Question

我有两个.net事件可以自行运行，但是一个阻止了另一个。

底部的完整代码和GUI

目标：我正在尝试将treenode拖放到数据网格视图中，并将我正在悬停的单元格选中/突出显示。

突出显示单元格的事件：

    Private Sub TreeView1_MouseDown(sender As Object, e As MouseEventArgs) Handles TreeView1.MouseDown
        move_item = True
    End Sub

    Private Sub TreeView1_MouseMove(sender As Object, e As MouseEventArgs) Handles TreeView1.MouseMove
        If move_item Then
            On Error GoTo quit
            Dim item2move As New Label
            item2move.Text = TreeView1.SelectedNode.Text
            item2move.DoDragDrop(item2move.Text, DragDropEffects.Copy)
            Debug.Print(TreeView1.SelectedNode.Text)

        End If
        move_item = False
quit:
        Exit Sub
    End Sub

    Private Sub DataGridView1_DragEnter(sender As Object, e As DragEventArgs) Handles DataGridView1.DragEnter
        If (e.Data.GetDataPresent(DataFormats.Text)) Then
            e.Effect = DragDropEffects.Copy
        Else
            e.Effect = DragDropEffects.None
        End If
    End Sub

    Private Sub DataGridView1_DragDrop(sender As Object, e As DragEventArgs) Handles DataGridView1.DragDrop

        With DataGridView1
            Dim Col As Integer = .CurrentCell.ColumnIndex
            Dim row As Integer = .CurrentCell.RowIndex
            .Item(Col, row).Value = e.Data.GetDataPresent(DataFormats.Text)
        End With
    End Sub

拖放事件：

TreeView1_MouseDown - 设置布尔值以确定鼠标是否已关闭
TreeView1_MouseMove - 获取要拖动的项目
DataGridView1_DragEnter - 拖动时的样式
DataGridView1_Dragdrop - 将项目放入datagridview

我的问题是（任何）mousedown事件阻止了cellmouseenter事件。我尝试在表单中的其他地方进行mousedown，然后在数据网格视图上盘旋，我的CellMouseEnter事件无效。

结果是该项目被放入在mousedown之前选择的单元格中。（从技术上讲，这个细胞仍然被选中b / c cellmouseenter不会将选定的细胞更新到悬停细胞）

所以我看到它的方式，我需要构建一个类似于CellMouseEnter的自定义事件，它不被mousedown阻止，但我甚至不知道从哪里开始。我试过Peek Definition，但我找不到CellMouseEnter的实际方法公共事件CellMouseEnter As DataGridViewCellEventHandler。

有更好的方法吗？

这是我的拖放事件：

Public Class Form1
    Dim move_item As Boolean

    'Add some rows to the treemap on load
    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles Me.Load
        For i = 1 To 20
            DataGridView1.Rows.Add()
        Next
    End Sub

    'JSON to treemap
    Private Sub btn_jsontotreemap_Click(sender As Object, e As EventArgs) Handles btn_jsontotreemap.Click

        Try
            Dim json As String = rtb_inputjson.Text
            Dim obj As New JObject
            obj = JObject.Parse(json)
            TreeView1.Nodes.Clear()
            Dim parent As TreeNode = Json2Tree(obj)
            parent.Text = "Root Object"
            TreeView1.Nodes.Add(parent)

        Catch ex As Exception
            MsgBox(ex.Message)
        End Try
    End Sub
    Private Function Json2Tree(ByVal obj As JObject) As TreeNode
        'creates the parent node
        Dim parent As TreeNode = New TreeNode()

        'loop through the obj all token should be pair <key, value>
        For Each token In obj
            parent.Text = token.Key.ToString()
            'create child node
            Dim child As TreeNode = New TreeNode()
            child.Text = token.Key.ToString()

            'self call :) 
            If token.Value.Type.ToString() = "Object" Then
                Dim o As JObject = CType(token.Value, JObject)
                child = Json2Tree(o)
                child.Text = token.Key.ToString()
                parent.Nodes.Add(child)

                'but if it is an array...
            ElseIf token.Value.Type.ToString() = "Array" Then
                Dim ix As Integer = -1
                For Each itm In token.Value

                    'check each item of the array to see if they are objects or arrays
                    If itm.Type.ToString() = "Object" Then
                        Dim objTN As TreeNode = New TreeNode()
                        ix += 1
                        Dim o As JObject = CType(itm, JObject)

                        'self call :)
                        objTN = Json2Tree(o)
                        objTN.Text = token.Key.ToString() & "[" & ix & "]"
                        child.Nodes.Add(objTN)

