从用户控件获取对父控件的访问权限 - C#

Question

How do I get access to the parent controls of user control in C# (winform). I am using the following code but it is not applicable on all types controls such as ListBox.

Control[] Co = this.TopLevelControl.Controls.Find("label7", true);
Co[0].Text = "HelloText"

Actually, I have to add items in Listbox placed on parent 'Form' from a user control.

Answer 1

Description

You can get the parent control using Control.Parent .

Sample

So if you have a Control placed on a form this.Parent would be your Form.

Within your Control you can do

Form parentForm = (this.Parent as Form);

More Information

• MSDN: Control.Parent Property

Update after a comment by Farid-ur-Rahman ( He was asking the question )

My Control and a listbox (listBox1) both are place on a Form (Form1). I have to add item in a listBox1 when user press a button placed in my Control.

You have two possible ways to get this done.

1. Use `Control.Parent

Sample

MyUserControl

    private void button1_Click(object sender, EventArgs e)
    {
        if (this.Parent == null || this.Parent.GetType() != typeof(MyForm))
            return;

        ListBox listBox = (this.Parent as MyForm).Controls["listBox1"] as ListBox;
        listBox.Items.Add("Test");
    }

or

2.

• put a property public MyForm ParentForm { get; set; } public MyForm ParentForm { get; set; } public MyForm ParentForm { get; set; } to your UserControl
• set the property in your Form
• assuming your ListBox is named listBox1 otherwise change the name

Sample

MyForm

public partial class MyForm : Form
{
    public MyForm()
    {
        InitializeComponent();
        this.myUserControl1.ParentForm = this;
    }
}

MyUserControl

public partial class MyUserControl : UserControl
{
    public MyForm ParentForm { get; set; }

    public MyUserControl()
    {
        InitializeComponent();
    }

    private void button1_Click(object sender, EventArgs e)
    {
        if (ParentForm == null)
            return;

        ListBox listBox = (ParentForm.Controls["listBox1"] as ListBox);
        listBox.Items.Add("Test");

    }
}

Answer 2

You can use Control.Parent to get the parent of the control or Control.FindForm to get the first parent Form the control is on. There is a difference between the two in terms of finding forms, so one may be more suitable to use than the other.:

The control's Parent property value might not be the same as the Form returned by FindForm method. For example, if a RadioButton control is contained within a GroupBox control, and the GroupBox is on a Form, the RadioButton control's Parent is the GroupBox and the GroupBox control's Parent is the Form.

Answer 3

Control has a property called Parent, which will give the parent control. http://msdn.microsoft.com/en-us/library/system.windows.forms.control.parent.aspx

eg Control p = this.Parent;

Answer 4

A generic way to get a parent of a control that I have used is:

public static T GetParentOfType<T>(this Control control)
{
    const int loopLimit = 100; // could have outside method
    var current = control;
    var i = 0;

    do
    {
        current = current.Parent;

        if (current == null) throw new Exception("Could not find parent of specified type");
        if (i++ > loopLimit) throw new Exception("Exceeded loop limit");

    } while (current.GetType() != typeof(T));

    return (T)Convert.ChangeType(current, typeof(T));
}

It needs a bit of work (eg returning null if not found or error) ... but hopefully could help someone.

Usage:

var parent = currentControl.GetParentOfType<TypeWanted>();

Enjoy!

Answer 5

You can get the Parent of a control via

myControl.Parent

See MSDN: Control.Parent

Answer 6

Not Ideal, but try this...

Change the usercontrol to Component class (In the code editor), build the solution and remove all the code with errors (Related to usercontrols but not available in components so the debugger complains about it)

Change the usercontrol back to usercontrol class...

Now it recognises the name and parent property but shows the component as non-visual as it is no longer designable.

Answer 7

According to Ruskins answer and the comments here I came up with the following (recursive) solution:

public static T GetParentOfType<T>(this Control control) where T : class
{
    if (control?.Parent == null)
        return null;

    if (control.Parent is T parent)
        return parent;

    return GetParentOfType<T>(control.Parent);
}

Answer 8

((frmMain)this.Owner).MyListControl.Items.Add("abc");

确保在frmMain MyListControl Private 以外的 Modifiers 属性中提供您想要的访问级别

Answer 9

If you want to get any parent by any child control you can use this code, and when you find the UserControl/Form/Panel or others you can call funnctions or set/get values:

Control myControl= this;
while (myControl.Parent != null)
{

    if (myControl.Parent!=null)
    {
        myControl = myControl.Parent;
        if  (myControl.Name== "MyCustomUserControl")
        {
            ((MyCustomUserControl)myControl).lblTitle.Text = "FOUND IT";
        }
    }

}