ScrollBar.Scroll Kejadian

Definisi

Ruang nama:

System.Windows.Forms

Rakitan:

System.Windows.Forms.dll

Terjadi ketika kotak gulir telah dipindahkan oleh aksi mouse atau keyboard.

public:
 event System::Windows::Forms::ScrollEventHandler ^ Scroll;

public event System.Windows.Forms.ScrollEventHandler? Scroll;

member this.Scroll : System.Windows.Forms.ScrollEventHandler 

Public Custom Event Scroll As ScrollEventHandler 

Jenis Acara

ScrollEventHandler

Contoh

Contoh berikut menggulir gambar dalam kotak gambar. Ini menggunakan Value bilah gulir untuk menggambar ulang bagian baru gambar setiap kali pengguna menggulir. Contoh kode ini adalah bagian dari contoh yang lebih besar yang disediakan untuk ScrollBar gambaran umum kelas.

Catatan

Untuk petunjuk tentang cara menjalankan contoh ini di Visual Studio, lihat Cara: Mengkompilasi dan Menjalankan Contoh Kode Formulir Windows Lengkap Menggunakan Visual Studio.

private void HandleScroll(Object sender, ScrollEventArgs e)
{
    //Create a graphics object and draw a portion of the image in the PictureBox.
    Graphics g = pictureBox1.CreateGraphics();

    int xWidth = pictureBox1.Width;
    int yHeight = pictureBox1.Height;

    int x;
    int y;

    if (e.ScrollOrientation == ScrollOrientation.HorizontalScroll)
    {
        x = e.NewValue;
        y = vScrollBar1.Value;
    }
    else //e.ScrollOrientation == ScrollOrientation.VerticalScroll
    {
        y = e.NewValue;
        x = hScrollBar1.Value;
    }

    g.DrawImage(pictureBox1.Image,
      new Rectangle(0, 0, xWidth, yHeight),  //where to draw the image
      new Rectangle(x, y, xWidth, yHeight),  //the portion of the image to draw
      GraphicsUnit.Pixel);

    pictureBox1.Update();
}

Private Sub HandleScroll(ByVal sender As [Object], ByVal e As ScrollEventArgs) _
  Handles vScrollBar1.Scroll, hScrollBar1.Scroll

    'Create a graphics object and draw a portion of the image in the PictureBox.
    Dim g As Graphics = pictureBox1.CreateGraphics()

    Dim xWidth As Integer = pictureBox1.Width
    Dim yHeight As Integer = pictureBox1.Height

    Dim x As Integer
    Dim y As Integer

    If (e.ScrollOrientation = ScrollOrientation.HorizontalScroll) Then

        x = e.NewValue
        y = vScrollBar1.Value

    Else 'e.ScrollOrientation == ScrollOrientation.VerticalScroll

        y = e.NewValue
        x = hScrollBar1.Value
    End If

    'First Rectangle: Where to draw the image.
    'Second Rectangle: The portion of the image to draw.

    g.DrawImage(pictureBox1.Image, _
      New Rectangle(0, 0, xWidth, yHeight), _
      New Rectangle(x, y, xWidth, yHeight), _
      GraphicsUnit.Pixel)

    pictureBox1.Update()
End Sub

Contoh kode berikut menggunakan kelas VScrollBarturunan . Penanganan aktivitas untuk Scroll peristiwa dan ValueChanged dibuat. Kode ini mengasumsikan bahwa Label dan Button telah dibuat pada formulir dan bahwa tombol memiliki penanganan aktivitas untuk peristiwa tersebut Click . Saat tombol diklik, Value properti bilah gulir disesuaikan dalam kode. Label akan menampilkan nilai Value properti saat ini dan peristiwa yang mengubahnya. Anda akan melihat bahwa ketika nilai gulir diubah oleh peristiwa tombol Click , hanya peristiwa yang ValueChanged dinaikkan. Sebaliknya, ketika bilah gulir digulir secara manual, Scroll peristiwa dinaikkan segera setelah ValueChanged peristiwa.

void AddMyScrollEventHandlers()
{
   // Create and initialize a VScrollBar.
   VScrollBar^ vScrollBar1 = gcnew VScrollBar;