                    ElseIf itm.Type.ToString() = "Array" Then
                        ix += 1
                        Dim dataArray As TreeNode = New TreeNode()
                        For Each i In itm
                            dataArray.Text = token.Key.ToString() & "[" & ix & "]"
                            dataArray.Nodes.Add(i.ToString())
                        Next

                        child.Nodes.Add(dataArray)
                    Else
                        child.Nodes.Add(itm.ToString())
                    End If
                Next

                parent.Nodes.Add(child)
            Else
                If token.Value.ToString() = "" Then child.Nodes.Add("N/A") Else child.Nodes.Add(token.Value.ToString())
                parent.Nodes.Add(child)
            End If
        Next

        Return parent
    End Function


    'drag & drop to datagridview
    Private Sub TreeView1_MouseDown(sender As Object, e As MouseEventArgs) Handles TreeView1.MouseDown
        move_item = True
    End Sub

    Private Sub TreeView1_MouseMove(sender As Object, e As MouseEventArgs) Handles TreeView1.MouseMove
        If move_item Then
            On Error GoTo quit
            Dim item2move As New Label
            item2move.Text = TreeView1.SelectedNode.Text
            item2move.DoDragDrop(item2move.Text, DragDropEffects.Copy)
            Debug.Print(TreeView1.SelectedNode.Text)
        End If
        move_item = False
quit:
        Exit Sub
    End Sub

    Public Sub DataGridView1_CellMouseEnter(ByVal sender As Object, ByVal e As System.Windows.Forms.DataGridViewCellEventArgs) Handles DataGridView1.CellMouseEnter
        Debug.Print("CellMouseEnter event raised")
        Try
            Me.DataGridView1.CurrentCell = Me.DataGridView1(DataGridView1.Columns(e.ColumnIndex).DisplayIndex, DataGridView1.Rows(e.RowIndex).Index)
        Catch
        End Try
    End Sub

    Private Sub DataGridView1_DragDrop(sender As Object, e As DragEventArgs) Handles DataGridView1.DragDrop

        With DataGridView1
            Dim Col As Integer = .CurrentCell.ColumnIndex
            Dim row As Integer = .CurrentCell.RowIndex
            .Item(Col, row).Value = e.Data.GetDataPresent(DataFormats.Text)
        End With
    End Sub

    Private Sub DataGridView1_DragEnter(sender As Object, e As DragEventArgs) Handles DataGridView1.DragEnter
        If (e.Data.GetDataPresent(DataFormats.Text)) Then
            e.Effect = DragDropEffects.Copy
        Else
            e.Effect = DragDropEffects.None
        End If
    End Sub



    'Sample json for textbox
    '{data:[{"symbol":"A","name":"Agilent Technologies Inc.","date":"2018-03-19","isEnabled":true,"type":"cs","iexId":"2"},{"symbol":"AA","name":"Alcoa Corporation","date":"2018-03-19","isEnabled":true,"type":"cs","iexId":"12042"},{"symbol":"AABA","name":"Altaba Inc.","date":"2018-03-19","isEnabled":true,"type":"cs","iexId":"7653"},{"symbol":"AAC","name":"AAC Holdings Inc.","date":"2018-03-19","isEnabled":true,"type":"cs","iexId":"9169"},{"symbol":"AADR","name":"AdvisorShares Dorsey Wright ADR","date":"2018-03-19","isEnabled":true,"type":"et","iexId":"5"},{"symbol":"AAL","name":"American Airlines Group Inc.","date":"2018-03-19","isEnabled":true,"type":"cs","iexId":"8148"},{"symbol":"AAMC","name":"Altisource Asset Management Corp Com","date":"2018-03-19","isEnabled":true,"type":"cs","iexId":"7760"},{"symbol":"AAME","name":"Atlantic American Corporation","date":"2018-03-19","isEnabled":true,"type":"cs","iexId":"7"},{"symbol":"AAN","name":"Aaron's Inc.","date":"2018-03-19","isEnabled":true,"type":"cs","iexId":"8"},{"symbol":"AAOI","name":"Applied Optoelectronics Inc.","date":"2018-03-19","isEnabled":true,"type":"cs","iexId":"7790"},{"symbol":"AAON","name":"AAON Inc.","date":"2018-03-19","isEnabled":true,"type":"cs","iexId":"9"},{"symbol":"AAP","name":"Advance Auto Parts Inc W/I","date":"2018-03-19","isEnabled":true,"type":"cs","iexId":"10"},{"symbol":"AAPL","name":"Apple Inc.","date":"2018-03-19","isEnabled":true,"type":"cs","iexId":"11"},{"symbol":"AAT","name":"American Assets Trust Inc.","date":"2018-03-19","isEnabled":true,"type":"cs","iexId":"12"},{"symbol":"AAU","name":"Almaden Minerals Ltd.","date":"2018-03-19","isEnabled":true,"type":"cs","iexId":"13"},{"symbol":"AAV","name":"Advantage Oil & Gas Ltd","date":"2018-03-19","isEnabled":true,"type":"cs","iexId":"14"},{"symbol":"AAWW","name":"Atlas Air Worldwide Holdings","date":"2018-03-19","isEnabled":true,"type":"cs","iexId":"15"}]}

