C++实现屏幕截图

上回分享了一个全屏截图的代码，保存为BMP，参考：C++实现屏幕截图（全屏截图）

实际使用的过程中我发现截图文件实在大，无奈又整成了PNG截图，现在分享出来。

MakePNG.h

//MakePNG.h 
 
#pragma once 
#include <GdiPlus.h> 
using namespace Gdiplus; 
#pragma comment(lib,"GdiPlus.lib") 
 
class CMakePNG 
{ 
public: 
 CMakePNG(void); 
 ~CMakePNG(void); 
 
 BOOL MakePNG(HDC hDC,CRect rect,CString strFilePath); 
 BOOL BMptoPNG(LPCWSTR StrBMp,LPCWSTR StrPNG); 
 BOOL PNGtoBMp(LPCWSTR StrPNG,LPCWSTR StrBMp); 
 BOOL GetEncoderClsid(WCHAR* pFormat,CLSID* pClsid); 
private: 
 GdiplusStartupInput m_gdiplusStartupInput; 
 ULONG_PTR m_pGdiToken; 
}; 

MakePNG.cpp

//MakePNG.cpp 
 
#include "StdAfx.h" 
#include "MakePNG.h" 
 
CMakePNG::CMakePNG(void) 
{ 
 GdiplusStartup(&m_pGdiToken,&m_gdiplusStartupInput,NULL); 
} 
 
CMakePNG::~CMakePNG(void) 
{ 
} 
 
/***************************************************************************/ 
/* 功能： 根据rect屏幕抓图，保存为文件名为strFilePath的PNG图像文件 */ 
/* 输入参数： HDC hDC   屏幕HDC；    */ 
/*  CRect rect  需要的矩形;   */ 
/*  CString strFilePath 保存文件全路径（含后缀名）; */ 
/***************************************************************************/ 
BOOL CMakePNG::MakePNG(HDC hDC, CRect rect, CString strFilePath) 
{ 
 BITMAP bmp; 
 PBITMAPINFO pbmi; 
 PBITMAPINFOHEADER pbih; // bitmap info-header 
 BITMAPFILEHEADER hdr; // bitmap file-header 
 WORD cClrBits; 
 LPBYTE lpBits;  // memory pointer 
 DWORD dwTmp; 
 DWORD cb;   // incremental count of bytes 
 BYTE *hp;   // byte pointer 
 HANDLE hfile;  // file handle 
 CString szBMPFilename = strFilePath.Left(strFilePath.GetLength() - 3) + _T("bmp");//先保存成位图 
 HDC hdcCompatible = CreateCompatibleDC(hDC); 
 HBITMAP hbmScreen = CreateCompatibleBitmap(hDC, rect.Width(), rect.Height()); 
 
 if (hbmScreen == NULL) 
 { 
 AfxMessageBox(_T("CreateCompatibleBitmap() error")); 
 return FALSE; 
 } 
 
 // Select the bitmaps into the compatible DC. 
 
 if (!SelectObject(hdcCompatible, hbmScreen)) 
 { 
 AfxMessageBox(_T("Compatible Bitmap Selection error")); 
 return FALSE; 
 } 
 
 //Copy color data for the entire display into a 
 //bitmap that is selected into a compatible DC. 
 
 if (!BitBlt(hdcCompatible, 
 0,0, 
 rect.Width(), rect.Height(), 
 hDC, 
 rect.left,rect.top, 
 SRCCOPY)) 
 { 
 AfxMessageBox(_T("Screen to Compat Blt Failed")); 
 return FALSE; 
 } 
 
 // Retrieve the bitmap's color format, width, and height. 
 if (!GetObject(hbmScreen, sizeof(BITMAP), (LPSTR)&bmp)) 
 { 
 AfxMessageBox(_T("GetObject()出错！")); 
 return FALSE; 
 } 
 // Convert the color format to a count of bits. 
 cClrBits = (WORD)(bmp.bmPlanes * bmp.bmBitsPixel); 
 if (cClrBits == 1) 
 cClrBits = 1; 
 else if (cClrBits <= 4) 
 cClrBits = 4; 
 else if (cClrBits <= 8) 
 cClrBits = 8; 
 else if (cClrBits <= 16) 
 cClrBits = 16; 
 else if (cClrBits <= 24) 
 cClrBits = 24; 
 else cClrBits = 32; 
 
 // Allocate memory for the BITMAPINFO structure. (This structure 
 // contains a BITMAPINFOHEADER structure and an array of RGBQUAD 
 // data structures.) 
 
