C / C++ / MFC

case WM_ERASEBKGND:
                {
                    return (LRESULT) 1;
                }
                break;

case WM_ERASEBKGND:
            {
                return (LRESULT)1;
            }
            break;

            case WM_CTLCOLORSTATIC:
            {
                return (LRESULT)GetStockObject(NULL_BRUSH);
            }
            break;
            case WM_PAINT:
            {
                PAINTSTRUCT test;
                BeginPaint(hwnd, &test);
                image imglabel(test.rcPaint.right-test.rcPaint.left,test.rcPaint.bottom - test.rcPaint.top);
                brush brshbackcolor(inst->clrBackColor);
                brshbackcolor.ToDC(imglabel);
                brush brshTransparent;

                FillRect(imglabel,&test.rcPaint,brshbackcolor);
                if(inst->imgtest.haveimage())
                    DrawHICONtoHDC(imglabel, inst->imgtest,1,1);
                SetBkMode(imglabel,TRANSPARENT);
                char *text=(char*)inst->strCaption.c_str();
                SetTextColor(imglabel,inst->clrTextColor );
                DrawTextEx(imglabel,text,-1,&test.rcPaint,DT_LEFT,NULL);
                if(inst->blnBorder==true)
                    DrawEdge(imglabel, &test.rcPaint,BDR_SUNKENINNER | BDR_RAISEDOUTER,BF_RECT);
                TransparentBlt(test.hdc,0,0,test.rcPaint.right,test.rcPaint.bottom,imglabel,0,0,test.rcPaint.right,test.rcPaint.bottom, inst->clrBackColor);
                //BitBlt(test.hdc,0,0,test.rcPaint.right,test.rcPaint.bottom,imglabel,0,0, SRCCOPY);
                EndPaint(hwnd, &test);
                return 0;
            }
            break;

RECT d;
                GetClientRect(hwnd,&d);
                RedrawWindow(hwnd,&d,nullptr,RDW_UPDATENOW | RDW_INVALIDATE | RDW_ERASENOW);

unsigned dist(const unsigned char *vec1, const unsigned char *vec2, unsigned dim)
{
    const unsigned char popCountTable[] =
    {
        0, 1, 1, 2, 1, 2, 2, 3, 1, 2, 2, 3, 2, 3, 3, 4, 1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
        1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5, 2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
        1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5, 2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
        2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6, 3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
        1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5, 2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
        2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6, 3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
        2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6, 3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
        3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7, 4, 5, 5, 6, 5, 6, 6, 7, 5, 6, 6, 7, 6, 7, 7, 8
    };
    unsigned dist_ = 0;
    for (unsigned i = 0; i != dim; ++i)
    {
        dist_ += popCountTable[vec1[i] ^ vec2[i]];
    }
    return dist_;
}