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Custom Component on Windows Forms not loading correctly

I am new to Windows Forms and am trying to create a custom Panel which has a header bar with two labels. I want to be able to set the text of those labels from the designer when this panel is added to another form.
Here is the code for my Panel:
public partial class TitledPanel : Panel
{
public string Title { get; set; } = "";
public string TitleNumber
{
get { return numberedLabel.Text; }
set { numberedLabel.Text = value; }
}
public TitledPanel()
{
SetStyle(ControlStyles.UserPaint | ControlStyles.ResizeRedraw | ControlStyles.DoubleBuffer | ControlStyles.AllPaintingInWmPaint, true);
InitializeComponent();
}
protected override void OnPaint(PaintEventArgs e)
{
using (SolidBrush brush = new SolidBrush(BackColor))
e.Graphics.FillRectangle(brush, ClientRectangle);
e.Graphics.DrawRectangle(
new Pen(Color.FromArgb(((int)(((byte)(229)))), ((int)(((byte)(229)))), ((int)(((byte)(229)))))), 0, 0, ClientSize.Width - 1, ClientSize.Height - 1);
}
private void InitializeComponent()
{
this.titleLabel = new System.Windows.Forms.Label();
this.mainHeaderPanel = new System.Windows.Forms.Panel();
this.numberedLabel = new System.Windows.Forms.Label();
this.mainHeaderPanel.SuspendLayout();
this.SuspendLayout();
//
// titleLabel
//
this.titleLabel.AutoSize = true;
this.titleLabel.Font = new System.Drawing.Font("Microsoft Sans Serif", 26F, System.Drawing.FontStyle.Regular, System.Drawing.GraphicsUnit.Pixel, ((byte)(0)));
this.titleLabel.Location = new System.Drawing.Point(75, 27);
this.titleLabel.Margin = new System.Windows.Forms.Padding(32,32,32,32);
this.titleLabel.Name = "titleLabel";
this.titleLabel.Size = new System.Drawing.Size(193, 30);
this.titleLabel.TabIndex = 2;
this.titleLabel.Text = "";
//
// mainHeaderPanel
//
this.mainHeaderPanel.BackColor = System.Drawing.Color.FromArgb(((int)(((byte)(229)))), ((int)(((byte)(229)))), ((int)(((byte)(229)))));
this.mainHeaderPanel.Controls.Add(this.numberedLabel);
this.mainHeaderPanel.Controls.Add(this.titleLabel);
this.mainHeaderPanel.Dock = System.Windows.Forms.DockStyle.Top;
this.mainHeaderPanel.ForeColor = System.Drawing.SystemColors.ControlText;
this.mainHeaderPanel.Location = new System.Drawing.Point(64, 140);
this.mainHeaderPanel.Margin = new System.Windows.Forms.Padding(64, 140, 64, 0);
this.mainHeaderPanel.Name = "mainHeaderPanel";
this.mainHeaderPanel.Size = new System.Drawing.Size(1126, 80);
this.mainHeaderPanel.TabIndex = 4;
//
// numberedLabel
//
this.numberedLabel.AutoSize = true;
this.numberedLabel.BackColor = System.Drawing.Color.FromArgb(((int)(((byte)(4)))), ((int)(((byte)(103)))), ((int)(((byte)(198)))));
this.numberedLabel.Font = new System.Drawing.Font("Microsoft Sans Serif", 28F, System.Drawing.FontStyle.Regular, System.Drawing.GraphicsUnit.Pixel, ((byte)(0)));
this.numberedLabel.ForeColor = System.Drawing.Color.White;
this.numberedLabel.Location = new System.Drawing.Point(23, 26);
this.numberedLabel.Name = "numberedLabel";
this.numberedLabel.Size = new System.Drawing.Size(31, 32);
this.numberedLabel.TabIndex = 3;
this.numberedLabel.Text = "0";
var path = new System.Drawing.Drawing2D.GraphicsPath();
path.AddEllipse(-1, 0, numberedLabel.Width, numberedLabel.Height);
this.numberedLabel.Region = new Region(path);
//
// TitledPanel
//
this.AutoSize = true;
this.BackColor = System.Drawing.Color.White;
this.Controls.Add(this.mainHeaderPanel);
this.Name = "BeforeYouStartForm";
this.Size = new System.Drawing.Size(1254, 839);
this.Text = "GetStarted";
this.mainHeaderPanel.ResumeLayout(false);
this.mainHeaderPanel.PerformLayout();
this.ResumeLayout(false);
this.PerformLayout();
}
private System.Windows.Forms.Label titleLabel;
private System.Windows.Forms.Panel mainHeaderPanel;
private System.Windows.Forms.Label numberedLabel;
}
When I put this panel on a form and run the app, it looks like it should. However the fields Title and TitleNumber show up in the designer with the text Object reference not set to an instance of an object. next to them. Also the panel does not load in the designer, when I add it to a form, it looks like the default Panel would, and it only loads when I actually run the app.
How can I get the TitledPanel to load in the designer and how can I get Title and TitleNumber to show correctly in the designer.
Thanks

