GridForm.cs

// Copyright (c) 2012-2026 The Hello World Writer (https://www.thehelloworldwriter.com).
// Licensed under the MIT License. See the LICENSE file in the project root for more information.

namespace GridlyDots;

using System.Diagnostics;

/// <summary>The main grid form. Displays a transparent dot grid overlay across the screen.</summary>
public class GridForm : Form
{
    /// <summary>Win32 message sent when the app gains or loses focus.</summary>
    private const int WM_ACTIVATEAPP = 0x001C;

    /// <summary>Win32 extended style for layered (transparent) windows.</summary>
    private const int WS_EX_LAYERED = 0x00080000;

    /// <summary>Win32 extended style for click-through windows.</summary>
    private const int WS_EX_TRANSPARENT = 0x00000020;

    private readonly GridPainter gridPainter = new();
    private readonly NotifyIcon notifyIcon = new();
    private readonly ContextMenuStrip contextMenuStrip = new();
    private readonly System.Windows.Forms.Timer topmostTimer = new();
    private readonly ToolStripMenuItem settingsMenuItem = new(Strings.SettingsMenuItem);

    public GridForm()
    {
        SuspendLayout();

        // Dimensions BEFORE mode (setting the mode clears dimensions)
        AutoScaleDimensions = new SizeF(96F, 96F);
        AutoScaleMode = AutoScaleMode.Dpi;

        Icon = Icon.ExtractAssociatedIcon(Application.ExecutablePath!);
        FormBorderStyle = FormBorderStyle.None;
        TopMost = true;
        ShowInTaskbar = false;
        BackColor = Color.Black;
        TransparencyKey = Color.Black;
        DoubleBuffered = true;

        CreateControls();

        Load += OnFormLoad;
        Paint += OnFormPaint;
        FormClosed += OnFormClosed;

        ResumeLayout(false);
        PerformLayout();
    }

    /// <summary>Builds the timer, context menu, and notification icon.</summary>
    private void CreateControls()
    {
        // Topmost timer — brings form back to front after another app activates
        topmostTimer.Interval = 500;
        topmostTimer.Tick += OnTopmostTimerTick;

        // Context menu — Settings (bold)
        settingsMenuItem.Font = new Font(settingsMenuItem.Font, settingsMenuItem.Font.Style | FontStyle.Bold);
        settingsMenuItem.Click += OnSettingsMenuItemClick;

        // Context menu — Stealth Mode
        var stealthModeMenuItem = new ToolStripMenuItem(Strings.StealthModeMenuItem)
        {
            ToolTipText = Strings.StealthModeTooltip,
        };
        stealthModeMenuItem.Click += OnStealthModeMenuItemClick;

        // Context menu — About...
        var aboutMenuItem = new ToolStripMenuItem(Strings.AboutMenuItem);
        aboutMenuItem.Click += OnAboutMenuItemClick;

        // Context menu — Quit
        var quitMenuItem = new ToolStripMenuItem(Strings.QuitMenuItem);
        quitMenuItem.Click += (s, e) => Close();

        // Assemble context menu
        // TODO: Check if this is still needed e.g. on 4K 200% displays
        // contextMenuStrip.Font = SystemFonts.MessageBoxFont;
        contextMenuStrip.RenderMode = ToolStripRenderMode.System;
        contextMenuStrip.Items.AddRange([
            settingsMenuItem,
            stealthModeMenuItem,
            new ToolStripSeparator(),
            aboutMenuItem,
            new ToolStripSeparator(),
            quitMenuItem,
        ]);

        // System tray icon
        notifyIcon.Icon = Icon;
        notifyIcon.ContextMenuStrip = contextMenuStrip;
        notifyIcon.Text = Strings.AppName;
        notifyIcon.Visible = true;
        notifyIcon.MouseClick += OnNotifyIconMouseClick;
    }

    /// <summary>Gets the grid painter instance.</summary>
    public GridPainter GPainter => gridPainter;

    /// <summary>Adds layered and transparent extended window styles for click-through transparency.</summary>
    protected override CreateParams CreateParams
    {
        get
        {
            CreateParams cp = base.CreateParams;
            cp.ExStyle |= WS_EX_LAYERED | WS_EX_TRANSPARENT;
            return cp;
        }
    }

