBlt( 10, 50, bm.bmWidth, bm.bmHeight,
// &srcDC, 0, 0, SRCCOPY );
// (CBitmap *)srcDC.SelectObject(pOldBitmap);
TIA
--
Ian Turnbull
0961 931941
Web : www.turnbui.freeserve.co.uk
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| Fri, 26 Sep 2003 01:10:25 GMT |
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Mike
#2 / 4
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BitBlt in MFC - can someone assist please? LoadImage() does not return a CBitmap type object. Take a look at CBitmap::FromHandle();
Quote: > Folks, > I have got the BitBlt to work in a non-MFC prog using HDCs but can't get an > MFC version to work. > I think it's the SelectObject that is thr problem. Coded as below I get an > Access violation and when I code it as > CBitmap* pOldBitmap = srcDC.SelectObject((CBitmap *)&pBitmap); > /* this works */ > it "works" but I get 0 in pOldBitmap. Obviously there is an > incompatibility with the way I'm using > LoadImage??? > CBitmap * pBitmap;
> CBitmap cBitmap;
> BITMAP bm;
> int ret;
> bool bret;
> LPCTSTR lpszImg = "D:\\Chip16.bmp";
> pBitmap = (CBitmap *)LoadImage (0, lpszImg, IMAGE_BITMAP, 0, 0,
> LR_CREATEDIBSECTION | LR_LOADFROMFILE | LR_DEFAULTSIZE );
> // create an in-memory DC
> CDC srcDC;
> int inta = srcDC.CreateCompatibleDC(pDC);
> // select bitmap into in-memory DC
> CBitmap* pOldBitmap = srcDC.SelectObject((CBitmap *)pBitmap);
> /* this fails */
> int intb = GetObject(pBitmap, sizeof(BITMAP), &bm );
> // CBitmap* pOldBitmap = dc.SelectObject((CBitmap* )&pBitmap);
> ret = pDC->BitBlt( 50, 30, bm.bmWidth, bm.bmHeight,
> &srcDC, 0, 0, BLACKNESS );
> // bret = dc.BitBlt( 10, 50, bm.bmWidth, bm.bmHeight,
> // &srcDC, 0, 0, SRCCOPY );
> // (CBitmap *)srcDC.SelectObject(pOldBitmap);
> TIA
> --
> Ian Turnbull
> 0961 931941
> Web : www.turnbui.freeserve.co.uk
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| Fri, 26 Sep 2003 04:17:14 GMT |
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Sam Hobb
#3 / 4
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BitBlt in MFC - can someone assist please? Graphics is not my specialty and the one CodeGuru article I have is the result of my learning. It might be enough to help you here though. See: http://www.codeguru.com/bitmap/SimpleBMPViewer.shtml
Quote: > Folks, > I have got the BitBlt to work in a non-MFC prog using HDCs but can't get an > MFC version to work. > I think it's the SelectObject that is thr problem. Coded as below I get an > Access violation and when I code it as > CBitmap* pOldBitmap = srcDC.SelectObject((CBitmap *)&pBitmap); > /* this works */ > it "works" but I get 0 in pOldBitmap. Obviously there is an > incompatibility with the way I'm using > LoadImage??? > CBitmap * pBitmap;
> CBitmap cBitmap;
> BITMAP bm;
> int ret;
> bool bret;
> LPCTSTR lpszImg = "D:\\Chip16.bmp";
> pBitmap = (CBitmap *)LoadImage (0, lpszImg, IMAGE_BITMAP, 0, 0,
> LR_CREATEDIBSECTION | LR_LOADFROMFILE | LR_DEFAULTSIZE );
> // create an in-memory DC
> CDC srcDC;
> int inta = srcDC.CreateCompatibleDC(pDC);
> // select bitmap into in-memory DC
> CBitmap* pOldBitmap = srcDC.SelectObject((CBitmap *)pBitmap);
> /* this fails */
> int intb = GetObject(pBitmap, sizeof(BITMAP), &bm );
> // CBitmap* pOldBitmap = dc.SelectObject((CBitmap* )&pBitmap);
> ret = pDC->BitBlt( 50, 30, bm.bmWidth, bm.bmHeight,
> &srcDC, 0, 0, BLACKNESS );
> // bret = dc.BitBlt( 10, 50, bm.bmWidth, bm.bmHeight,
> // &srcDC, 0, 0, SRCCOPY );
> // (CBitmap *)srcDC.SelectObject(pOldBitmap);
> TIA
> --
> Ian Turnbull
> 0961 931941
> Web : www.turnbui.freeserve.co.uk
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| Fri, 26 Sep 2003 01:40:58 GMT |
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roy l fin
#4 / 4
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BitBlt in MFC - can someone assist please? Ian, LoadImage returns a handle to a system resource - not a pointer to a bitmap.