Create and display label via code

I want to create a label and display it to the user, but I can not.
I have tried to copy the code for any label in InitializeComponent() ...
(I added a label to Form1 using the toolbox.)
partial class Form1
{
private System.Windows.Forms.Label label1;
private void InitializeComponent()
{
this.label1.AutoSize = true;
this.label1.Location = new System.Drawing.Point(0, 0);
this.label1.Name = "label1";
this.label1.Size = new System.Drawing.Size(35, 13);
this.label1.TabIndex = 0;
this.label1.Text = "label1";
}
}
... and then to apply it to my label.
(I removed the label I added earlier.)
public partial class Form1 : Form
{
private Label label;
public Form1()
{
InitializeComponent();
label = new Label();
label.AutoSize = true;
label.Location = new System.Drawing.Point(0, 0);
label.Name = "label";
label.Size = new System.Drawing.Size(0, 0);
label.TabIndex = 0;
label.Text = "Test";
//label.Enabled = true;
label.Visible = true;
//label.Select();
//label.Show();
}
}
But it does not work.
How to do ?

You need to add te label to add it to the forms' list of controls.
So, in your Form1() function, add the follwoing after the label is created:
this.Controls.Add(label);

You forgot vital part, i.e. add label to the form's ControlCollection:
this.Controls.Add(label);

Resize 4 picture boxes when form is resized

I am implementing a winform application in c# so that it contains four picture boxes and some control buttons in one corner.
My main problem is that I cannot achieve the behaviour shown in the picture. The idea is to automatically resize the picture boxes when the form is resized. The area of the control panel should stay the same and only the area containing the boxes should be resized accordingly.
I have been playing with anchor and dock properties but I dont get the desire output.
Anyone could give me a hint?
Thanks and kind regards,
Bilbinight

So, let's say you have the following picture boxes:
pictureBox1 | pictureBox2 | panel
------------|------------
pictureBox3 | pictureBox4
Then the following should do the trick:
set the forms Resize event to this eventhandler:
private void Form1_Resize(object sender, EventArgs e)
{
int spaceBetweenPictures = 19;
int widthToFill = (this.Width - 40 - panel.Width) - spaceBetweenPictures;
int heightToFill = this.Height - 80;
pictureBox1.Width = widthToFill / 2;
pictureBox1.Height = heightToFill / 2;
// Setting the sizes of all the three pictureboxes to the sizes of the first one.
pictureBox2.Width = pictureBox1.Width;
pictureBox2.Height = pictureBox1.Height;
pictureBox3.Width = pictureBox1.Width;
pictureBox3.Height = pictureBox1.Height;
pictureBox4.Width = pictureBox1.Width;
pictureBox4.Height = pictureBox1.Height;
// Setting the positions:
pictureBox2.Location = new Point(pictureBox1.Width + spaceBetweenPictures, pictureBox1.Location.Y);
pictureBox3.Location = new Point(pictureBox1.Location.X, pictureBox1.Height + spaceBetweenPictures);
pictureBox4.Location = new Point(pictureBox2.Location.X, pictureBox3.Location.Y);
}
Of course you should modify the magic numbers in this code (19, 40, 80) accordingly, to suit your program (that depends a lot on whether you use border on your form or not).
UPDATE:
If you want your pictureboxes square shaped then just ignore the heightToFill variable and use widthToFill instead when setting the Height of pictureBox1. Or set:
pictureBox1.Height = pictureBox.Width;
And I also forgot to mention that the panel of course should be aligned Top, Right. So set the panel's Anchor property to:
AnchorStyles.Top | AnchorStyles.Right;

