using System;
using System.Collections.Generic;
using System.Text;
namespace FastGridApp
{
/// <summary>
/// This class provides a space-efficient method of storing which
/// rows are selected in the table diff control. We want to avoid
/// a case where there are millions of selected rows where each
/// row index is stored indvidually in the grid control (which is
/// the default behavior). This case can cause the software to run
/// out of memory. So we use a more efficient means of storing
/// selection information. Basically we store ranges of selection
/// instead of individual row indexes.
/// </summary>
public class FastGridSelection : ICloneable
{
#region Events
public event EventHandler SelectionChanged;
#endregion
#region Constructors
public FastGridSelection()
{
}
#endregion
#region ICloneable Members
public object Clone()
{
FastGridSelection res = new FastGridSelection();
foreach (SelectionRange range in _selection)
res._selection.Add((SelectionRange)range.Clone());
return res;
}
#endregion
#region Public Properties
public List<SelectionRange> SelectionRanges
{
get { return _selection; }
}
#endregion
#region Public Methods
/// <summary>
/// Clear all selection ranges
/// </summary>
public void Clear()
{
_selection.Clear();
if (SelectionChanged != null)
SelectionChanged(this, EventArgs.Empty);
}
/// <summary>
/// Combines clearing the selection with adding a new selection.
/// </summary>
/// <param name="startRowId">The start ROW ID of the selection range to add</param>
/// <param name="endRowId">The end ROW ID of the selection range to add</param>
public void SetSelection(long startRowId, long endRowId)
{
_selection.Clear();
AddSelection(startRowId, endRowId);
}
/// <summary>
/// Add a new selection range
/// </summary>
/// <param name="startRowId">The start ROW ID of the selection range to add</param>
/// <param name="endRowId">The end ROW ID of the selection range to add</param>
public void AddSelection(long startRowId, long endRowId)
{
if (startRowId > endRowId)
{
long temp = endRowId;
endRowId = startRowId;
startRowId = temp;
}
for (int i = 0; i < _selection.Count; i++)
{
SelectionRange range = _selection[i];
if (range.Contains(startRowId))
{
if (range.Contains(endRowId))
return;
// Adjust the current range to expand to the end-row-id
range.EndRowId = endRowId;
// Merge selection ranges if necessary
MergeRanges();
if (SelectionChanged != null)
SelectionChanged(this, EventArgs.Empty);
return;
}
else if (range.Contains(endRowId))
{
// This range includes the end row id but not the start row id, so
// we need to adjust its start row id to expand to the new start-row-id
range.StartRowId = startRowId;
// Merge selection ranges if necessary
MergeRanges();
if (SelectionChanged != null)
SelectionChanged(this, EventArgs.Empty);
return;
}
else if (range.StartRowId > endRowId)
{
_selection.Insert(i, new SelectionRange(startRowId, endRowId));
MergeRanges();
if (SelectionChanged != null)
SelectionChanged(this, EventArgs.Empty);
return;
}
} // for
// Add a new selection range because if is not even partialy contained in any
// of th existing selection ranges
_selection.Add(new SelectionRange(startRowId, endRowId));
// Merge ranges if necessary
MergeRanges();
if (SelectionChanged != null)
SelectionChanged(this, EventArgs.Empty);
}
/// <summary>
/// Deletes the specified selection range
/// </summary>
/// <param name="startRowId">The start row id</param>
/// <param name="endRowId">The end row id of the cleared selection range</param>
public void DelSelection(long startRowId, long endRowId)
{
if (startRowId > endRowId)
{
long temp = endRowId;
endRowId = startRowId;
startRowId = temp;
}
List<SelectionRange> removed = new List<SelectionRange>();
for(int i=0; i<_selection.Count; i++)
{
SelectionRange range = _selection[i];
if (range.StartRowId > endRowId)
{
// There is no selection range that need to be deleted
break;
}
else
{
if (range.Contains(startRowId))
{
if (range.Contains(endRowId))
{
// The deleted selection range is fully contained in the current
// selection range so we can remove it from the range.
