#region License
// Copyright (c) 2013, ClearCanvas Inc.
// All rights reserved.
// http://www.clearcanvas.ca
//
// This file is part of the ClearCanvas RIS/PACS open source project.
//
// The ClearCanvas RIS/PACS open source project is free software: you can
// redistribute it and/or modify it under the terms of the GNU General Public
// License as published by the Free Software Foundation, either version 3 of the
// License, or (at your option) any later version.
//
// The ClearCanvas RIS/PACS open source project is distributed in the hope that it
// will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
// Public License for more details.
//
// You should have received a copy of the GNU General Public License along with
// the ClearCanvas RIS/PACS open source project. If not, see
// <http://www.gnu.org/licenses/>.
#endregion
using System;
using System.Collections;
using System.Windows.Forms;
using System.ComponentModel;
using ClearCanvas.Common.Utilities;
namespace ClearCanvas.Desktop.View.WinForms
{
/// <summary>
/// Special combo-box that works with a <see cref="ISuggestionProvider"/> to populate the drop-down list
/// with suggested items as the user types.
/// </summary>
public class SuggestComboBox : ComboBox
{
private ISuggestionProvider _suggestionProvider;
private event EventHandler _valueChanged;
#region Public properties
/// <summary>
/// Gets or sets the <see cref="ISuggestionProvider"/>.
/// </summary>
[Browsable(false)]
public ISuggestionProvider SuggestionProvider
{
get { return _suggestionProvider; }
set
{
if (_suggestionProvider != null)
_suggestionProvider.SuggestionsProvided -= ItemsProvidedEventHandler;
_suggestionProvider = value;
if (_suggestionProvider != null)
{
_suggestionProvider.SuggestionsProvided += ItemsProvidedEventHandler;
// Bug #2222: only call SetQuery if this is a "simple" dropdown, in which case
// we need to populate the list immediately
// calling it for other styles causes behaviour described in #2222,
// and there is really no need to get suggestions until user actually types
if (this.DropDownStyle == ComboBoxStyle.Simple)
_suggestionProvider.SetQuery(this.Text);
}
}
}
/// <summary>
/// Gets or sets the current value of the control.
/// </summary>
[Browsable(false)]
public object Value
{
get { return this.SelectedItem; }
set
{
if(!Equals(this.SelectedItem, value))
{
// in order to set the value, the Items collection must contain the value
// but if the value is null, can just use an empty list
// (also need to check for DBNull, for some stupid reason)
var items = new ArrayList();
if(value != null && value != DBNull.Value)
{
items.Add(value);
}
else
{
// if value is null or DBNull, clear the text
this.Text = null;
}
UpdateListItems(items);
this.SelectedItem = value;
OnValueChanged(EventArgs.Empty);
}
}
}
/// <summary>
/// Occurs when the <see cref="Value"/> property changes.
/// </summary>
[Browsable(false)]
public event EventHandler ValueChanged
{
add { _valueChanged += value; }
remove { _valueChanged -= value; }
}
#endregion
#region Overrides and Helpers
protected virtual void OnValueChanged(EventArgs args)
{
EventsHelper.Fire(_valueChanged, this, EventArgs.Empty);
}
protected override void OnCreateControl()
{
this.SelectedItem = null;
base.OnCreateControl();
}
protected override void OnSelectionChangeCommitted(EventArgs e)
{
// there are 2 ways that the value can change
// either the selection change is comitted, or the control loses focus
OnValueChanged(EventArgs.Empty);
base.OnSelectionChangeCommitted(e);
}
protected override void OnLeave(EventArgs e)
{
UpdateSelectionFromText();
base.OnLeave(e);
}
// Defect #5876: SuggestComboxBox mishandles 'Esc' once input is resolved
// Override this method to clear the text when the ESC key is pressed.
// Otherwise the component hosting the combobox will eat the ESC key,
// and close the component if the CancelButton is defined.
protected override bool ProcessCmdKey(ref Message msg, Keys k)
{
if (k == Keys.Escape)
{
this.Text = null;
UpdateSelectionFromText();
this.DroppedDown = false;
return true;
}
return base.ProcessCmdKey(ref msg, k);
}
protected override void OnKeyDown(KeyEventArgs e)
{
switch (e.KeyCode)
{
case Keys.Escape:
this.Text = null;
OnSelectionChangeCommitted(e);
break;
default:
break;
}
base.OnKeyDown(e);
}
protected override void OnTextUpdate(EventArgs e)
{
base.OnTextUpdate(e);
CursorReset();
_suggestionProvider.SetQuery(this.Text);
}
protected override void Dispose(bool disposing)
{
if (disposing)
{
// setting this to null will also unsubscribe from the last subscribed-to provider
this.SuggestionProvider = null;
}
base.Dispose(disposing);
}
private void ItemsProvidedEventHandler(object sender, SuggestionsProvidedEventArgs e)
{
// Remember the current text and selection start,
// as they exists prior to modifying the items collection
var curText = this.Text;
var cursorPosition = this.SelectionStart;
if (e.Items.Count == 0)
{
try
{
this.DroppedDown = false;
// there are no suggestions, so clear the items list
this.Items.Clear();
// reset text back to original text
// and return the cursor to the original position
this.Text = curText;
this.SelectionStart = cursorPosition;
}
catch (ArgumentOutOfRangeException)
{
// just in case...it throws the exception while clearing the list
}
}
else
{
// at least 1 suggestion exists
// open the dropdown menu
this.DroppedDown = true;
// update list
UpdateListItems(e.Items);
// set cursor to the end
this.Text = curText;
this.SelectionStart = curText.Length;
this.SelectionLength = 0;
}
}
private void UpdateListItems(ICollection items)
{
this.Items.Clear();
if (items.Count > 0)
{
var array = new object[items.Count];
items.CopyTo(array, 0);
this.Items.AddRange(array);
}
}
#endregion
private static void CursorReset()
{
Cursor.Current = Cursors.Default;
Cursor.Show();
}
private void UpdateSelectionFromText()
{
try
{
// do a case-insensitive search
var itemIndex = this.FindStringExact(this.Text);
if (itemIndex > -1)
{
// update the selected index
this.SelectedIndex = itemIndex;
// also update the visible text, because the upper/lower-casing may not match
var item = this.Items[itemIndex];
this.Text = GetItemText(item);
}
else
{
// doesn't match any suggestions, clear the text
this.Text = null;
}
}
catch (ArgumentOutOfRangeException)
{
// if the combo box is dropped down, and the control loses focus (calling OnLeave),
// it seems WinForms throws an exception from this.Text
// not sure why this happens, but there is really nothing that can be done in terms of recovery
}
// there are 2 ways that the value can change
// either the selection change is comitted, or the control loses focus
OnValueChanged(EventArgs.Empty);
}
}
}