#include<windows.h>

LRESULT CALLBACK WindowProc(HWND hWnd,UINT uMsg,WPARAM wParam,LPARAM lParam)
{
	HDC hdc;
	PAINTSTRUCT ps;
	static BITMAPINFO bmpInfo;
	static LPDWORD lpPixel;
	static HBITMAP hBitmap;
	static HDC hMemDC;

	HWND desktop;
	RECT rc;
	static int width,height;

	switch(uMsg) {
		case WM_CREATE:
			//スクリーンの情報を得る
			desktop=GetDesktopWindow();
			GetWindowRect(desktop,&rc);
			width=rc.right;
			height=rc.bottom;

			//DIBの情報を設定する
			bmpInfo.bmiHeader.biSize=sizeof(BITMAPINFOHEADER);
			bmpInfo.bmiHeader.biWidth=width;
			bmpInfo.bmiHeader.biHeight=height;
			bmpInfo.bmiHeader.biPlanes=1;
			bmpInfo.bmiHeader.biBitCount=32;
			bmpInfo.bmiHeader.biCompression=BI_RGB;

			//DIBSection作成
			hdc=GetDC(hWnd);
			hBitmap=CreateDIBSection(hdc,&bmpInfo,DIB_RGB_COLORS,(void**)&lpPixel,NULL,0);
			hMemDC=CreateCompatibleDC(hdc);
			SelectObject(hMemDC,hBitmap);
			ReleaseDC(hWnd,hdc);

			//スクリーンをDIBSectionにコピー
			hdc=GetDC(desktop);
			BitBlt(hMemDC,0,0,width,height,hdc,0,0,SRCCOPY);
			ReleaseDC(desktop,hdc);
			return 0;
		case WM_DESTROY:
			//自らlpPixelを解放するべからず
			DeleteDC(hMemDC);
			DeleteObject(hBitmap);	//BMPを削除した時、lpPixelも自動的に解放される
			PostQuitMessage(0);
			return 0;
		case WM_PAINT:
			hdc=BeginPaint(hWnd,&ps);
			//表画面へ転送
			BitBlt(hdc,0,0,width,height,hMemDC,0,0,SRCCOPY);
			EndPaint(hWnd,&ps);
			return 0;
	}
	return DefWindowProc(hWnd,uMsg,wParam,lParam);
}

int WINAPI WinMain(
	HINSTANCE hInstance,HINSTANCE hPrevInstance,PSTR lpCmdLine,int nCmdShow)
{
	WNDCLASS wc;
	MSG msg;

	wc.style		 = CS_HREDRAW | CS_VREDRAW;
	wc.lpfnWndProc	 = WindowProc;
	wc.cbClsExtra	 = 0;
	wc.cbWndExtra	 = 0;
	wc.hInstance	 = hInstance;
	wc.hIcon		 = LoadIcon(NULL,IDI_APPLICATION);
	wc.hCursor		 = LoadCursor(NULL,IDC_ARROW);
	wc.hbrBackground = (HBRUSH)GetStockObject(WHITE_BRUSH);
	wc.lpszMenuName	 = NULL;
	wc.lpszClassName = __FILE__;
	if(!RegisterClass(&wc)) return 0;

	HWND hWnd=CreateWindow(
		__FILE__,"スクリーンキャプチャ",
		WS_OVERLAPPEDWINDOW | WS_VISIBLE,
		CW_USEDEFAULT,CW_USEDEFAULT,
		CW_USEDEFAULT,CW_USEDEFAULT, 
		NULL,NULL,hInstance,NULL);
	if(hWnd==NULL) return 0;

	BOOL bRet;
	while((bRet=GetMessage(&msg,NULL,0,0))!=0){
		if(bRet==-1) break;
		DispatchMessage(&msg);
	}

	return (int)msg.wParam;
}