Are four image boxes supposed to support resizing at runtime (allowing end user to resize)? if not then following will give you desired result.
1 TableLayoutPanel with 2 rows and two columns. Set the initial size to fill the desired area, set the anchor to all four directions.
Add 4 picture boxes to 4 cells and set Dock to Fill for all Picture Boxes.
Add a panel to the right side of form, and make it fit to cover your controls area. Set the anchor Top, Bottom, Right.
Here is sample code:
//frmResizing.cs
using System.Windows.Forms;
namespace WindowsFormsApplication1
{
public partial class frmResizing : Form
{
public frmResizing()
{
InitializeComponent();
}
}
}
//frmResizing.Designer.cs code
namespace WindowsFormsApplication1
{
partial class frmResizing
{
/// <summary>
/// Required designer variable.
/// </summary>
private System.ComponentModel.IContainer components = null;
/// <summary>
/// Clean up any resources being used.
/// </summary>
/// <param name="disposing">true if managed resources should be disposed; otherwise, false.</param>
protected override void Dispose(bool disposing)
{
if (disposing && (components != null))
{
components.Dispose();
}
base.Dispose(disposing);
}
#region Windows Form Designer generated code
/// <summary>
/// Required method for Designer support - do not modify
/// the contents of this method with the code editor.
/// </summary>
private void InitializeComponent()
{
this.tableLayoutPanel1 = new System.Windows.Forms.TableLayoutPanel();
this.panel1 = new System.Windows.Forms.Panel();
this.pictureBox4 = new System.Windows.Forms.PictureBox();
this.pictureBox3 = new System.Windows.Forms.PictureBox();
this.pictureBox2 = new System.Windows.Forms.PictureBox();
this.pictureBox1 = new System.Windows.Forms.PictureBox();
this.tableLayoutPanel1.SuspendLayout();
((System.ComponentModel.ISupportInitialize)(this.pictureBox4)).BeginInit();
((System.ComponentModel.ISupportInitialize)(this.pictureBox3)).BeginInit();
((System.ComponentModel.ISupportInitialize)(this.pictureBox2)).BeginInit();
((System.ComponentModel.ISupportInitialize)(this.pictureBox1)).BeginInit();
this.SuspendLayout();
//
// tableLayoutPanel1
//
this.tableLayoutPanel1.Anchor = ((System.Windows.Forms.AnchorStyles)((((System.Windows.Forms.AnchorStyles.Top | System.Windows.Forms.AnchorStyles.Bottom)
| System.Windows.Forms.AnchorStyles.Left)
| System.Windows.Forms.AnchorStyles.Right)));
this.tableLayoutPanel1.ColumnCount = 2;
this.tableLayoutPanel1.ColumnStyles.Add(new System.Windows.Forms.ColumnStyle(System.Windows.Forms.SizeType.Percent, 50F));
this.tableLayoutPanel1.ColumnStyles.Add(new System.Windows.Forms.ColumnStyle(System.Windows.Forms.SizeType.Percent, 50F));
this.tableLayoutPanel1.Controls.Add(this.pictureBox4, 1, 1);
this.tableLayoutPanel1.Controls.Add(this.pictureBox3, 0, 1);
this.tableLayoutPanel1.Controls.Add(this.pictureBox2, 1, 0);
this.tableLayoutPanel1.Controls.Add(this.pictureBox1, 0, 0);
this.tableLayoutPanel1.Location = new System.Drawing.Point(2, 1);
this.tableLayoutPanel1.Name = "tableLayoutPanel1";
this.tableLayoutPanel1.RowCount = 2;
this.tableLayoutPanel1.RowStyles.Add(new System.Windows.Forms.RowStyle(System.Windows.Forms.SizeType.Percent, 50F));
this.tableLayoutPanel1.RowStyles.Add(new System.Windows.Forms.RowStyle(System.Windows.Forms.SizeType.Percent, 50F));
this.tableLayoutPanel1.Size = new System.Drawing.Size(544, 561);
