我需要从另一个类访问控制表（C＃） [英] I need to access a form control from another class (C#)

问题描述

在我的表，我有一个Panel容器，命名为panelShowList。

On my form, I have one Panel container, named "panelShowList".

在我的项目，我添加了一个新的类，它是这样的：

On my project, i added a new class, which look like this:

class myNewClass
{
    private int newPanelPos = 30;
    private const int spaceBetweenElements = 30;
    private const int panelWidth = 90;
    private const int panelHeight = 40;
    private int elementPos = 0;

    private ArrayList myPanels = new ArrayList() { };

    // some irelevant methods

    public void addElementPanels(Panel dataPanel, Panel nextPanel)
    {
        myPanels.Add(dataPanel);
        myPanels.Add(nextPanel);
    }

    public void displayPanels()
    {
        foreach (Panel tmp in myPanels)
        {
            // here i'm stuck

            // i need to do something like this :
            // myMainForm.panelShowList.Controls.Add(tmp);
            // of course this is wrong! but i need a method to acces that control
        }
    }
}

基本上，我需要一种方法来从我的ArrayList中添加从我的形式panelShowList控制所有的面板。

Basically, I need a way to add all Panels from my ArrayList on "panelShowList" control from my form.

我想是这样的：

public void displayPanels()
    {
        frmMain f = new frmMain();
        foreach (Panel tmp in myPanels)
        {

            f.display(tmp);
            // where display(Panel tmp) is a function in my Form, who access
            // "panelShowList" control and add a new Panel
        }
    }

但是，如果我这样做，它只能：

But it only works if i do this:

f.ShowDialog();

和另一种形式是开放的。

and another form is open.

任何建议将AP preciated。

Any suggestions will be appreciated.

推荐答案

也许有点晚，但通过各种手段，这里是另一种方法，那就是更干净而大卫的做法：

Maybe a bit late, but by all means, here is another approach, that's still more clean than David's approach:

您应该在你的 MyNewClass 添加一个事件处理程序。然后，你可以从你的表单中订阅该事件。

You should add an EventHandler in your MyNewClass. Then you can subscribe to that event from within your form.

public partial class Form1 : Form
{
    private readonly MyNewClass _myNewClass;

    public Form1()
    {
        InitializeComponent();
        _myNewClass = new MyNewClass();
        _myNewClass.DisplayPanelsInvoked += DisplayPanelsInvoked;
    }

    private void DisplayPanelsInvoked(object sender, DisplayPanelsEventArgs e)
    {
        var panels = e.Panels; // Add the panels somewhere on the UI ;)
    }
}

internal class MyNewClass
{
    private IList<Panel> _panels = new List<Panel>();

    public void AddPanel(Panel panel)
    {
        _panels.Add(panel);
    }

    public void DisplayPanels()
    {
        OnDisplayPanels(new DisplayPanelsEventArgs(_panels));
    }

    protected virtual void OnDisplayPanels(DisplayPanelsEventArgs e)
    {
        EventHandler<DisplayPanelsEventArgs> handler = DisplayPanelsInvoked;
        if (handler != null)
        {
            handler(this, e);
        }
    }

    public event EventHandler<DisplayPanelsEventArgs> DisplayPanelsInvoked;
}

internal class DisplayPanelsEventArgs : EventArgs
{
    public DisplayPanelsEventArgs(IList<Panel> panels)
    {
        Panels = panels;
    }

    public IList<Panel> Panels { get; private set; }
}

在我看来，这是一个更好的解决方案，因为你并不需要提供形式向MyNewClass实例的引用。因此，这种方法降低耦合，因为只有形式具有相关性的MyNewClass。

In my opinion it's a better solution, because you don't need to provide a reference of the form to the MyNewClass instance. So this approach reduces coupling, because only the form has a dependency to the MyNewClass.

如果你总是想升级只要添加一个面板的形式，你可以删除 DisplayPanels -method，缩短了code这样：

If you always want to "update" the form whenever a panel is added, you could remove the DisplayPanels-method and shorten the code to this:

public partial class Form1 : Form
{
    private readonly MyNewClass _myNewClass;

    public Form1()
    {
        InitializeComponent();
        _myNewClass = new MyNewClass();
        _myNewClass.PanelAdded += PanelAdded;
    }

    private void PanelAdded(object sender, DisplayPanelsEventArgs e)
    {
        var panels = e.AllPanels; // Add the panels somewhere on the UI ;)
    }
}

internal class MyNewClass
{
    private IList<Panel> _panels = new List<Panel>();

    public void AddPanel(Panel panel)
    {
        _panels.Add(panel);
        OnPanelAdded(new DisplayPanelsEventArgs(_panels, panel)); // raise event, everytime a panel is added
    }

    protected virtual void OnPanelAdded(DisplayPanelsEventArgs e)
    {
        EventHandler<DisplayPanelsEventArgs> handler = PanelAdded;
        if (handler != null)
        {
            handler(this, e);
        }
    }

    public event EventHandler<DisplayPanelsEventArgs> PanelAdded;
}

internal class DisplayPanelsEventArgs : EventArgs
{
    public DisplayPanelsEventArgs(IList<Panel> allPanels, Panel panelAddedLast)
    {
        AllPanels = allPanels;
        PanelAddedLast = panelAddedLast;
    }

    public IList<Panel> AllPanels { get; private set; }
    public Panel PanelAddedLast { get; private set; }
}

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