   // Add event handlers for the OnScroll and OnValueChanged events.
   vScrollBar1->Scroll += gcnew ScrollEventHandler( this, &Form1::vScrollBar1_Scroll );
   vScrollBar1->ValueChanged += gcnew EventHandler( this, &Form1::vScrollBar1_ValueChanged );
}

// Create the ValueChanged event handler.
void vScrollBar1_ValueChanged( Object^ /*sender*/, EventArgs^ /*e*/ )
{
   // Display the new value in the label.
   label1->Text = String::Format( "vScrollBar Value:(OnValueChanged Event) {0}", vScrollBar1->Value );
}

// Create the Scroll event handler.
void vScrollBar1_Scroll( Object^ /*sender*/, ScrollEventArgs^ e )
{
   // Display the new value in the label.
   label1->Text = String::Format( "VScrollBar Value:(OnScroll Event) {0}", e->NewValue );
}

void button1_Click( Object^ /*sender*/, EventArgs^ /*e*/ )
{
   // Add 40 to the Value property if it will not exceed the Maximum value.
   if ( vScrollBar1->Value + 40 < vScrollBar1->Maximum )
   {
      vScrollBar1->Value = vScrollBar1->Value + 40;
   }
}

private void AddMyScrollEventHandlers()
 {
    // Create and initialize a VScrollBar.
    VScrollBar vScrollBar1 = new VScrollBar();
 
    // Add event handlers for the OnScroll and OnValueChanged events.
    vScrollBar1.Scroll += new ScrollEventHandler(
       this.vScrollBar1_Scroll);
    vScrollBar1.ValueChanged += new EventHandler(
       this.vScrollBar1_ValueChanged); 
 }
 
 // Create the ValueChanged event handler.
 private void vScrollBar1_ValueChanged(Object sender, 
                                       EventArgs e)
 {
     // Display the new value in the label.
     label1.Text = "vScrollBar Value:(OnValueChanged Event) " + vScrollBar1.Value.ToString();
 }
 
 // Create the Scroll event handler.
 private void vScrollBar1_Scroll(Object sender, 
                                 ScrollEventArgs e)
 {
     // Display the new value in the label.
     label1.Text = "VScrollBar Value:(OnScroll Event) " + e.NewValue.ToString();
 }
 
 private void button1_Click(Object sender, 
                           EventArgs e)
 {
    // Add 40 to the Value property if it will not exceed the Maximum value.
    if (vScrollBar1.Value + 40 < vScrollBar1.Maximum)
    {
        vScrollBar1.Value = vScrollBar1.Value + 40;
    }
 }

Private Sub AddMyScrollEventHandlers()
    ' Create and initialize a VScrollBar.
    Dim vScrollBar1 As New VScrollBar()
    
    ' Add event handlers for the OnScroll and OnValueChanged events.
    AddHandler vScrollBar1.Scroll, AddressOf Me.vScrollBar1_Scroll
    AddHandler vScrollBar1.ValueChanged, AddressOf Me.vScrollBar1_ValueChanged
End Sub    

' Create the ValueChanged event handler.
Private Sub vScrollBar1_ValueChanged(sender As Object, e As EventArgs)
    ' Display the new value in the label.
    label1.Text = "vScrollBar Value:(OnValueChanged Event) " & _
        vScrollBar1.Value.ToString()
End Sub    

' Create the Scroll event handler.
Private Sub vScrollBar1_Scroll(sender As Object, e As ScrollEventArgs)
    ' Display the new value in the label.
    label1.Text = "VScrollBar Value:(OnScroll Event) " & _
        e.NewValue.ToString()
End Sub    

Private Sub button1_Click(sender As Object, e As EventArgs)
    ' Add 40 to the Value property if it will not exceed the Maximum value.
    If vScrollBar1.Value + 40 < vScrollBar1.Maximum Then
        vScrollBar1.Value = vScrollBar1.Value + 40
    End If
End Sub

Keterangan

Untuk informasi selengkapnya tentang cara menangani peristiwa, lihat Menangani dan Menaikkan Peristiwa.

Lihat juga

• OnScroll(ScrollEventArgs)
• ScrollEventHandler