DIB の拡大/縮小

DIB のサイズ変更

int StretchDIBits(
	HDC hdc,
	int XDest , int YDest ,
	int nDestWidth , int nDestHeight ,
	int XSrc , int YSrc ,
	int nSrcWidth , int nSrcHeight ,
	CONST VOID *lpBits,
	CONST BITMAPINFO *lpBitsInfo,
	UINT iUsage , DWORD dwRop
);

#include <windows.h>

BITMAPFILEHEADER bmpFileHeader;
BITMAPINFO * bmpInfo;
BYTE * bPixelBits;

LRESULT CALLBACK WndProc(HWND hWnd , UINT msg , WPARAM wp , LPARAM lp) {
	HDC hdc;
	PAINTSTRUCT ps;
	RECT rect;

	switch (msg) {
	case WM_DESTROY:
		free(bPixelBits);
		free(bmpInfo);
		PostQuitMessage(0);
		return 0;
	case WM_PAINT:
		hdc = BeginPaint(hWnd , &ps);
		GetClientRect(hWnd , &rect);
		SetStretchBltMode(hdc , COLORONCOLOR);
		StretchDIBits(
			hdc , 0 , 0 , rect.right , rect.bottom , 0 , 0 ,
			bmpInfo->bmiHeader.biWidth , bmpInfo->bmiHeader.biHeight ,
			bPixelBits , bmpInfo , DIB_RGB_COLORS , SRCCOPY 
		);
		EndPaint(hWnd , &ps);
		return 0;
	}
	return DefWindowProc(hWnd , msg , wp , lp);
}

int WINAPI WinMain(HINSTANCE hInstance , HINSTANCE hPrevInstance ,
			PSTR lpCmdLine , int nCmdShow) {
	HWND hWnd;
	MSG msg;
	WNDCLASS winc;
	HANDLE hFile;
	DWORD dwBytes;

	hFile = CreateFile(lpCmdLine , GENERIC_READ , 0 , NULL ,
		OPEN_EXISTING , FILE_ATTRIBUTE_NORMAL , NULL);
	if (hFile == INVALID_HANDLE_VALUE) return 1;

	ReadFile(hFile , &bmpFileHeader , sizeof (BITMAPFILEHEADER) , &dwBytes , NULL);
	if (bmpFileHeader.bfType != 0x4D42) {
		MessageBox(NULL , TEXT("This is not a bitmap file") , NULL , MB_OK);
		return 1;
	}

	bmpInfo = (BITMAPINFO *) malloc (bmpFileHeader.bfOffBits - dwBytes);
	ReadFile(hFile , bmpInfo , bmpFileHeader.bfOffBits - dwBytes , &dwBytes , NULL);
	bPixelBits = (BYTE *) malloc (bmpFileHeader.bfSize - bmpFileHeader.bfOffBits);
	ReadFile(hFile ,bPixelBits ,
		bmpFileHeader.bfSize - bmpFileHeader.bfOffBits , &dwBytes , NULL);
	CloseHandle(hFile);

	winc.style 		= CS_HREDRAW | CS_VREDRAW;
	winc.lpfnWndProc		= WndProc;
	winc.cbClsExtra		= winc.cbWndExtra	= 0;
	winc.hInstance		= hInstance;
	winc.hIcon		= LoadIcon(NULL , IDI_APPLICATION);
	winc.hCursor		= LoadCursor(NULL , IDC_ARROW);
	winc.hbrBackground	= (HBRUSH)GetStockObject(WHITE_BRUSH);
	winc.lpszMenuName	= NULL;
	winc.lpszClassName	= TEXT("KITTY");

	if (!RegisterClass(&winc)) return 1;

	hWnd = CreateWindow(
			TEXT("KITTY") , TEXT("Kitty on your lap") ,
			WS_OVERLAPPEDWINDOW | WS_VISIBLE ,
			CW_USEDEFAULT , CW_USEDEFAULT ,
			CW_USEDEFAULT , CW_USEDEFAULT ,
			NULL , NULL , hInstance , NULL
	);

	if (hWnd == NULL) return 1;

	while (GetMessage(&msg , NULL , 0 , 0 )) {
		TranslateMessage(&msg);
		DispatchMessage(&msg);
	}

	return msg.wParam;
}

StretchDIBits()

int StretchDIBits(
	HDC hdc,
	int XDest , int YDest ,
	int nDestWidth , int nDestHeight ,
	int XSrc , int YSrc ,
	int nSrcWidth , int nSrcHeight ,
	CONST VOID *lpBits,
	CONST BITMAPINFO *lpBitsInfo,
	UINT iUsage , DWORD dwRop
);