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Needless to say that a bitmap is the gateway between different raster image formats and GDI image representation.
Device Independent Bitmaps or DIBs are important objects that allow us to save, load and draw images without thinking
of display mode in device context - independent way. OS will do its best to output them as close to original, as
it is able, because DIBs contain all necessary color usage, color depth, and image resolution information. There
are many, or better say, numerous classes that support DIB operations through wrapping Windows API functions. This
MFC extension DLL contains such class and a bit more to make bitmap usage easier and more flexible.
All class declarations are included in the bmpext.h header.
Device dependent bitmap (DDB) extension class CDDBDrawEx:
This class is intended for on-stack allocation and usage within the single scope, as it has no default constructor
and no "real" data members, only pointers to externally defined ones.
It exposes public methods as follows:
CDDBDrawEx(CDC* pDC, CBitmap* pbmSrc, CBitmap* pbmBack = NULL);
void Fill(CRect& rDest);
void Draw(CRect& rDest, CPoint& pntSrc);
void DrawTransparent(CRect& rDest, CPoint& pntSrc, COLORREF crMask);
HRGN MakeRgn(COLORREF cTransparentColor = 0, COLORREF cTolerance = 0x101010);
DIBitmap encapsulation class CDib:
This class and the Frankenstein monster have much in common :) Part of its code was taken from samples shipped
with MFC 4.0 book, partially from CodeGuru and other sources. I have modified it, put it together, and said "It's
alive... ALIVE!" :)
It exposes public methods as follows:
<CODE>// Default constructor.
// Several self-explanatory methods.
WORD NumColors( BITMAPINFOHEADER& bmiHeader );
// Object validation checking method.
// Frees internal DIB member data, making object invalid. (IsValid returns false)
// Drawing method, automatically invokes DIB stretching.
BOOL Draw(CDC*, CRect& rectDC, CRect& rectDIB);
// Direct DIB pixel access methods.
void SetPixel( int iX, int iY, RGBQUAD& rgbPixel );
RGBQUAD GetPixel(int iX, int iY);
// Save DIB to disk file.
DWORD Save(CFile& file);
// Read DIB from file, support resource reading. If bFromResource = TRUE,
// then it just skips DIB file marker read phase.
DWORD Read(CFile& file, BOOL bFromResource = FALSE );
// Reads DIB from resource, basing on its nResID. Internally invokes previous Read method.
DWORD ReadFromResource(UINT nResID);
// Next two methods create DDB from DIB object.
HBITMAP CreateDDBitmap(CDC* pDC);
HBITMAP CreateDDBitmap( HDC hDC );
// Tries to compress DIB first making it DDB, then changing compression attribute and
// converting it back to DIB.
BOOL Compress(CDC* pDC, BOOL bCompress );
// Assignment operator
CDib& operator = (CDib& dib);</CODE>
Extension Classes Usage
CDDBDrawEx class usage:
// CDC* pDC, CBitmap* bmImg, CRect rDest, and COLORREF crImgMask are declared and initialized elsewhere
// inplace construction
CDDBDrawEx ddbDrawEx(pDC, bmImg);
// Do transparent drawing
ddbDrawEx.DrawTransparent(rDest, CPoint(0), crImgMask );
// Do bitmapped fill
ddbDrawEx.Fill( rDest )
// Region creation. CBitmap bmSkin is declared and initialized elsewhere
CDDBDrawEx ddbDrawEx(NULL, &m_bmSkin );
return ddbDrawEx.MakeRgn( m_crTransparent, m_crTolerance );
CDib class usage:
CDC* pDC = CDC::FromHandle( ::GetDC( NULL ) );
// nResID is declared and initialized elsewhere
dibTemp.ReadFromResource( nResID );
Demo project implementing these extensions also includes class template for customizing dialog frame. I'm going
to describe this template in detailed review which I plan to publish in a week. It will cover the window frames
customization technique and will be supplemented with couple of helper template class. That's all so far, but I
will supply several useful control and animation class libs packaged as MFC extension DLL in the nearest future.
Additions, corrections and suggestions are always welcomed, as I often haven't enough time to optimize my source
or make it more elegant. Mail me at: firstname.lastname@example.org.