mcp-windows/src/tools/display.ts

/* Copyright (C) 2026 Moko Consulting <hello@mokoconsulting.tech>
 * SPDX-License-Identifier: GPL-3.0-or-later
 *
 * Tools: windows_display_get (#9), windows_display_set (#10), windows_screenshot (#11)
 */

import { McpServer } from '@modelcontextprotocol/sdk/server/mcp.js';
import { z } from 'zod';
import { runPowerShell } from '../shell.js';
import { readFile } from 'node:fs/promises';
import { resolve } from 'node:path';
import { tmpdir } from 'node:os';

export function registerDisplayTools(server: McpServer): void {
	server.tool(
		'windows_display_get',
		'Get display configuration: resolution, refresh rate, scaling, multi-monitor layout, HDR status.',
		{},
		async () => {
			const ps = `
Add-Type -AssemblyName System.Windows.Forms

$screens = [System.Windows.Forms.Screen]::AllScreens
$monitors = Get-CimInstance -Namespace root\\wmi -ClassName WmiMonitorBasicDisplayParams -ErrorAction SilentlyContinue
$videoCtrl = Get-CimInstance Win32_VideoController

$i = 0
$screens | ForEach-Object {
  $s = $_
  $vc = $videoCtrl | Where-Object { $_.Name -match $s.DeviceName -or $true } | Select-Object -First 1
  $dpiScale = [math]::Round(($s.Bounds.Width / $s.WorkingArea.Width) * 100, 0)

  # Try to get real scaling from registry
  $regScale = $null
  try {
    $regPath = "HKCU:\\Control Panel\\Desktop\\PerMonitorSettings"
    if (Test-Path $regPath) {
      $regScale = (Get-ChildItem $regPath -ErrorAction SilentlyContinue | Select-Object -Index $i | Get-ItemProperty -ErrorAction SilentlyContinue).DpiValue
    }
  } catch {}

  [PSCustomObject]@{
    Index = $i
    Name = $s.DeviceName
    Primary = $s.Primary
    Resolution = "$($s.Bounds.Width)x$($s.Bounds.Height)"
    RefreshRate = if ($vc) { "$($vc.CurrentRefreshRate) Hz" } else { 'Unknown' }
    Scaling = if ($regScale) { "$($regScale)%" } else { 'System default' }
    Position = "($($s.Bounds.X), $($s.Bounds.Y))"
    WorkArea = "$($s.WorkingArea.Width)x$($s.WorkingArea.Height)"
    BitsPerPixel = if ($vc) { $vc.CurrentBitsPerPixel } else { $null }
  }
  $i++
} | ConvertTo-Json -Depth 3 -Compress`;

			const result = await runPowerShell(ps, { timeout: 10000 });
			if (result.exitCode !== 0) {
				return { content: [{ type: 'text', text: `Error: ${result.stderr}` }], isError: true };
			}

			const displays = Array.isArray(JSON.parse(result.stdout)) ? JSON.parse(result.stdout) : [JSON.parse(result.stdout)];
			const lines = displays.map((d: { Index: number; Name: string; Primary: boolean; Resolution: string; RefreshRate: string; Scaling: string; Position: string; WorkArea: string }) =>
				[
					`Monitor ${d.Index}: ${d.Name}${d.Primary ? ' (Primary)' : ''}`,
					`  Resolution: ${d.Resolution} @ ${d.RefreshRate}`,
					`  Scaling: ${d.Scaling}`,
					`  Position: ${d.Position}`,
					`  Work area: ${d.WorkArea}`,
				].join('\n'),
			);

			return { content: [{ type: 'text', text: lines.join('\n\n') }] };
		},
	);

	server.tool(
		'windows_display_set',
		'Change display settings: resolution, brightness.',
		{
			resolution: z.string().optional().describe('Resolution as "WIDTHxHEIGHT" (e.g. "1920x1080")'),
			brightness: z.number().min(0).max(100).optional().describe('Screen brightness 0-100 (laptops only)'),
		},
		async ({ resolution, brightness }) => {
			const results: string[] = [];

