How to set Display Settings to EXTEND mode in Windows 7 using C++?

[sachintha81]

In my C++ Win32 program I want to set the current Display Settings to "Extend" mode. I Googled and found out that SetDisplayConfig() is the way to go forward in Windows 7 (I'm on Windows 7) but now I am kind of stuck how to proceed as the MSDN explanation (link here) is pretty confusing. I am very much new to C++ and API programming so I am finding it difficult to understand this.

I would highly appreciate some code sample and an explanation. Thanks in advance!

[sachintha81]

Okay so I figured out the answer.

To identify the current configuration:

UINT32 PathArraySize = 0;
UINT32 ModeArraySize = 0;
DISPLAYCONFIG_PATH_INFO* PathArray;
DISPLAYCONFIG_MODE_INFO* ModeArray;
DISPLAYCONFIG_TOPOLOGY_ID CurrentTopology;

GetDisplayConfigBufferSizes(QDC_ALL_PATHS, &PathArraySize, &ModeArraySize);
	
PathArray =   (DISPLAYCONFIG_PATH_INFO*)malloc(PathArraySize * sizeof(DISPLAYCONFIG_PATH_INFO));
memset(PathArray, 0, PathArraySize * sizeof(DISPLAYCONFIG_PATH_INFO));

ModeArray =   (DISPLAYCONFIG_MODE_INFO*)malloc(ModeArraySize * sizeof(DISPLAYCONFIG_MODE_INFO));
memset(ModeArray, 0, ModeArraySize * sizeof(DISPLAYCONFIG_MODE_INFO));

LONG ret = QueryDisplayConfig(QDC_DATABASE_CURRENT,&PathArraySize, PathArray, &ModeArraySize, ModeArray, &CurrentTopology);
// Above CurrentTopology variable will aquire the current display setting (ie Extend, Duplicate etc)

free(PathArray);
free(ModeArray);

To set the required display setting (Extend, Duplicate etc):

SetDisplayConfig(0,NULL,0,NULL,SDC_TOPOLOGY_EXTEND|SDC_APPLY);

or

SetDisplayConfig(0,NULL,0,NULL,SDC_TOPOLOGY_CLONE|SDC_APPLY);

[sriv]

hi,
this code is setting some time build-in display as primary and soem time external display as primary. suppose if i want to specify which display want to be primary how can i do that ?