GaugeControl双击事件处理程序

Question

我的GaugeControl有三个量规。我编写了双击事件处理程序，如下所示：

AddHandler gc.DoubleClick, AddressOf HandleGaugeDoubleClick

Private Sub HandleGaugeDoubleClick(sender As Object, e As EventArgs)
   'Gauge Information
End Sub

其中gc被decalred为GaugeControl类型，并且其中添加了三个GaugeControls。

我的问题是，如何获取双击哪个Gauge的信息？

注意这些仪表位于一个 GaugeControl 中，并在其集合中逐个添加。我如何能够获得双击的仪表信息。

修改

第一次，此代码段运行正常，但在点击相同的Gauge时第二次NullReferenceException。

Dim hi As BasePrimitiveHitInfo = DirectCast(gc, IGaugeContainer).CalcHitInfo(e.Location) ' hi becomes Nothing when double clicked second time on same Gauge
If Not (TypeOf hi.Element Is DevExpress.XtraGauges.Core.Model.BaseGaugeModel) Then
    Dim model = DevExpress.XtraGauges.Core.Model.BaseGaugeModel.Find(hi.Element)
    If model IsNot Nothing AndAlso model.Owner IsNot Nothing Then
        gauge = model.Owner
    End If
End If

当双击同一个Gauge时，变量hi变为null / Nothing第二次。由于hi变为 Nothing ，因此条件变为false，其余代码生成NullReferenceException。

请参阅以下代码段：

If (Not (gauge.Scales Is Nothing) And (gauge.Scales.Count > 0)) Then ' Actual exception here
    For i As Integer = 0 To gauge.Scales.Count - 1
        scaleComponent = gauge.Scales(i)
        cGaugeToBeShown.Scales.Add(scaleComponent)
    Next
End If

cGaugeToBeShown 为Dim cGaugeToBeShown As New CircularGauge。

Answer 1

我建议您使用GaugeControl.MouseDoubleClick事件，如下所示：

using DevExpress.XtraGauges.Base;
using DevExpress.XtraGauges.Core.Primitive;
//...
void gaugeControl1_MouseDoubleClick(object sender, MouseEventArgs e) {
    BasePrimitiveHitInfo hi = ((IGaugeContainer)gaugeControl1).CalcHitInfo(e.Location);
    if(!(hi.Element is DevExpress.XtraGauges.Core.Model.BaseGaugeModel)) {
        var model = DevExpress.XtraGauges.Core.Model.BaseGaugeModel.Find(hi.Element);
        if(model != null && model.Owner != null) {
            IGauge gauge = model.Owner;
            // do something with gauge
        }
    }
}

Imports DevExpress.XtraGauges.Base
Imports DevExpress.XtraGauges.Core.Primitive
'...
Private Sub gaugeControl1_MouseDoubleClick(sender As Object, e As MouseEventArgs)
    Dim hi As BasePrimitiveHitInfo = DirectCast(gaugeControl1, IGaugeContainer).CalcHitInfo(e.Location)
    If Not (TypeOf hi.Element Is DevExpress.XtraGauges.Core.Model.BaseGaugeModel) Then
        Dim model = DevExpress.XtraGauges.Core.Model.BaseGaugeModel.Find(hi.Element)
        If model IsNot Nothing AndAlso model.Owner IsNot Nothing Then
            Dim gauge As IGauge = model.Owner
            ' do something with gauge
        End If
    End If
End Sub

相关示例：How to provide a custom mouse interaction with the GaugeControl.