允許最終用戶移動控件

Question

我發現了一個很好的示例Here，但我遇到了一些問題。 1.它不會將控件放置在鼠標停止的正確位置，因爲控件是一個很大的控件。

1. 它可能會被推出屏幕..我希望它應該保持在屏幕邊界內。

這是我的代碼：

Public Sub Form1_MouseMove(ByVal sender As Object, ByVal e As MouseEventArgs) Handles MyControl.MouseMove 
    If Not _capturingMoves Then 
     Return 
    End If 
    X = e.X 
    Y = e.Y 
End Sub 

Public Sub Form1_MouseUp(ByVal sender As Object, ByVal e As MouseEventArgs) Handles MyControl.MouseUp 
    If _capturingMoves Then 
     ' Do any final placement 
     MyControl.Location = New Point(X, Y) 
     _capturingMoves = False 
    End If 
End Sub 

Answer 1

我寫了這樣的事情在網頁上拖動的div ...

一般的做法是，以節省鼠標按下座標，獲得座標在mouseup上，並根據差異移動對象的位置。

下面是一些示例代碼：

我做了一個DragInfo類，保持最初的鼠標COORDS和初始位置。然後我保存這些傢伙中的一個控件的Tag上鼠標按下事件：

Public Class DragInfo 
    Public Property InitialMouseCoords As Point 
    Public Property InitialLocation As Point 

    Public Sub New(ByVal MouseCoords As Point, ByVal Location As Point) 
     InitialMouseCoords = MouseCoords 
     InitialLocation = Location 
    End Sub 

    Public Function NewLocation(ByVal MouseCoords As Point) As Point 
     Dim loc As New Point(InitialLocation.X + (MouseCoords.X - InitialMouseCoords.X), InitialLocation.Y + (MouseCoords.Y - InitialMouseCoords.Y)) 
     Return loc 
    End Function 
End Class 

我的測試控制僅僅是我從工具箱中把一個面板。這可能是我猜想的任何事情。這裏是我的鼠標按下，鼠標移動和鼠標鬆開事件的處理程序面板（Panel1）：

Private Sub Panel1_MouseDown(sender As System.Object, e As System.Windows.Forms.MouseEventArgs) Handles Panel1.MouseDown 
    Panel1.Tag = New DragInfo(Form.MousePosition, Panel1.Location) 
End Sub 

Private Sub Panel1_MouseMove(sender As System.Object, e As System.Windows.Forms.MouseEventArgs) Handles Panel1.MouseMove 
    If Panel1.Tag IsNot Nothing Then 
     Dim info As DragInfo = CType(Panel1.Tag, DragInfo) 
     Dim newLoc As Point = info.NewLocation(Form.MousePosition) 
     If Me.ClientRectangle.Contains(New Rectangle(newLoc, Panel1.Size)) Then Panel1.Location = newLoc 
    End If 
End Sub 

Private Sub Panel1_MouseUp(sender As System.Object, e As System.Windows.Forms.MouseEventArgs) Handles Panel1.MouseUp 
    Panel1.Tag = Nothing 
End Sub 

你去那裏！這樣可行。請注意，mousemove方法檢查控件是否在窗體的clientrectangle內。

或者，更通用的路要走：

Private Sub MakeDraggable(ByVal Control As Control) 
    AddHandler Control.MouseDown, Sub(sender As Object, e As MouseEventArgs) StartDrag(Control) 
    AddHandler Control.MouseMove, Sub(sender As Object, e As MouseEventArgs) Drag(Control) 
    AddHandler Control.MouseUp, Sub(sender As Object, e As MouseEventArgs) StopDrag(Control) 
End Sub 
Private Sub StartDrag(ByVal Control As Control) 
    Control.Tag = New DragInfo(Form.MousePosition, Control.Location) 
End Sub 
Private Sub Drag(ByVal Control As Control) 
    If Control.Tag IsNot Nothing AndAlso TypeOf Control.Tag Is DragInfo Then 
     Dim info As DragInfo = CType(Control.Tag, DragInfo) 
     Dim newLoc As Point = info.NewLocation(Form.MousePosition) 
     If Me.ClientRectangle.Contains(New Rectangle(newLoc, Control.Size)) Then Control.Location = newLoc 
    End If 
End Sub 
Private Sub StopDrag(ByVal Control As Control) 
    Control.Tag = Nothing 
End Sub 

現在，你可以只使用MakeDraggable(Panel1)或任何其他控件，使其可拖動！

編輯：這兩個示例現在保持控件不被拖出界限。