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How to refactor duplicated code in Windows Forms?

I'm currently working on refactoring a lot of duplicated code in a couple of UserControls in Windows Forms project.
The architecture leaves much to be desired with a lot of logic implemented inside the UI layer. This will be fixed eventually, I'm now working on improving what I have on my hands now.
The problem is, that a lot of duplicated code relates directly to controls, for instance:
private void InitDestinationPathControls(string path)
{
if (someField)
{
tbOne.Enabled = false;
tbOne.Visible = false;
btnTwo.Enabled = false;
btnTwo.Visible = false;
tbOne.Text = string.Empty;
return;
}
// (...)
}
Don't get too attached to the cited code itself, it is just an example.
I'd like to move this code to a common base class, but it relies directly on specific fields (even though they are exactly the same in all controls too). Those fields, on the other hand, are generated by the designer, so I cannot extract them to the base class.
The only thing that comes to my mind is to pass those fields as parameters to a method in base class, but then if some method uses a lot of them, I'll end up with a monstrous interface part and that won't actually improve the readability too much.
How can I deal with such common parts of user controls in Windows Forms?

Apparently you have a combination of several controls that appears in several forms. In other words: you have for instance some buttons, comboboxes, etc, that you want to show on different forms, and you want them to have the same behaviour.
If not only the behaviour of these controls is the same on all forms, but also the layout, then consider to create a class derived from UserControl.
The UserControl hides from the outside world which controls are shown, how they are visualized and how they behave.
I assume that you already pulled the model out of the visualisation of the data.
If all instances of this user control should all call the same functions of possibly a different object of the same class, then give your special user control a property that represents this class, or at least an interface. During construction you can plug in the actual class that should handle the actions after operator input.
If, on the other hand, the layout differs on each form, but the collection of buttons, comboboxes, etc and their behaviour is similar on all forms that show this collection of controls and they have a lot of common behaviour, consider to create your own ControlCollection.
For instance, if on several forms you have a button to select a (text) file, labels with the name, size and creation date of the selected file, and an edit box that shows the content of the text file, but you want to layout them differently, consider something like this:
class FileDisplayControls : IDisposable
{
public Button ButtonSelectFile {get;} = new Button();
public Label labelFileName {get; } = new Label();
public Label labelFileSize {get; } = new Label();
public TextBox textFileContents {get; } = new FileContents();
private void ButtonSelectFile_Clicked(object sender, ...)
{
// TODO: open file dialog, display result in labels and text box
}
}
Constructor can set initial layout properties of the controls, and subscribe to events, such that the controls will react on user input.
The user of the class (= code, not operator) immediately has a collection of controls that have some standard behaviour, like react on button click. All he has to do is set the location of the items in his own form. If desired change other layout properties (colour, background) and put them on his own form.
If you want to prevent that others change other visual aspects of the controls than the position, don't publish the control themselves, only the position of the control:
public System.Drawing.Point LocationSelectFileButton
{
get => this.buttonSelectFile.Location;
set => this.buttonSelectFile.Location = value;
}
public System.Drawing.Point LocationFileContentTextBox
{
get => this.textBoxFileContent.Location;
set => this.textBoxFileContent.Location = value;
}
etc.
If needed, you can add events for users:
public event EventHandler SelectedFileChanged;
public string FileName => this.labelFileName.Text;
public string FileContents => this.textBoxFileContent.Text;
etc.
Conclusion
The solution that you choose depends on the similarity between the controls on the various forms:
if Behaviour and Layout are all the same: UserControl
If only position and a few properties different: special class with the properties that are different. This way you can force a more similar style: all "Select File" buttons look similar.
If only one or two behaviours are different: add Action<...> properties or events
If you want full control of the layout: expose the Controls.
The behaviour that is common for all you forms that show these controls (in my example: how to select a file and what to do when a file is selected) is inside the class.

