WinForm Multiple forms

Multiple forms:
First of all, the question to be thought of is:
1. Which is the main form
Problem: The main form is hidden, after closing other forms, the main form is not displayed/closed, then the program is closed

Method: Use the constructor to pass a value to the form to upload it to another form.

Form1:

usingSystem;usingSystem.Collections.Generic;usingSystem.ComponentModel;usingSystem.Data;usingSystem.Drawing;usingSystem.Linq;usingSystem.Text;usingSystem.Windows.Forms;namespacemultiple Forms { Public Partial classForm1:form { PublicForm1 () {InitializeComponent (); }        Private voidButton1_Click (Objectsender, EventArgs e) {            //Form1 is the login form, Form2 the main form,//How to open Form2 with the Form1 button, then let Form1 hide Form2 displayForm2 F2 =NewForm2 ( This); F2.            Show ();  This. Hide ();//This is the current form, which refers to Form1, and then hide hides        }    }}

Form2:

usingSystem;usingSystem.Collections.Generic;usingSystem.ComponentModel;usingSystem.Data;usingSystem.Drawing;usingSystem.Linq;usingSystem.Text;usingSystem.Windows.Forms;namespacemultiple Forms { Public Partial classform2:form {Form1 F1=NULL;  PublicForm2 (Form1 F1) {InitializeComponent (); F1=F1; }        Private voidForm2_load (Objectsender, EventArgs e) {                    }        Private voidForm2_formclosing (Objectsender, FormClosingEventArgs e) {F1.        Close (); }    }}

2. The form can only open one

Creates a global generic collection in order to place all open forms
1, before the form opens, determine whether there is a name consistent form in the collection, if there is a description is open, do not open the

Issue: When the form is open and closed, it cannot be opened again
Workaround: Clears this form object record from the collection in Form1 when the form is closed

Form1:

usingSystem;usingSystem.Collections.Generic;usingSystem.ComponentModel;usingSystem.Data;usingSystem.Drawing;usingSystem.Linq;usingSystem.Text;usingSystem.Windows.Forms;namespacemultiple Forms { Public Partial classForm1:form {//to create a global generic collectionList<form> flist =NewList<form>();  PublicForm1 () {InitializeComponent (); }        Private voidButton1_Click (Objectsender, EventArgs e) {            BOOLhas =false; //Form1 is the login form, Form2 the main form,//How to open Form2 with the Form1 button, then let Form1 hide Form2 displayForm2 F2 =NewForm2 ( This); foreach(Form FinchFlist)//go through the collection first to see if there are any forms and Form2 form content            {                if(F.name = = F2. Name)//If there is a match{ has=true; }            }            if(HAS)//If has is true            {            }            Else//if has is not true{flist.add (F2); F2.            Show (); }                   }//Issue: Click the button to open a form, close the form and then click on the form will not open//method: When the Form2 is closed, the Form1 collection is emptied, and the methods in Form1 are called in Form2         Public voidDeleteform (Form f) {flist.remove (f);//It's written here to remove.        }    }}

Form2:

usingSystem;usingSystem.Collections.Generic;usingSystem.ComponentModel;usingSystem.Data;usingSystem.Drawing;usingSystem.Linq;usingSystem.Text;usingSystem.Windows.Forms;namespacemultiple Forms { Public Partial classform2:form {Form1 F1=NULL;  PublicForm2 (Form1 F1) {InitializeComponent (); F1=F1; }        Private voidForm2_load (Objectsender, EventArgs e) {                    }        Private voidForm2_formclosing (Objectsender, FormClosingEventArgs e) {            //prevent error, Judge            if(F1! =NULL) {F1. Deleteform ( This); }        }    }}

Issue: When the form is already open, clicking the Open button again will not re-display the open form and focus into
Workaround: Locate the Open object and set the WindowState property to:
Locate the object that has the form open and use the focus method;

Form1:

 Private voidButton1_Click (Objectsender, EventArgs e) {            BOOLhas =false; //Form1 is the login form, Form2 the main form,//How to open Form2 with the Form1 button, then let Form1 hide Form2 displayForm2 F2 =NewForm2 ( This); foreach(Form FinchFlist)//go through the collection first to see if there are any forms and Form2 form content            {                if(F.name = = F2. Name)//If there is a match{ has=true; F.windowstate= Formwindowstate.normal;//first set the WindowState property to: NormalF.focus ();//Focus into                }            }            if(HAS)//If has is true{F2. Close ();//release the newly created form            }            Else//if has is not true{flist.add (F2); F2.            Show (); }                   }

3. Transfer values and controls between forms

Pass value: Constructor pass value

Form1:

usingSystem;usingSystem.Collections.Generic;usingSystem.ComponentModel;usingSystem.Data;usingSystem.Drawing;usingSystem.Linq;usingSystem.Text;usingSystem.Windows.Forms;namespacetransfer values and controls between forms { Public Partial classForm1:form { PublicForm1 () {InitializeComponent (); }        Private voidButton1_Click (Objectsender, EventArgs e) {            //determine if user name input is correct            if(TextBox1.Text = ="Zhangsan"&& TextBox2.Text = ="1234") {Form2 F2=NewForm2 ( This, TextBox1.Text); F2.                Show ();  This.            Hide (); }        }    }}

Form2:

usingSystem;usingSystem.Collections.Generic;usingSystem.ComponentModel;usingSystem.Data;usingSystem.Drawing;usingSystem.Linq;usingSystem.Text;usingSystem.Windows.Forms;namespacetransfer values and controls between forms { Public Partial classform2:form {Form1 F1=NULL;//Global Variables//constructor overload, call this constructor, pass over a Form1 object, and string Uname         PublicForm2 (Form1 F1,stringUname)            {InitializeComponent (); F1=F1; Label1. Text="Welcome Back! "+Uname; }    }}

Control: The first step, find the Form object,

The second step is to change the control value of the form object
Note: To modify the access rights of objects in a form

Form1.designer:

        Private System.Windows.Forms.TextBox textBox1;         Private System.Windows.Forms.TextBox textBox2;         Private System.Windows.Forms.Label Label1;         Private System.Windows.Forms.Label Label2;          Public System.Windows.Forms.Button button1;

Form2:

Private void button1_click (object  sender, EventArgs e)        {            // Remove the value of TextBox1  TextBox1.Text;            if NULL             {                // Form1.designer inside Button1 private to public, so F1 can point out button1                F1.button1.Text = textbox1.text;            }        }

4. The form of the prompt box type

ShowDialog ();

Action: The current form can be manipulated and other forms cannot be manipulated

Close the current form before you can manipulate other forms

Form1:

Private void button2_click (object  sender, EventArgs e)        {            Form2 f2=new Form2 (  this,"111");            F2. ShowDialog ();        }

WinForm Multiple forms