Полный ооп

//========================     https://***********/threads/screenshot-v-cv-mat.51042/
 
class Screen{
public:
Screen(){
// Параметры экрана
HWND hwnd = GetDesktopWindow(); 
hWDC = GetWindowDC( hwnd );
width = GetSystemMetrics( SM_CXSCREEN );
height = GetSystemMetrics( SM_CYSCREEN );
 
// Совместимый контекст в памяти
hScreen = CreateCompatibleDC( hWDC ); // - DeleteDC( hScreen );
hBM = CreateCompatibleBitmap( hWDC, width, height ); // - DeleteObject( hBM );
hBM_Temp = SelectObject( hScreen, hBM ); // - SelectObject( hScreen, hBM_Temp );

#include <windows.h>
#include <stdio.h>
//-----------------------------
int     w, h;
void *  p;
 
void dump_bmp()
{
int                 i;
BITMAPFILEHEADER    bfh;
BITMAPINFOHEADER    bmi;
FILE *              fp;
 
memset( &bfh, 0, sizeof( BITMAPFILEHEADER ) );
memset( &bmi, 0, sizeof( BITMAPINFOHEADER ) );
 
bfh.bfType      = 0x4d42; // "BM"
bfh.bfSize      = sizeof( BITMAPFILEHEADER ) + w * h * 4;
bfh.bfOffBits   = sizeof( BITMAPFILEHEADER ) + sizeof( BITMAPINFOHEADER );
 
bmi.biSize          = sizeof( BITMAPINFOHEADER );
bmi.biWidth         = w;
bmi.biHeight        = h;
bmi.biPlanes        = 1;
bmi.biBitCount      = 32;
bmi.biCompression   = BI_RGB;
 
fp = fopen( "ss.bmp", "wb+" );
 
fwrite( &bfh, sizeof( BITMAPFILEHEADER ), 1, fp );
fwrite( &bmi, sizeof( BITMAPINFOHEADER ), 1, fp );
fwrite( p, w * h * 4, 1, fp );
 
fclose( fp );
}
 
 
//====================================================
//====================================================
int main()
{
HDC                 hdc;
HBITMAP             dib;
BITMAPINFOHEADER    bi;
 
w = GetSystemMetrics( SM_CXSCREEN );
h = GetSystemMetrics( SM_CYSCREEN );
 
bi.biSize           = sizeof( BITMAPINFOHEADER );
bi.biWidth          = w;
bi.biHeight         = h;
bi.biPlanes         = 1;
bi.biBitCount       = 32;
bi.biCompression    = BI_RGB;
hdc = CreateCompatibleDC( NULL );
dib = CreateDIBSection( hdc, (BITMAPINFO *)&bi, DIB_RGB_COLORS, (void **)&p, NULL, 0 );
SelectObject( hdc, dib );
 
BitBlt( hdc, 0, 0, w, h, GetDC( NULL ), 0, 0, SRCCOPY );
 
dump_bmp();
 
return 0;
}

color GetPixel(int x, int y)
    {
        if (y<0 || y > windowY || x <0 || x > windowX)
        {
        }
        else
        {
            return{ int(bufWindow[(y * windowX + x) * 3 + 2]),
                int(bufWindow[(y * windowX + x) * 3 + 1]),
                int(bufWindow[(y * windowX + x) * 3]) };
        }
        return{ -1, -1, -1 };
    }