ScrollBar.ValueChanged 事件
重要
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public:
event EventHandler ^ ValueChanged;C#
public event EventHandler ValueChanged;C#
public event EventHandler? ValueChanged;member this.ValueChanged : EventHandler Public Custom Event ValueChanged As EventHandler 下面的代码示例使用派生类 VScrollBar。 创建 和 ValueChanged 事件的事件处理程序Scroll。 此代码假定 Label 已在窗体上创建了 和 Button ，并且 按钮具有事件的 Click 事件处理程序。 单击按钮时， Value 滚动条的 属性将在代码中进行调整。 标签将显示属性的 Value 当前值以及更改该属性的事件。 你会注意到，当滚动值由按钮的事件 Click 更改时，只会引发 该 ValueChanged 事件。 相反，当手动滚动滚动条时，事件 Scroll 在事件发生后 ValueChanged 立即引发。
备注
有关如何在 Visual Studio 中运行此示例的说明，请参阅如何：使用 Visual Studio 编译和运行完整的Windows 窗体代码示例。
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;
}
}
C#
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
有关如何处理事件的详细信息，请参阅 处理和引发事件。
| 产品 | 版本 |
|---|---|
| .NET Framework | 1.1, 2.0, 3.0, 3.5, 4.0, 4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8, 4.8.1 |
| Windows Desktop | 3.0, 3.1, 5, 6, 7, 8, 9, 10 |