this.tableLayoutPanel1.TabIndex = 0;
//
// panel1
//
this.panel1.Anchor = ((System.Windows.Forms.AnchorStyles)(((System.Windows.Forms.AnchorStyles.Top | System.Windows.Forms.AnchorStyles.Bottom)
| System.Windows.Forms.AnchorStyles.Right)));
this.panel1.BackColor = System.Drawing.Color.Red;
this.panel1.Location = new System.Drawing.Point(553, 1);
this.panel1.Name = "panel1";
this.panel1.Size = new System.Drawing.Size(107, 561);
this.panel1.TabIndex = 1;
//
// pictureBox4
//
this.pictureBox4.Dock = System.Windows.Forms.DockStyle.Fill;
this.pictureBox4.Image = global::WindowsFormsApplication1.Properties.Resources.download;
this.pictureBox4.Location = new System.Drawing.Point(275, 283);
this.pictureBox4.Name = "pictureBox4";
this.pictureBox4.Size = new System.Drawing.Size(266, 275);
this.pictureBox4.SizeMode = System.Windows.Forms.PictureBoxSizeMode.StretchImage;
this.pictureBox4.TabIndex = 3;
this.pictureBox4.TabStop = false;
//
// pictureBox3
//
this.pictureBox3.Dock = System.Windows.Forms.DockStyle.Fill;
this.pictureBox3.Image = global::WindowsFormsApplication1.Properties.Resources.pizza_page;
this.pictureBox3.Location = new System.Drawing.Point(3, 283);
this.pictureBox3.Name = "pictureBox3";
this.pictureBox3.Size = new System.Drawing.Size(266, 275);
this.pictureBox3.SizeMode = System.Windows.Forms.PictureBoxSizeMode.StretchImage;
this.pictureBox3.TabIndex = 2;
this.pictureBox3.TabStop = false;
//
// pictureBox2
//
this.pictureBox2.Dock = System.Windows.Forms.DockStyle.Fill;
this.pictureBox2.Image = global::WindowsFormsApplication1.Properties.Resources.images;
this.pictureBox2.Location = new System.Drawing.Point(275, 3);
this.pictureBox2.Name = "pictureBox2";
this.pictureBox2.Size = new System.Drawing.Size(266, 274);
this.pictureBox2.SizeMode = System.Windows.Forms.PictureBoxSizeMode.StretchImage;
this.pictureBox2.TabIndex = 1;
this.pictureBox2.TabStop = false;
//
// pictureBox1
//
this.pictureBox1.Dock = System.Windows.Forms.DockStyle.Fill;
this.pictureBox1.Image = global::WindowsFormsApplication1.Properties.Resources.download__1_;
this.pictureBox1.Location = new System.Drawing.Point(3, 3);
this.pictureBox1.Name = "pictureBox1";
this.pictureBox1.Size = new System.Drawing.Size(266, 274);
this.pictureBox1.SizeMode = System.Windows.Forms.PictureBoxSizeMode.StretchImage;
this.pictureBox1.TabIndex = 0;
this.pictureBox1.TabStop = false;
//
// Form2
//
this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 13F);
this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
this.ClientSize = new System.Drawing.Size(660, 562);
this.Controls.Add(this.panel1);
this.Controls.Add(this.tableLayoutPanel1);
this.Name = "Form2";
this.Text = "Form2";
this.tableLayoutPanel1.ResumeLayout(false);
((System.ComponentModel.ISupportInitialize)(this.pictureBox4)).EndInit();
((System.ComponentModel.ISupportInitialize)(this.pictureBox3)).EndInit();
((System.ComponentModel.ISupportInitialize)(this.pictureBox2)).EndInit();
((System.ComponentModel.ISupportInitialize)(this.pictureBox1)).EndInit();
this.ResumeLayout(false);
}
#endregion
private System.Windows.Forms.TableLayoutPanel tableLayoutPanel1;
private System.Windows.Forms.PictureBox pictureBox4;
private System.Windows.Forms.PictureBox pictureBox3;
private System.Windows.Forms.PictureBox pictureBox2;
private System.Windows.Forms.PictureBox pictureBox1;
private System.Windows.Forms.Panel panel1;
}
}

