Replace Color of a bitmap with a new color

1. Fill the DC with the new color

2. Draw the bitmap transparently into the DC with the Old Color (the color to be replaced) as the mask color

Example Code :

BOOL CMFCBitmap::ReplaceColor(COLORREF crOld, COLORREF crNew)

{

CDC memDC;

CBitmap bmpTrans;

CBitmap *pOldBitmap;

POINT ptSize;

BOOL bResult;

// Create one DC to hold temporary data.

bResult = memDC.Attach(::CreateCompatibleDC(NULL));

if(bResult == FALSE)

return FALSE;

// Compute the bitmap dimension

if(!this->GetBitmapSize(&(ptSize.x), &(ptSize.y)))

return FALSE;

// Convert from device

memDC.DPtoLP(&ptSize, 1);

BITMAP bm;

GetObject(m_hBitmap, sizeof(BITMAP), (LPSTR)&bm);

CMFCBitmap bmp;

if(bmp.CopyBitmap(m_hBitmap, MFCBI_NORMAL) == FALSE)

return FALSE;

// Create the transparent bitmap

bmpTrans.Attach(this->Detach());

Attach(bmp.Detach());

// Select the bitmap

pOldBitmap = (CBitmap*)memDC.SelectObject(&bmpTrans);

CRect rc(0,0, ptSize.x, ptSize.y);

memDC.FillSolidRect(rc, crNew);

DrawTransparent(&memDC, 0,0, crOld);

memDC.SelectObject(pOldBitmap);

// Destroy the previous bitmap

DeleteObject(Detach());

HBITMAP hMaskedBitmap = (HBITMAP)bmpTrans.Detach();

// Attach to the transparent bitmap

if(!Attach(hMaskedBitmap))

{

DeleteObject((HGDIOBJ)hMaskedBitmap);

return FALSE;

}

return TRUE;

}