			if (brightness !== undefined) {
				const ps = `
try {
  $monitors = Get-CimInstance -Namespace root/WMI -ClassName WmiMonitorBrightnessMethods -ErrorAction Stop
  $monitors | Invoke-CimMethod -MethodName WmiSetBrightness -Arguments @{Timeout=1; Brightness=${brightness}} -ErrorAction Stop
  "Brightness set to ${brightness}%"
} catch {
  "Error: Brightness control not available (requires laptop/integrated display). $_"
}`;
				const r = await runPowerShell(ps);
				results.push(r.stdout || r.stderr);
			}

			if (resolution) {
				const match = resolution.match(/^(\d+)x(\d+)$/);
				if (!match) {
					results.push('Invalid resolution format. Use WIDTHxHEIGHT (e.g. 1920x1080)');
				} else {
					const ps = `
Add-Type @'
using System;
using System.Runtime.InteropServices;

public class DisplaySettings {
    [DllImport("user32.dll")]
    public static extern int EnumDisplaySettings(string deviceName, int modeNum, ref DEVMODE devMode);
    [DllImport("user32.dll")]
    public static extern int ChangeDisplaySettings(ref DEVMODE devMode, int flags);

    [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi)]
    public struct DEVMODE {
        [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 32)]
        public string dmDeviceName;
        public short dmSpecVersion;
        public short dmDriverVersion;
        public short dmSize;
        public short dmDriverExtra;
        public int dmFields;
        public int dmPositionX;
        public int dmPositionY;
        public int dmDisplayOrientation;
        public int dmDisplayFixedOutput;
        public short dmColor;
        public short dmDuplex;
        public short dmYResolution;
        public short dmTTOption;
        public short dmCollate;
        [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 32)]
        public string dmFormName;
        public short dmLogPixels;
        public int dmBitsPerPel;
        public int dmPelsWidth;
        public int dmPelsHeight;
        public int dmDisplayFlags;
        public int dmDisplayFrequency;
    }

    public static string SetResolution(int width, int height) {
        DEVMODE dm = new DEVMODE();
        dm.dmSize = (short)Marshal.SizeOf(typeof(DEVMODE));
        if (EnumDisplaySettings(null, -1, ref dm) != 0) {
            dm.dmPelsWidth = width;
            dm.dmPelsHeight = height;
            dm.dmFields = 0x80000 | 0x100000; // DM_PELSWIDTH | DM_PELSHEIGHT
            int result = ChangeDisplaySettings(ref dm, 0);
            if (result == 0) return "Resolution changed to " + width + "x" + height;
            return "Failed to change resolution (code: " + result + "). Resolution may not be supported.";
        }
        return "Failed to enumerate display settings.";
    }
}
'@ -ErrorAction Stop
[DisplaySettings]::SetResolution(${match[1]}, ${match[2]})`;
					const r = await runPowerShell(ps);
					results.push(r.stdout || r.stderr);
				}
			}

			if (results.length === 0) {
				return { content: [{ type: 'text', text: 'No changes specified. Provide resolution or brightness.' }], isError: true };
			}

			return { content: [{ type: 'text', text: results.join('\n') }] };
		},
	);

	server.tool(
		'windows_screenshot',
		'Capture a screenshot of the screen, a specific window, or a region. Returns as base64 image.',
		{
			target: z.enum(['screen', 'window', 'region']).default('screen').describe('What to capture'),
			monitor: z.number().default(0).describe('Monitor index (for screen capture)'),
			window_title: z.string().optional().describe('Window title substring (for window capture)'),
			x: z.number().optional().describe('Region X (for region capture)'),
			y: z.number().optional().describe('Region Y'),
			width: z.number().optional().describe('Region width'),
			height: z.number().optional().describe('Region height'),
			save_path: z.string().optional().describe('Save to file instead of returning base64'),
		},
		async ({ target, monitor, window_title, x, y, width, height, save_path }) => {
			const outPath = save_path ? resolve(save_path) : resolve(tmpdir(), `screenshot_${Date.now()}.png`);

			let ps: string;

