CBitmap

[raul]

Hey, can anybody help me??
i'm trying to do this about 2 weeks but i can't get it...
the problem is how to load and draw a Cbitmap object from a bmp file. I have read the section in this web site about bitmaps and paletts, but it doesn't work. I would like to get an example for aplication to load bmp file and then drawing it, can you do that??
Thanks in anticipation.

[DiDi]

Try this function to load a Bitmap into a CBitmap Objekt from a file:

sBMPFile...The file you want to load
bitmap...The CBitmap Objekt you want to fill with your File.
pPal...Can be NULL

BOOL LoadBMPImage( LPCTSTR sBMPFile, CBitmap& bitmap, CPalette *pPal )
{
CFile file;
if( !file.Open( sBMPFile, CFile::modeRead) ) return FALSE;

BITMAPFILEHEADER bmfHeader; // Read file header

if (file.Read((LPSTR)&bmfHeader, sizeof(bmfHeader)) != sizeof(bmfHeader))
return FALSE;

// File type should be 'BM'

if (bmfHeader.bfType != ((WORD) ('M' << 8) | 'B')) return FALSE;


// Get length of the remainder of the file and allocate memory
DWORD nPackedDIBLen = file.GetLength() - sizeof(BITMAPFILEHEADER);

HGLOBAL hDIB = ::GlobalAlloc(GMEM_FIXED, nPackedDIBLen);
if (hDIB == 0)
return FALSE; // Read the remainder of the bitmap file.

if (file.ReadHuge((LPSTR)hDIB, nPackedDIBLen) != nPackedDIBLen )
{
::GlobalFree(hDIB);
return FALSE;
}

BITMAPINFOHEADER &bmiHeader = *(LPBITMAPINFOHEADER)hDIB ;

BITMAPINFO &bmInfo = *(LPBITMAPINFO)hDIB ;
// If bmiHeader.biClrUsed is zero we have to infer the number
// of colors from the number of bits used to specify it.
int nColors = bmiHeader.biClrUsed ? bmiHeader.biClrUsed :
1 << bmiHeader.biBitCount; LPVOID lpDIBBits;

if( bmInfo.bmiHeader.biBitCount > 8 )
lpDIBBits = (LPVOID)((LPDWORD)(bmInfo.bmiColors + bmInfo.bmiHeader.biClrUsed) +
((bmInfo.bmiHeader.biCompression == BI_BITFIELDS) ? 3 : 0));
else
lpDIBBits = (LPVOID)(bmInfo.bmiColors + nColors);

// Create the logical palette
if( pPal != NULL )
{ // Create the palette

if( nColors <= 256 )
{
UINT nSize = sizeof(LOGPALETTE) + (sizeof(PALETTEENTRY) * nColors);
LOGPALETTE *pLP = (LOGPALETTE *) new BYTE[nSize];
pLP->palVersion = 0x300;
pLP->palNumEntries = nColors;
for( int i=0; i < nColors; i++)
{
pLP->palPalEntry[i].peRed = bmInfo.bmiColors[i].rgbRed;
pLP->palPalEntry[i].peGreen = bmInfo.bmiColors[i].rgbGreen;
pLP->palPalEntry[i].peBlue = bmInfo.bmiColors[i].rgbBlue;
pLP->palPalEntry[i].peFlags = 0;
}

pPal->CreatePalette( pLP );

delete[] pLP;
}
}
CClientDC dc(NULL);
CPalette* pOldPalette = NULL;
if( pPal )
{ pOldPalette = dc.SelectPalette( pPal, FALSE );

dc.RealizePalette();
}
HBITMAP hBmp = CreateDIBitmap( dc.m_hDC, // handle to device context
&bmiHeader, // pointer to bitmap size and format data
CBM_INIT, // initialization flag
lpDIBBits, // pointer to initialization data
&bmInfo, // pointer to bitmap color-format data
DIB_RGB_COLORS); // color-data usage

bitmap.Attach( hBmp );
if( pOldPalette ) dc.SelectPalette( pOldPalette, FALSE );
::GlobalFree(hDIB);
return TRUE;
}

And Try this to Draw it with one Transparent color:

void CCISBitmap::DrawTransparent(CDC * pDC, int x, int y, COLORREF crColour)
{
COLORREF crOldBack = pDC->SetBkColor(m_crWhite);
COLORREF crOldText = pDC->SetTextColor(m_crBlack);
CDC dcImage, dcTrans;

// Create two memory dcs for the image and the mask
dcImage.CreateCompatibleDC(pDC);
dcTrans.CreateCompatibleDC(pDC);

// Select the image into the appropriate dc
CBitmap* pOldBitmapImage = dcImage.SelectObject(this);

// Create the mask bitmap
CBitmap bitmapTrans;
int nWidth = Width();
int nHeight = Height();
bitmapTrans.CreateBitmap(nWidth, nHeight, 1, 1, NULL);

// Select the mask bitmap into the appropriate dc
CBitmap* pOldBitmapTrans = dcTrans.SelectObject(&bitmapTrans);

// Build mask based on transparent colour
dcImage.SetBkColor(crColour);
dcTrans.BitBlt(0, 0, nWidth, nHeight, &dcImage, 0, 0, SRCCOPY);

// Do the work - True Mask method - cool if not actual display
pDC->BitBlt(x, y, nWidth, nHeight, &dcImage, 0, 0, SRCINVERT);
pDC->BitBlt(x, y, nWidth, nHeight, &dcTrans, 0, 0, SRCAND);
pDC->BitBlt(x, y, nWidth, nHeight, &dcImage, 0, 0, SRCINVERT);

// Restore settings
dcImage.SelectObject(pOldBitmapImage);
dcTrans.SelectObject(pOldBitmapTrans);
pDC->SetBkColor(crOldBack);
pDC->SetTextColor(crOldText);
}

If you want to draw it just drawn look at the CDC Dokumentation in the MSDN.

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