TrackBar.Scroll Gebeurtenis

public:
 event EventHandler ^ Scroll;

public event EventHandler Scroll;

member this.Scroll : EventHandler 

Public Custom Event Scroll As EventHandler 

Gebeurtenistype

Voorbeelden

In het volgende codevoorbeeld ziet u hoe u de Scroll gebeurtenis implementeert om informatielabels in een formulier te wijzigen, op basis van het schuiven van het schuifvak op een trackbalk. Voor het voorbeeld zijn Form drie trackbalken en drie labels vereist.

void showColorValueLabels()
{
   label1->Text = String::Format( "Red value is : {0}", trackBar1->Value );
   label2->Text = String::Format( "Green Value is : {0}", trackBar2->Value );
   label3->Text = String::Format( "Blue Value is : {0}", trackBar3->Value );
}

void trackBar_Scroll( Object^ sender, System::EventArgs^ /*e*/ )
{
   System::Windows::Forms::TrackBar^ myTB;
   myTB = dynamic_cast<System::Windows::Forms::TrackBar^>(sender);
   panel1->BackColor = Color::FromArgb( trackBar1->Value, trackBar2->Value, trackBar3->Value );
   myTB->Text = String::Format( "Value is {0}", myTB->Value );
   showColorValueLabels();
}

void showColorValueLabels()
{
    label1.Text = "Red value is : " + trackBar1.Value.ToString();
    label2.Text = "Green Value is : " + trackBar2.Value.ToString();
    label3.Text = "Blue Value is : " + trackBar3.Value.ToString();
}
void trackBar_Scroll(object sender, EventArgs e)
{
    System.Windows.Forms.TrackBar myTB = (System.Windows.Forms.TrackBar)sender;
    panel1.BackColor = Color.FromArgb(trackBar1.Value, trackBar2.Value, trackBar3.Value);
    myTB.Text = "Value is " + myTB.Value.ToString();
    showColorValueLabels();
}

Private Sub showColorValueLabels()
    _label1.Text = "Red value is : " & trackBar1.Value.ToString()
    _label2.Text = "Green Value is : " & trackBar2.Value.ToString()
    _label3.Text = "Blue Value is : " & trackBar3.Value.ToString()
End Sub

Private Sub trackBar_Scroll(ByVal sender As Object, ByVal e As EventArgs) Handles trackBar1.Scroll, trackBar2.Scroll, trackBar3.Scroll
    Dim myTB As System.Windows.Forms.TrackBar
    myTB = sender
    _panel1.BackColor = Color.FromArgb(trackBar1.Value, trackBar2.Value, trackBar3.Value)
    myTB.Text = "Value is " & myTB.Value.ToString()
    showColorValueLabels()
End Sub

In het volgende codevoorbeeld wordt een formulier weergegeven dat een TrackBar besturingselement en een TextBox besturingselement bevat. In het voorbeeld ziet u hoe u de Maximum, TickFrequencyen LargeChangeeigenschappen instelt SmallChange en de Scroll gebeurtenis verwerkt. De TextBox inhoud wordt bijgewerkt naar de Value eigenschapswaarde wanneer de Scroll gebeurtenis plaatsvindt.

using namespace System;
using namespace System::Drawing;
using namespace System::Windows::Forms;
public ref class Form1: public System::Windows::Forms::Form
{
private:
   System::Windows::Forms::TrackBar^ trackBar1;
   System::Windows::Forms::TextBox^ textBox1;

public:
   Form1()
   {
      this->textBox1 = gcnew System::Windows::Forms::TextBox;
      this->trackBar1 = gcnew System::Windows::Forms::TrackBar;
      
      // TextBox for TrackBar::Value update.
      this->textBox1->Location = System::Drawing::Point( 240, 16 );
      this->textBox1->Size = System::Drawing::Size( 48, 20 );
      
      // Set up how the form should be displayed and add the controls to the form.
      this->ClientSize = System::Drawing::Size( 296, 62 );
      array<System::Windows::Forms::Control^>^formControls = {this->textBox1,this->trackBar1};
      this->Controls->AddRange( formControls );
      this->Text = "TrackBar Example";
      
      // Set up the TrackBar.
      this->trackBar1->Location = System::Drawing::Point( 8, 8 );
      this->trackBar1->Size = System::Drawing::Size( 224, 45 );
      this->trackBar1->Scroll += gcnew System::EventHandler( this, &Form1::trackBar1_Scroll );
      
      // The Maximum property sets the value of the track bar when
      // the slider is all the way to the right.
      trackBar1->Maximum = 30;
      
      // The TickFrequency property establishes how many positions
      // are between each tick-mark.
      trackBar1->TickFrequency = 5;
      