Centering OK button within a MessageBox in winforms

I am learning C#, and as a part of it I wrote small app that consists of form with two groups of buttons, two buttons each. Button for closing of app is added as well. And everything works ok. Also there is MessageBox, showing that the app is going to be closed. And here is little problem that bugs me: OK button within that MessageBox is NOT centered horizontally. I guess there is a method to align that button, but what puzzles me is why it's is not centered by default? As illustration here are screenshots:
Here is code as well:
using System;
using System.Drawing;
using System.Windows.Forms;
public class myForm : Form
{
private GroupBox gboxGrp1;
private GroupBox gboxGrp2;
private RadioButton butn1a;
private RadioButton butn1b;
private RadioButton butn2a;
private RadioButton butn2b;
private Button btnClose;
public myForm()
{
InitializeComponent();
}
private void InitializeComponent()
{
this.btnClose = new Button();
this.gboxGrp1 = new GroupBox();
this.gboxGrp2 = new GroupBox();
this.butn1a = new RadioButton();
this.butn1b = new RadioButton();
this.butn2a = new RadioButton();
this.butn2b = new RadioButton();
//myForm
this.Text = "My Form";
this.StartPosition = FormStartPosition.CenterScreen;
this.Height = 350;
this.Width = 200;
//btnClose
this.Controls.Add(btnClose);
this.btnClose.Text = "Close";
this.btnClose.Location = new Point(60, 260);
this.btnClose.Click += new EventHandler(btnClose_Click);
//gboxgrp1
this.gboxGrp1.Location = new Point(20, 20);
this.gboxGrp1.Text = "Group Box 1";
this.gboxGrp1.Width = 150;
this.gboxGrp1.Height = 100;
//gboxgrp2
this.gboxGrp2.Text = "Group Box 2";
this.gboxGrp2.Location = new Point(20, 130);
this.gboxGrp2.Width = 150;
this.gboxGrp2.Height = 100;
//Radio buttons
this.butn1a.Text = "Radio 1a";
this.butn1a.Location = new Point(30, 30);
this.butn1a.Size = new Size(90, 15);
this.butn1b.Text = "Radio 1b";
this.butn1b.Location = new Point(30, 60);
this.butn1b.Size = new Size(90, 15);
this.butn2a.Text = "Radio 2a";
this.butn2a.Location = new Point(30, 30);
this.butn2a.Size = new Size(90, 15);
this.butn2b.Text = "Radio 2b";
this.butn2b.Location = new Point(30, 70);
this.butn2b.Size = new Size(90, 15);
//Controls
this.Controls.Add(gboxGrp1);
this.Controls.Add(gboxGrp2);
this.gboxGrp1.Controls.Add(butn1a);
this.gboxGrp1.Controls.Add(butn1b);
this.gboxGrp2.Controls.Add(butn2a);
this.gboxGrp2.Controls.Add(butn2b);
}
private void btnClose_Click(object sender, EventArgs e)
{
MessageBox.Show("Closing Application");
Application.Exit();
}
}
public class MyApp
{
public static void Main()
{
Application.Run(new myForm());
}
}

You can't restyle the default MessageBox as that's completely depends on the windows OS theme. However you could create your own message box by simply creating a new form and then call it by using newMessagebox.ShowDialog();

Align controls to center in a FlowLayout

I have a flowlayout as follows:
I need to center all the controls on the form (In other words, let's say the form's width is 200. btnOpt1 to btnOpt4 should have their Left starting at 100 minus half of the button width, not 0.)

