KvmWatcher_v4.1.ps1

# =================================================================================
# KvmWatcher_v4.1.ps1 - Native In-Memory DDC/CI (Targeted)
#
# Description: Embeds C# code to access the Windows DXVA2 API directly.
#              Filters commands to ONLY affect the specified monitor name.
#              Reacts instantly to USB events.
# =================================================================================

# --- Configuration ---
$dp_value            = 15
$hdmi_value          = 17
# The name to match (Case-insensitive partial match)
# Based on your previous logs, this is "DELL S2721DGF"
$target_monitor_name = "DELL S2721DGF"

$kvm_device_ids = @(
    'HID\VID_413C&PID_2010&MI_00\9&5D7FD22&0&0000',
    'HID\VID_046D&PID_C539&MI_00\8&279BBDB6&0&0000',
    'HID\VID_046D&PID_C539&MI_01&COL01\8&1BCA673&0&0000'
)

# --- Embedded C# Code for Native Monitor Control ---
$MonitorControlSource = @"
using System;
using System.Runtime.InteropServices;
using System.Collections.Generic;

public class MonitorControl
{
    [DllImport("user32.dll")]
    private static extern bool EnumDisplayMonitors(IntPtr hdc, IntPtr lprcClip, MonitorEnumDelegate lpfnEnum, IntPtr dwData);

    [DllImport("dxva2.dll", SetLastError = true)]
    private static extern bool GetPhysicalMonitorsFromHMONITOR(IntPtr hMonitor, uint dwPhysicalMonitorArraySize, [Out] PHYSICAL_MONITOR[] pPhysicalMonitorArray);

    [DllImport("dxva2.dll", SetLastError = true)]
    private static extern bool GetNumberOfPhysicalMonitorsFromHMONITOR(IntPtr hMonitor, out uint pdwNumberOfPhysicalMonitors);

    [DllImport("dxva2.dll", SetLastError = true)]
    private static extern bool DestroyPhysicalMonitors(uint dwPhysicalMonitorArraySize, [In] PHYSICAL_MONITOR[] pPhysicalMonitorArray);

    [DllImport("dxva2.dll", SetLastError = true)]
    private static extern bool SetVCPFeature(IntPtr hMonitor, byte bVCPCode, uint dwNewValue);

    private delegate bool MonitorEnumDelegate(IntPtr hMonitor, IntPtr hdcMonitor, ref Rect lprcMonitor, IntPtr dwData);

    [StructLayout(LayoutKind.Sequential)]
    public struct Rect {
        public int left;
        public int top;
        public int right;
        public int bottom;
    }

    [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
    public struct PHYSICAL_MONITOR {
        public IntPtr hPhysicalMonitor;
        [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 128)]
        public string szPhysicalMonitorDescription;
    }

    // Updated signature to accept a target name
    public static void SetInputSource(uint inputValue, string targetName)
    {
        EnumDisplayMonitors(IntPtr.Zero, IntPtr.Zero, 
            delegate(IntPtr hMonitor, IntPtr hdcMonitor, ref Rect lprcMonitor, IntPtr dwData)
            {
                uint count;
                if (!GetNumberOfPhysicalMonitorsFromHMONITOR(hMonitor, out count)) return true;

                PHYSICAL_MONITOR[] physicalMonitors = new PHYSICAL_MONITOR[count];
                if (!GetPhysicalMonitorsFromHMONITOR(hMonitor, count, physicalMonitors)) return true;

                foreach (var physMonitor in physicalMonitors)
                {
                    // Only proceed if the monitor description contains our target name
                    if (physMonitor.szPhysicalMonitorDescription.IndexOf(targetName, StringComparison.OrdinalIgnoreCase) >= 0)
                    {
                        // VCP Code 60 is Input Select
                        SetVCPFeature(physMonitor.hPhysicalMonitor, 0x60, inputValue);
                        
                        // Optional: We could return false here to stop enumerating if we only expect one monitor,
                        // but continuing is safer in case you have two of the same monitor.
                    }
                }

                DestroyPhysicalMonitors(count, physicalMonitors);
                return true;
            }, IntPtr.Zero);
    }
}
"@

# Compile the C# code into memory
try {
    Add-Type -TypeDefinition $MonitorControlSource -Language CSharp
} catch {
    # Ignore error if type already exists
}

# --- Functions ---
function Is-KvmOnPc {
    $devices_on_pc = Get-PnpDevice -InstanceId $kvm_device_ids -Status 'OK' -ErrorAction SilentlyContinue
    return [bool]$devices_on_pc
}

function Sync-MonitorState {
    Write-Host "$(Get-Date -Format 'yyyy-MM-dd HH:mm:ss'): KVM Event detected. Syncing..."
    $is_kvm_on_pc = Is-KvmOnPc

    # We now pass the $target_monitor_name to the C# function
    if ($is_kvm_on_pc) {
        Write-Host "  -> KVM found on PC. Forcing DisplayPort ($dp_value) on '$target_monitor_name'..."
        [MonitorControl]::SetInputSource($dp_value, $target_monitor_name)
    }
    else {
        Write-Host "  -> KVM is AWAY. Forcing HDMI ($hdmi_value) on '$target_monitor_name'..."
        [MonitorControl]::SetInputSource($hdmi_value, $target_monitor_name)
    }
}


# --- Main --------------------------------------------------------------------
Write-Host "Starting KVM 'Native Speed' Watcher (Targeted). Press Ctrl+C to exit."

$script:lastKvmState = Is-KvmOnPc
Write-Host "Initial KVM state: $(if($script:lastKvmState){'ON PC'} else {'AWAY'}) (No action taken)"

$query = "SELECT * FROM Win32_DeviceChangeEvent WHERE EventType = 2 OR EventType = 3"

try {
    Register-CimIndicationEvent -Query $query -SourceIdentifier 'KvmUsbChangeWatcher'

    Write-Host "Watcher is active (Native Mode)..."
    while ($true) {
        $event = Wait-Event -SourceIdentifier 'KvmUsbChangeWatcher'
        $current = Is-KvmOnPc
        
        if ($current -ne $script:lastKvmState) {
            $script:lastKvmState = $current
            Sync-MonitorState
        }
        Remove-Event -EventIdentifier $event.EventIdentifier
    }
}
finally {
    Write-Host "Stopping..."
    Unregister-Event -SourceIdentifier 'KvmUsbChangeWatcher' -ErrorAction SilentlyContinue
}