Advanced MFC Programming

Chapter 11. Sample: Simple Paint
drawing tool to rectangular selection (if it is not). By doing this, everything will go on as if we just selected
a portion of image using the rectangular selection tool.
When the user executes Edit | Paste command, function CGDIDoc::OnEditPaste()will be called. The
DIB data in the clipboard will be replicated and passed to function CGDIView::PasteDIB(…). Within the
function, a new bitmap will be created using variable m_bmpSelBackup, and the DIB data contained in the
clipboard will be copied to it. Please note we must replicate the clipboard data instead of using it directly
because the data may be used by other applications later. The following is the implementation of function
CGDIDoc::OnEditPaste():
void CGDIDoc::OnEditPaste()
{
if(GetCGDIView()->OpenClipboard() == TRUE)
{
HGLOBAL hDIB;
LPBYTE lpByte;
HGLOBAL hDIBPaste;
LPBYTE lpBytePaste;
}
}
ASSERT(hDIB != NULL);
hDIB=::GetClipboardData(CF_DIB);
ASSERT(hDIB);
hDIBPaste=::GlobalAlloc(GHND, ::GlobalSize(hDIB));
ASSERT(hDIBPaste);
lpByte=(LPBYTE)::GlobalLock(hDIB);
ASSERT(lpByte);
lpBytePaste=(LPBYTE)::GlobalLock(hDIBPaste);
ASSERT(lpBytePaste);
memcpy(lpBytePaste, lpByte, ::GlobalSize(hDIB));
::GlobalUnlock(hDIB);
::GlobalUnlock(hDIBPaste);
::CloseClipboard();
GetCGDIView()->PasteDIB(hDIB);
::GlobalFree(hDIBPaste);
The following portion of function CGDIView::PasteDIB(…) shows how to copy the clipboard DIB data
to the backup DIB image by calling function ::SetDIBits(…) (the clipboard data is passed through
parameter hData):
void CGDIView::PasteDIB(HGLOBAL hData)
{
CClientDC dc(this);
LPBITMAPINFO lpBi;
int nRatio;
CGDIDoc *pDoc;
pDoc=GetDocument();
ASSERT_VALID(pDoc);
AfxGetApp()->DoWaitCursor(TRUE);
lpBi=(LPBITMAPINFO)::GlobalLock(hData);
ASSERT(lpBi);
if(lpBi->bmiHeader.biBitCount != 8)
{
::GlobalUnlock(hData);
return;
}
nRatio=pDoc->GetRatio();
if(m_bmpSelBackup.GetSafeHandle() != NULL)m_bmpSelBackup.DeleteObject();
m_bmpSelBackup.CreateCompatibleBitmap
(
&dc,
lpBi->bmiHeader.biWidth,
lpBi->bmiHeader.biHeight
364