Evento TreeView.DrawNode (System.Windows.Forms)

Imports System
Imports System.Drawing
Imports System.Windows.Forms

Public Class TreeViewOwnerDraw
    Inherits Form

    Private WithEvents myTreeView As TreeView
    
    ' Create a Font object for the node tags.
    Private tagFont As New Font("Helvetica", 8, FontStyle.Bold)
    
    Public Sub New()

        ' Create and initialize the TreeView control.
        myTreeView = New TreeView()
        myTreeView.Dock = DockStyle.Fill
        myTreeView.BackColor = Color.Tan
        myTreeView.CheckBoxes = True
        
        ' Add nodes to the TreeView control.
        Dim node As TreeNode
        Dim x As Integer
        For x = 1 To 3

            ' Add a root node to the TreeView control.
            node = myTreeView.Nodes.Add(String.Format("Task {0}", x))
            Dim y As Integer
            For y = 1 To 3 

                ' Add a child node to the root node.
                node.Nodes.Add(String.Format("Subtask {0}", y))
            Next y
        Next x
        myTreeView.ExpandAll()
        
        ' Add tags containing alert messages to a few nodes 
        ' and set the node background color to highlight them.
        myTreeView.Nodes(1).Nodes(0).Tag = "urgent!"
        myTreeView.Nodes(1).Nodes(0).BackColor = Color.Yellow
        myTreeView.SelectedNode = myTreeView.Nodes(1).Nodes(0)
        myTreeView.Nodes(2).Nodes(1).Tag = "urgent!"
        myTreeView.Nodes(2).Nodes(1).BackColor = Color.Yellow
        
        ' Configure the TreeView control for owner-draw.
        myTreeView.DrawMode = TreeViewDrawMode.OwnerDrawText

        ' Add a handler for the MouseDown event so that a node can be 
        ' selected by clicking the tag text as well as the node text.
        AddHandler myTreeView.MouseDown, AddressOf myTreeView_MouseDown
        
        ' Initialize the form and add the TreeView control to it.
        Me.ClientSize = New Size(292, 273)
        Me.Controls.Add(myTreeView)
    End Sub 'New
    
    <STAThreadAttribute()> _
    Shared Sub Main()
        Application.Run(New TreeViewOwnerDraw())
    End Sub 'Main
    
    ' Draws a node.
    Private Sub myTreeView_DrawNode(ByVal sender As Object, _
        ByVal e As DrawTreeNodeEventArgs) Handles myTreeView.DrawNode

        ' Draw the background and node text for a selected node.
        If (e.State And TreeNodeStates.Selected) <> 0 Then

            ' Draw the background of the selected node. The NodeBounds
            ' method makes the highlight rectangle large enough to
            ' include the text of a node tag, if one is present.
            e.Graphics.FillRectangle(Brushes.Green, NodeBounds(e.Node))

            ' Retrieve the node font. If the node font has not been set,
            ' use the TreeView font.
            Dim nodeFont As Font = e.Node.NodeFont
            If nodeFont Is Nothing Then
                nodeFont = CType(sender, TreeView).Font
            End If

            ' Draw the node text.
            e.Graphics.DrawString(e.Node.Text, nodeFont, Brushes.White, _
                e.Bounds.Left - 2, e.Bounds.Top)

        ' Use the default background and node text.
        Else
            e.DrawDefault = True
        End If

        ' If a node tag is present, draw its string representation 
        ' to the right of the label text.
        If Not (e.Node.Tag Is Nothing) Then
            e.Graphics.DrawString(e.Node.Tag.ToString(), tagFont, _
                Brushes.Yellow, e.Bounds.Right + 2, e.Bounds.Top)
        End If

        ' If the node has focus, draw the focus rectangle large, making
        ' it large enough to include the text of the node tag, if present.
        If (e.State And TreeNodeStates.Focused) <> 0 Then
            Dim focusPen As New Pen(Color.Black)
            Try
                focusPen.DashStyle = System.Drawing.Drawing2D.DashStyle.Dot
                Dim focusBounds As Rectangle = NodeBounds(e.Node)
                focusBounds.Size = New Size(focusBounds.Width - 1, _
                    focusBounds.Height - 1)
                e.Graphics.DrawRectangle(focusPen, focusBounds)
            Finally
                focusPen.Dispose()
            End Try
        End If

