Thanks, actually Resample is obsolete function now - was added when ImageManager didn't support alpha images in Win9x.  Now you can draw alpha bitmap in all OS, so you don't need call Resample.

Hi,

Oleg wrote: Hi, Thanks, I see. Will review this code.

I have seen your code in CXTPImageManager::ResampleAlphaLayer function of the Codejock ToolkitPro MFC v15.1.3.0908 & this is what I would like to say:

First:
This is the true, global & final math formula used in re-sampling 32bit alpha bitmaps to 24bit bitmaps. I have been working last night to find it.


Second:

In your code you used this:
pTarget[0] = (BYTE)((pSource[0] * (255 - iAlpha) + pSource[0] * iAlpha) >> 8);
pTarget[1] = (BYTE)((pSource[1] * (255 - iAlpha) + pSource[1] * iAlpha) >> 8);
pTarget[2] = (BYTE)((pSource[2] * (255 - iAlpha) + pSource[2] * iAlpha) >> 8);

And as known:

(x * y) + (x * z) = x * (y + z)

So, your code is the same as the below:

pTarget[0] = (BYTE)((pSource[0] * 255) >> 8);
pTarget[1] = (BYTE)((pSource[1] * 255) >> 8);
pTarget[2] = (BYTE)((pSource[2] * 255) >> 8);

Third:

R G B & A values of a bitmap are stored in like this: BGRA BGRA BGRA BGRA BGRA ...
and not RGBA as you did. (You confused Red with Blue).

Fourth:

This is the last CXTPImageManager::ResampleAlphaLayer function that should be:

HBITMAP CXTPImageManager::ResampleAlphaLayer(HBITMAP hBitmapAlpha, COLORREF clrMask)
{
    LPBYTE lpbytBits = NULL;
    LPBITMAPINFO lpBitmapInfo = NULL;
    UINT uiSize;
   
    if (!CXTPImageManagerIcon::GetBitmapBits(*CDC::FromHandle(::CreateCompatibleDC(NULL)), hBitmapAlpha, lpBitmapInfo, (LPVOID&)lpbytBits, uiSize))
        return NULL;
   
    LPBYTE lpbytTarget = NULL;
    LPBYTE lpbytSource = lpbytBits;
   
    lpBitmapInfo->bmiHeader.biBitCount = 24;
    lpBitmapInfo->bmiHeader.biCompression = BI_RGB;
    lpBitmapInfo->bmiHeader.biSizeImage = 0;
   
    HBITMAP hBitmapResult = ::CreateDIBSection(::CreateCompatibleDC(NULL), lpBitmapInfo, DIB_RGB_COLORS, (LPVOID *)&lpbytTarget, NULL, 0);
   
    if (lpbytTarget && lpbytSource && hBitmapResult)
    {
        for (int i = 0; i < lpBitmapInfo->bmiHeader.biHeight; i ++)
        {
            for (int j = 0; j < lpBitmapInfo->bmiHeader.biWidth; j ++)
            {
                lpbytTarget[0] = (BYTE)(GetBValue(clrMask) + lpbytSource[3] * (lpbytSource[0] - GetBValue(clrMask)) / 255);
                lpbytTarget[1] = (BYTE)(GetGValue(clrMask) + lpbytSource[3] * (lpbytSource[1] - GetGValue(clrMask)) / 255);
                lpbytTarget[2] = (BYTE)(GetRValue(clrMask) + lpbytSource[3] * (lpbytSource[2] - GetRValue(clrMask)) / 255);
               
                lpbytTarget += 3;
                lpbytSource += 4;
            }

            lpbytTarget += -(lpBitmapInfo->bmiHeader.biWidth * 3) & 3;
        }
    }
   
    FREE(lpbytBits);
    FREE(lpBitmapInfo);
   
    return hBitmapResult;
}

This is a result of the comparison of an image and some variable masks.
Original Image:


Mask = RGB(255, 255, 255)
  

Mask = RGB(255, 0, 0)
  

Mask = RGB(0, 255, 0)
  

Mask = RGB(0, 0, 255)
  

& Finally:

Thank you for your understand & PLEASE do this fix in the next hotfix