Advanced MFC Programming

Chapter 10. Bitmap
Sample
Sample 10.2\GDI demonstrates how to extract color table from DIB and convert it to DDB. It is based
on sample 10.1-2\GDI.
Because we need to implement logical palette, first a variable and a function are added to class
CGDIDoc:
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……
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class CGDIDoc : public CDocument
{
protected:
public:
}
CPalette m_palDraw;
CPalette *GetPalette(){return &m_palDraw;}
Variable m_palDraw is added for creating logical palette and function GetPalette() is used to access it
outside class CGDIDoc.
In class CGDIView, some new variables are added for bitmap drawing:
……
class CGDIView : public CScrollView
{
protected:
CDC m_dcMem;
CPalette *m_pPalMemOld;
CBitmap *m_pBmpMemOld;
BITMAP m_bmInfo;
CGDIView();
DECLARE_DYNCREATE(CGDIView)
}
Variable m_dcMem will be used to implement memory DC at the initialization stage of the client
window. It will be used later for drawing bitmap. By implementing memory DC this way, we don’t have to
create it every time. Also, we will select the bitmap and palette into the memory DC after they are avialabe,
and selet them out of the DC when the window is being destroyed. For this purpose, two pointers
m_pPalMemOld and m_pBmpMemOld are declared, they will be used to select the palette and bitmap out of DC.
Variable m_bmInfo is used to store the information of bitmap.
The best place to create bitmap and palette is in CGDIView::OnInitialUpdate(). First, we must locate
and load the bitmap resource:
void CGDIView::OnInitialUpdate()
{
CClientDC dc(this);
CGDIDoc *pDoc;
CBitmap *pBmp;
CPalette *pPalDraw;
LPBITMAPINFO lpBi;
LPLOGPALETTE lpLogPal;
CPalette *pPalOld;
int nSizeCT;
int i;
HBITMAP hBmp;
HRSRC hRes;
HGLOBAL hData;
CScrollView::OnInitialUpdate();
pDoc=GetDocument();
ASSERT_VALID(pDoc);
if
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