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C++实现屏幕截图（全屏截图）

︶ㄣ速达网 メ
米米素材网V管理员 / 阅读
0715

屏幕截图已经成为了所有IM即时通讯软件的必备模块，也是日常办公中使用最频繁的功能之一。今天我们从C++开发的角度，来看看屏幕截图的主要功能点是如何实现的，感兴趣的可以了解一下

上回分享了一个全屏截图的代码，保存为BMP，

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，无赖又整成了PNG截图，现在分享出来。

MakePNG.h

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//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

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//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：

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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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原文链接：https://blog.csdn.net/chenlycly/article/details/121197726