    End Sub 'myTreeView_DrawNode

    ' Selects a node that is clicked on its label or tag text.
    Private Sub myTreeView_MouseDown(ByVal sender As Object, ByVal e As MouseEventArgs)
        Dim clickedNode As TreeNode = myTreeView.GetNodeAt(e.X, e.Y)
        If NodeBounds(clickedNode).Contains(e.X, e.Y) Then
            myTreeView.SelectedNode = clickedNode
        End If
    End Sub 'myTreeView_MouseDown

    ' Returns the bounds of the specified node, including the region 
    ' occupied by the node label and any node tag displayed.
    Private Function NodeBounds(ByVal node As TreeNode) As Rectangle

        ' Set the return value to the normal node bounds.
        Dim bounds As Rectangle = node.Bounds
        If Not (node.Tag Is Nothing) Then

            ' Retrieve a Graphics object from the TreeView handle
            ' and use it to calculate the display width of the tag.
            Dim g As Graphics = myTreeView.CreateGraphics()
            Dim tagWidth As Integer = CInt(g.MeasureString( _
                node.Tag.ToString(), tagFont).Width) + 6

            ' Adjust the node bounds using the calculated value.
            bounds.Offset(tagWidth \ 2, 0)
            bounds = Rectangle.Inflate(bounds, tagWidth \ 2, 0)
            g.Dispose()
        End If
        Return bounds
    End Function 'NodeBounds

End Class 'TreeViewOwnerDraw 

using System;
using System.Drawing;
using System.Windows.Forms;

public class TreeViewOwnerDraw : Form
{
    private TreeView myTreeView;

    // Create a Font object for the node tags.
    Font tagFont = new Font("Helvetica", 8, FontStyle.Bold);

    public TreeViewOwnerDraw()
    {
        // Create and initialize the TreeView control.
        myTreeView = new TreeView();
        myTreeView.Dock = DockStyle.Fill;
        myTreeView.BackColor = Color.Tan;
        myTreeView.CheckBoxes = true;

        // Add nodes to the TreeView control.
        TreeNode node;
        for (int x = 1; x < 4; ++x)
        {
            // Add a root node to the TreeView control.
            node = myTreeView.Nodes.Add(String.Format("Task {0}", x));
            for (int y = 1; y < 4; ++y)
            {
                // Add a child node to the root node.
                node.Nodes.Add(String.Format("Subtask {0}", y));
            }
        }
        myTreeView.ExpandAll();

        // Add tags containing alert messages to a few nodes 
        // and set the node background color to highlight them.
        myTreeView.Nodes[1].Nodes[0].Tag = "urgent!";
        myTreeView.Nodes[1].Nodes[0].BackColor = Color.Yellow;
        myTreeView.SelectedNode = myTreeView.Nodes[1].Nodes[0];
        myTreeView.Nodes[2].Nodes[1].Tag = "urgent!";
        myTreeView.Nodes[2].Nodes[1].BackColor = Color.Yellow;

        // Configure the TreeView control for owner-draw and add
        // a handler for the DrawNode event.
        myTreeView.DrawMode = TreeViewDrawMode.OwnerDrawText;
        myTreeView.DrawNode += 
            new DrawTreeNodeEventHandler(myTreeView_DrawNode);

        // Add a handler for the MouseDown event so that a node can be 
        // selected by clicking the tag text as well as the node text.
        myTreeView.MouseDown += new MouseEventHandler(myTreeView_MouseDown);

        // Initialize the form and add the TreeView control to it.
        this.ClientSize = new Size(292, 273);
        this.Controls.Add(myTreeView);
    }

    // Clean up any resources being used.        
    protected override void Dispose(bool disposing)
    {
        if (disposing)
        {
            tagFont.Dispose();
        }
        base.Dispose(disposing);
    }

    [STAThreadAttribute()]
    static void Main() 
    {
        Application.Run(new TreeViewOwnerDraw());
    }

    // Draws a node.
    private void myTreeView_DrawNode(
        object sender, DrawTreeNodeEventArgs e)
    {
        // Draw the background and node text for a selected node.
        if ((e.State & TreeNodeStates.Selected) != 0)
        {
            // Draw the background of the selected node. The NodeBounds
            // method makes the highlight rectangle large enough to
            // include the text of a node tag, if one is present.
            e.Graphics.FillRectangle(Brushes.Green, NodeBounds(e.Node));