			if (target === 'window' && window_title) {
				ps = `
Add-Type -AssemblyName System.Windows.Forms
Add-Type -AssemblyName System.Drawing
Add-Type @'
using System;
using System.Runtime.InteropServices;
public class Win32Window {
    [DllImport("user32.dll")] public static extern IntPtr FindWindow(string lpClassName, string lpWindowName);
    [DllImport("user32.dll")] public static extern bool GetWindowRect(IntPtr hWnd, out RECT lpRect);
    [DllImport("user32.dll")] public static extern IntPtr GetForegroundWindow();
    [DllImport("user32.dll")] public static extern bool SetForegroundWindow(IntPtr hWnd);
    [DllImport("user32.dll", CharSet = CharSet.Auto)] public static extern int GetWindowText(IntPtr hWnd, System.Text.StringBuilder text, int count);
    [DllImport("user32.dll")] public static extern bool EnumWindows(EnumWindowsProc lpEnumFunc, IntPtr lParam);
    public delegate bool EnumWindowsProc(IntPtr hWnd, IntPtr lParam);
    [StructLayout(LayoutKind.Sequential)]
    public struct RECT { public int Left, Top, Right, Bottom; }
}
'@
$target = '${window_title.replace(/'/g, "''")}'
$found = $null
[Win32Window]::EnumWindows({
  param($hWnd, $lParam)
  $sb = New-Object System.Text.StringBuilder 256
  [Win32Window]::GetWindowText($hWnd, $sb, 256) | Out-Null
  $title = $sb.ToString()
  if ($title -like "*$target*") { $script:found = $hWnd; return $false }
  return $true
}, [IntPtr]::Zero) | Out-Null

if (-not $found) { throw "Window not found: $target" }

$rect = New-Object Win32Window+RECT
[Win32Window]::GetWindowRect($found, [ref]$rect) | Out-Null
$w = $rect.Right - $rect.Left
$h = $rect.Bottom - $rect.Top
$bmp = New-Object System.Drawing.Bitmap($w, $h)
$g = [System.Drawing.Graphics]::FromImage($bmp)
$g.CopyFromScreen($rect.Left, $rect.Top, 0, 0, [System.Drawing.Size]::new($w, $h))
$g.Dispose()
$bmp.Save('${outPath.replace(/'/g, "''")}', [System.Drawing.Imaging.ImageFormat]::Png)
$bmp.Dispose()
"saved"`;
			} else if (target === 'region' && x !== undefined && y !== undefined && width && height) {
				ps = `
Add-Type -AssemblyName System.Drawing
$bmp = New-Object System.Drawing.Bitmap(${width}, ${height})
$g = [System.Drawing.Graphics]::FromImage($bmp)
$g.CopyFromScreen(${x}, ${y}, 0, 0, [System.Drawing.Size]::new(${width}, ${height}))
$g.Dispose()
$bmp.Save('${outPath.replace(/'/g, "''")}', [System.Drawing.Imaging.ImageFormat]::Png)
$bmp.Dispose()
"saved"`;
			} else {
				// Full screen
				ps = `
Add-Type -AssemblyName System.Windows.Forms
Add-Type -AssemblyName System.Drawing
$screen = [System.Windows.Forms.Screen]::AllScreens[${monitor}]
$bounds = $screen.Bounds
$bmp = New-Object System.Drawing.Bitmap($bounds.Width, $bounds.Height)
$g = [System.Drawing.Graphics]::FromImage($bmp)
$g.CopyFromScreen($bounds.X, $bounds.Y, 0, 0, $bounds.Size)
$g.Dispose()
$bmp.Save('${outPath.replace(/'/g, "''")}', [System.Drawing.Imaging.ImageFormat]::Png)
$bmp.Dispose()
"saved"`;
			}

			const result = await runPowerShell(ps, { timeout: 10000 });
			if (result.exitCode !== 0) {
				return { content: [{ type: 'text', text: `Error: ${result.stderr}` }], isError: true };
			}

			if (save_path) {
				return { content: [{ type: 'text', text: `Screenshot saved: ${outPath}` }] };
			}

			// Return as base64 image
			try {
				const data = await readFile(outPath);
				// Clean up temp file
				await import('node:fs/promises').then(fs => fs.unlink(outPath)).catch(() => {});
				return {
					content: [{
						type: 'image' as const,
						data: data.toString('base64'),
						mimeType: 'image/png',
					}],
				};
			} catch {
				return { content: [{ type: 'text', text: `Screenshot captured at ${outPath} but failed to read back.` }] };
			}
		},
	);
}