DrawTreeNodeEventArgs Sınıf

Tanım

public ref class DrawTreeNodeEventArgs : EventArgs

public class DrawTreeNodeEventArgs : EventArgs

type DrawTreeNodeEventArgs = class
    inherit EventArgs

Public Class DrawTreeNodeEventArgs
Inherits EventArgs

Devralma

Object

EventArgs

DrawTreeNodeEventArgs

Örnekler

Aşağıdaki kod örneği, sahip çizimini kullanarak bir TreeView denetimin nasıl özelleştirileceği gösterilmektedir. Örnekteki TreeView denetim, standart düğüm etiketlerinin yanında isteğe bağlı düğüm etiketlerini görüntüler. Düğüm etiketleri özelliği kullanılarak TreeNode.Tag belirtilir. Denetim TreeView ayrıca özel bir vurgu rengi de dahil olmak üzere özel renkler kullanır.

Renk özelliklerini ayarlayarak renklerin TreeView çoğunu özelleştirebilirsiniz, ancak seçim vurgu rengi özellik olarak kullanılamaz. Ayrıca, varsayılan seçim vurgu dikdörtgeni yalnızca bir düğüm etiketinin çevresinde genişletir. Sahip çizimi, düğüm etiketlerini çizmek ve düğüm etiketi içerecek kadar büyük özelleştirilmiş bir vurgu dikdörtgeni çizmek için kullanılmalıdır.

Örnekte, olay işleyicisi TreeView.DrawNode düğüm etiketlerini çizer ve özel seçim el ile vurgulanır. Seçilmemiş düğümlerin özelleştirmeye ihtiyacı yoktur. Bunlar için, DrawDefault işletim sistemi tarafından çizilmeleri için true özelliği olarak ayarlanır.

Ayrıca, olay işleyicisi Control.MouseDown isabet testi sağlar. Varsayılan olarak, bir düğüm yalnızca etiketinin etrafındaki bölgeye tıklanarak seçilebilir. Olay işleyicisi Control.MouseDown , varsa bu bölge içinde veya düğüm etiketinin etrafındaki bölgede herhangi bir yere tıklanan bir düğümü seçer.

#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

Açıklamalar

Sahip çizimini DrawNode kullanarak denetimdeki TreeView düğümlerin görünümünü özelleştirmek için olayını kullanın.

Özelliği DrawNode veya TreeViewDrawMode.OwnerDrawText olarak ayarlandığında TreeViewDrawMode.OwnerDrawAll ve bir düğüm görüntülendiğinde veya güncelleştirildiğinde TreeView.DrawMode olay bir denetim tarafından TreeView oluşturulur. olay DrawTreeNodeEventArgs işleyicisine geçirilen, çizilecek düğüm hakkındaki bilgileri ve düğümü çizmenize yardımcı olacak yöntemler sağlar.

State Çizecek düğüm hakkındaki bilgileri almak için veya Node özelliklerini kullanın. Graphics Özelliği tarafından Bounds belirtilen alan içinde gerçek çizimi yapmak için özelliğini kullanın. İşletim sisteminin sahip çizilmesi gerekmeyen bir düğüm çizmesini sağlamak için özelliğini olarak trueayarlayınDrawDefault.

TreeView.DrawMode özelliği olarak TreeViewDrawMode.OwnerDrawTextayarlandığında, özelliği tarafından Bounds belirtilen alan yalnızca düğümün etiket bölümünü içerir. TreeView.DrawMode özelliği olarak TreeViewDrawMode.OwnerDrawAllBounds ayarlandığında, alan genellikle simgeler, onay kutuları, artı ve eksi işaretleri ve düğümleri bağlayan çizgiler için kullanılan alan da dahil olmak üzere düğümün tamamını içerir.

Oluşturucular

Özellikler

Yöntemler

Şunlara uygulanır

Ayrıca bkz.

• TreeView
• DrawMode
• DrawNode
• TreeViewDrawMode