            // Retrieve the node font. If the node font has not been set,
            // use the TreeView font.
            Font nodeFont = e.Node.NodeFont;
            if (nodeFont == null) nodeFont = ((TreeView)sender).Font;

            // Draw the node text.
            e.Graphics.DrawString(e.Node.Text, nodeFont, Brushes.White,
                Rectangle.Inflate(e.Bounds, 2, 0));
        }

        // Use the default background and node text.
        else 
        {
            e.DrawDefault = true;
        }

        // If a node tag is present, draw its string representation 
        // to the right of the label text.
        if (e.Node.Tag != null)
        {
            e.Graphics.DrawString(e.Node.Tag.ToString(), tagFont,
                Brushes.Yellow, e.Bounds.Right + 2, e.Bounds.Top);
        }

        // If the node has focus, draw the focus rectangle large, making
        // it large enough to include the text of the node tag, if present.
        if ((e.State & TreeNodeStates.Focused) != 0)
        {
            using (Pen focusPen = new Pen(Color.Black))
            {
                focusPen.DashStyle = System.Drawing.Drawing2D.DashStyle.Dot;
                Rectangle focusBounds = NodeBounds(e.Node);
                focusBounds.Size = new Size(focusBounds.Width - 1, 
                focusBounds.Height - 1);
                e.Graphics.DrawRectangle(focusPen, focusBounds);
            }
        }
    }

    // Selects a node that is clicked on its label or tag text.
    private void myTreeView_MouseDown(object sender, MouseEventArgs e)
    {
        TreeNode clickedNode = myTreeView.GetNodeAt(e.X, e.Y);
        if (NodeBounds(clickedNode).Contains(e.X, e.Y))
        {
            myTreeView.SelectedNode = clickedNode;
        }
    }

    // Returns the bounds of the specified node, including the region 
    // occupied by the node label and any node tag displayed.
    private Rectangle NodeBounds(TreeNode node)
    {
        // Set the return value to the normal node bounds.
        Rectangle bounds = node.Bounds;
        if (node.Tag != null)
        {
            // Retrieve a Graphics object from the TreeView handle
            // and use it to calculate the display width of the tag.
            Graphics g = myTreeView.CreateGraphics(); 
            int tagWidth = (int)g.MeasureString
                (node.Tag.ToString(), tagFont).Width + 6;

            // Adjust the node bounds using the calculated value.
            bounds.Offset(tagWidth/2, 0);
            bounds = Rectangle.Inflate(bounds, tagWidth/2, 0);
            g.Dispose();
         }
        
        return bounds;
        
    }

}

import System.*;
import System.Drawing.*;
import System.Windows.Forms.*;

public class TreeViewOwnerDraw extends Form
{
    private TreeView myTreeView;

    // Create a Font object for the node tags.
    private Font tagFont = new Font("Helvetica", 8, FontStyle.Bold);

    public TreeViewOwnerDraw()
    {
        // Create and initialize the TreeView control.
        myTreeView = new TreeView();
        myTreeView.set_Dock(DockStyle.Fill);
        myTreeView.set_BackColor(Color.get_Tan());
        myTreeView.set_CheckBoxes(true);
        // Add nodes to the TreeView control.
        TreeNode node;
        for (int x = 1; x < 4; ++x) {
            // Add a root node to the TreeView control.
            node = myTreeView.get_Nodes().Add(String.Format("Task {0}",
                (Int32)x));
            for (int y = 1; y < 4; ++y) {
                // Add a child node to the root node.
                node.get_Nodes().Add(String.Format("Subtask {0}", (Int32)y));
            }
        }
        myTreeView.ExpandAll();
        // Add tags containing alert messages to a few nodes 
        // and set the node background color to highlight them.
        myTreeView.get_Nodes().get_Item(1).get_Nodes().get_Item(0).
            set_Tag("urgent!");
        myTreeView.get_Nodes().get_Item(1).get_Nodes().get_Item(0).
            set_BackColor(Color.get_Yellow());
        myTreeView.set_SelectedNode(myTreeView.get_Nodes().get_Item(1).
            get_Nodes().get_Item(0));
        myTreeView.get_Nodes().get_Item(2).get_Nodes().get_Item(1).
            set_Tag("urgent!");
        myTreeView.get_Nodes().get_Item(2).get_Nodes().get_Item(1).
            set_BackColor(Color.get_Yellow());