End Class

完整代码：注意一些示例JSON在最后的注释中，将其放在RichtextBox中 - rtb_inputjson

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控件及其名称：

Answer 1

使用Drop()事件，您的优势在于，当Private Sub dataGridView1_DragEnter(sender As Object, e As DragEventArgs) e.Effect = If(e.Data.GetDataPresent(DataFormats.Text) = True, DragDropEffects.Copy, DragDropEffects.None) Private Sub dataGridView1_DragDrop(sender As Object, e As DragEventArgs) 'Check whether the current Cell supports this Drop() DataGridView1.CurrentCell.Value = e.Data.GetDataPresent(DataFormats.Text).ToString() End Sub Private Sub dataGridView1_DragOver(sender As Object, e As DragEventArgs) Dim ClientAreaLocation As Point = dataGridView1.PointToClient(New Point(e.X, e.Y)) Dim CellPosition As DataGridView.HitTestInfo = dataGridView1.HitTest(ClientAreaLocation.X, ClientAreaLocation.Y) If CellPosition.ColumnIndex > -1 AndAlso CellPosition.RowIndex > -1 Then 'Enable if this Cell supports this Drop() dataGridView1.CurrentCell = dataGridView1(CellPosition.ColumnIndex, CellPosition.RowIndex) End If End Sub操作生效时，用户可以获得单元格的视觉反馈，因为鼠标悬停的单元格变为活动状态，跟随鼠标移动。

您还可以验证鼠标指针下的单元格是否可以接收掉落，如果没有，则可以避免选择它。

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Answer 2

我最终使用HittestInfo来获取正确的单元格，而不是选择CellMouseEnter的单元格，我决定在序列的开头取消选择所有单元格。我还添加了一个悬停以选择正确的树视图项。

Private Sub TreeView1_MouseDown(sender As Object, e As MouseEventArgs) Handles TreeView1.MouseDown
    move_item = True
End Sub

Private Sub TreeView1_MouseMove(sender As Object, e As MouseEventArgs) Handles TreeView1.MouseMove

    If move_item Then
        On Error GoTo quit
        'Deselect all cells in datagridview
        DataGridView1.ClearSelection()
        DataGridView1.CurrentCell = Nothing

        'Begin Drag/drop
        Dim item2move As New Label
        item2move.Text = TreeView1.SelectedNode.Text
        item2move.DoDragDrop(item2move.Text, DragDropEffects.Copy)

    End If
    move_item = False
quit:
    Exit Sub
End Sub


Private Sub DataGridView1_DragEnter(ByVal sender As Object, ByVal e As System.Windows.Forms.DragEventArgs) Handles DataGridView1.DragEnter
    If (e.Data.GetDataPresent(DataFormats.Text)) Then
        e.Effect = DragDropEffects.Copy
    Else
        e.Effect = DragDropEffects.None
    End If
End Sub


Private Sub DataGridView1_DragDrop(ByVal sender As Object, ByVal e As System.Windows.Forms.DragEventArgs) Handles DataGridView1.DragDrop
    Try
        Dim clickedcell As DataGridViewCell
        Dim ptscreen As New Point(e.X, e.Y)
        Dim ptclient = DataGridView1.PointToClient(ptscreen)

        Dim hit As DataGridView.HitTestInfo = DataGridView1.HitTest(ptclient.X, ptclient.Y)
        clickedcell = DataGridView1.Rows(hit.RowIndex).Cells(hit.ColumnIndex)
        DataGridView1.Item(clickedcell.ColumnIndex, clickedcell.RowIndex).Value = e.Data.GetData(DataFormats.Text).ToString

    Catch
    End Try
End Sub

Private Sub TreeView1_NodeMouseHover(sender As Object, e As TreeNodeMouseHoverEventArgs) Handles TreeView1.NodeMouseHover
    TreeView1.SelectedNode = e.Node
End Sub

Mousedown事件与cellmouseenter事件冲突

2 个答案: