ResSwitch & ResList v1.2 - Easily change screen resolution

Introduction

Also included is ResList which is a simple console app which lists the available video modes which ResSwitch can use.

The source zip file contains the ResSwitch and ResList source code, a very handy MFC class to wrap access to the two underlying APIs. ResSwitch and ResList use and a prebuilt binary version of both programs. The enclosed binary requires that you have the MFC 4.2b DLLs already installed. If you haven't already got them on your machine (MFC42.DLL in your Windows system directory), then grab them from Microsoft's web site at http://activex.microsoft.com/controls/vc/mfc42.cab.

Usage

• To use the class in your code simply include videomod.cpp in your project and #include videomod.h in which ever of your modules needs to make calls to the class.
• Your code will need to include MFC either statically or dynamically.
• You will also need to have afxtempl.h in your precompiled header.
• To see the class in action, have a look at the code in the main function in the module ResList.cpp or the Winmain function in the module ResSwitch.cpp.

History

• Changed name QuickerRes to QRes to avoid conflict with a similarly named third party product.
• Now supports setting the monitor frequency (NT only according to the documentation).
• Inclusion of a new console mode program called QList (binary & source code) with enumerates all the video modes available. Comes in helpful if QRes is reporting that some options you select are unavailable.

v1.2 (4 January 1999)

• Changed name (yet again) from QRes to ResSwitch to avoid conflict with another similarly named third party product.
• Source code now ships with Visual C++ 5 workspace files now as standard.
• All source code is now fully UNICODE enabled and UNICODE build configurations are now provided.
• General tidy up of the codebase.

API Reference

CVideoMode
CVideoModes::GetCurrentVideoMode
CVideoModes::GetAvailableVideoModes
CVideoModes::ChangeVideoModePermanently
CVideoModes::ChangeVideoModeTemporarily
CVideoModes::CanChangeVideoMode
CVideoModes::RevertVideoModeToDefault

CVideoMode

Remarks:
This class is an encapsulation of a video mode. It contains 4 public member variables, namely:

• m_dwBitsPerPixel -- Specifies in bits per pixel the colour resolution of the display device. For example: 4 bits for 16 colours, 8 bits for 256 colours, or 16 bits for 65,536 colours.
• m_dwWidth -- Specifies the width, in pixels, of the display device.
• m_dwHeight -- Specifies the height, in pixels, of the display device.
• m_dwFrequency -- Specifies the frequency, in hertz of the display device in a particular mode. On some early builds of Windows 95, changing the frequency of the display adapter is not supported and this value should be set to 0 which means the default hardware value.

CVideoModes::GetCurrentVideoMode

static BOOL CVideoModes::GetCurrentVideoMode(CVideoMode& mode);

Return Value:
TRUE if the current video mode was retrieved successfully otherwise FALSE.

Parameters:

• mode -- Upon successful return this will contain the current video mode of the main display adapter.

Remarks:
Internally this retrieves the current settings GetDeviceCaps() function on a device context for the display.

CVideoModes::GetAvailableVideoModes

static BOOL CVideoModes::GetAvailableVideoModes(CAvailableVideoModes& modes);

Return Value:
TRUE if the available video modes were retrieved successfully otherwise FALSE.

Parameters:

• modes -- Upon successful return this will contain an array containing the available video modes of the main display adapter.

Remarks:
Returns all the video modes which the display adapter supports.

CAvailableVideoModes is defined as follows:
typedef CArray<CVideoMode, CVideoMode&> CAvailableVideoModes;

CVideoModes::ChangeVideoModePermanently

static LONG CVideoModes::ChangeVideoModePermanently(const CVideoMode& mode);

Return Value:
Returns one of the following values:

Value	Meaning
DISP_CHANGE_SUCCESSFUL	The settings change was successful.
DISP_CHANGE_RESTART	The computer must be restarted in order for the graphics mode to work.
DISP_CHANGE_BADFLAGS	An invalid set of flags was passed in.
DISP_CHANGE_FAILED	The display driver failed the specified graphics mode.
DISP_CHANGE_BADMODE	The graphics mode is not supported.
DISP_CHANGE_NOTUPDATED	Unable to write settings to the registry.

Parameters:

• mode -- The video mode to change into.

Remarks:
If this function succeeds then the changes are permanent, meaning that upon next boot of Windows the video mode will be the preserved to that which you just changed into.

CVideoModes::ChangeVideoModeTemporarily

static LONG CVideoModes::ChangeVideoModeTemporarily(const CVideoMode& mode);

Return Value:
The return value is the same as ChangeVideoModePermanently.

Parameters:

• mode -- The video mode to change into.

Remarks:
If this function succeeds then the changes are not permanent, meaning that upon next boot of Windows the video mode will be the the same as before you called this function.

CVideoModes::CanChangeVideoMode

static LONG CVideoModes::CanChangeVideoMode(const CVideoMode& mode);

Return Value:
The return value is the same as ChangeVideoModePermanently.

Parameters:

• mode -- he video mode to test whether or not the change can be made.

Remarks:
Using this function allows an application to determine if a specified graphics modes is actually valid, without causing the system to change to that graphics mode.

CVideoModes::RevertVideoModeToDefault

static LONG CVideoModes::RevertVideoModeToDefault();

Return Value:
The return value is the same as ChangeVideoModePermanently.

Remarks:
Using this function allows an application to determine if a specified graphics modes is actually valid, without causing the system to change to that graphics mode.

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