学步园

转载于:http://blog.csdn.net/yincheng01/article/details/7214049

我们都体验过QQ的截图功能特别好使，下面我们亲自来实践基于C++开发一个我们自己的截图功能

详见代码

// ScreenCap.cpp : Defines the entry point for the console application.
//

#include "stdafx.h"

#include <Windows.h>


HANDLE DDBtoDIB( HBITMAP bitmap, DWORD dwCompression, HPALETTE  hPal,DWORD * sizeimage) ;  
BOOL CapScreen(LPTSTR FileName);//截屏函数

HANDLE DDBtoDIB( HBITMAP bitmap, DWORD dwCompression, HPALETTE  hPal,DWORD * sizeimage) 
{
	BITMAP            bm;
	BITMAPINFOHEADER    bi;
	LPBITMAPINFOHEADER     lpbi;
	DWORD            dwLen;
	HANDLE            hDib;
	HANDLE            handle;
	HDC             hdc;

	//不支持BI_BITFIELDS类型
	if( dwCompression == BI_BITFIELDS )
		return NULL;

	//如果调色板为空，则用默认调色板
	if (hPal==NULL)
		hPal = (HPALETTE) GetStockObject(DEFAULT_PALETTE );

	//获取位图信息
	GetObject(bitmap,sizeof(bm),(LPSTR)&bm);

	//初始化位图信息头
	bi.biSize        = sizeof(BITMAPINFOHEADER);
	bi.biWidth        = bm.bmWidth;
	bi.biHeight         = bm.bmHeight;
	bi.biPlanes         = 1;
	bi.biBitCount        = bm.bmPlanes * bm.bmBitsPixel;
	bi.biCompression    = dwCompression;
	bi.biSizeImage        = 0;
	bi.biXPelsPerMeter    = 0;
	bi.biYPelsPerMeter    = 0;
	bi.biClrUsed        = 0;
	bi.biClrImportant    = 0;

	//计算信息头及颜色表大小
	int ncolors = (1 << bi.biBitCount); if( ncolors> 256 ) 
		ncolors = 0;
	dwLen  = bi.biSize + ncolors * sizeof(RGBQUAD);

	// we need a device context to get the dib from
	hdc = GetDC(NULL);
	hPal = SelectPalette(hdc,hPal,FALSE);
	RealizePalette(hdc);

	//为信息头及颜色表分配内存
	hDib = GlobalAlloc(GMEM_FIXED,dwLen);

	if (!hDib){
		SelectPalette(hdc,hPal,FALSE);
		ReleaseDC(NULL,hdc);
		return NULL;
	}

	lpbi = (LPBITMAPINFOHEADER)hDib;
	*lpbi = bi;
	//调用 GetDIBits 计算图像大小
	GetDIBits(hdc, bitmap, 0L, (DWORD)bi.biHeight,
		(LPBYTE)NULL, (LPBITMAPINFO)lpbi, (DWORD)DIB_RGB_COLORS );

	bi = *lpbi;
	//图像的每一行都对齐(32bit)边界
	if (bi.biSizeImage == 0){
		bi.biSizeImage = ((((bi.biWidth * bi.biBitCount) + 31) & ~31) / 8) 
			* bi.biHeight;
		if (dwCompression != BI_RGB)
			bi.biSizeImage = (bi.biSizeImage * 3) / 2;
	}

	//重新分配内存大小，以便放下所有数据
	dwLen += bi.biSizeImage;
	if (handle = GlobalReAlloc(hDib, dwLen, GMEM_MOVEABLE))
		hDib = handle;
	else{
		GlobalFree(hDib);

		//重选原始调色板
		SelectPalette(hdc,hPal,FALSE);
		ReleaseDC(NULL,hdc);
		return NULL;
	}

	//获取位图数据
	lpbi = (LPBITMAPINFOHEADER)hDib;

	//最终获得的DIB
	BOOL bgotbits = GetDIBits( hdc, bitmap,
		0L,                      //扫描行起始处
		(DWORD)bi.biHeight,      //扫描行数
		(LPBYTE)lpbi             //位图数据地址
		+ (bi.biSize + ncolors * sizeof(RGBQUAD)),
		(LPBITMAPINFO)lpbi,      //位图信息地址
		(DWORD)DIB_RGB_COLORS);  //颜色板使用RGB

	if( !bgotbits )
	{
		GlobalFree(hDib);

		SelectPalette(hdc,hPal,FALSE);
		ReleaseDC(NULL,hdc);
		return NULL;
	}

	SelectPalette(hdc,hPal,FALSE);
	ReleaseDC(NULL,hdc);
	*sizeimage=bi.biSizeImage;
	return hDib;
} 

BOOL CapScreen(LPTSTR FileName)
{
	DWORD sizeimage;
	HDC hdc = CreateDC(L"DISPLAY", NULL, NULL, NULL); 
	//HWND hwnd = ::FindWindow(NULL,L"TOOLS (D:)"); 
	//HDC hdc = GetDC(hwnd);//如果此处换成其他窗口的DC,那么就是对窗口的截图

	HDC CompatibleHDC = CreateCompatibleDC(hdc); 
	HBITMAP BmpScreen = CreateCompatibleBitmap(hdc,GetDeviceCaps(hdc, HORZRES),GetDeviceCaps(hdc, VERTRES)); 
	SelectObject(CompatibleHDC, BmpScreen);
	BitBlt(CompatibleHDC,0,0,GetDeviceCaps(hdc, HORZRES), GetDeviceCaps(hdc, VERTRES),hdc,0,0,SRCCOPY);

	
	HANDLE	pbitmapwithoutfileh=DDBtoDIB(BmpScreen, BI_RGB,0,&sizeimage);
	BITMAPFILEHEADER bfh;
	//设置位图信息头结构
	bfh.bfType = ((WORD)('M'<< 8)|'B');
	bfh.bfReserved1 = 0;
	bfh.bfReserved2 = 0;
	bfh.bfSize = 54+sizeimage;
	bfh.bfOffBits = 54;
	//创建位图文件    
	HANDLE  hFile=CreateFile(FileName,GENERIC_WRITE,0,0,CREATE_ALWAYS,FILE_ATTRIBUTE_NORMAL,0);
	DWORD dwWrite;
	// 写入位图文件头
	WriteFile(hFile,&bfh,sizeof(BITMAPFILEHEADER),&dwWrite,NULL);
	// 写入位图文件其余内容
	WriteFile(hFile,pbitmapwithoutfileh,bfh.bfSize,&dwWrite,NULL);  
	CloseHandle(hFile); /// 原文中有小的纰漏,应该是关闭文件句柄。
	DeleteDC(hdc);
	
	return true;
}


int _tmain(int argc, _TCHAR* argv[])
{
	CapScreen(L"C:\\Users\\\MSC\\\Desktop\\desktop.bmp");
	return 0;
}