Advanced MFC Programming

Chapter 10. Bitmap
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class CGDIDoc : public CDocument
{
protected:
}
int m_nBmpFormat;
The following macros are defined in the header file of class CGDIDoc:
#define BMP_FORMAT_NONE 0
#define BMP_FORMAT_MONO 1
#define BMP_FORMAT_16COLOR 2
#define BMP_FORMAT_256COLOR 3
#define BMP_FORMAT_24BIT 4
Variable CGDIDoc::m_nBmpFormat is initialized in the constructor:
……
CGDIDoc::CGDIDoc()
{
}
m_nBmpFormat=BMP_FORMAT_NONE;
Whenever a DIB is loaded, function CGDIDoc::GetColorTableSize(…) will be called by CGDIView::
OnInitialUpdate(), so it is convenient to set CGDIDoc::m_nBmpFormat to an appropriate value to indicate
the image format in this function. The following code fragment shows the modified function
CGDIDoc::GetColorTableSize():
DWORD CGDIDoc::GetColorTableSize(WORD wBitCount)
{
DWORD dwSizeCT;
}
switch(wBitCount)
{
case 1:
{
dwSizeCT=2;
m_nBmpFormat=BMP_FORMAT_MONO;
break;
}
case 4:
{
dwSizeCT=16;
m_nBmpFormat=BMP_FORMAT_16COLOR;
break;
}
case 8:
{
dwSizeCT=256;
m_nBmpFormat=BMP_FORMAT_256COLOR;
break;
}
case 24:
{
dwSizeCT=0;
m_nBmpFormat=BMP_FORMAT_24BIT;
}
}
return dwSizeCT;
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