【DevExpress】老版TreeList和GridControl 中控件 MouseWheel事件禁用解决方法

骑猪看日落 2021-11-05 01:18 333阅读 0赞

期望目标：TreeList和GridControl中禁用鼠标MouseWheel事件对控件值的更改。

处理思路：在TreeList\_ShownEditor事件中，增加对ActiveEditor的MouseWheel事件处理，禁用掉即可。

遇到问题：老版DevExpress中对ActiveEditor.MouseWheel的Handle=true无效。

参加官方问题地址 [http://www.devexpress.com/Support/Center/Question/Details/Q148215][http_www.devexpress.com_Support_Center_Question_Details_Q148215]

解决方法：

既然无法禁用值的改变，那就从改变后恢复着手。代码如下：

Private activeEditor As DevExpress.XtraEditors.BaseEdit = Nothing       '当前编辑控件
        Private isMouseWheelChanged As Boolean = False                          '是否为鼠标滚轮滚动改变
        Private oActiveEditorOldValue As Object = Nothing                       '初始值
    
        Private Sub TreeList_ShownEditor(ByVal sender As System.Object, ByVal e As System.EventArgs)
            activeEditor = m_tree.ActiveEditor
            oActiveEditorOldValue = activeEditor.EditValue
            AddHandler activeEditor.MouseWheel, AddressOf ActiveEditor_MouseWheel
            AddHandler activeEditor.EditValueChanging, AddressOf ActiveEditor_EditValueChanging
        End Sub
    
        Private Sub TreeList_HiddenEditor(ByVal sender As Object, ByVal e As System.EventArgs)
            If activeEditor IsNot Nothing Then
                isMouseWheelChanged = False
                oActiveEditorOldValue = Nothing
            End If
        End Sub
    
        ’出自 http://caryliu.cnblogs.com
        Private Sub ActiveEditor_MouseWheel(ByVal sender As System.Object, ByVal e As MouseEventArgs)
            isMouseWheelChanged = True
    
            If oActiveEditorOldValue IsNot Nothing Then
                Try
                    RemoveHandler activeEditor.EditValueChanging, AddressOf ActiveEditor_EditValueChanging
                    activeEditor.EditValue = oActiveEditorOldValue
                Catch ex As Exception
                Finally
                    AddHandler activeEditor.EditValueChanging, AddressOf ActiveEditor_EditValueChanging
                End Try
            End If
    
            '转化为列表滚动
            Dim scrollLines As Integer = SystemInformation.MouseWheelScrollLines
            If (scrollLines = -1) Then scrollLines = m_tree.ViewInfo.VisibleRowCount
    
            m_tree.TopVisibleNodeIndex += IIf(e.Delta > 0, -scrollLines, scrollLines)
        End Sub
    
    
        Private Sub ActiveEditor_EditValueChanging(ByVal sender As System.Object, ByVal e As DevExpress.XtraEditors.Controls.ChangingEventArgs)
            If isMouseWheelChanged Then
                e.Cancel = True
                Exit Sub
            End If
    
            oActiveEditorOldValue = e.OldValue
        End Sub

转载于:https://www.cnblogs.com/caryliu/archive/2013/02/27/2935373.html

[http_www.devexpress.com_Support_Center_Question_Details_Q148215]: http://www.devexpress.com/Support/Center/Question/Details/Q148215