DrawTreeNodeEventArgs Clase

Definición

public ref class DrawTreeNodeEventArgs : EventArgs

public class DrawTreeNodeEventArgs : EventArgs

type DrawTreeNodeEventArgs = class
    inherit EventArgs

Public Class DrawTreeNodeEventArgs
Inherits EventArgs

Herencia

Object

EventArgs

DrawTreeNodeEventArgs

Ejemplos

En el ejemplo de código siguiente se muestra cómo personalizar un control mediante el TreeView dibujo del propietario. El TreeView control del ejemplo muestra etiquetas de nodo opcionales junto con las etiquetas de nodo estándar. Las etiquetas de nodo se especifican mediante la TreeNode.Tag propiedad . El TreeView control también usa colores personalizados, incluido un color de resaltado personalizado.

Puede personalizar la mayoría de los TreeView colores estableciendo propiedades de color, pero el color de resaltado de selección no está disponible como una propiedad. Además, el rectángulo de resaltado de selección predeterminado solo se extiende alrededor de una etiqueta de nodo. El dibujo del propietario debe usarse para dibujar las etiquetas de nodo y para dibujar un rectángulo de resaltado personalizado lo suficientemente grande como para incluir una etiqueta de nodo.

En el ejemplo, un controlador para el TreeView.DrawNode evento dibuja las etiquetas de nodo y el resaltado de selección personalizado manualmente. Los nodos no seleccionados no necesitan personalización. Para estos, la DrawDefault propiedad se establece true en para que el sistema operativo los dibuje.

Además, un controlador para el Control.MouseDown evento proporciona pruebas de posicionamiento. De forma predeterminada, solo se puede seleccionar un nodo haciendo clic en la región alrededor de su etiqueta. El Control.MouseDown controlador de eventos selecciona un nodo en el que se hace clic en cualquier parte de esta región o dentro de la región alrededor de una etiqueta de nodo, si está presente.

#using <System.dll>
#using <System.Windows.Forms.dll>
#using <System.Drawing.dll>

using namespace System;
using namespace System::Drawing;
using namespace System::Windows::Forms;
public ref class TreeViewOwnerDraw: public Form
{
private:
   TreeView^ myTreeView;

   // Create a Font object for the node tags.
   System::Drawing::Font^ tagFont;

public:

   TreeViewOwnerDraw()
   {
      tagFont = gcnew System::Drawing::Font( "Helvetica",8,FontStyle::Bold );

      // Create and initialize the TreeView control.
      myTreeView = gcnew 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 += gcnew DrawTreeNodeEventHandler( this, &TreeViewOwnerDraw::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 += gcnew MouseEventHandler( this, &TreeViewOwnerDraw::myTreeView_MouseDown );
      
      // Initialize the form and add the TreeView control to it.
      this->ClientSize = System::Drawing::Size( 292, 273 );
      this->Controls->Add( myTreeView );
   }

protected:
   // Clean up any resources being used.        
   ~TreeViewOwnerDraw()
   {
      if ( tagFont != nullptr )
      {
         delete tagFont;
      }
   }

   // 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) != (TreeNodeStates)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.
         System::Drawing::Font^ nodeFont = e->Node->NodeFont;
         if ( nodeFont == nullptr )
                  nodeFont = (dynamic_cast<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 != nullptr )
      {
         e->Graphics->DrawString( e->Node->Tag->ToString(), tagFont, Brushes::Yellow, (float)e->Bounds.Right + 2, (float)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) != (TreeNodeStates)0 )
      {
         Pen^ focusPen = gcnew Pen( Color::Black );
         try
         {
            focusPen->DashStyle = System::Drawing::Drawing2D::DashStyle::Dot;
            Rectangle focusBounds = NodeBounds( e->Node );
            focusBounds.Size = System::Drawing::Size( focusBounds.Width - 1, focusBounds.Height - 1 );
            e->Graphics->DrawRectangle( focusPen, focusBounds );
         }
         finally
         {
            if ( focusPen )
               delete safe_cast<IDisposable^>(focusPen);
         }

      }
   }

   // Selects a node that is clicked on its label or tag text.
   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.
   Rectangle NodeBounds( TreeNode^ node )
   {
      // Set the return value to the normal node bounds.
      Rectangle bounds = node->Bounds;
      if ( node->Tag != nullptr )
      {
         // 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->~Graphics();
      }

      return bounds;
   }
};

[STAThreadAttribute]
int main()
{
   Application::Run( gcnew 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;
    }
}

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
    
    <STAThreadAttribute()> _
    Shared Sub Main()
        Application.Run(New TreeViewOwnerDraw())
    End Sub
    
    ' 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 (e.Node.Tag IsNot 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

    ' 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

    ' 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 (node.Tag IsNot 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

Comentarios

Use el DrawNode evento para personalizar la apariencia de los nodos en un control mediante el TreeView dibujo del propietario.

Un control genera el DrawNodeTreeView evento cuando su TreeView.DrawMode propiedad está establecida TreeViewDrawMode.OwnerDrawAll en o TreeViewDrawMode.OwnerDrawText y se muestra o actualiza un nodo. El DrawTreeNodeEventArgs objeto pasado al controlador de eventos contiene información sobre el nodo que se va a dibujar, así como proporcionar métodos para ayudarle a dibujar el nodo.

Use las State propiedades o Node para recuperar información sobre el nodo que se va a dibujar. Utilice la Graphics propiedad para realizar el dibujo real dentro del área especificada por la Bounds propiedad . Para que el sistema operativo dibuje un nodo que no necesita ser propietario dibujado, establezca la DrawDefault propiedad trueen .

Cuando la TreeView.DrawMode propiedad se establece TreeViewDrawMode.OwnerDrawTexten , el área indicada por la Bounds propiedad incluye solo la parte de etiqueta del nodo. Cuando la TreeView.DrawMode propiedad se establece TreeViewDrawMode.OwnerDrawAllen , el Bounds área incluye todo el nodo, incluido el área que se usa normalmente para iconos, casillas, signos más y menos, y líneas que conectan los nodos.

Constructores

Propiedades

Métodos

Se aplica a

Consulte también

• TreeView
• DrawMode
• DrawNode
• TreeViewDrawMode