WinForm窗体之间交互的一些方法

在窗体间传递数据的方法比较多：
1，在子窗体中自定义一个构造函数，参数类型是主窗体，当要显示子窗体的时候，就用这个构造函数来实例化子窗体,然后把this指针传进去，说起来太抽象了，我大概一写大家应该就明白了：
   public class frmMain:Form
   {
        ...
        frmControl controlForm=new frmControl(this);
        controlForm.Show();
    }

    public class frmControl:Form  //子窗体，用来控制主窗体的某些显示！
    {
         private frmMain mainForm;
         public frmControl(frmMain mainForm)
         {
              this.mainForm=mainForm;
          }
          private void button1_Click(object sender,EventArgs e)

               {

                           frmMain.textBox1.Text=this.textBox1.Text;  //把子窗体的文本框值传递给主窗体的文本框！

               }

     }
2，上面的方法不是很好，虽然实现起来很简单，只是想改变窗体的标题文本，就把整个主窗体的引用都传递给子窗体，这样的方式不是很幽雅，我们用接口来改进上面的方法，这样可以限制暴露给子窗体的功能，降低窗体之间的耦合度：
   public interface IChangeTitle:
   {
        void ChangeTitle(string title);
    }
   public class frmMain:Form,IChangeTitle
   {
        ...
        frmControl controlForm=new frmControl(this);
        controlForm.Show();
        public void ChangeTitle(string title)
        {
             this.Text=title;
         }        
    }

    public class frmControl:Form  //子窗体，用来控制主窗体的某些显示！
    {
         private IChangeTitle ichangeTitle;
         public frmControl(IChangeTitle ichangeTitle)
         {
              this.ichangeTitle=ichangeTitle;
          }
          private void button1_Click(object sender,EventArgs e)

               {

                           ichangeTitle.ChangeTitle(this.textBox1.Text);  //通过接口来调用方法

               }

     }
3，为了进一步降低窗体之间的耦合度，我们可以用委托来实现这个需求：
    public partial class ChildForm : Form
    {
        public delegate void TitleChangedHandler(string title);
        public TitleChangedEventHandler TitleChanged;
        public ChildForm()
        {
            InitializeComponent();
        }

        
        private void btn_Ok_Click(object sender, EventArgs e)
        {            
            if (TitleChanged != null)
                TitleChanged("Test Title"); //委托调用
            
        }
    }
主窗体给委托变量赋值就可以了：
    public partial class MainForm : Form
    {
        private ChildForm loginForm = new ChildForm();
        public MainForm()
        {
            InitializeComponent();
            loginForm.TitleChanged = new ChildForm.TitleChangedEventHandler(FormTitleChanged);
        }

        protected void FormTitleChanged(string title)
        {
            this.Text = title;
        }

        private void button1_Click(object sender, EventArgs e)
        {
            loginForm.Show();
        }
    }

4,也可以在子窗体中定义一个自定义的事件，然后自定义一个事件参数，用来传递你想传递的一些信息：
    public partial class ChildForm : Form
    {
        public class TitleChangedEventArgs : EventArgs //事件参数类
        {
            private string title = "";
            public string Title
            {
                get
                {
                    return title;
                }
                set
                {
                    title = value;
                }
            }
        }
        public delegate void TitleChangedEventHandler(object sender, TitleChangedEventArgs e);
        public event TitleChangedEventHandler TitleChanged;
        public ChildForm()
        {
            InitializeComponent();
        }

        
        private void btn_Ok_Click(object sender, EventArgs e)
        {
            TitleChangedEventArgs e1=new TitleChangedEventArgs();
            e1.Title="Login sucessed";
            OnTitleChanged(e1);//触发事件
            
        }

        protected virtual void OnTitleChanged(TitleChangedEventArgs e)   //触发事件的方法
        {
            if (TitleChanged != null)
                TitleChanged(this, e);
        }
    }

主窗体订阅这个事件就可以了：
    public partial class MainForm : Form
    {
        private ChildForm loginForm = new ChildForm();
        public MainForm()
        {
            InitializeComponent();
            loginForm.TitleChanged += new ChildForm.TitleChangedEventHandler(FormTitleChanged);
        }

        protected void FormTitleChanged(object sender, ChildForm.TitleChangedEventArgs e)
        {
            this.Text = e.Title;
        }

        private void button1_Click(object sender, EventArgs e)
        {
            loginForm.Show();
        }
    }