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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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Not supported Jason Lieber 14:31 3 Jun '08   In reading the threads I see that the command line build may reference the adapter to determine whether or not the graphics mode is supported. If the error is received that the graphics mode is not supported and it is supported when using display settings control panel what would you recommend? Reslist - 800 x 480 isn't on there, it only has 800 x 600 Thanks in advance Sign In·View Thread·PermaLink Thanks Buddy prda 21:34 15 Apr '08   Nice Article Sign In·View Thread·PermaLink Some hints Dmitry_Bond 23:09 10 Apr '08   Hi. Yes. Good tool but... 1) if you are using command line interface - there should not be any MessageBoxes at all!!! Example - when start "ResSwitch.exe /?" it displays MessageBox. It should print error message to console. Any GUI elements in command line interface is nonsense. 2) It is good to provide some basic help on usage by "/?" or "/help" command line switch. Regards, Dmitry. Sign In·View Thread·PermaLink Visual Basic james.howell 9:49 9 Aug '07   Is there any chance these could be made into code / class / dll files that could be used in a visual basic .net 2005 program? I have been using this software from .cmd files for years and think the program is awesome, but I have now started poking around with vb and would like to make use of the code on offer. Well done on a great program I have relied on and made use of for a long time! Sign In·View Thread·PermaLink 1.00/5 change color depth without reboot on win95 Rudy Scott 16:25 8 Aug '03   Changing color depth requires a reboot on older versions of Windows (some versions of Windows 95 in particular exhibit this problem). If the user has some form of DirectX installed there is a nifty trick that will allow you to bypass this reboot. 1) Change the display settings with the appropriate API calls (as shown in this article). 2) Open a full-screen, exclusive mode directX window. 3) Close the window. That's it! Opening and closing DirectX in full screen mode causes GDI to reintialize with your new color depth settings. --Rudy Sign In·View Thread·PermaLink Re: change color depth without reboot on win95 sabrown100 6:58 2 Jan '08   What's the point when .NET won't run on Windows 95? Sign In·View Thread·PermaLink Problem in Compiling error MFC42.lib not found Azhar Javaid 21:55 5 Aug '03   Hello Thanx for the code but there ias a problem when i compile the code it gives me an error that mfc42.lib not found i have downloaded the specified mfc42.exe but it did not solve the problem Sign In·View Thread·PermaLink Re: Problem in Compiling error MFC42.lib not found pjnaughter 0:15 6 Aug '03   If it really is MFC42.lib causing problems then either your install of VC is screwed up or you need to update your lib settings. I'd bet that it is not this and it is "MFC42U.LIB" or "MFC42UD.LIB". If this is the case, then I'd suggest you build the Win32 Ascii or Win32 Debug configuration (if you are not interested in a Unicode build) or else do a custom reinstall of VC specifying that you want the MFC Unicode libraries installed. Sign In·View Thread·PermaLink 1.00/5 WoW - great work! Yovav 6:16 7 Apr '03   What great piece of work ! + Does it allow keeping the changed screen mode after restarting the computer ? (how ?) Best Regards - Yovav Gad EMail: Dev@SuperMain.com Web-Site: www.SuperMain.com Sign In·View Thread·PermaLink Re: WoW - great work! pjnaughter 7:25 7 Apr '03   I'm pretty sure the changes it make are persistant. Sign In·View Thread·PermaLink Re: WoW - great work! Yovav 8:14 7 Apr '03   10X 4 the fast reply. I changed on XP (using ResSwitch.exe), from 1024x768 to 800x600 after Restart it become 1024x768 again should I use specific function to remember the last switch ? Best Regards - Yovav Gad EMail: Dev@SuperMain.com Web-Site: www.SuperMain.com Sign In·View Thread·PermaLink Re: WoW - great work! pjnaughter 9:33 7 Apr '03   To have the change affect any logged in user as opposed to the current user, you need to use the CDS_GLOBAL flag in the call to ChangeDisplaySettings. Currently my class and app does not support this, which I will add for the next user. Sign In·View Thread·PermaLink controlling rescopy output ? flashkid 12:45 1 May '03   Hi, Great work pjnaufter . I'm not a C++ programmer but I want to use your resList/resCopy with a batch script that only outputs user's current display settings in one line .txt file. eg. .txt file : 1024 768 32 60 ---------------------- This is because I want to firstly detect and save the current display settings then change it to 640 480 ,run a program , when exit return to previous user display settings is this possible ? Thanx La Elaha Ella Allah ------------------------- http://flashkid.8m.com Sign In·View Thread·PermaLink Re: controlling rescopy output ? pjnaughter 13:18 1 May '03   The simplest solution to this would be to just use the C++ class which resList uses and drop it into a new console app which can write to a file or whatever you desire. If you want, contact me directly (pjna@naughter.com) if you want to contract me to do this. Alternatively you could do it yourself if you have access to a C++ compiler Sign In·View Thread·PermaLink Re: WoW - great work! Steve Goodman 11:57 19 Nov '03   A workaround that doesn't involve any C++ coding: In the batch script that changes the resolution, include a line that creates a file in the user's Windows startup folder with the same resolution that you are changing to. I.E. If your batch file looks like this: @echo off ResSwitch.exe 1024 768 32 85 include a line that creates a file called "resSwitch.cmd" in C:\Documents and Settings\JohnDoe\Start Menu\Programs\Startup\ that also includes the above. Make sure that if you have different batch files for different resolutions, the file you generate always has the same name (e.g. resSwitch.cmd), so that it overwrites whatever's in the startup directory. Otherwise, I would think that Windows will run all the scripts in a row, which I wouldn't think would be too healthy for your screen card or screen. CAVEAT EMPTOR: I haven't tried the above solution yet, but I intend to. Sign In·View Thread·PermaLink Problem: Taskbar doesn't move Maciek Niedzielski 12:48 3 Dec '02   In Win2k, when I switch from 800x600 24 to 1024x768, taskbar stays on it's position. This means, it's 800px wide, and is 600px from the top of the screen. Why does it happen and how to fix this?? BTW: In Win2k, is it possible to let every user have different screen resolution? Maciek Niedzielski Sign In·View Thread·PermaLink Re: Problem: Taskbar doesn't move pjnaughter 13:41 3 Dec '02   The API's which the code uses is very dependent on the quality of the graphic card drivers. A couple of ideas: 1. Try it on other machines with the same OS, but different graphics cards to confirm it is a driver issue. 2. Check you graphics card vendor for updates. 3. Consult the MSDN for any possible KB articles. Sign In·View Thread·PermaLink 1.00/5 Good job, but... FranFLY 0:45 26 Nov '02   Good job, but you can do the same thing using control Desk.cpl,,3 Francesc Sign In·View Thread·PermaLink 1.00/5 Re: Good job, but... pjnaughter 23:53 26 Nov '02   Maybe so, but I thought Code Project was about sharing code on how to do things in Windows. Pointing out that Windows has a built in way of achieving the same is not much good to the programmer who wants to find out the API calls which MS use and provide. Sign In·View Thread·PermaLink Re: Good job, but... Yovav 6:14 7 Apr '03   Hi, How it is possible to execute this ? executing "control Desk.cpl,,3" just brings me the screen resolution change screen, + does it allow U to know what are the available modes ? Thanks in advanced. Best Regards - Yovav Gad EMail: Dev@SuperMain.com Web-Site: www.SuperMain.com Sign In·View Thread·PermaLink Re: Good job, but... pjnaughter 7:27 7 Apr '03   Using this command line is just a shortcut to bringing up control panel applets. It will do nothing more than that. If you want to get the list of modes, then just use the Windows API just like the ResList app does i.e. just look at the code in it!. Sign In·View Thread·PermaLink Can you help me? Raducu 14:47 21 Aug '02   How can I modify Gamma, Brightness, Contrast or temperature for my video dispaly from my program ? Thank you! Sign In·View Thread·PermaLink Re: Can you help me? pjnaughter 0:29 22 Aug '02   This is adapter specific and AFAIK there is no documented Win32 API's to allow you to do this. You will need to contact the developers of your monitor to see if they allow this functionality to be programatically change. For example my Mitsubshi DiamondPro monitor provides an App which changes these settings via a USB connection. Sign In·View Thread·PermaLink Kudos! Glenn 5:53 8 Feb '02   Very, very cool. Thanks for sharing this. Sign In·View Thread·PermaLink Excellent, well done... Pete Sampson 22:45 23 Nov '00   Easy to use and works perfect without any problems, for my needs! Sign In·View Thread·PermaLink 3.50/5

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