You can get a pointer to a temporary CBitMap object given a handle to a
system gdi bitmap using the static FromHandle method of CBitMap, and passing
the system gdi bitmap handle to the CBitMap method. See the MSDN help on
this method -- the CBitMap pointer is a temp pointer, and is valid only
until the next time the trash is taken out. You are however, guaranteed
that it will be valid for the duration of the current/any single windows
message - the WM_PAINT for instance.
I have carved and sanitized a snip from one of our programs that uses the
LoadImage method to get to a CBitMap reference that is then passed to the
CDC::SelectObject method...
best regards
roy fine
//
//
// --------------------------------------------------------------
void CSplashWnd::OnPaint(){
CPaintDC dc(this);
CDC dcImage;
if (!dcImage.CreateCompatibleDC(&dc)) return;
HBITMAP hndImage =
(HBITMAP)::LoadImage(NULL,strIPath,IMAGE_BITMAP,0,0,LR_LOADFROMFILE);
m_bitmap = CBitmap::FromHandle( hndImage);
BITMAP bm;
m_bitmap->GetBitmap(&bm);
// Paint the image.
CBitmap* pOldBitmap = dcImage.SelectObject(m_bitmap);
dc.BitBlt(0, 0, bm.bmWidth, bm.bmHeight, &dcImage, 0, 0, SRCCOPY);
dcImage.SelectObject(pOldBitmap);
Quote: }
Quote: > Folks, > I have got the BitBlt to work in a non-MFC prog using HDCs but can't get an > MFC version to work. > I think it's the SelectObject that is thr problem. Coded as below I get an > Access violation and when I code it as > CBitmap* pOldBitmap = srcDC.SelectObject((CBitmap *)&pBitmap); > /* this works */ > it "works" but I get 0 in pOldBitmap. Obviously there is an > incompatibility with the way I'm using > LoadImage??? > CBitmap * pBitmap;
> CBitmap cBitmap;
> BITMAP bm;
> int ret;
> bool bret;
> LPCTSTR lpszImg = "D:\\Chip16.bmp";
> pBitmap = (CBitmap *)LoadImage (0, lpszImg, IMAGE_BITMAP, 0, 0,
> LR_CREATEDIBSECTION | LR_LOADFROMFILE | LR_DEFAULTSIZE );
> // create an in-memory DC
> CDC srcDC;
> int inta = srcDC.CreateCompatibleDC(pDC);
> // select bitmap into in-memory DC
> CBitmap* pOldBitmap = srcDC.SelectObject((CBitmap *)pBitmap);
> /* this fails */
> int intb = GetObject(pBitmap, sizeof(BITMAP), &bm );
> // CBitmap* pOldBitmap = dc.SelectObject((CBitmap* )&pBitmap);
> ret = pDC->BitBlt( 50, 30, bm.bmWidth, bm.bmHeight,
> &srcDC, 0, 0, BLACKNESS );
> // bret = dc.BitBlt( 10, 50, bm.bmWidth, bm.bmHeight,
> // &srcDC, 0, 0, SRCCOPY );
> // (CBitmap *)srcDC.SelectObject(pOldBitmap);
> TIA
> --
> Ian Turnbull
> 0961 931941
> Web : www.turnbui.freeserve.co.uk
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| Fri, 26 Sep 2003 02:11:26 GMT |
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