Graphics

#define WIN32_LEAN_AND_MEAN
#include <windows.h>
#include <fstream>

int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow)
{
	HWND hWnd = GetDesktopWindow();
	HDC hDc = GetDC(hWnd);

	WINDOWINFO window_info;
	window_info.cbSize = sizeof(WINDOWINFO);
	GetWindowInfo(hWnd, &window_info);
	
	const unsigned width = window_info.rcClient.right - window_info.rcClient.left;
	const unsigned height = window_info.rcClient.bottom - window_info.rcClient.top;
	const unsigned size = ((width * 24 + 31) & ~31) / 8 * height;

	PSTR pixels = NULL;

	BITMAPINFO bitmap_info = {0};
	bitmap_info.bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
	bitmap_info.bmiHeader.biWidth = width;
	bitmap_info.bmiHeader.biHeight = height;
	bitmap_info.bmiHeader.biPlanes = 1;
	bitmap_info.bmiHeader.biBitCount = 24;
	bitmap_info.bmiHeader.biCompression = BI_RGB;
	bitmap_info.bmiHeader.biSizeImage = size;

	HDC hCompatibleDc = CreateCompatibleDC(hDc);
	HBITMAP hBitmap = CreateDIBSection(NULL, &bitmap_info, DIB_RGB_COLORS, (void **)&pixels, NULL, 0);
	SelectObject(hCompatibleDc, hBitmap);
	BitBlt(hCompatibleDc, 0, 0, width, height, hDc, window_info.rcClient.left, window_info.rcClient.top, SRCCOPY);

	BITMAPFILEHEADER file_header = {0};
	file_header.bfType = 0x4d42;
	file_header.bfSize = sizeof(BITMAPFILEHEADER) + sizeof(BITMAPINFOHEADER) + size;
	file_header.bfOffBits = sizeof(BITMAPFILEHEADER) + sizeof(BITMAPINFOHEADER); 

	std::ofstream image("image.bmp");
	image.write((PSTR)&file_header, sizeof(BITMAPFILEHEADER));
	image.write((PSTR)&bitmap_info.bmiHeader, sizeof(BITMAPINFOHEADER));
	image.write(pixels, size);
	image.close();

	SelectObject(hCompatibleDc, NULL);
	DeleteObject(hBitmap);
	DeleteDC(hCompatibleDc);
	ReleaseDC(hWnd, hDc);

	return 0;
}</fstream></windows.h>