Data interaction between C ＃ WinForm development forms

Originally, I learned it for the first time Winform Development did not expect to use multiple forms , But I found that some functions are really difficult to realize without multiple forms , So you still have to use multiple forms , One of the problems faced by multiple forms is data interaction , For example, my main interface is a question bank , Sub interface is a topic , Then I won't tell the sub topic which topic and which path , Obviously, I don't know which sub topic to show .

How to realize the interaction between forms , There are about three options ：

(1) Modify the constructor of the subform

I think this is the simplest and crudest , It's also one I use , The principle is very simple, that is, you can directly modify the constructor , Here's an example ：

stay Form1.cs in , The definition code is as follows ：

album_SendTo_ANS = A;
node_SendTo_ANS = thisNode;
Form Form2 = new Form(this);
Form2.ShowDialog();

So in Form2.cs in , You can get the constructor as follows ：

public Form2(Form1 form1)
        {
            InitializeComponent();
            album_SendTo_ANS = form1.get_album_SendTo_ANS();
            node_SendTo_ANS = form1.get_node_SendTo_ANS();
        }

Of course, here I set the two passed parameters to form1 Private members of , Therefore, encapsulation is still used here get To get . This is actually Form Form2 = new Form(this); You can set parameters according to your own needs , Because the number of parameters here may change , Therefore, choose the simple method of directly transferring the form , Generally, parameters are transmitted .

(2) Add dependent properties to the subform

Here we want to make the child form belong to the parent form , Therefore, you can set the Owner attribute ,Owner The value of the property is a reference to the parent form . When a child form belongs to the parent form, it has the following features ：

① The child form is minimized and closed with the parent form . for example , If subform Form2 Parent form Form1 all , Then close or minimize Form1 when , It also turns off or minimizes Form2.

② The child form does not appear after the parent form . Subsidiary forms can be used to find and replace windows such as windows , When the owner form is selected , These windows should not disappear . To determine the form owned by a parent form , have access to OwnedForms attribute .

There are two ways ：

Form2 form2 = new Form2();
form2.Owner = this;
form2.ShowDialog();

Form2 form2 = new Form2();
form2.ShowDialog(this);

When the affiliation is determined , You can modify parameters in the following ways ：

Form1 form1 = (Form1)this.Owner;   
this.Data1 = form1.Data2;

(3) By way of entrustment

Compared with the above two methods , This method may be more complicated , But the basic idea is the same , The changes are as follows ：
① stay Form2.cs Add delegate function definitions in ：public delegate void SendFun(string str);

② stay Form2.cs Add delegation examples in ：public event SendFun SendToParent;

③ stay Form2.cs Add a button to , And add the following events ：
                private void button1_Click(object sender, EventArgs e)
                {
                    if (Send != null)
                    {
                        Send(this.textBox1.Text);
                    }
                }

 ④ stay Form1.cs Add method in RecvInfo() The method is as follows ：
                private void RecvInfo (string str)
                {
                    textBox1.Text = str;
                }
⑤ stay Form1.Designer.cs Medium InitializeComponent() Method to add a delegate instance definition ：
                this.myForm.Send += new Example3_Form2. SendFun (RecvInfo);

That is to say Form Communication between , I haven't realized this scheme yet , I also saw it on other blogs , So record .