[ATL/WTL]_[中级]_[保存CBitmap到文件-保存屏幕内容到文件]

场景:

1. 在做图片处理时，比方放大后或加特效后须要保存CBitmap(HBITMAP)到文件.

2.截取屏幕内容到文件时.

3.不须要增加第3方库时.

说明: 这段代码部分来自网上。第一次学atl/wtl。gdi不是非常熟悉。以后转换为wtl版本号吧。

当然wtl项目直接用也没问题. 如今想想wxWidgets的wxImage类对这类操作方便多了。仅仅须要调用一个SaveFile方法。

保存HBITMAP到文件:

static bool SaveBitmapToFile(CBitmap& bitmap, LPWSTR lpFileName)

{

	HBITMAP hBitmap;	// 为刚才的屏幕位图句柄

	HDC hDC; //设备描写叙述表

	int iBits; //当前显示分辨率下每一个像素所占字节数

	WORD wBitCount; //位图中每一个像素所占字节数

	DWORD dwPaletteSize = 0, //定义调色板大小

		dwBmBitsSize,  //位图中像素字节大小

		dwDIBSize,	 //位图文件大小

		dwWritten;  //写入文件字节数

	BITMAP Bitmap; //位图属性结构

	BITMAPFILEHEADER bmfHdr; //位图文件头结构

	BITMAPINFOHEADER bi; //位图信息头结构

	LPBITMAPINFOHEADER lpbi; //指向位图信息头结构

	HANDLE fh,	 //定义文件

		hDib,	 //分配内存句柄

		hPal,	//调色板句柄

		hOldPal = NULL;

	//计算位图文件每一个像素所占字节数

	hBitmap = bitmap;

	hDC = CreateDC(L"DISPLAY",NULL,NULL,NULL);

	iBits =	GetDeviceCaps(hDC, BITSPIXEL) * GetDeviceCaps(hDC, PLANES);

	DeleteDC(hDC);

	if (iBits <= 1)

		wBitCount =	1;

	else if	(iBits <= 4)

		wBitCount =	4;

	else if (iBits <= 8)

		wBitCount =	8;

	else if	(iBits <= 24)

		wBitCount =	24;

	else if (iBits <= 32)

		wBitCount = 32;

	//计算调色板大小

	if (wBitCount <= 8)

		dwPaletteSize =	(1 << wBitCount) * sizeof (RGBQUAD);

	//设置位图信息头结构

	GetObject(hBitmap, sizeof (BITMAP), (LPSTR)&Bitmap);

	bi.biSize = sizeof (BITMAPINFOHEADER);

	bi.biWidth = Bitmap.bmWidth;

	bi.biHeight = Bitmap.bmHeight;

	bi.biPlanes = 1;

	bi.biBitCount =	wBitCount;

	bi.biCompression = BI_RGB;

	bi.biSizeImage = 0;

	bi.biXPelsPerMeter = 0;

	bi.biYPelsPerMeter = 0;

	bi.biClrUsed = 0;

	bi.biClrImportant = 0;  

	dwBmBitsSize = ((Bitmap.bmWidth * wBitCount+31) / 32) * 4 * Bitmap.bmHeight;  

	//为位图内容分配内存

	hDib = GlobalAlloc(GHND, dwBmBitsSize + dwPaletteSize + sizeof (BITMAPINFOHEADER));

	lpbi = (LPBITMAPINFOHEADER)GlobalLock(hDib);

	*lpbi =	bi;

	// 处理调色板

	hPal = GetStockObject(DEFAULT_PALETTE);

	if (hPal)

	{

		hDC = ::GetDC(NULL);

		hOldPal = ::SelectPalette(hDC, (HPALETTE)hPal, FALSE);

		RealizePalette(hDC);

	}  

	//	 获取该调色板下新的像素值

	GetDIBits(hDC, hBitmap,	0, (UINT) Bitmap.bmHeight,

		(LPSTR)lpbi + sizeof (BITMAPINFOHEADER)	+ dwPaletteSize,

		(LPBITMAPINFO)lpbi,	DIB_RGB_COLORS);  