 if (cClrBits != 24) 
 pbmi = (PBITMAPINFO) LocalAlloc(LPTR, 
 sizeof(BITMAPINFOHEADER) + 
 sizeof(RGBQUAD) * (1<< cClrBits)); 
 
 // There is no RGBQUAD array for the 24-bit-per-pixel format. 
 
 else 
 pbmi = (PBITMAPINFO) LocalAlloc(LPTR, 
 sizeof(BITMAPINFOHEADER)); 
 
 // Initialize the fields in the BITMAPINFO structure. 
 
 pbmi->bmiHeader.biSize = sizeof(BITMAPINFOHEADER); 
 pbmi->bmiHeader.biWidth = bmp.bmWidth; 
 pbmi->bmiHeader.biHeight = bmp.bmHeight; 
 pbmi->bmiHeader.biPlanes = bmp.bmPlanes; 
 pbmi->bmiHeader.biBitCount = bmp.bmBitsPixel; 
 if (cClrBits < 24) 
 pbmi->bmiHeader.biClrUsed = (1<<cClrBits); 
 
 // If the bitmap is not compressed, set the BI_RGB flag. 
 pbmi->bmiHeader.biCompression = BI_RGB; 
 
 // Compute the number of bytes in the array of color 
 // indices and store the result in biSizeImage. 
 pbmi->bmiHeader.biSizeImage = ((pbmi->bmiHeader.biWidth * cClrBits +31) & ~31) /8 
 * pbmi->bmiHeader.biHeight; 
 // Set biClrImportant to 0, indicating that all of the device colors are important. 
 pbmi->bmiHeader.biClrImportant = 0; 
 
 pbih = (PBITMAPINFOHEADER) pbmi; 
 lpBits = (LPBYTE) GlobalAlloc(GMEM_FIXED, pbih->biSizeImage); 
 
 if (!lpBits) 
 { 
 AfxMessageBox(_T("内存分配错误！")); 
 return FALSE; 
 } 
 // Retrieve the color table (RGBQUAD array) and the bits 
 // (array of palette indices) from the DIB. 
 if (!GetDIBits(hDC, hbmScreen, 0, (WORD) pbih->biHeight, lpBits, pbmi, 
 DIB_RGB_COLORS)) 
 { 
 AfxMessageBox(_T("GetDIBits() error")); 
 return FALSE; 
 } 
 
 // Create the .BMP file. 
 hfile = CreateFile(szBMPFilename, 
 GENERIC_READ | GENERIC_WRITE, 
 (DWORD) 0, 
 NULL, 
 CREATE_ALWAYS, 
 FILE_ATTRIBUTE_NORMAL, 
 (HANDLE) NULL); 
 if (hfile == INVALID_HANDLE_VALUE) 
 { 
  AfxMessageBox(_T("创建文件失败")); 
 return false; 
 } 
 hdr.bfType = 0x4d42; // 0x42 = "B" 0x4d = "M" 
 // Compute the size of the entire file. 
 hdr.bfSize = (DWORD) (sizeof(BITMAPFILEHEADER) + 
 pbih->biSize + pbih->biClrUsed 
 * sizeof(RGBQUAD) + pbih->biSizeImage); 
 hdr.bfReserved1 = 0; 
 hdr.bfReserved2 = 0; 
 
 // Compute the offset to the array of color indices. 
 hdr.bfOffBits = (DWORD) sizeof(BITMAPFILEHEADER) + 
 pbih->biSize + pbih->biClrUsed 
 * sizeof (RGBQUAD); 
 
 // Copy the BITMAPFILEHEADER into the .BMP file. 
 if (!WriteFile(hfile, (LPVOID) &hdr, sizeof(BITMAPFILEHEADER), 
 (LPDWORD) &dwTmp, NULL)) 
 { 
  AfxMessageBox(_T("写BMP文件头失败")); 
 return FALSE; 
 } 
 
 // Copy the BITMAPINFOHEADER and RGBQUAD array into the file. 
 if (!WriteFile(hfile, (LPVOID) pbih, sizeof(BITMAPINFOHEADER) 
 + pbih->biClrUsed * sizeof (RGBQUAD), 
 (LPDWORD) &dwTmp, ( NULL))) 
 { 
  AfxMessageBox(_T("写BMP文件头失败")); 
 return FALSE; 
 } 
 
