SourceCode/PROMS/Volian.Controls.Library/FlagEnumEditor.cs

using System;
using System.Collections;
using System.ComponentModel;
using System.Drawing;
using System.Data;
using System.Windows.Forms;
using System.Drawing.Design;
using System.Windows.Forms.Design;


namespace Volian.Controls.Library
{

	public class FlagCheckedListBox : CheckedListBox
	{
		private System.ComponentModel.Container components = null;

		public FlagCheckedListBox()
		{
			// This call is required by the Windows.Forms Form Designer.
			InitializeComponent();

			// TODO: Add any initialization after the InitForm call

		}

		protected override void Dispose(bool disposing)
		{
			if (disposing)
			{
				if (components != null)
					components.Dispose();
			}
			base.Dispose(disposing);
		}

		#region Component Designer generated code
		private void InitializeComponent()
		{
			// 
			// FlaggedCheckedListBox
			// 
			this.CheckOnClick = true;

		}
		#endregion

		// Adds an integer value and its associated description
		public FlagCheckedListBoxItem Add(uint v, string c)
		{
			FlagCheckedListBoxItem item = new FlagCheckedListBoxItem(v, c);
			Items.Add(item);
			return item;
		}

		public FlagCheckedListBoxItem Add(FlagCheckedListBoxItem item)
		{
			Items.Add(item);
			return item;
		}

		protected override void OnItemCheck(ItemCheckEventArgs e)
		{
			base.OnItemCheck(e);

			if (isUpdatingCheckStates)
				return;

			// Get the checked/unchecked item
			FlagCheckedListBoxItem item = Items[e.Index] as FlagCheckedListBoxItem;
			// Update other items
			UpdateCheckedItems(item, e.NewValue);
		}

		// Checks/Unchecks items depending on the give bitvalue
		protected void UpdateCheckedItems(uint value)
		{

			isUpdatingCheckStates = true;

			// Iterate over all items
			for (int i = 0; i < Items.Count; i++)
			{
				FlagCheckedListBoxItem item = Items[i] as FlagCheckedListBoxItem;

				if (item.value == 0)
				{
					SetItemChecked(i, value == 0);
				}
				else
				{

					// If the bit for the current item is on in the bitvalue, check it
					if ((item.value & value) == item.value && item.value != 0)
						SetItemChecked(i, true);
					// Otherwise uncheck it
					else
						SetItemChecked(i, false);
				}
			}

			isUpdatingCheckStates = false;

		}

		// Updates items in the checklistbox
		// composite = The item that was checked/unchecked
		// cs = The check state of that item
		protected void UpdateCheckedItems(FlagCheckedListBoxItem composite, CheckState cs)
		{

			// If the value of the item is 0, call directly.
			if (composite.value == 0)
				UpdateCheckedItems(0);


			// Get the total value of all checked items
			uint sum = 0;
			for (int i = 0; i < Items.Count; i++)
			{
				FlagCheckedListBoxItem item = Items[i] as FlagCheckedListBoxItem;

				// If item is checked, add its value to the sum.
				if (GetItemChecked(i))
					sum |= item.value;
			}

			// If the item has been unchecked, remove its bits from the sum
			if (cs == CheckState.Unchecked)
				sum = sum & (~composite.value);
			// If the item has been checked, combine its bits with the sum
			else
				sum |= composite.value;

			// Update all items in the checklistbox based on the final bit value
			UpdateCheckedItems(sum);

		}

		private bool isUpdatingCheckStates = false;

		// Gets the current bit value corresponding to all checked items
		public uint GetCurrentValue()
		{
			uint sum = 0;

			for (int i = 0; i < Items.Count; i++)
			{
				FlagCheckedListBoxItem item = Items[i] as FlagCheckedListBoxItem;

				if (GetItemChecked(i))
					sum |= item.value;
			}

			return sum;
		}

		Type enumType;
		Enum enumValue;

		// Adds items to the checklistbox based on the members of the enum
		private void FillEnumMembers()
		{
			foreach (string name in Enum.GetNames(enumType))
			{
				object val = Enum.Parse(enumType, name);
				uint intVal = (uint)Convert.ChangeType(val, typeof(uint));

				Add(intVal, name);
			}
		}

		// Checks/unchecks items based on the current value of the enum variable
		private void ApplyEnumValue()
		{
			uint intVal = (uint)Convert.ChangeType(enumValue, typeof(uint));
			UpdateCheckedItems(intVal);

		}

		[DesignerSerializationVisibilityAttribute(DesignerSerializationVisibility.Hidden)]
		public Enum EnumValue
		{
			get
			{
				object e = Enum.ToObject(enumType, GetCurrentValue());
				return (Enum)e;
			}
			set
			{

				Items.Clear();
				enumValue = value; // Store the current enum value
				enumType = value.GetType(); // Store enum type
				FillEnumMembers(); // Add items for enum members
				ApplyEnumValue(); // Check/uncheck items depending on enum value

			}
		}


	}

	// Represents an item in the checklistbox
	public class FlagCheckedListBoxItem
	{
		public FlagCheckedListBoxItem(uint v, string c)
		{
			value = v;
			caption = c;
		}

		public override string ToString()
		{
			return caption;
		}

		// Returns true if the value corresponds to a single bit being set
		public bool IsFlag
		{
			get
			{
				return ((value & (value - 1)) == 0);
			}
		}

		// Returns true if this value is a member of the composite bit value
		public bool IsMemberFlag(FlagCheckedListBoxItem composite)
		{
			return (IsFlag && ((value & composite.value) == value));
		}

		public uint value;
		public string caption;
	}


	// UITypeEditor for flag enums
	public class FlagEnumUIEditor : UITypeEditor
	{
		// The checklistbox
		private FlagCheckedListBox flagEnumCB;

		public FlagEnumUIEditor()
		{
			flagEnumCB = new FlagCheckedListBox();
			flagEnumCB.BorderStyle = BorderStyle.None;
		}

		public override object EditValue(ITypeDescriptorContext context, IServiceProvider provider, object value)
		{
			if (context != null
				&& context.Instance != null
				&& provider != null)
			{

				IWindowsFormsEditorService edSvc = (IWindowsFormsEditorService)provider.GetService(typeof(IWindowsFormsEditorService));

				if (edSvc != null)
				{

					Enum e = (Enum)Convert.ChangeType(value, context.PropertyDescriptor.PropertyType);
					flagEnumCB.EnumValue = e;
					edSvc.DropDownControl(flagEnumCB);
					return flagEnumCB.EnumValue;

				}
			}
			return null;
		}

		public override UITypeEditorEditStyle GetEditStyle(ITypeDescriptorContext context)
		{
			return UITypeEditorEditStyle.DropDown;
		}


	}

}