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Fade All Monitors Except the Primary Monitor to Black

Fades all monitors except the primary monitor to black over a two second period.
Minimum Version
Created By
Date Created
Jun 24, 2015
Date Last Modified
Nov 5, 2019

Scripted Function (Macro) Code

using System;
using System.Drawing;
using System.Windows.Forms;
using System.Threading;
using System.Collections.Generic;

// Fade all monitors except the primary monitor to black over a two second period
// Adjust 

// Based entirely on Thomas Malloch's very brilliant Dim All Monitors Except Primary
// Hope he will forgive the change to K&R style and general clean-up to be more abbreviated

// The 'windowHandle' parameter will contain the window handle for the:
//   - Active window when run by hotkey
//   - Window Location target when run by a Window Location rule
//   - TitleBar Button owner when run by a TitleBar Button
//   - Jump List owner when run from a Taskbar Jump List
//   - Currently focused window if none of these match
public static class DisplayFusionFunction {
	private static readonly string SettingName = "BlackenMonitors_Run";
	public static void Run(IntPtr windowHandle) {
		//toggle the setting from running to not running, and vice versa

		if (RunFadeMonitors()) {
            //add all but the primary monitor to the list of monitors that will be dimmed
            var forms = new List<Form>();
            uint primaryMonitorID = BFS.Monitor.GetPrimaryMonitorID();
            foreach(uint id in BFS.Monitor.GetMonitorIDs())
                if(id != primaryMonitorID)
                    forms.Add(new TransparentForm(id));
            //this will open the forms we added to the list by using our custom application context
            Application.Run(new MultipleFormApplicationContext(forms));
	//this function allows us to see the currect state of the script
	private static bool RunFadeMonitors() {
		return BFS.ScriptSettings.ReadValue(SettingName) == "run";

	//this function toggles the script settings from running to not running
	private static void ToggleSetting() {
		BFS.ScriptSettings.WriteValue(SettingName, RunFadeMonitors() ? "not" : "run");

	//extend the ApplicationContext class to support opening multiple forms
	private class MultipleFormApplicationContext : ApplicationContext {
		internal MultipleFormApplicationContext(List<Form> forms) {
			//open each of the forms, and add our closing event to them
			foreach(Form form in forms) {
				form.FormClosed += OnFormClosed;

		//when all the forms close, make sure to exit the application
		private void OnFormClosed(object sender, EventArgs e) {
			if(Application.OpenForms.Count == 0)
	//extend the Form class to get the behavior we want
	private class TransparentForm : Form {
		//this will tell us what monitor to open on
		private uint MonitorId;
		private uint FadeWait;
		private decimal TransparentIncrement;
        private IntPtr HandleTHREADSAFE;
		//this will tell us our current transparency
		private decimal Transparency;
		//the contructor for our class
		internal TransparentForm(uint monitorId) {		
			MonitorId = monitorId;
			Transparency = 0m;
			const decimal FadeTime = 2.0m; // seconds
			TransparentIncrement = 1m; // percent
			FadeWait = (uint)(TransparentIncrement * 10m * FadeTime);
			//setup the layout of this form
			BackColor = Color.Black;
			FormBorderStyle = FormBorderStyle.None;
			ShowInTaskbar = false;
			//move the window to the desired monitor
			Rectangle bounds = BFS.Monitor.GetMonitorBoundsByID(MonitorId);
			Location = new Point(bounds.X, bounds.Y);
			Size = new Size(bounds.Width, bounds.Height);
			StartPosition = FormStartPosition.Manual;
			BFS.Window.SetAlwaysOnTop(Handle, true);
			BFS.Window.SetTransparency(Handle, Transparency);

			//setup the form load event
			Load += Form_Load;			
		private void Form_Load(object sender, EventArgs e) {
            HandleTHREADSAFE = Handle;
			//add a windows style to the current style that will
			//tell this window to ignore user input
			uint style = (uint)BFS.Window.GetWindowStyleEx(Handle) | (uint)BFS.WindowEnum.WindowStyleEx.WS_EX_TRANSPARENT | (uint)BFS.WindowEnum.WindowStyleEx.WS_EX_LAYERED;
			BFS.Window.SetWindowStyleEx((BFS.WindowEnum.WindowStyleEx)style, Handle);
			//start up a thread to listen for an exit event
			new Thread(new ThreadStart(ExitListener)).Start();

		private void ExitListener() {
            try {
                while(true) {
                    //if we should close, tell the main thread to close the form
                    if(RunFadeMonitors()) {
                        // Fade to Black
                        if (Transparency < 100m) {
                            Transparency += TransparentIncrement;
                            BFS.Window.SetTransparency(HandleTHREADSAFE, Transparency);

                        BFS.General.ThreadWait((Transparency < 100m) ? FadeWait : 250u);				
                    else {
                        if (this.Transparency > 0m) {
                            // Fade back in
                            Transparency -= TransparentIncrement;
                            BFS.Window.SetTransparency(HandleTHREADSAFE, Transparency);

                            BFS.General.ThreadWait((Transparency < 100m) ? FadeWait : 250u);
                        else {
                            try {
                                this.Invoke((MethodInvoker) delegate {
                            catch { //something went wrong, ignore
			catch { }