 // Copy the array of color indices into the .BMP file. 
 cb = pbih->biSizeImage; 
 hp = lpBits; 
 if (!WriteFile(hfile, (LPSTR) hp, (int) cb, (LPDWORD) &dwTmp,NULL)) 
 { 
 AfxMessageBox(_T("写入BMP文件失败")); 
 return FALSE; 
 } 
 
 // Close the .BMP file. 
 if (!CloseHandle(hfile)) 
 { 
  AfxMessageBox(_T("Can't close BMP file.")); 
 } 
 
 // Free memory. 
 GlobalFree((HGLOBAL)lpBits); 
 
 //转换成PNG 
 if(!BMptoPNG(szBMPFilename,strFilePath)) 
 { 
 DeleteFile(szBMPFilename); 
 return FALSE; 
 } 
 DeleteObject(hbmScreen); 
 DeleteFile(szBMPFilename); 
 return TRUE; 
} 
// //转换BMP文件为PNG文件  
BOOL CMakePNG::BMptoPNG(LPCWSTR StrBMp,LPCWSTR StrPNG) 
{ 
 CLSID encoderClsid; 
 Status stat; 
 Image* image = NULL; 
 image = Bitmap::FromFile(StrBMp,TRUE); 
 if (!GetEncoderClsid(L"image/png",&encoderClsid)) 
 { 
 return FALSE; 
 } 
 stat = image->Save(StrPNG,&encoderClsid,NULL); 
 if (stat != Ok) 
 { 
 return FALSE; 
 } 
 delete image; 
 return TRUE; 
} 
 
// 功能描述: 转换PNG文件为BMP文件 
BOOL CMakePNG::PNGtoBMp(LPCWSTR StrPNG,LPCWSTR StrBMp) 
{ 
 CLSID encoderClsid; 
 Status stat; 
 Image* pImage; 
 pImage = Bitmap::FromFile(StrPNG,TRUE); 
 if (!GetEncoderClsid(L"image/bmp",&encoderClsid)) 
 { 
 return FALSE; 
 } 
 stat = pImage->Save(StrBMp,&encoderClsid,NULL); 
 if (stat != Ok) 
 { 
 return FALSE; 
 } 
 delete pImage; 
 return TRUE; 
} 
 
BOOL CMakePNG::GetEncoderClsid(WCHAR* pFormat,CLSID* pClsid) 
{ 
 UINT num = 0,size = 0; 
 ImageCodecInfo* pImageCodecInfo = NULL; 
 GetImageEncodersSize(&num,&size); 
 if (size == 0) 
 { 
 return FALSE; 
 } 
 pImageCodecInfo = (ImageCodecInfo*)(malloc(size)); 
 if (pImageCodecInfo == NULL) 
 { 
 return FALSE; 
 } 
 GetImageEncoders(num,size,pImageCodecInfo); 
 BOOL bfound = FALSE; 
 for (UINT i = 0;!bfound && i < num; i++) 
 { 
 if (_wcsicmp(pImageCodecInfo[i].MimeType,pFormat) == 0) 
 { 
  *pClsid = pImageCodecInfo[i].Clsid; 
  bfound = TRUE; 
 } 
 } 
 free(pImageCodecInfo); 
 return bfound; 
} 

以上两个文件实际上是CMakePNG类，使用时需要把他们添加到项目中，调用方法如下：

wstring GetAppPathW() 
{ 
 wchar_t szExePath[MAX_PATH] = {0}; 
 GetModuleFileNameW(NULL, szExePath, MAX_PATH); 
 wchar_t *pstr = wcsrchr(szExePath, '\\'); 
 memset(pstr + 1, 0, 2); 
 wstring strAppPath(szExePath); 
 return strAppPath; 
} 
 
// 屏幕截图 
CString CDemoDlg::ScreenShot(void) 
{ 
 CWnd *pDesktop = GetDesktopWindow(); 
 CDC *pDC = pDesktop->GetDC(); 
 CRect rect; 
 //获取窗口的大小 
 pDesktop->GetClientRect(&rect); 
 
 //保存到的文件名 
 CString strFileName(GetAppPathW().c_str()); 
 strFileName += _T("ScreenShot\\"); 
 CreateDirectory((LPCTSTR)strFileName,NULL); 
 CTime t = CTime::GetCurrentTime(); 
 CString tt = t.Format("%Y%m%d_%H%M%S"); 
 strFileName += tt; 
 strFileName += _T(".PNG"); 
 //保存为PNG 
 CMakePNG MakePNG; 
 MakePNG.MakePNG(pDC->m_hDC,rect,strFileName); 
 ReleaseDC(pDC); 
 return strFileName; 
} 

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