You can do it two ways but with some limitation of each one.
Using Anchor property
Using the layout control with help of Docking and Anchor properties.
Method 1: Anchor Property
Controls are anchored by default to the top left of the form which
means when the form size will be changed, their distance from the top
left side of the form will remain constant. If you change the control
anchor to bottom left, then the control will keep the same distance
from the bottom and left sides of the form when the form if resized.
Turning off the anchor in a direction will keep the control centred in
that direction when resizing.
Example :
public TestForm12()
{
InitializeComponent();
Button btn = new Button();
btn.Width = this.Width - 10;
btn.Height = 20;
btn.Left = (this.ClientSize.Width - btn.Width) / 2;
btn.Top = (this.ClientSize.Height - btn.Height) / 2;
btn.Text = "click me";
this.Controls.Add(btn);
btn.Anchor = AnchorStyles.None;
}
2. Using the layout control
Add TableLayout Control, Set it’s Dock property to Fill.
Add 1 Row with Size Type style Percent 100%
Add 3 Columns Column1(Size Type – Percent(100%)), Column2(Size Type – Absolute(200px)), Column3(Size Type – Percent(100%)).
Now Add Panel Control to Column2 and Set it’s Dock property to Fill
Add Buttons to this control and set their Size as you want and Set Their Anchor Property to AnchorStyles.Left | AnchorStyles.Right | AnchorStyles.Top
Example - Designer.cs code snippet of the form.
private void InitializeComponent()
{
this.tableLayoutPanel1 = new System.Windows.Forms.TableLayoutPanel();
this.panel1 = new System.Windows.Forms.Panel();
this.button1 = new System.Windows.Forms.Button();
this.button2 = new System.Windows.Forms.Button();
this.tableLayoutPanel1.SuspendLayout();
this.panel1.SuspendLayout();
this.SuspendLayout();
//
// tableLayoutPanel1
//
this.tableLayoutPanel1.ColumnCount = 3;
this.tableLayoutPanel1.ColumnStyles.Add(new System.Windows.Forms.ColumnStyle(System.Windows.Forms.SizeType.Percent, 50F));
this.tableLayoutPanel1.ColumnStyles.Add(new System.Windows.Forms.ColumnStyle(System.Windows.Forms.SizeType.Absolute, 200F));
this.tableLayoutPanel1.ColumnStyles.Add(new System.Windows.Forms.ColumnStyle(System.Windows.Forms.SizeType.Percent, 50F));
this.tableLayoutPanel1.Controls.Add(this.panel1, 1, 0);
this.tableLayoutPanel1.Dock = System.Windows.Forms.DockStyle.Fill;
this.tableLayoutPanel1.Location = new System.Drawing.Point(0, 0);
this.tableLayoutPanel1.Name = "tableLayoutPanel1";
this.tableLayoutPanel1.RowCount = 1;
this.tableLayoutPanel1.RowStyles.Add(new System.Windows.Forms.RowStyle(System.Windows.Forms.SizeType.Percent, 100F));
this.tableLayoutPanel1.Size = new System.Drawing.Size(284, 262);
this.tableLayoutPanel1.TabIndex = 0;
//
// panel1
//
this.panel1.Controls.Add(this.button2);
this.panel1.Controls.Add(this.button1);
this.panel1.Dock = System.Windows.Forms.DockStyle.Fill;
this.panel1.Location = new System.Drawing.Point(45, 3);
this.panel1.Name = "panel1";
this.panel1.Size = new System.Drawing.Size(194, 256);
this.panel1.TabIndex = 0;
//
// button1
//
this.button1.Anchor = ((System.Windows.Forms.AnchorStyles)(((System.Windows.Forms.AnchorStyles.Top | System.Windows.Forms.AnchorStyles.Left)
| System.Windows.Forms.AnchorStyles.Right)));
this.button1.Location = new System.Drawing.Point(3, 9);
this.button1.Name = "button1";
this.button1.Size = new System.Drawing.Size(188, 23);
this.button1.TabIndex = 0;
this.button1.Text = "button1";
this.button1.UseVisualStyleBackColor = true;
//
// button2
//
this.button2.Anchor = ((System.Windows.Forms.AnchorStyles)(((System.Windows.Forms.AnchorStyles.Top | System.Windows.Forms.AnchorStyles.Left)
| System.Windows.Forms.AnchorStyles.Right)));
this.button2.Location = new System.Drawing.Point(3, 38);
this.button2.Name = "button2";
this.button2.Size = new System.Drawing.Size(188, 23);
this.button2.TabIndex = 0;
this.button2.Text = "button1";
this.button2.UseVisualStyleBackColor = true;
//
// TestForm11
//
this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 13F);
this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
this.ClientSize = new System.Drawing.Size(284, 262);
this.Controls.Add(this.tableLayoutPanel1);
this.Name = "TestForm11";
this.Text = "TestForm11";
this.tableLayoutPanel1.ResumeLayout(false);
this.panel1.ResumeLayout(false);
this.ResumeLayout(false);
}
#endregion
private System.Windows.Forms.TableLayoutPanel tableLayoutPanel1;
private System.Windows.Forms.Panel panel1;
private System.Windows.Forms.Button button2;
private System.Windows.Forms.Button button1;
Hope this help..

