Vb.net 如何仅在特定条件下显示文本框的工具提示

在VB6中，我可以轻松创建一个气球消息，该消息将显示在文本框旁边。 文本一旦更改，它就会自动消失。 我可以使用这个气球工具提示来显示诸如“输入有效的电子邮件地址！”

我使用Windows API创建了这个气球。我已经附上下面的代码

这方面没有框架解决方案吗？ 谢谢你的帮助

Option Explicit

Private Const ECM_FIRST = &H1500                    '// Edit control messages

Private Const EM_SETCUEBANNER = (ECM_FIRST + 1)
Private Const EM_GETCUEBANNER = (ECM_FIRST + 2)     '// Set the cue banner with the lParm = LPCWSTR

Private Type EDITBALLOONTIP
    cbStruct As Long
    pszTitle As Long
    pszText As Long
    ttiIcon As Long ' ; // From TTI_*
End Type

Private Const EM_SHOWBALLOONTIP = (ECM_FIRST + 3)      '// Show a balloon tip associated to the edit control
Private Const EM_HIDEBALLOONTIP = (ECM_FIRST + 4)       '// Hide any balloon tip associated with the edit control
Private Declare Function SendMessageW Lib "user32" ( _
   ByVal hwnd As Long, _
   ByVal wMsg As Long, _
   ByVal wParam As Long, _
   lParam As Any) As Long

Private Declare Function LocalAlloc Lib "kernel32" (ByVal wFlags As Long, ByVal wBytes As Long) As Long
Private Declare Function LocalLock Lib "kernel32" (ByVal hMem As Long) As Long
Private Declare Function LocalUnlock Lib "kernel32" (ByVal hMem As Long) As Long
Private Declare Function LocalFree Lib "kernel32" (ByVal hMem As Long) As Long
Private Const GMEM_FIXED = &H0
Private Const GMEM_ZEROINIT = &H40
Private Const GPTR = (GMEM_FIXED Or GMEM_ZEROINIT)

Private m_hWnd As Long
Private m_sCueBanner As String
Private m_sTitle As String
Private m_sText As String
Private m_eIcon As BalloonTipIconConstants

Public Property Let TextBox(txtThis As TextBox)
   m_hWnd = txtThis.hwnd
End Property

Public Property Let CueBanner(ByVal value As String)
   m_sCueBanner = value
   setCueBanner
End Property
Public Property Get CueBanner() As String
   CueBanner = m_sCueBanner
End Property
Public Property Let BalloonTipTitle(ByVal value As String)
   m_sTitle = value
End Property
Public Property Get BalloonTipTitle() As String
   BalloonTipTitle = m_sTitle
End Property
Public Property Let BalloonTipText(ByVal value As String)
   m_sText = value
End Property
Public Property Get BalloonTipText() As String
   BalloonTipText = m_sText
End Property
Public Property Let BalloonTipIcon(ByVal value As BalloonTipIconConstants)
   m_eIcon = value
End Property
Public Property Get BalloonTipIcon() As BalloonTipIconConstants
   BalloonTipIcon = m_eIcon
End Property

Public Sub ShowBalloonTip()

Dim lR As Long
   Dim tEBT As EDITBALLOONTIP
   tEBT.cbStruct = LenB(tEBT)
   tEBT.pszText = StrPtr(m_sText)
   tEBT.pszTitle = StrPtr(m_sTitle)
   tEBT.ttiIcon = m_eIcon
   lR = SendMessageW(m_hWnd, EM_SHOWBALLOONTIP, 0, tEBT)
End Sub
Public Sub HideBalloonTip()
    Dim lR As Long
   lR = SendMessageLongW(m_hWnd, EM_HIDEBALLOONTIP, 0, 0)
   Debug.Print lR
End Sub
Private Sub setCueBanner()
Dim lR As Long
   ' Reports success, but doesn'/t actually work...
   ' (is this because the VB text box is ANSI?)
   lR = SendMessageLongW(m_hWnd, EM_SETCUEBANNER, 0, StrPtr(m_sCueBanner))
   Debug.Print lR
End Sub

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可以像这样设置工具提示

Dim toolTip1 As New ToolTip()

toolTip1.SetToolTip(Me.textbox1, "Hello World")

并使用隐藏工具提示

toolTip1.SetToolTip(Me.textbox1, "")

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请注意，您还可以将

工具提示

-控件添加到工具箱的窗体中，而不是以编程方式创建它。它神奇地将

工具提示

-属性添加到属性窗口中的所有控件中，您可以在其中输入工具提示消息。但是，控件本身不会获得

ToolTip

属性，您只能通过代码中的

ToolTip.SetToolTip

方法来设置或删除工具提示。

我认为这只能通过API的方式来实现。 我在这里找到了我的VB6示例的完美移植：

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为什么不使用内置工具提示组件？那些VB6声明在VB.Net中不起作用。