如何检测父窗体的属性何时发生变化？ [英] How can I detect when parentform's properties are changing?

问题描述

我最近正在处理几个 UserControls ，这次是自定义 TitleBar 。我想做的是检测当设计时间 ParentForm的属性（例如 ControlBox ）正由开发人员更改 b>然后更新我的 TitleBar 。



我尝试了什么：



所以我在 UserControl 中添加了计时器来完成工作。它有效，但我认为这不是最合适的方法......

 私有  Sub  Timer_Tick（sender  As   Object ，e  As  EventArgs）句柄 Timer.Tick 
 我 .ControlBox =  Me  .ParentForm.ControlBox 
  If  ParentForm.ControlBox =  True  然后 ControlsBox_FlowLayoutPanel.Visible =  True   Else  ControlsBox_FlowLayoutPanel.Visible =  False  
 如果 ParentForm .MinimizeBox =  True  然后 MinimizeButton_PictureBox .Visible =  True   Else  MinimizeButton_PictureBox.Visible =  False  
  Me  .MinimizeBox =  Me  .ParentForm.MinimizeBox 
 如果 ParentForm.MaximizeBox =  True  那么 MaximizeButton_PictureBox.Visible =  True   Else  MaximizeButton_PictureBox.Visible =  False  
 我 .MaximizeBox = 我 .ParentForm.MaximizeBox 
 结束  Sub  

有没有其他方法可以做到而不是使用定时器？例如，要检测 ParentForm 的文本属性，然后更新我的 UserControl 文字，我这样做......

 私人  WithEvents  _ParentForm  As 表格
 
 受保护的 覆盖  Sub  OnParentChanged（e  As  EventArgs）
  MyBase  .OnParentChanged（e）
 _ParentForm = 我 .ParentForm 
 调用 ParentForm_TextChanged（）
 结束  Sub  
 
 私有  Sub  ParentForm_TextChanged（）< span class =code-keyword>句柄 _ParentForm.TextChanged 
 如果 _ParentForm   没什么 然后 
 FormTitle_Label.Text = FormTitle_Label.Text 
 否则 
 FormTitle_Label .Text = _ParentForm.Text 
 结束 如果 
 Invalidate（）
 结束  Sub  

ControlBox <等属性是否有类似内容？ / b>， MinimizeBox 和 MaximizeBox ？

解决方案

我不确定你到底想要什么实现。从来没有......而不是使用Timer你可以采取ParentForm的StyleChanged-Event。

你们每个请求的属性（ControlBox，MinimizeBox，MaximizeBox等）正在改变的风格形成并举起这个活动 - 所以你可以在这个新方法中更好地调用你的Timer_Tick-Method的内容...



为了检测ParentForm，我不会使用OnParentChanged-Method ...我会使用OnHandleCreated-Method ......但是结果会是一样的......

这里有一个关于我们如何检测ParentForm的示例属性正在改变，然后做我们的东西...

 私有  WithEvents  _ParentForm  As 表格
 
 受保护 覆盖  Sub  OnParentChanged（e 正如 EventArgs）
  MyBase  .OnParentChanged（e）
 _ParentForm = 我 .ParentForm 
 调用 ParentForm_TextChanged（）
 调用 ParentForm_StyleChanged（）
 结束  Sub  
 
 私有  Sub  ParentForm_TextChanged（）句柄 _ParentForm.TextChanged 
  If  _ParentForm  IsNot   Nothing  然后 FormTitle_Label.Text = _ParentForm.Text 
 Invalidate（）
 结束  Sub  
 
 私有  Sub  ParentForm_StyleChanged（）句柄 _ParentForm.StyleChanged 
 如果 _ParentForm  IsNot  无 然后 
 如果 _ParentForm.ControlBox =  True  然后 ControlsBox_FlowLayoutPanel.Visible =  True  其他 ControlsBox_FlowLayoutPanel.Visible =  False  
 如果 _ParentForm.MinimizeBox =  True  那么 MinimizeButton_PictureBox.Visible =  True   Else  MinimizeButton_PictureBox.Visible =  False  
 如果 _ParentForm.MaximizeBox =  True  然后 MaximizeButton_PictureBox.Visible =  True   Else  MaximizeButton_PictureBox.Visible =  False  
 结束 如果 
 结束  Sub  

I am working on a couple of UserControls lately and this time is a custom TitleBar. What I want to do is to detect when ParentForm's properties (like ControlBox for example) is changing by developer in Design Time and then update my TitleBar.