    /// <summary>Intercepts the WM_ACTIVATEAPP message to restore always-on-top state.</summary>
    protected override void WndProc(ref Message m)
    {
        if (m.Msg == WM_ACTIVATEAPP && Visible)
        {
            topmostTimer.Start();
        }

        base.WndProc(ref m);
    }

    /// <summary>Sets the form bounds to cover all screens and loads settings.</summary>
    private void OnFormLoad(object? sender, EventArgs e)
    {
        Bounds = SystemInformation.VirtualScreen;
        LoadSettings();
    }

    /// <summary>Paints the dot grid on the form surface.</summary>
    private void OnFormPaint(object? sender, PaintEventArgs e)
    {
        gridPainter.Draw(e.Graphics, ClientRectangle);
    }

    /// <summary>Saves settings when the form is closed.</summary>
    private void OnFormClosed(object? sender, FormClosedEventArgs e)
    {
        SaveSettings();
    }

    /// <summary>Brings the form to front after the timer delay, restoring always-on-top state.</summary>
    private void OnTopmostTimerTick(object? sender, EventArgs e)
    {
        topmostTimer.Stop();

        if (Visible && !contextMenuStrip.Visible)
        {
            BringToFront();
        }
    }

    /// <summary>Confirms and hides the notification icon, entering stealth mode.</summary>
    private void OnStealthModeMenuItemClick(object? sender, EventArgs e)
    {
        var result = MessageBox.Show(this,
            Strings.StealthModeConfirmMessage,
            Strings.StealthModeConfirmCaption,
            MessageBoxButtons.YesNo,
            MessageBoxIcon.Warning,
            MessageBoxDefaultButton.Button2);

        if (result == DialogResult.Yes)
        {
            notifyIcon.Visible = false;
        }
    }

    /// <summary>Opens the settings dialog.</summary>
    private void OnSettingsMenuItemClick(object? sender, EventArgs e)
    {
        BringToFront();
        using var settingsForm = new SettingsForm();
        settingsForm.ShowDialog(this);
    }

    /// <summary>Opens the about dialog.</summary>
    private void OnAboutMenuItemClick(object? sender, EventArgs e)
    {
        BringToFront();
        using var aboutForm = new AboutForm();
        aboutForm.ShowDialog(this);
    }

    /// <summary>Opens settings on left-click of the tray icon.</summary>
    private void OnNotifyIconMouseClick(object? sender, MouseEventArgs e)
    {
        if (e.Button == MouseButtons.Left)
        {
            settingsMenuItem.PerformClick();
        }
    }

    /// <summary>Loads grid settings from the JSON settings file.</summary>
    private void LoadSettings()
    {
        try
        {
            var settingsFile = ProgramSettings.CreateSettingsFile();
            var settings = settingsFile.Load();

            gridPainter.DotSize = settings.DotSize > 0 ? settings.DotSize : 2;
            gridPainter.DotSpacing = settings.DotSpacing > 0 ? settings.DotSpacing : 24;
            gridPainter.DotColor = !string.IsNullOrEmpty(settings.DotColorCode)
                ? ColorTranslator.FromHtml(settings.DotColorCode)
                : Color.Gray;
            Opacity = settings.Opacity > 0 ? settings.Opacity : 0.30;
        }
        catch (Exception ex)
        {
            Debug.WriteLine(Strings.FailedToLoadSettings(ex));
        }
    }

    /// <summary>Saves current grid settings to the JSON settings file.</summary>
    private void SaveSettings()
    {
        try
        {
            var settingsFile = ProgramSettings.CreateSettingsFile();
            var settings = new ProgramSettings
            {
                DotSize = gridPainter.DotSize,
                DotSpacing = gridPainter.DotSpacing,
                DotColorCode = ColorTranslator.ToHtml(gridPainter.DotColor),
                Opacity = Opacity,
            };
            // force: true creates the file if it doesn't exist yet. This is essential for
            // installed mode (first run, no settings file) and harmless for portable mode
            // (settings file already exists next to the executable).
            settingsFile.Save(settings, force: true);
        }
        catch (Exception ex)
        {
            Debug.WriteLine(Strings.FailedToSaveSettings(ex));
        }
    }

    /// <summary>Disposes components not in the Controls hierarchy.</summary>
    protected override void Dispose(bool disposing)
    {
        if (disposing)
        {
            topmostTimer.Dispose();
            notifyIcon.Dispose();
            contextMenuStrip.Dispose();
        }

        base.Dispose(disposing);
    }
}