Knowledge Base Nr: 00241 screenshot.cpp - http://www.swe-kaiser.de

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Win32: Screenshots mit Programm erstellen

  
//nur ausschnitt des desktops
int Screenshot(HDC hDC, int nStartX, int nStartY, int nSizeX, int nSizeY);

//ganzer desktop oder nur ein komplettes fenster
int Screenshot(HWND hWnd = HWND_DESKTOP);

//////////////////////////////////////
// implementierung

int CImageSupport::Screenshot(HDC hDC, int nStartX, int nStartY, int nSizeX, int nSizeY)
{
  if (!hDC || (nStartX < 0) || (nStartY < 0)
           || (nSizeX <= 0) || (nSizeY <= 0))
    return IS_NODATA;

  if (m_pRGB)
  {
    GlobalFree(m_pRGB);
    m_pRGB = 0;
    m_nWidth = m_nHeight = m_nBits = 0;
  }

  m_pRGB = ISDCToRGB(hDC, nStartX, nStartY, nSizeX, nSizeY);
  if (m_pRGB)
  {
    m_nWidth = nSizeX;
    m_nHeight = nSizeY;
    m_nBits = 24;
  }

  return m_pRGB ? IS_OK : IS_LIBERROR;
}

int CImageSupport::Screenshot(HWND hWnd)
{
  if (m_pRGB)
  {
    GlobalFree(m_pRGB);
    m_pRGB = 0;
    m_nWidth = m_nHeight = m_nBits = 0;
  }

  HWND hWndDesktop = HWND_DESKTOP;
  HDC hDC = ::GetDC(hWndDesktop);

  int nStartX, nStartY, nSizeX, nSizeY;

  if (hWnd != HWND_DESKTOP)
  {
    RECT rect;
    ::GetWindowRect(hWnd, &rect);
    nStartX = rect.left;
    nStartY = rect.top;
    nSizeX = rect.right - rect.left;
    nSizeY = rect.bottom - rect.top;
  }
  else
  {
    nStartX = 0;
    nStartY = 0;
    nSizeX = ::GetSystemMetrics(SM_CXSCREEN);
    nSizeY = ::GetSystemMetrics(SM_CYSCREEN);
  }

  int nErr = Screenshot(hDC, nStartX, nStartY, nSizeX, nSizeY);

  if (hWndDesktop && hDC)
    ::ReleaseDC(hWndDesktop, hDC);

  return nErr;
}


///////////////////////////////////////////////////
// beispiel

#include "../cpp_classes/ImgSupport.h"

void CCursortestDlg::OnScreenshot()
{
 CImageSupport img;

  HWND hWnd = GetSafeHwnd();

  int nErr = img.Screenshot(hWnd);
  ASSERT(!nErr);

  nErr = img.SavePNG("c:/temp/screenshot_app.png");
  ASSERT(!nErr);
}

void CCursortestDlg::OnScreenshot2()
{
  CImageSupport img;

  int nErr = img.Screenshot();
  ASSERT(!nErr);

  nErr = img.SavePNG("c:/temp/screenshot_desktop.png");
  ASSERT(!nErr);
}