TrackBar.Scroll Evento

Riferimento

Definizione

Spazio dei nomi:: System.Windows.Forms

Assembly:: System.Windows.Forms.dll

Importante

Alcune informazioni sono relative alla release non definitiva del prodotto, che potrebbe subire modifiche significative prima della release definitiva. Microsoft non riconosce alcuna garanzia, espressa o implicita, in merito alle informazioni qui fornite.

Si verifica quando la casella di scorrimento viene spostata a seguito di un'operazione con il mouse o la tastiera.

public:
 event EventHandler ^ Scroll;

public event EventHandler Scroll;

public event EventHandler? Scroll;

member this.Scroll : EventHandler

Public Custom Event Scroll As EventHandler

Tipo evento

EventHandler

Esempio

Nell'esempio di codice seguente viene illustrato come implementare l'evento Scroll per modificare le etichette di informazioni in un modulo, in base allo scorrimento della casella di scorrimento su una barra di traccia. L'esempio richiede un Form oggetto con tre barre di traccia e tre etichette posizionate su di esso.

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

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

Private Sub trackBar_Scroll(ByVal sender As Object, ByVal e As System.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

Nell'esempio di codice seguente viene visualizzato un modulo che contiene un TrackBar controllo e un TextBox controllo. L'esempio illustra l'impostazione delle Maximumproprietà , TickFrequency, LargeChangee SmallChange e della gestione dell'evento Scroll . Il TextBox contenuto viene aggiornato al valore della Value proprietà quando si verifica l'evento Scroll .

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

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