[C # Learning] calling controls between forms

First, Method 1:

If there are two forms, form_a and Form_b, each form has a key, button_a and Button_b, to implement click Button_a to display Form B, then the program for the Buttom_a click event in form a should be:

Private void Button_a_click (object  sender, EventArgs e) {    form_b  new  Form_b ( );    F.show ();}

If you want to change the background color of form a by clicking the key button_b in form B, then you need to do:

1. Add the following code to the class in the Form_b form:

 Public form_a FB;  Public Form_b (form_a  f) {    InitializeComponent ();     = F;} Private void Button_b_click (object  sender, EventArgs e) {    = color.brown;}

2. The Button_a click event in the Form_a form becomes:

Private void Button_a_click (object  sender, EventArgs e) {    new form_b ( this );    F.show ();}

The complete program is as follows

Form_a:

usingSystem;usingSystem.Collections.Generic;usingSystem.ComponentModel;usingSystem.Data;usingSystem.Drawing;usingSystem.Linq;usingSystem.Text;usingSystem.Windows.Forms;namespaceformexam{ Public Partial classForm_a:form { PublicForm_a () {InitializeComponent (); }        Private voidButton_a_click (Objectsender, EventArgs e) {Form_b F=NewForm_b ( This);        F.show (); }        Private voidForm_a_load (Objectsender, EventArgs e) {        }    }}

Form_b:

usingSystem;usingSystem.Collections.Generic;usingSystem.ComponentModel;usingSystem.Data;usingSystem.Drawing;usingSystem.Linq;usingSystem.Text;usingSystem.Windows.Forms;namespaceformexam{ Public Partial classForm_b:form { PublicForm_a FB;  PublicForm_b (form_a f) {InitializeComponent (); FB=F; }        Private voidButton_b_click (Objectsender, EventArgs e) {fb. BackColor=Color.brown; }    }}

Ii. Method 2: Implementation through delegation

1. Define a delegate type outside the class of Form_b

 Public Delegate void Changeformcolor ();

2. Define a delegate's method within the class of Form_b

 Public Event Changeformcolor ChangeColor;

3. Button_b Click event to

Private void Button_b_click (object  sender, EventArgs e) {    changecolor ();}

4. The Click event in Form_a is

Private void Button_a_click (object  sender, EventArgs e) {    new  form_b ();     New Changeformcolor (f_changecolor);    F.show ();}

5. Write a method to change the form_a background color

void F_changecolor () {    this. BackColor = Color.brown;}

The complete procedure is as follows:

Form_a:

usingSystem;usingSystem.Collections.Generic;usingSystem.ComponentModel;usingSystem.Data;usingSystem.Drawing;usingSystem.Linq;usingSystem.Text;usingSystem.Windows.Forms;namespaceformexam{ Public Partial classForm_a:form { PublicForm_a () {InitializeComponent (); }        Private voidButton_a_click (Objectsender, EventArgs e) {Form_b F=NewForm_b (); F.changecolor+=NewChangeformcolor (F_changecolor);        F.show (); }        voidF_changecolor () { This. BackColor =Color.brown; }    }}

Form_b:

usingSystem;usingSystem.Collections.Generic;usingSystem.ComponentModel;usingSystem.Data;usingSystem.Drawing;usingSystem.Linq;usingSystem.Text;usingSystem.Windows.Forms;namespaceformexam{ Public Delegate voidChangeformcolor ();  Public Partial classForm_b:form { Public EventChangeformcolor ChangeColor;  PublicForm_b () {InitializeComponent (); }        Private voidButton_b_click (Objectsender, EventArgs e)        {ChangeColor (); }    }}