/// <summary>
/// Compare two VirtualTreeStartDragData structures
/// </summary>
/// <param name="operand1">Left operand</param>
/// <param name="operand2">Right operand</param>
/// <returns>true if operands are equal</returns>
public static bool Compare(VirtualTreeStartDragData operand1, VirtualTreeStartDragData operand2)
{
return operand1.myData == operand2.myData && operand1.myAllowedEffects == operand2.myAllowedEffects;
}
/// <summary>
/// Compare two VirtualTreeStartDragData structures
/// </summary>
/// <param name="operand1">Left operand</param>
/// <param name="operand2">Right operand</param>
/// <returns>true if operands are equal</returns>
public static bool Compare(VirtualTreeStartDragData operand1, VirtualTreeStartDragData operand2)
{
return(operand1.myData == operand2.myData && operand1.myAllowedEffects == operand2.myAllowedEffects);
}
/// <summary>
/// Package a drag object to use with DoDragDrop or Copy/Paste operations. Use the passed in location
/// for a single select tree, and the current selection state for a multiselect tree. Derived
/// classes can override this function to add extra information to the returned drag data. Any override
/// should first defer to the base implementation.
/// </summary>
/// <param name="row">Target row in the tree</param>
/// <param name="nativeColumn">The native column</param>
/// <param name="dragReason">The reason for retrieving the drop object</param>
/// <returns>A populated drag structure. IsEmpty may be true.</returns>
protected virtual VirtualTreeStartDragData PopulateDragData(int row, int nativeColumn, DragReason dragReason)
{
ClearDragSources();
if (GetStyleFlag(VTCStyleFlags.MultiSelect))
{
var iter = CreateSelectedItemEnumerator();
if (iter != null)
{
var finished = false;
try
{
List<VirtualTreeStartDragData> sourceData = null;
var firstDragData = new VirtualTreeStartDragData();
var intersectEffects = GetStateFlag(VTCStateFlags.CombineDragEffectsWithAnd);
var allowedEffects = DragDropEffects.None;
var totalCount = 0;
while (iter.MoveNext())
{
var dragData = iter.Branch.OnStartDrag(this, iter.RowInBranch, iter.ColumnInBranch, dragReason);
if (dragReason == DragReason.CanCut
|| dragReason == DragReason.CanCopy)
{
// special handling for cut/copy queries.
if (dragData == VirtualTreeStartDragData.AllowCutCopy)
{
firstDragData = dragData;
totalCount = 1;
}
else
{
// bail out, operation is not supported
finished = true;
return VirtualTreeStartDragData.Empty;
}
}
else if (!dragData.IsEmpty)
{
if (totalCount == 0)
{
// Store the first one without using the lists, we return it directly in this case
mySingleDragSource = new DragSourceOwner(iter.Branch, iter.RowInBranch, iter.ColumnInBranch);
firstDragData = dragData;
allowedEffects = dragData.AllowedEffects;
++totalCount;
}
else
{
if (totalCount == 1)
{
// We're moving from a single item to multiple items.
// Move our single drag data and source information into
// lists.
sourceData = new List<VirtualTreeStartDragData>();
sourceData.Add(firstDragData);
if (myDragSources == null)
{
myDragSources = new List<DragSourceOwner>();
}
myDragSources.Add(mySingleDragSource);
mySingleDragSource.Clear();
}
// Add source owners before the potential cancel coming from intersectAffects
myDragSources.Add(new DragSourceOwner(iter.Branch, iter.RowInBranch, iter.ColumnInBranch));
if (intersectEffects)
{
allowedEffects &= dragData.AllowedEffects;
if (allowedEffects == 0)
{
// The finaly clause will clear out the data sources gracefully
// if we don't set the finished signal.
return VirtualTreeStartDragData.Empty;
}
}
else
{
allowedEffects |= dragData.AllowedEffects;
}
sourceData.Add(dragData);
++totalCount;
}
}
}
finished = true;
if (totalCount == 1)
{
return firstDragData;
}
else if (totalCount > 1)
{
// Keep this CLS compliant and just return the array of structures
// as returned by the branches.
return new VirtualTreeStartDragData(sourceData.ToArray(), allowedEffects);
}
}
finally
{
if (!finished)
{
ForceCancelDataSources();
}
}
}
}
else
{
var info = myTree.GetItemInfo(row, nativeColumn, false);
var dragData = info.Branch.OnStartDrag(this, info.Row, info.Column, dragReason);
if (!dragData.IsEmpty)
{
mySingleDragSource = new DragSourceOwner(info.Branch, info.Row, info.Column);
return dragData;
}
}
return VirtualTreeStartDragData.Empty;
}