/// <summary>
/// Process the DragOver node in order to determine whether drop action as appropriate
/// </summary>
private void TreeViewEditor_DragOver(object sender, System.Windows.Forms.DragEventArgs e)
{
e.Effect = DragDropEffects.None; // By default, drag and drop is denied
if (project == null) return;
TreeView senderTreeView = sender as TreeView;
if (senderTreeView != this) return;
// Determine source and destination nodes
Point pt = PointToClient(new Point(e.X, e.Y));
TreeNode dropNode = GetNodeAt(pt);
if (dropNode == null) return;
if (e.Data.GetDataPresent("System.Drawing.Design.ToolboxItem", false))
{
ToolboxItem source = e.Data.GetData("System.Drawing.Design.ToolboxItem") as ToolboxItem;
if (source != null && dropNode != null)
{
// Drop is available - highlight destination node
this.SelectedNode = dropNode;
if (project.IsChildElementAllowed(dropNode, source.TypeName))
{
if (this.SelectedNode != null)
this.SelectedNode.Expand();
e.Effect = DragDropEffects.Copy;
}
}
//e.Effect = DragDropEffects.None;
}
// Fired continuously while a tree node is dragged. We need to override this to
// provide appropriate feedback
else if (e.Data.GetDataPresent("System.Windows.Forms.TreeNode", false))
{
TreeNode dragNode = e.Data.GetData("System.Windows.Forms.TreeNode") as TreeNode;
if (dragNode == null) return;
int OffsetY = pt.Y - dropNode.Bounds.Top;
bool isList = project.IsList(dropNode);
bool isGroup = project.IsGroup(dropNode);
if (isList) // Adding a child is the only option for a list
{
if (IsDragAllowed(dragNode, dropNode, DropSide.Inside))
{
e.Effect = DragDropEffects.Move;
if (dropNode != prevDropNode || prevDropSide != DropSide.Inside)
{
prevDropNode = dropNode;
prevDropSide = DropSide.Inside;
DrawAddToFolderPlaceholder(dropNode);
}
}
}
else if (isGroup) // There are 3 options for a Group
{
if (OffsetY < (dropNode.Bounds.Height / 3)) // top third
{
if (IsDragAllowed(dragNode, dropNode, DropSide.Top))
{
e.Effect = DragDropEffects.Move;
if (prevDropNode != dropNode || prevDropSide != DropSide.Top)
{
prevDropNode = dropNode;
prevDropSide = DropSide.Top;
DrawLeafTopPlaceholders(dropNode);
}
}
}
// It is not allowed to drag a node just below an expanded Group node
else if (OffsetY > (2 * dropNode.Bounds.Height / 3) && dropNode.IsExpanded == false) // bottom third
{
if (IsDragAllowed(dragNode, dropNode, DropSide.Bottom))
{
e.Effect = DragDropEffects.Move;
if (prevDropNode != dropNode || prevDropSide != DropSide.Bottom)
{
prevDropNode = dropNode;
prevDropSide = DropSide.Bottom;
DrawLeafBottomPlaceholders(dropNode);
}
}
}
else // middle => Add dragComp as a child
{
if (IsDragAllowed(dragNode, dropNode, DropSide.Inside))
{
e.Effect = DragDropEffects.Move;
if (dropNode != prevDropNode || prevDropSide != DropSide.Inside)
{
prevDropNode = dropNode;
prevDropSide = DropSide.Inside;
DrawAddToFolderPlaceholder(dropNode);
}
}
}
}
else // 2 options for an ordinary component: Top or Bottom
{
if (IsDragAllowed(dragNode, dropNode, DropSide.Top))
{
e.Effect = DragDropEffects.Move;
if (OffsetY < (dropNode.Bounds.Height / 2)) // top half
{
if (prevDropNode != dropNode || prevDropSide != DropSide.Top)
{
prevDropNode = dropNode;
prevDropSide = DropSide.Top;
DrawLeafTopPlaceholders(dropNode);
}
}
else // bottom half
{
if (prevDropNode != dropNode || prevDropSide != DropSide.Bottom)
{
prevDropNode = dropNode;
prevDropSide = DropSide.Bottom;
DrawLeafBottomPlaceholders(dropNode);
}
}
}
}
if (e.Effect == DragDropEffects.None)
{
// Need to clear the drop markers, but only once to avoid flickering!
if (prevDropNode != null)
{
prevDropNode = null;
Refresh();
}
}
// Determine source and destination nodes
// Point pt = senderTreeView.PointToClient(new Point(e.X, e.Y));
// TreeNode sourceTreeNode = e.Data.GetData("System.Windows.Forms.TreeNode") as TreeNode;
// TreeNode destinationTreeNode = senderTreeView.GetNodeAt(pt);
//
// // Deny drag and drop when
// // destinationNode is the same as source
// // destination node is a parent of a source node
// // destination and source node belong to the different TreeViews
// if (sourceTreeNode == null || destinationTreeNode == null
// || sourceTreeNode == destinationTreeNode
// || (sourceTreeNode.Parent != null && sourceTreeNode.Parent == destinationTreeNode)
// || sourceTreeNode.TreeView != destinationTreeNode.TreeView)
// {
// e.Effect = DragDropEffects.None;
// return;
// }
//
// // if destination node lies in a subtree of source node - restrict drop action to avoid circles
// TreeNode checkParentNode = destinationTreeNode.Parent;
// while (checkParentNode != null)
// {
// if (checkParentNode == sourceTreeNode)
// {
// e.Effect = DragDropEffects.None;
// return;
// }
// checkParentNode = checkParentNode.Parent;
// }
//
// // Drop is available - highlight destination node
// this.SelectedNode = destinationTreeNode;
// if (this.SelectedNode != null)
// {
// this.SelectedNode.Expand();
// }
//
// // determine a type of drug and drop action (move or copy)
// if ((e.KeyState & 8) == 8)
// {
// // CTRL Keystate for copy
// e.Effect = DragDropEffects.Copy;
// }
// else
// {
// e.Effect = DragDropEffects.Move;
// }
}
//scrolling code
int delta = Height - pt.Y;
if ((delta < Height / 2) && (delta > 0))
{
TreeNode tn = GetNodeAt(pt);
if (tn.NextVisibleNode != null)
tn.NextVisibleNode.EnsureVisible();
}
if ((delta > Height / 2) && (delta < Height))
{
TreeNode tn = GetNodeAt(pt);
if (tn.PrevVisibleNode != null)
tn.PrevVisibleNode.EnsureVisible();
}
}
private bool IsDragAllowed(TreeNode dragNode, TreeNode dropNode, DropSide dropSide)
{
// Deny drag and drop when
// destinationNode is the same as source
// destination node is a parent of a source node
// destination and source node belong to the different TreeViews
if (dragNode == null || dropNode == null || dragNode == dropNode
|| (dragNode.Parent != null && dragNode.Parent == dropNode)
|| dragNode.TreeView != dropNode.TreeView)
{
return false;
}
if (project != null && project.IsDragAllowed(dragNode, dropNode, dropSide == DropSide.Inside))
return true;
return false;
}
