readme.md

Hello

This is a program I've wrote in order to automaticly change Windows orientation, based on the information gathered from my screen ( HP Z24n G2 ), which has a built in accelerometer, and supplies this information via DDC/CI.

ScreenRotation.cpp

#include <Windows.h>
#include <iostream>
#include <lowlevelmonitorconfigurationapi.h>
#include <physicalmonitorenumerationapi.h>

#pragma comment(lib, "Dxva2.lib")

using namespace std;

BOOL CALLBACK MyInfoEnumProc(HMONITOR hMonitor, HDC hdcMonitor, LPRECT lprcMonitor, LPARAM dwData)
{
	*reinterpret_cast<HMONITOR*>(dwData) = hMonitor;
	return true;
}

DWORD CheckScreenOrientation() {
	HMONITOR monitorHandle = NULL; // Monitor handle
	DWORD* numnerofPhysicalMonitors = new DWORD; //Needed to get physical Monitors
	DWORD* currentOrinetation = new DWORD;

	EnumDisplayMonitors(NULL, NULL, MyInfoEnumProc, reinterpret_cast<LPARAM>(&monitorHandle));
	GetNumberOfPhysicalMonitorsFromHMONITOR(monitorHandle, numnerofPhysicalMonitors);

	_PHYSICAL_MONITOR* physical_monitors = new _PHYSICAL_MONITOR[numnerofPhysicalMonitors[0]]; // Allocate array for physical monitors

	if (monitorHandle != 0) {
		GetPhysicalMonitorsFromHMONITOR(monitorHandle, *numnerofPhysicalMonitors, physical_monitors);
	}

	GetVCPFeatureAndVCPFeatureReply(physical_monitors->hPhysicalMonitor, 0xAA, NULL, currentOrinetation, NULL);

	/*
	Returned values ar as fallows:
	00 -> Shall be ignored
	01 -> Normal
	02 ->  90deg clockwise
	03 -> 180deg
	04 -> 270deg clockwise
	05 - FE -> Shall be ignored
	FF -> Device doesn't support screen orientation
	*/

	if (currentOrinetation[0] > 4 || currentOrinetation[0] < 1) {
		return 0xFF;
	}


	cout << "Current Orientation is: " << currentOrinetation[0] << endl;
	return currentOrinetation[0];
}

void rotateDesktop(int arg) {
	arg -= 1; // Adjustment for the DEVMODE structure

	DEVMODE dm;
	memset(&dm, 0, sizeof(dm));
	dm.dmSize = sizeof(dm);

	if (0 != EnumDisplaySettings(NULL, ENUM_CURRENT_SETTINGS, &dm))
	{
		DEVMODE savemode = dm;
		dm.dmDisplayOrientation = arg; // Change the value in the DEVMODE structure

		// Swap height and width if they don't match the desired orientation, otherwise ChangeDisplaySetting will return DISP_CHANGE_BADPARAM
		if ((arg == 0x01 || arg == 0x03) && dm.dmPelsHeight < dm.dmPelsWidth ||
			(arg == 0x00 || arg == 0x02) && dm.dmPelsHeight > dm.dmPelsWidth) {
			dm.dmPelsHeight ^= dm.dmPelsWidth;
			dm.dmPelsWidth ^= dm.dmPelsHeight;
			dm.dmPelsHeight ^= dm.dmPelsWidth;
		}
		LONG result = ChangeDisplaySettings(&dm, 0); // Apply the new DEVMODE to the device

		if (result == DISP_CHANGE_SUCCESSFUL)
		{
			cout << "Screen orientation changed!" << endl;

			//Add a dialog to ask the user to confirm.
			//The dialog should close automatically if user is unable to confirm
			//if (confirm()) return;
			//Sleep(5000);
			// if not, disable this feature
			//ChangeDisplaySettings(&savemode, 0);
		}
		else
		{
			cout << "Error" << endl;
		}
	}
}

int main()
{
	DWORD LastOrientation = CheckScreenOrientation();

	if (LastOrientation == 0xFF) {
		cout << "This screen doesn't support automatic rotation. Sorry..";
		return -1;
	}

	while (true)
	{
		if (CheckScreenOrientation() != LastOrientation) { // If orientation has changed
			LastOrientation = CheckScreenOrientation(); // Save new as last
			rotateDesktop(LastOrientation); // Rotate the desktop to the new orientation
		}
		Sleep(5000); // Interval of checking
	}

	return 0;
}