OnPaint event is not updating the form - winforms

Question

I know this code will work in Visual Studio 2010, but for some reason it is not updating the form in Visual Studio 2022. I alread tried DoubleBuffer and User styles... Any clue what is wrong with this code?
`
namespace Kaledoscópio
{
public partial class frmMain : Form
{
private readonly Random randomColor = new Random();
public frmMain()
{
InitializeComponent();
tmrStep.Tick += TmrStep_Tick;
tmrStep.Start();
}
private void TmrStep_Tick(object? sender, EventArgs e)
{
this.Invalidate();
}
private void frmMain_OnPaint(object sender, PaintEventArgs e)
{
base.OnPaint(e);
Graphics g = e.Graphics;
Color defaultColor = Color.FromArgb(randomColor.Next(255), randomColor.Next(255), randomColor.Next(255));
using (Pen defaultPen = new Pen(defaultColor, 2))
{
int intHeight = this.ClientSize.Height;
int intWidth = this.ClientSize.Width;
int intMiddleHeight = intHeight / 2;
int intMiddleWidth = intWidth / 2;
Point posTopLeft = new Point(0, 0);
Point posTopRight = new Point(intWidth, 0);
Point posBottomLeft = new Point(0, intHeight);
Point posBottomRight = new Point(intWidth, intHeight);
Point posMiddle = new Point(intMiddleWidth, intMiddleHeight);
Point posMiddleTop = new Point(intMiddleWidth, 0);
Point posMiddleLeft = new Point(0, intMiddleHeight);
Point posMiddleRight = new Point(intWidth, intMiddleHeight);
Point posMiddleBottom = new Point(intMiddleWidth, intHeight);
int defaultStep = randomColor.Next(3, 10);
int b1;
for (b1 = 0; b1 <= intMiddleWidth; b1 += defaultStep)
{
g.DrawLine(defaultPen, posTopLeft.X + b1, posTopLeft.Y, posMiddle.X - b1, posMiddle.Y);
g.DrawLine(defaultPen, posTopRight.X - b1, posTopRight.Y, posMiddle.X + b1, posMiddle.Y);
g.DrawLine(defaultPen, posMiddle.X - b1, posMiddle.Y, posBottomLeft.X + b1, posBottomLeft.Y);
g.DrawLine(defaultPen, posMiddle.X + b1, posMiddle.Y, posBottomRight.X - b1, posBottomRight.Y);
}
int b2;
for (b2 = 0; b2 <= intMiddleHeight; b2 += defaultStep)
{
g.DrawLine(defaultPen, posMiddleTop.X, posMiddleTop.Y + b2, posMiddleLeft.X, posMiddleLeft.Y - b2);
g.DrawLine(defaultPen, posMiddleTop.X, posMiddleTop.Y + b2, posMiddleRight.X, posMiddleRight.Y - b2);
g.DrawLine(defaultPen, posMiddleRight.X, posMiddleRight.Y + b2, posMiddleBottom.X, posMiddleBottom.Y - b2);
g.DrawLine(defaultPen, posMiddleLeft.X, posMiddleLeft.Y + b2, posMiddleBottom.X, posMiddleBottom.Y - b2);
}
}
}
}
}
Actually, it will works if I force a call to Paint() event inside OnPaint() event, but frankly, I don´t think this is the right way to deal with this... Paint() event should be called internally.

Answer 1

Base on your advices I found one solution.
No sure about any colletaral effect, but it works.
I just commented base.OnPaint(e) and it works.
Here is the final code:
namespace Kaledoscópio
{
public partial class frmMain : Form
{
private readonly Random randomColor = new Random();
public frmMain()
{
InitializeComponent();
tmrStep.Tick += TmrStep_Tick;
tmrStep.Start();
}
private void TmrStep_Tick(object? sender, EventArgs e)
{
this.Refresh();
}
private void frmMain_Paint(object sender, PaintEventArgs e)
{
//base.OnPaint(e);
Graphics g = e.Graphics;
Color defaultColor = Color.FromArgb(randomColor.Next(255), randomColor.Next(255), randomColor.Next(255));
using (Pen defaultPen = new Pen(defaultColor, 2))
{
int intHeight = this.ClientSize.Height;
int intWidth = this.ClientSize.Width;
int intMiddleHeight = intHeight / 2;
int intMiddleWidth = intWidth / 2;
Point posTopLeft = new Point(0, 0);
Point posTopRight = new Point(intWidth, 0);
Point posBottomLeft = new Point(0, intHeight);
Point posBottomRight = new Point(intWidth, intHeight);
Point posMiddle = new Point(intMiddleWidth, intMiddleHeight);
Point posMiddleTop = new Point(intMiddleWidth, 0);
Point posMiddleLeft = new Point(0, intMiddleHeight);
Point posMiddleRight = new Point(intWidth, intMiddleHeight);
Point posMiddleBottom = new Point(intMiddleWidth, intHeight);
int defaultStep = randomColor.Next(3, 10);
int b1;
for (b1 = 0; b1 <= intMiddleWidth; b1 += defaultStep)
{
g.DrawLine(defaultPen, posTopLeft.X + b1, posTopLeft.Y, posMiddle.X - b1, posMiddle.Y);
g.DrawLine(defaultPen, posTopRight.X - b1, posTopRight.Y, posMiddle.X + b1, posMiddle.Y);
g.DrawLine(defaultPen, posMiddle.X - b1, posMiddle.Y, posBottomLeft.X + b1, posBottomLeft.Y);
g.DrawLine(defaultPen, posMiddle.X + b1, posMiddle.Y, posBottomRight.X - b1, posBottomRight.Y);
}
int b2;
for (b2 = 0; b2 <= intMiddleHeight; b2 += defaultStep)
{
g.DrawLine(defaultPen, posMiddleTop.X, posMiddleTop.Y + b2, posMiddleLeft.X, posMiddleLeft.Y - b2);
g.DrawLine(defaultPen, posMiddleTop.X, posMiddleTop.Y + b2, posMiddleRight.X, posMiddleRight.Y - b2);
g.DrawLine(defaultPen, posMiddleRight.X, posMiddleRight.Y + b2, posMiddleBottom.X, posMiddleBottom.Y - b2);
g.DrawLine(defaultPen, posMiddleLeft.X, posMiddleLeft.Y + b2, posMiddleBottom.X, posMiddleBottom.Y - b2);
}
}
}
}
}

Answer 2

Try
private void TmrStep_Tick(object? sender, EventArgs e)
{
this.Refresh();
}
This will force the repaint of the form. I assume you have the form .Paint event assigned to frmMain_OnPaint() already.