Question

我要从其他窗体中访问窗体的变量。点击主窗体中的按钮时, 我要将主窗体设置为父体, 然后将另一个窗体( 子窗体) 显示为主窗体的变量。我的点击处理程序如下:

private void btnSystem_Click(object sender, EventArgs e)
{
    Form_EnterPassword EP = new Form_EnterPassword();
    EP.Parent = this;        //error: Top-level control cannot be added to a control
    EP.ShowDialog();
}

它编译得很好,没有错误。但是, 当我运行主窗体并点击系统按钮时, 它会给我一个例外。我用同样的按钮点击其它代码( 不是我的代码) 做类似的事情, 并且不会遇到错误( 仅仅将主窗体设置为父体 ) 。

我做错什么了?

Answer 1

最佳方式是使用 EP.ShowDialog(这) 并随后使用 所有者 财产。

Answer 2

您需要设置 EP.Toplevel 属性为假。它会允许您设置其父性。

进一步阅读。

如果您只想要访问其它形式的变量和控件, 那么也许你可以以其他方式达到它, 而不是通过父母关系。

Answer 3

OK, apparently the way to do it is to call

Form_Child.ShowDialog(this)

然后我可以打电话

FromParent_aVariable = ((Form_Parent)this.Owner).aVariable;

或者如果我在命名空间属性中定义变量

FromParent_aVariable = NameSpace.Properties.Settings.Default.aVariable;

有两种方式。

Answer 4

Form_EnterPassword EP = new Form_EnterPassword();
EP.MdiParent = this;       
EP.Show();

这样尝试对我有用。您需要将主法设置为Mdicontainer = 真实的窗体属性

Answer 5

I had a similar situation recently. I was attempting something similar but by controlling the Child Forms from a different class.

Note(s): You re trying to set the Child Form(s) "TopMost" to something that does not allow it.
In this case the "MdiContainer".

<强> 要完成此任务:

• 禁用主形式“是Mdicontainer”财产(该财产的使用还是过时的)。

• 将表单顶部属性设置为真实。

• 你现在应该能够完成你的特点。

**Code Example:**

/* On your Main Form Class */

private void btnSystem_Click(object sender, EventArgs e)
{
    // Instantiate the Form_EnterPassword by passing the MainForm
    Form_EnterPassword EP = new Form_EnterPassword(this);
    EP.Show(); // No longer as modal Form to display in front.
}

/* Under your EnterPassword Form Class */

// Do not create a new Instance of MyMainForm.
// You want to use the same thread as your MainForm
private MyMainForm mainForm;

/* Constructor */
public Form_EnterPassword(MyMainForm form)
{
    mainForm = form;
    this.Owner = mainForm; // "this" refers to the: EnterPassword Form.
}

Remarks: The only additional thing that you (may) have to do, (to achieve perfection) is to check the MainForm > WindowState; and create a code block to minimize or bring the Forms to their specific state.

<强 > e:

if (WindowState == FormWindowState.Minimized)
{ /* Code to Minimize all the Child Forms. */ }

else { /* Code to bring all Forms to their "Normal" State */ }

Answer 6

以此写, 在父窗体中心进行对话框显示。

   Form_Child.StartPosition = FormStartPosition.CenterParent;
   Form_Child.ShowDialog(this);

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