What I have tried:

So I added a Timer into my UserControl to do this "work". It works, but I think this isn't the most appropriate approach...

Private Sub Timer_Tick(sender As Object, e As EventArgs) Handles Timer.Tick
	Me.ControlBox = Me.ParentForm.ControlBox
	If ParentForm.ControlBox = True Then ControlsBox_FlowLayoutPanel.Visible = True Else ControlsBox_FlowLayoutPanel.Visible = False
	If ParentForm.MinimizeBox = True Then MinimizeButton_PictureBox.Visible = True Else MinimizeButton_PictureBox.Visible = False
	Me.MinimizeBox = Me.ParentForm.MinimizeBox
	If ParentForm.MaximizeBox = True Then MaximizeButton_PictureBox.Visible = True Else MaximizeButton_PictureBox.Visible = False
	Me.MaximizeBox = Me.ParentForm.MaximizeBox
End Sub

Is there any other way to do that and not by using a Timer? For example, to detect ParentForm's Text property and then update my UserControl's Text, I do something like this...

Private WithEvents _ParentForm As Form

Protected Overrides Sub OnParentChanged(e As EventArgs)
	MyBase.OnParentChanged(e)
	_ParentForm = Me.ParentForm
	Call ParentForm_TextChanged()
End Sub

Private Sub ParentForm_TextChanged() Handles _ParentForm.TextChanged
	If _ParentForm Is Nothing Then
		FormTitle_Label.Text = FormTitle_Label.Text
	Else
		FormTitle_Label.Text = _ParentForm.Text
	End If
	Invalidate()
End Sub

Is there anything similar for properties like ControlBox, MinimizeBox and MaximizeBox?

解决方案

I'm not quiet sure what you exactly trying to achieve. Never the less ... instead of using a Timer you can take the StyleChanged-Event of the ParentForm.
Each of you requested Properties (ControlBox, MinimizeBox, MaximizeBox etc.) are changing the Style of the Form and raise this Event - so you can call the Content of your Timer_Tick-Method better in this new method ...

For detecting the ParentForm I would not use the OnParentChanged-Method ... I would use the OnHandleCreated-Method ... but the result will be the same ...

Well, here is an example on how we can detect when ParentForm's properties are changing and then do our stuff...

Private WithEvents _ParentForm As Form

Protected Overrides Sub OnParentChanged(e As EventArgs)
	MyBase.OnParentChanged(e)
	_ParentForm = Me.ParentForm
	Call ParentForm_TextChanged()
	Call ParentForm_StyleChanged()
End Sub

Private Sub ParentForm_TextChanged() Handles _ParentForm.TextChanged
	If _ParentForm IsNot Nothing Then FormTitle_Label.Text = _ParentForm.Text
	Invalidate()
End Sub

Private Sub ParentForm_StyleChanged() Handles _ParentForm.StyleChanged
	If _ParentForm IsNot Nothing Then
		If _ParentForm.ControlBox = True Then ControlsBox_FlowLayoutPanel.Visible = True Else ControlsBox_FlowLayoutPanel.Visible = False
		If _ParentForm.MinimizeBox = True Then MinimizeButton_PictureBox.Visible = True Else MinimizeButton_PictureBox.Visible = False
		If _ParentForm.MaximizeBox = True Then MaximizeButton_PictureBox.Visible = True Else MaximizeButton_PictureBox.Visible = False
	End If
End Sub

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