关于.net：自定义Winforms控件中的基准对齐线

Baseline snaplines in custom Winforms controls

我有一个带有文本框的自定义用户控件，我想在该自定义控件之外显示(文本框内文本的)基准线。我知道您创建了一个设计器(从ControlDesigner继承)，并且重写了SnapLines以访问细线，但是我想知道如何获取自定义用户控件公开的控件的文本基线。

作为Miral答案的更新，..以下是一些"遗漏步骤"，对于正在寻找如何执行此操作的新手。：)上面的C＃代码几乎已准备就绪，只是更改了一些值以引用将要修改的UserControl。

可能需要的参考文献：
System.Design(@robyaw)

需要的用途：

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using System.Windows.Forms.Design;
using System.Windows.Forms.Design.Behavior;
using System.ComponentModel;
using System.ComponentModel.Design;
using System.Collections;

在您的UserControl上，您需要以下属性：

1	[Designer(typeof(MyCustomDesigner))]

然后，您需要一个"设计器"类，该类将具有SnapLines覆盖：

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private class MyCustomerDesigner : ControlDesigner {
public override IList SnapLines {
get {
/* Code from above */
IList snapLines = base.SnapLines;

// *** This will need to be modified to match your user control
MyControl control = Control as MyControl;
if (control == null) { return snapLines; }

// *** This will need to be modified to match the item in your user control
// This is the control in your UC that you want SnapLines for the entire UC
IDesigner designer = TypeDescriptor.CreateDesigner(
control.textBoxValue, typeof(IDesigner));
if (designer == null) { return snapLines; }

// *** This will need to be modified to match the item in your user control
designer.Initialize(control.textBoxValue);

using (designer)
{
ControlDesigner boxDesigner = designer as ControlDesigner;
if (boxDesigner == null) { return snapLines; }

foreach (SnapLine line in boxDesigner.SnapLines)
{
if (line.SnapLineType == SnapLineType.Baseline)
{
// *** This will need to be modified to match the item in your user control
snapLines.Add(new SnapLine(SnapLineType.Baseline,
line.Offset + control.textBoxValue.Top,
line.Filter, line.Priority));
break;
}
}
}

return snapLines;
}

}
}
}

我只是有一个类似的需求，我这样解决了它：

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public override IList SnapLines
{
get
{
IList snapLines = base.SnapLines;

MyControl control = Control as MyControl;
if (control == null) { return snapLines; }

IDesigner designer = TypeDescriptor.CreateDesigner(
control.textBoxValue, typeof(IDesigner));
if (designer == null) { return snapLines; }
designer.Initialize(control.textBoxValue);

using (designer)
{
ControlDesigner boxDesigner = designer as ControlDesigner;
if (boxDesigner == null) { return snapLines; }

foreach (SnapLine line in boxDesigner.SnapLines)
{
if (line.SnapLineType == SnapLineType.Baseline)
{
snapLines.Add(new SnapLine(SnapLineType.Baseline,
line.Offset + control.textBoxValue.Top,
line.Filter, line.Priority));
break;
}
}
}

return snapLines;
}
}

这样，它实际上为子控件创建了一个临时子设计器，以找出"实际"基线对齐线在哪里。

这似乎在测试中表现合理，但是如果担心性能(并且内部文本框不移动)，则可以将大部分代码提取到Initialize方法中。

这也假定文本框是UserControl的直接子级。如果还有其他影响布局的控件，则偏移量计算将变得更加复杂。

感谢所有这些人的帮助。这是一项艰巨的任务。在每个UserControl中都有一个私有子类的想法不是很好。

我想出了这个基础课程来提供帮助。

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[Designer(typeof(UserControlSnapLineDesigner))]
public class UserControlBase : UserControl
{
protected virtual Control SnapLineControl { get { return null; } }

private class UserControlSnapLineDesigner : ControlDesigner
{
public override IList SnapLines
{
get
{
IList snapLines = base.SnapLines;

Control targetControl = (this.Control as UserControlBase).SnapLineControl;

if (targetControl == null)
return snapLines;

using (ControlDesigner controlDesigner = TypeDescriptor.CreateDesigner(targetControl,
typeof(IDesigner)) as ControlDesigner)
{
if (controlDesigner == null)
return snapLines;

controlDesigner.Initialize(targetControl);

foreach (SnapLine line in controlDesigner.SnapLines)
{
if (line.SnapLineType == SnapLineType.Baseline)
{
snapLines.Add(new SnapLine(SnapLineType.Baseline, line.Offset + targetControl.Top,
line.Filter, line.Priority));
break;
}
}
}
return snapLines;
}
}
}
}

接下来，从此基础派生UserControl：

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public partial class MyControl : UserControlBase
{
protected override Control SnapLineControl
{
get
{
return txtTextBox;
}
}

...

}

再次感谢您发布此信息。

VB.Net版本：
注意：您必须将txtDescription更改为文本框或使用的其他内部控件名称。和ctlUserControl到您的usercontrol名称

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<Designer(GetType(ctlUserControl.MyCustomDesigner))> _
Partial Public Class ctlUserControl
'...
'Your Usercontrol class specific code
'...
Class MyCustomDesigner
Inherits ControlDesigner
Public Overloads Overrides ReadOnly Property SnapLines() As IList
Get
' Code from above

Dim lines As IList = MyBase.SnapLines

' *** This will need to be modified to match your user control
Dim control__1 As ctlUserControl = TryCast(Me.Control, ctlUserControl)
If control__1 Is Nothing Then Return lines

' *** This will need to be modified to match the item in your user control
' This is the control in your UC that you want SnapLines for the entire UC
Dim designer As IDesigner = TypeDescriptor.CreateDesigner(control__1.txtDescription, GetType(IDesigner))
If designer Is Nothing Then
Return lines
End If

' *** This will need to be modified to match the item in your user control
designer.Initialize(control__1.txtDescription)

Using designer
Dim boxDesigner As ControlDesigner = TryCast(designer, ControlDesigner)
If boxDesigner Is Nothing Then
Return lines
End If

For Each line As SnapLine In boxDesigner.SnapLines
If line.SnapLineType = SnapLineType.Baseline Then
' *** This will need to be modified to match the item in your user control
lines.Add(New SnapLine(SnapLineType.Baseline, line.Offset + control__1.txtDescription.Top, line.Filter, line.Priority))
Exit For
End If
Next
End Using

Return lines
End Get
End Property
End Class

End Class

您走在正确的轨道上。您将需要在设计器中覆盖SnapLines属性，并执行以下操作：

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Public Overrides ReadOnly Property SnapLines() As System.Collections.IList
Get
Dim snapLinesList As ArrayList = TryCast(MyBase.SnapLines, ArrayList)

Dim offset As Integer
Dim ctrl As MyControl = TryCast(Me.Control, MyControl)
If ctrl IsNot Nothing AndAlso ctrl.TextBox1 IsNot Nothing Then
offset = ctrl.TextBox1.Bottom - 5
End If

snapLinesList.Add(New SnapLine(SnapLineType.Baseline, offset, SnapLinePriority.Medium))

Return snapLinesList

End Get
End Property

在此示例中，用户控件包含一个文本框。该代码添加了一个新的捕捉线，该捕捉线表示文本框的基线。重要的是要正确计算偏移量。