I'd go with TableLayoutPanel instead:
Put TableLayoutPanel on your form
Set dock style Fill to panel
Leave only one column inside panel
Create row for every button (and put buttons to table cells)
Set row size type Autosize
Set dock style Fill to every button, except last one
Set dock style Top to last button
BTW in your solution you should iterate over flowLayoutPanel controls instead of form controls. Also consider subtracting horizontal margin and padding from width:
foreach (Control control in flowLayoutPanel.Controls)
{
control.Size = new Size(flowLayoutPanel.Width - control.Margin.Horizontal,
control.Height);
}
But I advise you to use TableLayoutPanel instead.

I solved this by changing the margin values. I am adding my content to a panel though.
C#:
int horizontalMargin = (int)(0.5 * (this.containingPanelOrForm.Width - this.button.Width));
this.btnOptX.Margin = new Padding(horizontalMargin, 0, horizontalMargin, 0);

Or you can use Grid layout instead.

I´m not good in C# but you can also add a panel in flowlayoutpanel with the same width of flowlayoutpanel. Then you can add in the Panel created in running time the button you want and set the dock to left or right. As you wish. Let me show a example in VB.net and C# (used online converts)
VB.net
Dim btn As New Button
btn.Text = "Example"
btn.Name = "Button"
btn.Size = New Size(60,10)
Dim panel As New Panel
panel.Size = New Size(FlowLayoutPanel1.Width, 10) 'size of the flowlayoutpanel + height of button
btn.Dock = DockStyle.Right
FlowLayoutPanel1.Controls.Add(panel)
panel.controls.add(btn)
C#
Button btn = new Button();
btn.Text = "Example";
btn.Name = "Button";
btn.Size = new Size(60, 10);
Panel panel = new Panel();
panel.Size = new Size(FlowLayoutPanel1.Width, 10);
//size of the flowlayoutpanel + height of button
btn.Dock = DockStyle.Right;
FlowLayoutPanel1.Controls.Add(panel);
panel.controls.#add(btn);

Create empty Label with Name = lblEmpty and AutoSize = False. Put this control first in controls list in FlowLayoutPanel1, then add code below.
Example: Assuming three existing labels in FlowLayoutPanel1, the result should be lblEmpty, LabelExisting1, and LabelExisting2, in that order.
Dim MarginLabelEmpty As Integer = ((FlowLayoutPanel1.Width - (LabelExisting1.Width + LabelExisting2.Width)) / 2)
lblEmpty.Width = MarginLabelEmpty
I solved my problem by creating this code.
in your case with Button Controls, create 4 new labels with .Text=""(empty) and put each one at the beginning of each button, naming labels as follows: lblEmpty1, lblEmpty2, lblEmpty3, lblEmpty4.
Then Add the following code:
Dim MarginLeftbtnOptAll As Integer = ((FlowLayoutPanel1.Width - btnOpt1.Width) / 2)
lblEmpty1.AutoSize = False
lblEmpty1.Width = MarginLeftbtnOptAll
lblEmpty2.AutoSize = False
lblEmpty2.Width = MarginLeftbtnOptAll
lblEmpty3.AutoSize = False
lblEmpty3.Width = MarginLeftbtnOptAll
lblEmpty4.AutoSize = False
lblEmpty4.Width = MarginLeftbtnOptAll
This center button, increasing the width of the empty label according to the width of the FlowLayoutPanel1

Throwing the buttons directly to the form or a panel (not FlowLayoutPanel), and setting Anchor = Top (only Top) for all of them, they won't be centered but will always move proportional to the form's (or container's) sides when resizing.

Private Sub FlowLayoutPanel1_SizeChanged(sender As Object, e As EventArgs)` Handles FlowLayoutPanel1.SizeChanged
Dim TotalWidth As Integer = FlowLayoutPanel1.Controls.Count * button.Width
Dim LeftPadding As Integer = (FlowLayoutPanel1.Width - TotalWidth) / 2
Dim GapPadding As Integer = FlowLayoutPanel1.Controls.Count * 5
If TotalWidth <= FlowLayoutPanel1.Width Then
FlowLayoutPanel1.Padding = New Padding(LeftPadding - GapPadding, 0, 0, 0)
End If
End Sub