教程13：实现拖拽下拉功能

在此教程中，你将在True DBGrid for WinForms中学习到如何实现drag-and-drop功能性.

为WinForms 控件安装True DBGrid

完成下面的步骤:

开始一个新的.NET工程
放置两个 C1TrueDBGrid 控件(C1TrueDBGrid1, C1TrueDBGrid2)到窗体上。并在窗体上添加三个标签，并安排它们与下面的图片看起来一样.
在C1TrueDBGrid1的C1TrueDBGrid Tasks菜单上，定位选择数据源下拉框并选择添加项目数据源。在适配器的数据源的配置向导，或者选择一个连接到 C1NWind.mdb，或者创建一个连接到数据库。在向导的选择数据库对象页面，在Customers 表选择所有字段，并在数据集名称框中键入"DsCustomers" ，然后完成向导。
在C1TrueDBGrid2的C1TrueDBGrid Tasks菜单上，定位选择数据源下拉框并选择添加工程数据源. 在适配器的数据源配置向导，或者选择一个连接到C1NWind.mdb，或者创建一个新的连接到数据库。在向导的选择你的数据库对象页面，在CallList 表选择所有字段，并在数据集名称框中键入"DsCallList" ，然后退出向导。

在Form中，添加下面的声明:

To write code in Visual Basic

Visual Basic	拷贝代码
Dim _ptStartDrag As Point Dim _dragRow As Long

To write code in C#

C#	拷贝代码
Point _ptStartDrag; long _dragRow;

Visual Studio添加下面的代码到Form1 的Load 事件来填充新的数据集:

To write code in Visual Basic

Visual Basic	拷贝代码
Me.CallListTableAdapter.Fill(Me.DsCallList.CallList) Me.CustomersTableAdapter.Fill(Me.DsCustomers.Customers)

To write code in C#

对于第一个网格(C1TrueDBGrid1) 设置AllowDrag 属性为True。同时对于第二个网格，设置AllowDrop 属性为True.
右键C1TrueDBGrid1并选择Retrieve Fields。其它网格与之相同。
在属性窗口，通过点击紧邻着Columns属性的省略号按钮，来打开C1TrueDBGrid1 的C1TrueDBGrid 设计器。
通过点击每一列的Remove Column按钮，从网格中移除除了LastName, FirstName, Company, 和Phone的所有列。为其它网格键入C1TrueDBGrid Designer 并移除除了Customer, Phone, 和CallDate的所有列。
在属性窗口设置C1TrueDBGrid1的MarqueeStyle值为o SolidCellBorder。在C1TrueDBGrid Designer 设置列3的 (Phone) NumberFormat 属性为"(###)###-####"。为第二个网格打开C1TrueDBGrid Designer并设置它的列2的NumberFormat 属性为"(###)###-####"。网格应该与下面的看起来一样：

C#	拷贝代码
this.CallListTableAdapter.Fill(this.DsCallList.CallList); this.CustomersTableAdapter.Fill(this.DsCustomers.Customers);

添加代码到你的工程

该章节描述了代码需要从C1TrueDBGrid1到C1TrueDBGrid2拖动单元格或者行的内容。此代码设想，如果你想拖动数据的全部行到C1TrueDBGrid2并为了添加新的纪录。

添加下面的子程序到工程中，为每一个网格重设MarqueeStyle属性，此方法被用作在程序中拖拽时提供可见的反馈。这个重设的程序将在一个拖拽和下拉操作总结之后被调用来执行清除。

To write code in Visual Basic

Visual Basic	拷贝代码
Private Sub ResetDragDrop() ' Turn off drag-and-drop by resetting the highlight and label text. Me._ptStartDrag = Point.Empty Me._dragRow = - 1 Me.C1TrueDBGrid1.MarqueeStyle = C1.Win.C1TrueDBGrid.MarqueeEnum.SolidCellBorder Me.C1TrueDBGrid2.MarqueeStyle = C1.Win.C1TrueDBGrid.MarqueeEnum.SolidCellBorder Me.Label3.Text = "Drag a row from the top grid and drop it on the bottom grid." End Sub

To write code in C#

C#	拷贝代码
private void ResetDragDrop() { // Turn off drag-and-drop by resetting the highlight and label text. this._ptStartDrag = Point.Empty; this._dragRow = - 1; this.c1TrueDBGrid1.MarqueeStyle = C1.Win.C1TrueDBGrid.MarqueeEnum.SolidCellBorder; this.c1TrueDBGrid2.MarqueeStyle = C1.Win.C1TrueDBGrid.MarqueeEnum.SolidCellBorder; this.label3.Text = "Drag a row from the top grid and drop it on the bottom grid."; }

键入下面的代码来处理鼠标相关联的事件:

