ScrollBar.Scroll 事件
定義
重要
部分資訊涉及發行前產品，在發行之前可能會有大幅修改。 Microsoft 對此處提供的資訊，不做任何明確或隱含的瑕疵擔保。
發生於捲動方塊已經由滑鼠或鍵盤動作移動時。
public:
event System::Windows::Forms::ScrollEventHandler ^ Scroll;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 事件類型
範例
下列範例會在圖片方塊中捲動影像。 它會使用 Value 捲軸的 ，在使用者捲動時重新繪製影像的新部分。 此程式碼範例是類別概觀所提供較大範例的 ScrollBar 一部分。
注意
如需如何在 Visual Studio 中執行此範例的指示，請參閱如何：使用 Visual Studio 編譯和執行完整Windows Forms程式碼範例。
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
下列程式碼範例使用衍生類別 VScrollBar 。 會建立 和 ValueChanged 事件的事件處理常式 Scroll 。 此程式碼假設 Label 已在表單上建立 和 Button ，而且按鈕具有 事件的事件處理常式 Click 。 按一下按鈕時， Value 捲軸的 屬性會在程式碼中調整。 標籤會顯示內容的 Value 目前值，以及變更它的事件。 您會注意到，當按鈕 Click 的事件變更捲動值時，只會 ValueChanged 引發事件。 相反地，當捲軸手動捲動時， Scroll 事件會在事件之後 ValueChanged 立即引發。
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
備註
如需如何處理事件的詳細資訊，請參閱 處理和引發事件。