repeated code can be extracted to method (possibly in base class, or as static method in helper class)
public void DisableControls(params Control[] controls)
{
foreach(var c in Controls)
{
c.Enabled = false;
c.Visible = false;
if (c is TextBox t)
{
t.Text = string.Empty;
}
}
}
private void InitDestinationPathControls(string path)
{
if (someField)
{
DisableControls(tbOne, btnTwo);
return;
}
// (...)
}

Pass form to another class and extract controls and properties

This is more so a general question than an issue I have. I have a form with 30+ controls that I will use to populate a model, which eventually ends up in a database.
I was wondering, however, if I could just pass the whole form object to another class, and pull the contents out in the other class without setting up a whole bunch of getters and setters.
Let's say I have a form Form1, and I make this call:
OtherClass.Validate(this)
Then, in the OtherClass (which is in a different project in the same solution) I have:
public static void Validate(Form1 myForm)
I have played around with this a little. In the Validate() method, if I put a watch on myForm, I can see all the form controls and properties, but I don't know if there is a way to just pull them out. If I type myForm., intellisense shows me all the standard form methods and properties, but not the controls and properties specific to the form. Has anybody tried this successfully?

You may grab controls from a form object using
myForm.Controls
This gives you a collection of controls within the form. You may iterate through them with a foreach loop.
Example with this form containing two buttons. You may use the following code to get the controls text.
public static void Validate(Form1 myForm)
{
foreach (Control control in myForm.Controls)
{
string text = control.Text;
Console.WriteLine(text);
}
}
Triggering the above function prints the following to the console. (Using this form)
button2
button1
This method works for TextBox and other controls too. However, it may be trickier if you have controls within controls. You may solve that by making a recursive function.

Each control on a form has a property called "Modifiers":
It is "Private" by default (for a reason: UI is the most likely subject for changes, any logic outside the form should not depend on controls. One control can be replaced with another, a group of controls can be replaced with a custom control. When controls are public, such change is not incapsulated and triggers changes in many parts of the system)
Controls which are added on a form, are serialized into C# code in form.designer.cs file. Code for textBox1, when it has modifier Private:
private System.Windows.Forms.TextBox textBox1;
Change it to Public like shown on a screenshot, and it will become
public System.Windows.Forms.TextBox textBox1;
Public controls will be accessible like any other public fields:
public static void Validate(Form1 myForm)
{
if (String.IsNullOrEmpty(myForm.textBox1.text))
{
// do smth about empty field
}
}

Create property of UserControl Instances (not new)

I have a usercontrol where I want a property that can list all the other instances of the same usercontrols in the Windows Form.
Eg. I have a simple usercontrol (sidebarbutton). I drag-drop 2 instances of it in a UserForm. Now I want a property (in the usercontrol itself) that can list both of them.
I have written this property. However, when used in Property Browser Window of Visual Studio, it allows me to add new instances of sidebarButton control.
private List<SidebarButton> _sidebarButtons;
[Browsable(true), EditorBrowsable(EditorBrowsableState.Always), Category("Roshan")]
public List<SidebarButton> SidebarButtons
{
get { return this._sidebarButtons; }
set { this._sidebarButtons = value; }
}
How to add the 2 instances that I drag-droped in the form in this property.
I know the property needs to be modified but don't have a proper direction to take. Please HELP me.

One way of doing this could be that upon addition of the user control to the form, the user control notifies all other user controls of that type that it now exists. Your user control can implement an interface like so:
public interface INotifiable
{
public void AddToList(INotifiable newButton);
}
When the user control is added to the form you iterate through all the controls and check whether they implement this interface. If they do you call the AddToList method and pass the newly added control to it.