To write code in Visual Basic

Visual Basic	拷贝代码
Private Sub C1TrueDBGrid1_MouseDown(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles C1TrueDBGrid1.MouseDown Dim row, col As Integer Me._ptStartDrag = Point.Empty Me._dragRow = - 1 If Me.C1TrueDBGrid1.CellContaining(e.X, e.Y, row, col) Then ' Save the starting point of the drag operation. Me._ptStartDrag = New Point(e.X, e.Y) Me._dragRow = row End If End Sub Private Sub C1TrueDBGrid1_MouseMove(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles C1TrueDBGrid1.MouseMove ' If we don't have an empty start drag point, then the drag has been initiated. If Not Me._ptStartDrag.IsEmpty Then ' Create a rectangle that bounds the start of the drag operation by 2 pixels. Dim r As New Rectangle(Me._ptStartDrag, Size.Empty) r.Inflate(2, 2) ' If we've moved more than 2 pixels, start the drag operation. If Not r.Contains(e.X, e.Y) Then Me.C1TrueDBGrid1.Row = Me._dragRow Me.C1TrueDBGrid1.MarqueeStyle = C1.Win.C1TrueDBGrid.MarqueeEnum.HighlightRow Me.C1TrueDBGrid1.DoDragDrop(Me._dragRow, DragDropEffects.Copy) End If End If End Sub

To write code in C#

C#	拷贝代码
private void C1TrueDBGrid1_MouseDown(object sender, System.Windows.Forms.MouseEventArgs e) { int row, col; this._ptStartDrag = Point.Empty; this._dragRow = - 1; if (this.c1TrueDBGrid1.CellContaining(e.X, e.Y, row, col) ) { // Save the starting point of the drag operation. this._ptStartDrag = new Point(e.X, e.Y); this._dragRow = row; } } private void C1TrueDBGrid1_MouseMove(object sender, System.Windows.Forms.MouseEventArgs e) { // If we don't have an empty start drag point, then the drag has been initiated. if (!this._ptStartDrag.IsEmpty ) { // Create a rectangle that bounds the start of the drag operation by 2 pixels. Rectangle r = new Rectangle(this._ptStartDrag, Size.Empty); r.Inflate(2, 2); // If we've moved more than 2 pixels, start the drag operation. if (!r.Contains(e.X, e.Y) ) { this.c1TrueDBGrid1.Row = this._dragRow; this.c1TrueDBGrid1.MarqueeStyle = C1.Win.C1TrueDBGrid.MarqueeEnum.HighlightRow; this.c1TrueDBGrid1.DoDragDrop(this._dragRow, DragDropEffects.Copy); } } }

键入下面的代码来处理拖拽和下拉事件:

To write code in Visual Basic

Visual Basic	拷贝代码
Private Sub C1TrueDBGrid2_DragEnter(ByVal sender As Object, ByVal e As System.Windows.Forms.DragEventArgs) Handles C1TrueDBGrid2.DragEnter Me.Label3.Text = "Create a new record when dropped..." e.Effect = DragDropEffects.Copy End Sub Private Sub C1TrueDBGrid2_DragDrop(ByVal sender As Object, ByVal e As System.Windows.Forms.DragEventArgs) Handles C1TrueDBGrid2.DragDrop Try Dim row As Integer = CInt(e.Data.GetData(GetType(Integer))) ' Use the grid's indexer to get some data. Dim custname As String = Me.C1TrueDBGrid1(row, "FirstName").ToString() ' Use the CellText() method to get some data. custname += " " + Me.C1TrueDBGrid1.Columns("LastName").CellText(row) ' Use the CellValue() method to get some data. custname += " " + Me.C1TrueDBGrid1.Columns("Company").CellValue(row).ToString() ' Add a new row to the data set for the bottom grid. Dim drv As DataRowView = Me.DsCallList.CallList.DefaultView.AddNew() drv("CallDate") = DateTime.Now drv("Customer") = custname drv("Phone") = Me.C1TrueDBGrid1.Columns("Phone").Value.ToString() drv.EndEdit() Me.C1TrueDBGrid2.MoveLast() Me.C1TrueDBGrid2.Select() ' Commit changes to the database. Dim inserted As DataSet = Me.DsCallList.GetChanges(DataRowState.Added) If Not (inserted Is Nothing) Then Me.CallListTableAdapter.Update(inserted) End If Me.ResetDragDrop() Catch ex As System.Exception MessageBox.Show(ex.Message) End Try End Sub

Visual Basic

拷贝代码

Private Sub C1TrueDBGrid2_DragEnter(ByVal sender As Object, ByVal e As System.Windows.Forms.DragEventArgs) Handles C1TrueDBGrid2.DragEnter
    Me.Label3.Text = "Create a new record when dropped..."
    e.Effect = DragDropEffects.Copy
End Sub
 
Private Sub C1TrueDBGrid2_DragDrop(ByVal sender As Object, ByVal e As System.Windows.Forms.DragEventArgs) Handles C1TrueDBGrid2.DragDrop
    Try
        Dim row As Integer = CInt(e.Data.GetData(GetType(Integer)))
 
        ' Use the grid's indexer to get some data.
        Dim custname As String = Me.C1TrueDBGrid1(row, "FirstName").ToString()
 