      // The LargeChange property sets how many positions to move
      // if the bar is clicked on either side of the slider.
      trackBar1->LargeChange = 3;
      
      // The SmallChange property sets how many positions to move
      // if the keyboard arrows are used to move the slider.
      trackBar1->SmallChange = 2;
   }


private:
   void trackBar1_Scroll( Object^ /*sender*/, System::EventArgs^ /*e*/ )
   {
      
      // Display the trackbar value in the text box.
      textBox1->Text = String::Concat( "", trackBar1->Value );
   }

};


[STAThread]
int main()
{
   Application::Run( gcnew Form1 );
}

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

public class Form1 : System.Windows.Forms.Form
{
    private System.Windows.Forms.TrackBar trackBar1;
    private System.Windows.Forms.TextBox textBox1;

    [STAThread]
    static void Main() 
    {
        Application.Run(new Form1());
    }

    public Form1()
    {
        this.textBox1 = new System.Windows.Forms.TextBox();
        this.trackBar1 = new System.Windows.Forms.TrackBar();

        // TextBox for TrackBar.Value update.
        this.textBox1.Location = new System.Drawing.Point(240, 16);
        this.textBox1.Size = new System.Drawing.Size(48, 20);

        // Set up how the form should be displayed and add the controls to the form.
        this.ClientSize = new System.Drawing.Size(296, 62);
        this.Controls.AddRange(new System.Windows.Forms.Control[] {this.textBox1,this.trackBar1});
        this.Text = "TrackBar Example";

        // Set up the TrackBar.
        this.trackBar1.Location = new System.Drawing.Point(8, 8);
        this.trackBar1.Size = new System.Drawing.Size(224, 45);
        this.trackBar1.Scroll += new System.EventHandler(this.trackBar1_Scroll);

        // The Maximum property sets the value of the track bar when
        // the slider is all the way to the right.
        trackBar1.Maximum = 30;
        
        // The TickFrequency property establishes how many positions
        // are between each tick-mark.
        trackBar1.TickFrequency = 5;

        // The LargeChange property sets how many positions to move
        // if the bar is clicked on either side of the slider.
        trackBar1.LargeChange = 3;

        // The SmallChange property sets how many positions to move
        // if the keyboard arrows are used to move the slider.
        trackBar1.SmallChange = 2;
    }

    private void trackBar1_Scroll(object sender, System.EventArgs e)
    {
        // Display the trackbar value in the text box.
        textBox1.Text = "" + trackBar1.Value;
    }
}

Imports System.Drawing
Imports System.Windows.Forms

Public Class Form1
    Inherits System.Windows.Forms.Form

    Private WithEvents trackBar1 As System.Windows.Forms.TrackBar
    Private textBox1 As System.Windows.Forms.TextBox

    <System.STAThread()> _
    Public Shared Sub Main()
        System.Windows.Forms.Application.Run(New Form1)
    End Sub

    Public Sub New()
        Me.textBox1 = New System.Windows.Forms.TextBox
        Me.trackBar1 = New System.Windows.Forms.TrackBar

        ' TextBox for TrackBar.Value update.
        Me.textBox1.Location = New System.Drawing.Point(240, 16)
        Me.textBox1.Size = New System.Drawing.Size(48, 20)

        ' Set up how the form should be displayed and add the controls to the form.
        Me.ClientSize = New System.Drawing.Size(296, 62)
        Me.Controls.AddRange(New System.Windows.Forms.Control() {Me.textBox1, Me.trackBar1})
        Me.Text = "TrackBar Example"

        ' Set up the TrackBar.
        Me.trackBar1.Location = New System.Drawing.Point(8, 8)
        Me.trackBar1.Size = New System.Drawing.Size(224, 45)

        ' The Maximum property sets the value of the track bar when
        ' the slider is all the way to the right.
        trackBar1.Maximum = 30

        ' The TickFrequency property establishes how many positions
        ' are between each tick-mark.
        trackBar1.TickFrequency = 5

        ' The LargeChange property sets how many positions to move
        ' if the bar is clicked on either side of the slider.
        trackBar1.LargeChange = 3

        ' The SmallChange property sets how many positions to move
        ' if the keyboard arrows are used to move the slider.
        trackBar1.SmallChange = 2
    End Sub

    Private Sub trackBar1_Scroll(ByVal sender As Object, _
                    ByVal e As System.EventArgs) Handles trackBar1.Scroll

        ' Display the trackbar value in the text box.
        textBox1.Text = trackBar1.Value
    End Sub 

End Class

Opmerkingen

Zie Gebeurtenissen verwerken en genereren voor meer informatie over het afhandelen van gebeurtenissen.