videomod.cpp

改变屏幕的深度和分辨率

/*
Module : VIDEOMOD.CPP
Purpose: Implementation for some handy classes which wrap access 
         to the EnumDisplaySettings & ChangeDisplaySettings SDK functions
Created: PJN / 24-09-1997
History: PJN / 03-01-1999 Major tidy up of the code
                          UNICODE enabled the code

Copyright (c) 1997 by PJ Naughter.  
All rights reserved.

*/

/////////////////////////////////  Includes  //////////////////////////////////
#include "stdafx.h"
#include "videomod.h"




///////////////////////////////// defines /////////////////////////////////////

#ifdef _DEBUG
#define new DEBUG_NEW
#undef THIS_FILE
static char THIS_FILE[] = __FILE__;
#endif



//////////////////////////////// Implementation ///////////////////////////////
CVideoMode::CVideoMode()
{
  m_dwBitsPerPixel = 0;
  m_dwWidth = 0;
  m_dwHeight = 0;
  m_dwFrequency = 0;
}


CVideoMode::CVideoMode(DWORD BitsPerPixel, DWORD Width, DWORD Height, DWORD Frequency)
{
  m_dwBitsPerPixel = BitsPerPixel;
  m_dwWidth = Width;
  m_dwHeight = Height;
  m_dwFrequency = Frequency;
}


CVideoMode::CVideoMode(const CVideoMode& mode)
{
  *this = mode;
}


CVideoMode& CVideoMode::operator=(const CVideoMode& mode)
{
  m_dwBitsPerPixel = mode.m_dwBitsPerPixel;
  m_dwWidth = mode.m_dwWidth;
  m_dwHeight = mode.m_dwHeight;
  m_dwFrequency = mode.m_dwFrequency;

  return *this;
}



BOOL CVideoModes::GetCurrentVideoMode(CVideoMode& mode)
{
  HDC hdc = ::GetDC(NULL);  // Screen DC used to get current display settings
  if (hdc == NULL)
    return FALSE;

  CVideoMode m(GetDeviceCaps(hdc, BITSPIXEL), GetDeviceCaps(hdc, HORZRES),
               GetDeviceCaps(hdc, VERTRES), GetDeviceCaps(hdc, VREFRESH));
  mode = m;

  ::ReleaseDC(NULL, hdc);

  return TRUE;
}


BOOL CVideoModes::GetAvailableVideoModes(CAvailableVideoModes& modes)
{
  modes.SetSize(0, 5);
  int i=0;
  DEVMODE dm;
  
  while (EnumDisplaySettings(NULL, i, &dm))
  {
    CVideoMode thismode(dm.dmBitsPerPel, dm.dmPelsWidth, 
                        dm.dmPelsHeight, dm.dmDisplayFrequency);
    modes.SetAtGrow(i, thismode);
    ++i;
  }

  modes.FreeExtra();

  return (i>0);
}


LONG CVideoModes::RevertVideoModeToDefault()
{
  LONG rVal = ChangeDisplaySettings(NULL, 0);

#ifdef _DEBUG
  ReportChangeVideoErrorValue(rVal);
#endif

  return rVal;
}


void CVideoModes::ReportChangeVideoErrorValue(LONG lError)
{
  switch (lError)
  {
    case DISP_CHANGE_SUCCESSFUL: TRACE(_T("ChangeDisplaySettings: The settings change was successful\n")); break;
    case DISP_CHANGE_RESTART:	   TRACE(_T("ChangeDisplaySettings: The computer must be restarted in order for the graphics mode to work\n")); break;
    case DISP_CHANGE_BADFLAGS:	 TRACE(_T("ChangeDisplaySettings: An invalid set of flags was passed in\n")); break;
    case DISP_CHANGE_FAILED:	   TRACE(_T("ChangeDisplaySettings: The display driver failed the specified graphics mode\n")); break;
    case DISP_CHANGE_BADMODE:	   TRACE(_T("ChangeDisplaySettings: The graphics mode is not supported\n")); break;
    case DISP_CHANGE_NOTUPDATED: TRACE(_T("ChangeDisplaySettings: Unable to write settings to the registry\n")); break;
    default:                     TRACE(_T("ChangeDisplaySettings: Unexpected error value\n")); break;
  }
}


LONG CVideoModes::ChangeVideoModePermanently(const CVideoMode& mode)
{
  DEVMODE dm;
  CreateCompatibleDEVMODE(&dm, mode.m_dwBitsPerPixel, mode.m_dwWidth, mode.m_dwHeight, mode.m_dwFrequency);
  LONG rVal = ChangeDisplaySettings(&dm, CDS_UPDATEREGISTRY);

#ifdef _DEBUG
  ReportChangeVideoErrorValue(rVal);
#endif

  return rVal;
}


LONG CVideoModes::ChangeVideoModeTemporarily(const CVideoMode& mode)
{
  DEVMODE dm;
  CreateCompatibleDEVMODE(&dm, mode.m_dwBitsPerPixel, mode.m_dwWidth, mode.m_dwHeight, mode.m_dwFrequency);
  LONG rVal = ChangeDisplaySettings(&dm, 0);

#ifdef _DEBUG
  ReportChangeVideoErrorValue(rVal);
#endif

  return rVal;
}


LONG CVideoModes::CanChangeVideoMode(const CVideoMode& mode)
{
  DEVMODE dm;
  CreateCompatibleDEVMODE(&dm, mode.m_dwBitsPerPixel, mode.m_dwWidth, mode.m_dwHeight, mode.m_dwFrequency);
  LONG rVal = ChangeDisplaySettings(&dm, CDS_TEST);

#ifdef _DEBUG
  ReportChangeVideoErrorValue(rVal);
#endif

  return rVal;
}


void CVideoModes::CreateCompatibleDEVMODE(DEVMODE* pdm, DWORD BitsPerPixel, DWORD Width, DWORD Height, DWORD Frequency)
{
  ZeroMemory(pdm, sizeof(DEVMODE));
  pdm->dmSize = sizeof(DEVMODE);

  if (BitsPerPixel)
  {
    pdm->dmBitsPerPel = BitsPerPixel;
    pdm->dmFields |= DM_BITSPERPEL;
  }

  if (Width)
  {
    pdm->dmPelsWidth = Width;
    pdm->dmFields |= DM_PELSWIDTH;
  }

  if (Height)
  {
    pdm->dmPelsHeight = Height;
    pdm->dmFields |= DM_PELSHEIGHT;
  }

  if (Frequency)
  {
    pdm->dmDisplayFrequency = Frequency;
    pdm->dmFields |= DM_DISPLAYFREQUENCY;
  }
}