PersistWindowState.cs :  » Build-Systems » CruiseControl.NET » ThoughtWorks » CruiseControl » CCTrayLib » Presentation » C# / CSharp Open Source

using System;
using System.ComponentModel;
using System.Drawing;
using System.Windows.Forms;
using Microsoft.Win32;

namespace ThoughtWorks.CruiseControl.CCTrayLib.Presentation{
  /// <summary>
  /// Class originally by Joel Matthias, and published into the public domain on
  /// CodeProject.com at:
  /// http://www.codeproject.com/csharp/restoreformstate.asp
  /// 
  /// Adapted for use with ccnet-tray by Grant Drake.
  /// 
  /// Todo: Remove empty constructor, remove Parent.setter.
  /// This class should be used as a class (in a form's constructor), and not
  /// as a drop-on form component.
  /// </summary>
  public class PersistWindowState
  {
    public event EventHandler<WindowStateEventArgs> LoadState;
    public event EventHandler<WindowStateEventArgs> SaveState;

    private Form parent;
    private string regPath;
    private int normalLeft;
    private int normalTop;
    private int normalWidth;
    private int normalHeight;
    private bool visible;

    public PersistWindowState() {}

    public PersistWindowState(Form parent)
    {
      SetParentForm(parent);
    }

    public Form Parent
    {
      set
      {
        if (value != parent)
          SetParentForm(value);
      }
      get { return parent; }
    }

    private void SetParentForm(Form value) 
    {
      parent = value;

      // subscribe to parent form's events
      parent.Load += OnLoad;
      parent.Closing += OnClosing;
      parent.Move += OnMove;
      parent.Resize += OnResize;
      parent.VisibleChanged += OnVisibleChanged;

      // get initial width and height in case form is never resized
      normalWidth = parent.Width;
      normalHeight = parent.Height;
    }

    // registry key should be set in parent form's constructor
    public string RegistryPath
    {
      set { regPath = value; }
      get { return regPath; }
    }

    private void OnLoad(object sender, EventArgs e)
    {
      // attempt to read state from registry
      RegistryKey key = Registry.CurrentUser.OpenSubKey(regPath);
      if (key == null) 
        return;

      int left = (int) key.GetValue("Left", parent.Left);
      int top = (int) key.GetValue("Top", parent.Top);
      int width = (int) key.GetValue("Width", parent.Width);
      int height = (int) key.GetValue("Height", parent.Height);

      Point requestedLocation = new Point(left, top);
 
      foreach (Screen aScreen in Screen.AllScreens)
      {                   
        // only change the default location if the saved location
        // maps to an existing screen
        if (aScreen.Bounds.Contains(requestedLocation) )
        {
          // If we're placing the form on the primary screen, adjust for
          // placements that would be under a Task Bar docked to the top of the screen
          Point adjusted = requestedLocation;
          if (aScreen.Primary && adjusted.Y < SystemInformation.WorkingArea.Top)
            adjusted = new Point(requestedLocation.X, SystemInformation.WorkingArea.Top);

          parent.Location = adjusted;
          break;
        }
      }
        
      parent.Size = new Size(width, height);

      visible = 1 == (int) key.GetValue("Visible", 1);
      if (!visible)
      {
        parent.BeginInvoke(new MethodInvoker(HideParent));
      }
        
      // fire LoadState event
      if (LoadState != null)
        LoadState(this, new WindowStateEventArgs(key));
    }
    
    private void HideParent()
    {
      parent.Hide();
    }

    private void OnClosing(object sender, CancelEventArgs e)
    {
      // save position, size and state
      RegistryKey key = Registry.CurrentUser.CreateSubKey(regPath);
      if (key == null)
        return;

      key.SetValue("Left", normalLeft);
      key.SetValue("Top", normalTop);
      key.SetValue("Width", normalWidth);
      key.SetValue("Height", normalHeight);
      key.SetValue("Visible", visible ? 1 : 0);

      // fire SaveState event
      if (SaveState != null)
        SaveState(this, new WindowStateEventArgs(key));
    }

    private void OnMove(object sender, EventArgs e)
    {
      // save position
      if (parent.WindowState == FormWindowState.Normal)
      {
        normalLeft = parent.Left;
        normalTop = parent.Top;
      }
    }

    private void OnResize(object sender, EventArgs e)
    {
      // save width and height
      if (parent.WindowState == FormWindowState.Normal)
      {
        normalWidth = parent.Width;
        normalHeight = parent.Height;
      }
    }

    private void OnVisibleChanged(object sender, EventArgs e)
    {
      visible = parent.Visible;
    }
  }
}