ComponentOne WinForms Edition
Tree Grid / Node Operations
In This Topic
Node Operations
In This Topic

Tree Grid not only allows you to present the data in a structured form but it also supports performing various operations with the nodes. You can add, delete, move and fetch nodes by using various methods provided by the Node class.

Node operations

Add Node

You can add a node at a specific position in the Tree Grid using AddNode method of the Node class. This appends a new node row to the collection. The method takes NodeTypeEnum enumeration as its argument which lets you specify a node with respect to another given node.

The code below shows how to add a node in the WinForms Tree Grid at a specific location.

private void cmbAdd_SelectionChangeCommitted(object sender, System.EventArgs e)
{
   // Gets current row's node
   Node nd = flex.Rows[flex.Row].Node; 
   // Adds relative as requested by user
   // (could be a child or a sibling)
   nd.AddNode((NodeTypeEnum)(cmbAdd.SelectedIndex + 2), cmbAdd.Text);
   flex.Focus();
}

Delete Node

You can delete a selected node from the Tree Grid using RemoveNode method of the Node class.

Following code demonstrates how to delete a node from the WinForms Tree Grid.

private void btnDelete_Click(object sender, System.EventArgs e)
{
  // Gets current node
  Node nd = null;
  if ( flex.Rows.Count > 0 && flex.Row >= 0 && flex.Row < flex.Rows.Count)
  {
    nd = flex.Rows[flex.Row].Node;
  }
  if (nd != null)
  {
     // Removes node from FlexGrid
     nd.RemoveNode();
     flex.Focus();
  }
}

Move Node

The Tree Grid allows you to move the node rows to a new position using Move method of the Node class. The method takes NodeMoveEnum enumeration as an argument which lets you specify the direction in which node has to be moved.

Use the code below to move a node of the WinForms Tree Grid to a new position.

private void btnMove_Click(object sender, System.EventArgs e)
{
   // Gets current row's node
   Node nd = flex.Rows[flex.Row].Node; 
   // Applies movement selected by the user
   // (this will move the selected node)
   if (sender == btnMoveOut) nd.Move(NodeMoveEnum.Out);
   else if (sender == btnMoveIn) nd.Move(NodeMoveEnum.In);
   else if (sender == btnMoveUp) nd.Move(NodeMoveEnum.Up);
   else if (sender == btnMoveDown) nd.Move(NodeMoveEnum.Down);
   else if (sender == btnMoveFirst) nd.Move(NodeMoveEnum.First);
   else if (sender == btnMoveLast) nd.Move(NodeMoveEnum.Last);
   // Makes sure the node is still visible
   nd.EnsureVisible();
   flex.Focus();
}

Select Nodes

In Tree Grid, you can select the nodes to perform different operations using GetNode method of the Node class. The method takes a parameter called NodeTypeEnum enumeration which specifies a node with respect to another given node.

The code below specifies how to fetch a specific node of the WinForms Tree Grid and show it in selected state.

private void cmbSelect_SelectionChangeCommitted(object sender, System.EventArgs e)
{
   // Gets current row's node
   Node nd = flex.Rows[flex.Row].Node; 
   // Gets relative node selected by the user
   nd = nd.GetNode((NodeTypeEnum)cmbSelect.SelectedIndex);
   // If failed, show message
   if (nd == null)
   {
      MessageBox.Show("Can't find " + cmbSelect.Text + " for this node.");
      return;
    }
    // Selects node and make sure it's visible (by scrolling into view)
    nd.Select();
    nd.EnsureVisible();
    flex.Focus();
}

Expand and Collapse Nodes

You can expand and collapse all nodes in your Tree Grid application using the Collapsed property of Node class as shown in the code below. This feature makes it convenient to navigate through node headers as a group when required.

Following code shows how to expand and collapse nodes of the WinForms Tree Grid.

foreach (Row row in flex.Rows.Cast<Row>().Where(rw => rw.IsNode == true))
{
        Node node = row.Node;
        node.Collapsed = false;
}

foreach (Row row in flex.Rows.Cast<Row>().Where(rw => rw.IsNode == true))
{
        Node node = row.Node;
        node.Collapsed = true;
}

Drag and Drop Nodes

In Tree Grid, you can drag and drop a selected node to a specific position by handling the MouseUp, MouseDown and MouseMove events.

The code below lets the user drag and drop nodes of the WinForms Tree Grid.  

private void flex_MouseDown(object sender, MouseEventArgs e)
{
   m_DragInfo.checkDrag = false; 
   // Left button press, no shift: start tracking mouse to drag
   if (e.Button != MouseButtons.Left) return;
   if (!chkDrag.Checked || m_DragInfo.dragging) return;
   if (flex.MouseRow < flex.Rows.Fixed || flex.MouseCol != 0) return;
   // Saves current row and mouse position
   m_DragInfo.row = flex.Row;
   m_DragInfo.mouseDown = new Point(e.X, e.Y);
   // Starts checking
   m_DragInfo.checkDrag = true;
}

private void flex_MouseMove(object sender, MouseEventArgs e)
{
   // If checking and the user moved past our tolerance, start dragging
   if (!m_DragInfo.checkDrag || e.Button != MouseButtons.Left) return;
   if (Math.Abs(e.X - m_DragInfo.mouseDown.X) +
   Math.Abs(e.Y - m_DragInfo.mouseDown.Y) <= DRAGTOL) return;
   // Updates flags
   m_DragInfo.dragging = true;
   // Sets cursor and highlight node
   CellStyle cs = flex.Styles["SourceNode"];
   flex.Cursor = Cursors.NoMove2D;
   flex.SetCellStyle(m_DragInfo.row, 0, cs);
   // Checks whether we can drop here
   Cursor c = (NoDropHere()) ? Cursors.No : Cursors.NoMove2D;
   if (c != flex.Cursor) flex.Cursor = c;
}
     
private bool NoDropHere()
{
   // Row under mouse is not valid
   if (flex.MouseRow < flex.Rows.Fixed) return true;
   // Column under mouse is not valid
   if (flex.MouseCol < flex.Cols.Fixed) return true;
   if (flex.GetDataDisplay(flex.Row, 0) == "SKU") return true;
   return false;
}
      
private void flex_MouseUp(object sender, MouseEventArgs e)
{
   // We're not checking until the mouse goes down again
   m_DragInfo.checkDrag = false;
   // Not dragging? we're done
   if (!m_DragInfo.dragging) return;
   // Stops dragging
   m_DragInfo.dragging = false;
   flex.SetCellStyle(m_DragInfo.row, 0, (CellStyle)null);
   flex.Cursor = Cursors.Default;
   // Tests whether the drop is allowed
   if (NoDropHere()) return;
   // Moves node into new parent node
   Node ndSrc = flex.Rows[m_DragInfo.row].Node;
   Node ndDst = flex.Rows[flex.Row].Node;
   ndSrc.Move(NodeMoveEnum.ChildOf, ndDst);
   ndSrc.Select();
}

internal struct DRAGINFO
{
  public bool dragging;   // Currently dragging
  public bool checkDrag;  // Currently checking mouse to start dragging
  public int row;     // Index of row being dragged
  public Point mouseDown; // Mouse down position
}