Form of object created from another object in c#

I have a form containing a flowlayoutpanel, and a user control A is added to the panel. In the constructor of user control A, a pointer to the same flowlayoutpanel is passed, so that user control A creates another user control B in the same flowlayoutpanel. The problem is that user control B is first added, then A.
Form1.cs
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void addBtn_Click(object sender, EventArgs e)
{
flowLayoutPanel1.Controls.Add(new Graphic1(this.flowLayoutPanel1));
}
}
Graphic1.cs
public partial class Graphic1 : UserControl
{
public Graphic1(FlowLayoutPanel flowPointer)
{
InitializeComponent();
flowPointer.Controls.Add(new Graphic2());
}
}
Graphic2.cs is just a label
problem is that Graphic2.cs is added before Graphic1.cs in the panel

I see three possible solutions:
If the constructor of control A receives the flow layout panel, have control A add itself to the flow layout panel, then add its additional controls.
Instead of adding the additional control in the constructor of control A, add a method such as InitializeLayout to control A. You can invoke that method after adding control A to the flow layout panel, and that method could then add any additional controls to the flow layout panel.
Capture any changes to the Parent property of control A (not sure whether that is possible; that depends on the GUI toolkit you are using) and add the additional controls when the parent of control A has changed.

Windows form C# change user control by code

I have a windows form and i dont want to make any other windows forms just one windows form and different user controls how can i change between user controls for example hide one and show the other user control programmatically ?
private void Btt_info_Click(object sender, EventArgs e)
{
Frm_Main frm_main = new Frm_Main();
frm_main.Controls["panel1"].Controls.Clear();
UC_Info uc_info = new UC_Info();
frm_main.Controls["panel1"].Controls.Add(uc_info);
}
i added this but it doesnt work

Add a container control (if I remember correctly, there's a containers section in the toolbox?), like a panel. Create usercontrols for what you want to dynamically switch around. So make like a 'HomePage' usercontrol and a 'LoginPage' usercontrol. Dynamically add the usercontrol that you want to display to the container. WHen you want, remove it from the container and add a different usercontrol:
Panel myPanel = new Panel();
LoginPage ctlLoginPage = new LoginPage();
HomePage ctlHomePage = new HomePage();
//add the loginpage to the panel first
myPanel.Controls.Add(ctlLoginPage);
...do stuff...
//remove whatever control is currently in the Panel
myPanel.Controls.Clear();
//add the other control, the HomePage control instead now
myPanel.Controls.Add(ctlHomePage);
..do other stuff...
I usually do it this way so you leave your form itself open to add common controls and stuff that might be shared between your different 'pages'.
EDIT: Note that I normally would add the panel in the designer and not create it dynamically in the code. This was just an example.
EDIT: The interaction between your mainform and usercontrols can be handled in a few different ways, and I am not saying that any of these is the correct method.
You create a static property for your Panel on the Mainform, so that
you can always access it to swap your controls around.
In this example I'll also add a static method for it
enum PanelControlsEnum {HomePage, LoginPage};
public static Panel MyContainerPanel {get;set;}
public static void SwitchPanelControls(PanelControlsEnum selControl){
..put your switch panels code here..
}
Then inside your usercontrol you call a predefined method, something like:
MainForm.SwitchPanelControls(PanelControlsEnum.HomePage);
Another method is to bind the button click event on your mainform
instead of inside the form.
Like This:
HomePage ctlHomePage = new HomePage();
ctlHomePage.Click += MyClickEvent;
myPanel.Controls.Add(ctlHomePage)
...
private void MyClickEvent(object sender, RoutedEventArgs e)
{
..switch user control code here...
}

Create a method that returns a UserControl object. Then put conditions in that method as to which control you want to load at a specific condition and then in your main form code.
UserControl control = GetControlFromMyMethod();
form1.Controls.Add(control);
where 'control' is the returned control from your method.
To remove the existing one you have to loop through the form1.Controls and find out the control and call 'Remove'.
Update:
Mike C has a better idea of adding a panel and loading your desired control on the panel as then it's easy to remove your control and you then don't have to loop through the forms controls to find it and then remove it.

Try this:
this.Controls.Clear();
usercontrol load = new usercontrol ();
this.Controls.Add(load);
load.Show();

you could try this it will definitely help you as it did helped me a lot it short and straight to the point hope that will help