source: branches/2870_AutoDiff-nuget/HeuristicLab.ExtLibs/HeuristicLab.AvalonEdit/5.0.1/AvalonEdit-5.0.1/CodeCompletion/CompletionListBox.cs

// Copyright (c) 2014 AlphaSierraPapa for the SharpDevelop Team
// 
// Permission is hereby granted, free of charge, to any person obtaining a copy of this
// software and associated documentation files (the "Software"), to deal in the Software
// without restriction, including without limitation the rights to use, copy, modify, merge,
// publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons
// to whom the Software is furnished to do so, subject to the following conditions:
// 
// The above copyright notice and this permission notice shall be included in all copies or
// substantial portions of the Software.
// 
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
// INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
// PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE
// FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
// DEALINGS IN THE SOFTWARE.

using System;
using System.Windows;
using System.Windows.Controls;
using ICSharpCode.AvalonEdit.Utils;

namespace ICSharpCode.AvalonEdit.CodeCompletion
{
  /// <summary>
  /// The list box used inside the CompletionList.
  /// </summary>
  public class CompletionListBox : ListBox
  {
    internal ScrollViewer scrollViewer;
    
    /// <inheritdoc/>
    public override void OnApplyTemplate()
    {
      base.OnApplyTemplate();
      
      // Find the scroll viewer:
      scrollViewer = null;
      if (this.VisualChildrenCount > 0) {
        Border border = this.GetVisualChild(0) as Border;
        if (border != null)
          scrollViewer = border.Child as ScrollViewer;
      }
    }
    
    /// <summary>
    /// Gets the number of the first visible item.
    /// </summary>
    public int FirstVisibleItem {
      get {
        if (scrollViewer == null || scrollViewer.ExtentHeight == 0) {
          return 0;
        } else {
          return (int)(this.Items.Count * scrollViewer.VerticalOffset / scrollViewer.ExtentHeight);
        }
      }
      set {
        value = value.CoerceValue(0, this.Items.Count - this.VisibleItemCount);
        if (scrollViewer != null) {
          scrollViewer.ScrollToVerticalOffset((double)value / this.Items.Count * scrollViewer.ExtentHeight);
        }
      }
    }
    
    /// <summary>
    /// Gets the number of visible items.
    /// </summary>
    public int VisibleItemCount {
      get {
        if (scrollViewer == null || scrollViewer.ExtentHeight == 0) {
          return 10;
        } else {
          return Math.Max(
            3,
            (int)Math.Ceiling(this.Items.Count * scrollViewer.ViewportHeight
                              / scrollViewer.ExtentHeight));
        }
      }
    }
    
    /// <summary>
    /// Removes the selection.
    /// </summary>
    public void ClearSelection()
    {
      this.SelectedIndex = -1;
    }
    
    /// <summary>
    /// Selects the item with the specified index and scrolls it into view.
    /// </summary>
    public void SelectIndex(int index)
    {
      if (index >= this.Items.Count)
        index = this.Items.Count - 1;
      if (index < 0)
        index = 0;
      this.SelectedIndex = index;
      this.ScrollIntoView(this.SelectedItem);
    }
    
    /// <summary>
    /// Centers the view on the item with the specified index.
    /// </summary>
    public void CenterViewOn(int index)
    {
      this.FirstVisibleItem = index - VisibleItemCount / 2;
    }
  }
}