// Maybe we can remove the entire range ?
if (range.StartRowId == startRowId && range.EndRowId == endRowId)
{
removed.Add(range);
break;
}
else
{
if (range.StartRowId < startRowId && range.EndRowId > endRowId)
{
// We need to split this range into two separate ranges
if (i + 1 < _selection.Count)
_selection.Insert(i + 1, new SelectionRange(endRowId + 1, range.EndRowId));
else
_selection.Add(new SelectionRange(endRowId + 1, range.EndRowId));
range.EndRowId = startRowId - 1;
break;
} // if
else if (range.StartRowId < startRowId)
{
// We need to adjust the current range to exclude the cleared ids
range.EndRowId = startRowId - 1;
}
else if (range.EndRowId > endRowId)
{
// We need to adjust the current range to exclude the cleared ids
range.StartRowId = endRowId + 1;
}
} // else
break;
} // if
else
{
// We'll need to adjust the current range to exclude the removed row ids
if (startRowId-1 >= range.StartRowId)
range.EndRowId = startRowId - 1;
else
removed.Add(range);
// Now move forward and look for more ranges that we may need to remove or
// adjust in order to remove the cleared row ids.
} // else
} // if
else
{
if (range.Contains(endRowId))
{
if (endRowId >= range.EndRowId)
{
// In this case we'll remove this range
removed.Add(range);
}
else
{
// In this case we'll adjust the current range
range.StartRowId = endRowId + 1;
} // else
}
else if (startRowId <= range.StartRowId && endRowId >= range.EndRowId)
{
// In this case the range is contained entirely within the deleted selection
// so we need to delete it
removed.Add(range);
}
} // else
} // else
} // foreach
foreach (SelectionRange range in removed)
_selection.Remove(range);
if (removed.Count > 0)
{
if (SelectionChanged != null)
SelectionChanged(this, EventArgs.Empty);
}
}
/// <summary>
/// Check if the specified row ID should be selected
/// </summary>
/// <param name="rowId">The row ID to check</param>
/// <returns>TRUE if the row is selected, FALSE if not.</returns>
public bool IsRowSelected(long rowId)
{
foreach (SelectionRange range in _selection)
{
if (range.StartRowId > rowId)
return false;
else if (range.Contains(rowId))
return true;
} // foreach
return false;
}
/// <summary>
/// Returns the first selected row id in the selection
/// </summary>
/// <returns>The first selected row id in the selection or -1 if there is none.</returns>
public long GetSelectedRowId()
{
if (_selection.Count > 0)
return _selection[0].StartRowId;
else
return -1;
}
#endregion
#region Private Methods
private void MergeRanges()
{
int removed = 0;
for (int i = 0; i < _selection.Count-removed; i++)
{
SelectionRange prev = _selection[i];
if (i + 1 < _selection.Count-removed)
{
SelectionRange next = _selection[i + 1];
if (prev.Intersects(next))
{
_selection.Remove(next);
prev.EndRowId = next.EndRowId;
removed++;
i--;
}
}
} // for
if (removed > 0)
MergeRanges();
}
#endregion
#region Private Varaibles
private List<SelectionRange> _selection = new List<SelectionRange>();
#endregion
}
public class SelectionRange : ICloneable
{
public SelectionRange()
{
}
public SelectionRange(long start, long end)
{
StartRowId = start;
EndRowId = end;
}
public bool Contains(long point)
{
if (point >= StartRowId && point <= EndRowId)
return true;
return false;
}
public bool Intersects(SelectionRange range)
{
if (range.StartRowId >= StartRowId && range.StartRowId <= EndRowId)
return true;
if (StartRowId >= range.StartRowId && StartRowId <= range.EndRowId)
return true;
if (range.StartRowId == EndRowId + 1)
return true;
if (range.EndRowId == StartRowId - 1)
return true;
return false;
}
#region ICloneable Members
public object Clone()
{
SelectionRange res = new SelectionRange(StartRowId, EndRowId);
return res;
}
#endregion
public long StartRowId;
public long EndRowId;
}
/// <summary>
/// Provides the possible selection modes.
/// </summary>
public enum SelectionMode
{
/// <summary>
/// No selection mode
/// </summary>
None = 0,
/// <summary>
/// Single selection mode (e.g., pressing CTRL key and clicking with the mouse on
/// a grid row).
/// </summary>
SingleSelection = 1,
/// <summary>
/// Range selection mode (e.g., pressing SHIFT key and clicking with the mouse on
/// a grid row).
/// </summary>
RangeSelection = 2,
}
}
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