	//恢复调色板

	if (hOldPal)

	{

		SelectPalette(hDC, (HPALETTE)hOldPal, TRUE);

		RealizePalette(hDC);

		::ReleaseDC(NULL, hDC);

	}  

	//创建位图文件

	fh = CreateFile(lpFileName, GENERIC_WRITE,

		0, NULL, CREATE_ALWAYS,

		FILE_ATTRIBUTE_NORMAL |	FILE_FLAG_SEQUENTIAL_SCAN, NULL);  

	if (fh == INVALID_HANDLE_VALUE)

		return FALSE;  

	//	 设置位图文件头

	bmfHdr.bfType =	0x4D42; 	//	 "BM"

	dwDIBSize = sizeof (BITMAPFILEHEADER)

		+ sizeof (BITMAPINFOHEADER)

		+ dwPaletteSize	+ dwBmBitsSize;

	bmfHdr.bfSize =	dwDIBSize;

	bmfHdr.bfReserved1 = 0;

	bmfHdr.bfReserved2 = 0;

	bmfHdr.bfOffBits = (DWORD)sizeof (BITMAPFILEHEADER)

		+ (DWORD)sizeof (BITMAPINFOHEADER)

		+ dwPaletteSize;	

	//	 写入位图文件头

	WriteFile(fh, (LPSTR)&bmfHdr, sizeof(BITMAPFILEHEADER), &dwWritten,	NULL);	

	//	 写入位图文件其余内容

	WriteFile(fh, (LPSTR)lpbi, dwDIBSize,

		&dwWritten, NULL);

	//清除

	GlobalUnlock(hDib);

	GlobalFree(hDib);

	CloseHandle(fh);  

	return TRUE;

}

保存屏幕到文件:

static void SaveScreenToFile(LPCTSTR szFileName)

{

	HDC hScrDC = ::GetDC(NULL);

	HDC hMemDC = NULL;

	BYTE *lpBitmapBits = NULL; 

	int nWidth = GetSystemMetrics(SM_CXSCREEN);

	int nHeight = GetSystemMetrics(SM_CYSCREEN); 

	hMemDC = ::CreateCompatibleDC(hScrDC); 

	BITMAPINFO bi;

	ZeroMemory(&bi, sizeof(BITMAPINFO));

	bi.bmiHeader.biSize = sizeof(BITMAPINFOHEADER);

	bi.bmiHeader.biWidth = nWidth;

	bi.bmiHeader.biHeight = nHeight;

	bi.bmiHeader.biPlanes = 1;

	bi.bmiHeader.biBitCount = 24;

	HBITMAP bitmap = ::CreateDIBSection(hMemDC, &bi, DIB_RGB_COLORS, (LPVOID*)&lpBitmapBits, NULL, 0);

	HGDIOBJ oldbmp = ::SelectObject(hMemDC, bitmap); 

	::BitBlt(hMemDC, 0, 0, nWidth, nHeight, hScrDC, 0, 0, SRCCOPY);

	BITMAPFILEHEADER bh;

	ZeroMemory(&bh, sizeof(BITMAPFILEHEADER));

	bh.bfType = 0x4d42; //bitmap

	bh.bfOffBits = sizeof(BITMAPFILEHEADER) + sizeof(BITMAPINFOHEADER);

	bh.bfSize = bh.bfOffBits + ((nWidth*nHeight)*3);

	FILE* file = _wfopen(szFileName,L"wb");

	if(file)

	{

		fwrite(&bh,1,sizeof(BITMAPFILEHEADER),file);

		fwrite(&(bi.bmiHeader),1,sizeof(BITMAPINFOHEADER),file);

		fwrite(lpBitmapBits,1,3 * nWidth * nHeight,file);

		fclose(file);

	}

	::SelectObject(hMemDC, oldbmp);

	::DeleteObject(bitmap);

	::DeleteObject(hMemDC);

	::ReleaseDC(NULL, hScrDC);

}