自定义Winforms控件中的基线线

I have a custom user control with a textbox on it and I'd like to expose the baseline (of the text in the textbox) snapline outside of the custom control. I know that you create a designer (inherited from ControlDesigner) and override SnapLines to get access to the snaplines, but I'm wondering how to get the text baseline of a control that I have exposed by my custom user control.

我有一个带有文本框的自定义用户控件，我想在自定义控件之外公开基线(文本框中的文本)。我知道您创建了一个设计器(继承自ControlDesigner)并覆盖了SnapLines以访问SnapLines，但是我想知道如何获得我的自定义用户控件公开的控件的文本基线。

5 个解决方案

#1

I just had a similar need, and I solved it like this:

我也有类似的需要，我就这样解决了:

 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;
    }
}

This way it's actually creating a temporary sub-designer for the subcontrol in order to find out where the "real" baseline snapline is.

这样，它实际上是为子控件创建一个临时子设计器，以便找出“真正的”基线线在哪里。

This seemed reasonably performant in testing, but if perf becomes a concern (and if the internal textbox doesn't move) then most of this code can be extracted to the Initialize method.

这在测试中似乎表现得很好，但是如果perf成为一个关注点(如果内部文本框不移动)，那么可以将大部分代码提取到Initialize方法中。

This also assumes that the textbox is a direct child of the UserControl. If there are other layout-affecting controls in the way then the offset calculation becomes a bit more complicated.

这也假定文本框是UserControl的直接子控件。如果存在其他影响layout的控件，那么偏移计算将变得更加复杂。

#2

As an update to the Miral's answer.. here are a few of the "missing steps", for someone new that's looking how to do this. :) The C# code above is almost 'drop-in' ready, with the exception of changing a few of the values to reference the UserControl that will be modified.

作为Miral答案的更新。以下是一些“缺失的步骤”，对于那些正在寻找如何做到这一点的新人来说。:)上面的c#代码几乎已经准备好了，除了更改一些值以引用将要修改的UserControl之外。

Possible References Needed:
System.Design (@robyaw)

可能的引用需要:系统。设计(@robyaw)

Usings needed:

Usings需要:

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

On your UserControl you need the following Attribute:

在您的UserControl上，您需要以下属性:

[Designer(typeof(MyCustomDesigner))]

Then you need a "designer" class that will have the SnapLines override:

然后，您需要一个“设计器”类，它将具有SnapLines覆盖:

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;
}

    }
  }
}

#3

Thanks to all those for the help. This was a tough one to swallow. The thought having a private sub-class in every UserControl wasn't very palatable.

谢谢大家的帮助。这是难以下咽的。在每个用户控件中拥有一个私有子类的想法并不令人满意。

I came up with this base class to help out..

我设计了这个基础课程来帮助你。

[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;
            }
        }
    }
}

Next, derive your UserControl from this base:

接下来，从这个基础派生您的用户控件:

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

    ...

}

Thanks again for posting this.

再次感谢你发了这篇文章。

#4

VB.Net Version:
Note: you have to change the txtDescription to the Textbox or another internal control name that you use. and ctlUserControl to your usercontrol name

VB。注意:必须将txtDescription更改为文本框或使用的另一个内部控件名。以及ctlUserControl到您的usercontrol名称

<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

#5

You're on the right track. You will need to override the SnapLines property in your designr and do something like this:

你说得对。您需要重写设计中的SnapLines属性，并执行以下操作:

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

In this example the usercontrol contains a textbox. The code adds a new snapline that represents the baseline for the textbox. The important thing is to calculate the offset correctly.

在本例中，usercontrol包含一个文本框。代码添加了一个新的线来表示文本框的基线。重要的是正确计算偏移量。