        // Configure the TreeView control for owner-draw and add
        // a handler for the DrawNode event.
        myTreeView.set_DrawMode(TreeViewDrawMode.OwnerDrawText);
        myTreeView.add_DrawNode(new DrawTreeNodeEventHandler(
            myTreeView_DrawNode));
        // Add a handler for the MouseDown event so that a node can be 
        // selected by clicking the tag text as well as the node text.
        myTreeView.add_MouseDown(new MouseEventHandler(myTreeView_MouseDown));
        // Initialize the form and add the TreeView control to it.
        this.set_ClientSize(new Size(292, 273));
        this.get_Controls().Add(myTreeView);
    } //TreeViewOwnerDraw

    // Clean up any resources being used.        
    protected void Dispose(boolean disposing)
    {
        if (disposing) {
            tagFont.Dispose();
        }
        super.Dispose(disposing);
    } //Dispose

    /** @attribute STAThreadAttribute()
     */
    public static void main(String[] args)
    {
        Application.Run(new TreeViewOwnerDraw());
    } //main

    // Draws a node.
    private void myTreeView_DrawNode(Object sender, DrawTreeNodeEventArgs e)
    {
        // Draw the background and node text for a selected node.
        if ((int)(e.get_State() & TreeNodeStates.Selected) != 0) {
            // Draw the background of the selected node. The NodeBounds
            // method makes the highlight rectangle large enough to
            // include the text of a node tag, if one is present.
            e.get_Graphics().FillRectangle(Brushes.get_Green(),
                NodeBounds(e.get_Node()));
            // Retrieve the node font. If the node font has not been set,
            // use the TreeView font.
            Font nodeFont = e.get_Node().get_NodeFont();
            if (nodeFont == null) {
                nodeFont = ((TreeView)sender).get_Font();
            }
            // Draw the node text.
            e.get_Graphics().DrawString(e.get_Node().get_Text(),
                nodeFont, Brushes.get_White(),
                RectangleF.op_Implicit(Rectangle.Inflate(e.get_Bounds(), 2, 0)));
        }
        // Use the default background and node text.
        else {
            e.set_DrawDefault(true);
        }
        // If a node tag is present, draw its string representation 
        // to the right of the label text.
        if (e.get_Node().get_Tag() != null) {
            e.get_Graphics().DrawString(e.get_Node().get_Tag().ToString(),
                tagFont, Brushes.get_Yellow(), e.get_Bounds().get_Right() + 2,
                e.get_Bounds().get_Top());
        }
        // If the node has focus, draw the focus rectangle large, making
        // it large enough to include the text of the node tag, if present.
        if ((int)(e.get_State() & TreeNodeStates.Focused) != 0) { 
            Pen focusPen = new Pen(Color.get_Black());
            try {
                focusPen.set_DashStyle(System.Drawing.Drawing2D.DashStyle.Dot);
                Rectangle focusBounds = NodeBounds(e.get_Node());
                focusBounds.set_Size(new Size(focusBounds.get_Width() - 1,
                    focusBounds.get_Height() - 1));
                e.get_Graphics().DrawRectangle(focusPen, focusBounds);
            }
            finally {
                focusPen.Dispose();
            }            
        }
    } //myTreeView_DrawNode

    // Selects a node that is clicked on its label or tag text.
    private void myTreeView_MouseDown(Object sender, MouseEventArgs e)
    {
        TreeNode clickedNode = myTreeView.GetNodeAt(e.get_X(), e.get_Y());
        if (NodeBounds(clickedNode).Contains(e.get_X(), e.get_Y())) {
            myTreeView.set_SelectedNode(clickedNode);
        }
    } //myTreeView_MouseDown

    // Returns the bounds of the specified node, including the region 
    // occupied by the node label and any node tag displayed.
    private Rectangle NodeBounds(TreeNode node)
    {
        // Set the return value to the normal node bounds.
        Rectangle bounds = node.get_Bounds();
        if (node.get_Tag() != null) {
            // Retrieve a Graphics object from the TreeView handle
            // and use it to calculate the display width of the tag.
            Graphics g = myTreeView.CreateGraphics();
            int tagWidth = (int)(g.MeasureString(node.get_Tag().ToString(),
                tagFont).get_Width()) + 6;
            // Adjust the node bounds using the calculated value.
            bounds.Offset(tagWidth / 2, 0);
            bounds = Rectangle.Inflate(bounds, tagWidth / 2, 0);
            g.Dispose();
        }
        return bounds;
    } //NodeBounds
} //TreeViewOwnerDraw