#include<windows.h>

#define BMP_SUM		3	//画像の総数

LRESULT CALLBACK WindowProc(HWND hWnd,UINT uMsg,WPARAM wParam,LPARAM lParam)
{
	HDC hdc;
	PAINTSTRUCT ps;
	HBITMAP hBitmap;
	int i;
	const char *filename[BMP_SUM]={"Airplane.bmp","Lighthouse.bmp","Parrots.bmp"};
	static HDC hMemDC[BMP_SUM];
	static BITMAP bmp;
	static int bmp_index;	//現在の画像番号

	switch(uMsg) {
		case WM_CREATE:
			hdc=GetDC(hWnd);
			for(i=0;i<BMP_SUM;i++){
				hBitmap=(HBITMAP)LoadImage(0,filename[i],IMAGE_BITMAP,0,0,LR_LOADFROMFILE);
				hMemDC[i]=CreateCompatibleDC(hdc);
				SelectObject(hMemDC[i],hBitmap);
			}
			//画像のサイズは全て同じ(という設定)
			GetObject(hBitmap,sizeof(BITMAP),&bmp);
			DeleteObject(hBitmap);
			ReleaseDC(hWnd,hdc);
			return 0;
		case WM_DESTROY:
			for(i=0;i<BMP_SUM;i++) DeleteDC(hMemDC[i]);
			PostQuitMessage(0);
			return 0;
		case WM_LBUTTONDOWN:
			if(++bmp_index >= BMP_SUM) bmp_index=0;
			InvalidateRect(hWnd,NULL,FALSE);
			return 0;
		case WM_PAINT:
			hdc=BeginPaint(hWnd,&ps);
			BitBlt(hdc,0,0,bmp.bmWidth,bmp.bmHeight,hMemDC[bmp_index],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__,"複数画像の表示切り替え",
		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;
}