        ' Use the CellText() method to get some data.
        custname += " " + Me.C1TrueDBGrid1.Columns("LastName").CellText(row)
 
        ' Use the CellValue() method to get some data.
        custname += " " + Me.C1TrueDBGrid1.Columns("Company").CellValue(row).ToString()
 
        ' Add a new row to the data set for the bottom grid.
        Dim drv As DataRowView = Me.DsCallList.CallList.DefaultView.AddNew()
        drv("CallDate") = DateTime.Now
        drv("Customer") = custname
        drv("Phone") = Me.C1TrueDBGrid1.Columns("Phone").Value.ToString()
        drv.EndEdit()
        Me.C1TrueDBGrid2.MoveLast()
        Me.C1TrueDBGrid2.Select()
 
        ' Commit changes to the database.
        Dim inserted As DataSet = Me.DsCallList.GetChanges(DataRowState.Added)
        If Not (inserted Is Nothing) Then
            Me.CallListTableAdapter.Update(inserted)
        End If
        Me.ResetDragDrop()

    Catch ex As System.Exception
        MessageBox.Show(ex.Message)
    End Try
End Sub

To write code in C#

C#	拷贝代码
private void C1TrueDBGrid2_DragEnter(object sender, System.Windows.Forms.DragEventArgs e) { this.label3.Text = "Create a new record when dropped..."; e.Effect = DragDropEffects.Copy; } private void C1TrueDBGrid2_DragDrop(object sender, System.Windows.Forms.DragEventArgs e) { try { int row = (int)e.Data.GetData(typeof(int)); // Use the grid's indexer to get some data. string custname = this.c1TrueDBGrid1[row, "FirstName"].ToString(); // Use the CellText() method to get some data. custname += " " + this.c1TrueDBGrid1.Columns["LastName"].CellText(row); // Use the CellValue() method to get some data. custname += " " + this.c1TrueDBGrid1.Columns["Company"].CellValue(row).ToString(); // Add a new row to the data set for the bottom grid. DataRowView drv = this.DsCallList.CallList.DefaultView.AddNew(); drv["CallDate"] = DateTime.Now; drv["Customer"] = custname; drv["Phone"] = this.c1TrueDBGrid1.Columns["Phone"].Value.ToString(); drv.EndEdit(); this.c1TrueDBGrid2.MoveLast(); this.c1TrueDBGrid2.Select(); // Commit changes to the database. DataSet inserted = this.DsCallList.GetChanges(DataRowState.Added); if (! (inserted == null) ) { this.CallListTableAdapter.Update(inserted); } this.ResetDragDrop(); } catch (System.Exception ex) { MessageBox.Show(ex.Message); } }

拷贝代码

private void C1TrueDBGrid2_DragEnter(object sender,  System.Windows.Forms.DragEventArgs e) 
{
    this.label3.Text = "Create a new record when dropped...";
    e.Effect = DragDropEffects.Copy;
}
 
private void C1TrueDBGrid2_DragDrop(object sender,  System.Windows.Forms.DragEventArgs e) 
{
    try 
    {
        int row = (int)e.Data.GetData(typeof(int));
 
        // Use the grid's indexer to get some data.
        string  custname = this.c1TrueDBGrid1[row, "FirstName"].ToString();
 
        // Use the CellText() method to get some data.
        custname += " " + this.c1TrueDBGrid1.Columns["LastName"].CellText(row);
 
        // Use the CellValue() method to get some data.
        custname += " " + this.c1TrueDBGrid1.Columns["Company"].CellValue(row).ToString();
 
        // Add a new row to the data set for the bottom grid.
        DataRowView drv = this.DsCallList.CallList.DefaultView.AddNew();
        drv["CallDate"] = DateTime.Now;
        drv["Customer"] = custname;
        drv["Phone"] = this.c1TrueDBGrid1.Columns["Phone"].Value.ToString();
        drv.EndEdit();
        this.c1TrueDBGrid2.MoveLast();
        this.c1TrueDBGrid2.Select();
 
        // Commit changes to the database.
        DataSet inserted = this.DsCallList.GetChanges(DataRowState.Added);
        if (! (inserted == null) ) 
        {
            this.CallListTableAdapter.Update(inserted);
        }
         this.ResetDragDrop();

    } 
    catch (System.Exception ex) 
    { 
        MessageBox.Show(ex.Message);
    }
}

运行程序并观察下面的步骤:

如果在C1TrueDBGrid1中的列的一个条目被拖拽，在C1TrueDBGrid1中的全部行以高亮显示，以表明数据的全部行被拖拽了。
当拖拽TDBGrid2，当前的单元格选取框(单元格周围固体的边框) 消失.
如果数据在C1TrueDBGrid2中被下拉，一个新的纪录从C1TrueDBGrid1的当前行使用的数据被创建.

你已经成功地完成了在C1TrueDBGrid中实现拖拽和下拉；总结教程13.