If none of the brush, font and string arguments are null when debugger stops on that exception, then it could be some problem in GDI+ drawing strings at very small scales. Our developer will do some tests with that.

Regards,
Slavcho
Mindfusion

This crashes for us when you halve the scale about 50 times, maybe that specific machine's video driver reaches the limit at larger scales -

public Form1()
{
	InitializeComponent();
}

protected override void OnPaint(PaintEventArgs e)
{
	base.OnPaint(e);
	var state = e.Graphics.Save();
	e.Graphics.TextRenderingHint = System.Drawing.Text.TextRenderingHint.AntiAlias;
	e.Graphics.ScaleTransform(scale, scale);
	e.Graphics.DrawString(
		"scale: " + scale.ToString(),
		new Font("Arial", 20), Brushes.Black, 10, 10);
	e.Graphics.Restore(state);
}
private void button1_Click(object sender, EventArgs e)
{
	scale /= 2;
	Debug.WriteLine(scale);
	Invalidate();
}

float scale = 1; 

You could disable overview's DisplayText property when its ScaleFactor gets too small, or override Overview.OnPaint to catch and ignore the exception.

Regards,
Slavcho
Mindfusion

You are overriding overview's method, right? OnPaint is the only place it draws anything and is called as expected in our test -

class OverviewEx : Overview
{
	protected override void OnPaint(PaintEventArgs e)
	{
		try
		{
			Debug.WriteLine("OnPaint");
			base.OnPaint(e);
		}
		catch
		{
			//DisplayText = false;
			//Invalidate();
		}
	}
} 

Regards,
Slavcho
Mindfusion

We have had the same or similar problem reported with the DiagramView...

Message                 : Parameter is not valid.
Source                  : System.Drawing
Stack Trace             :
   at System.Drawing.Graphics.CheckErrorStatus(Int32 status)
   at System.Drawing.Graphics.DrawString(String s, Font font, Brush brush, RectangleF layoutRectangle, StringFormat format)
   at MindFusion.Drawing.GdiGraphics.DrawString(String s, Font font, Brush brush, RectangleF layoutRectangle, StringFormat format)
   at MindFusion.Diagramming.ShapeNode.c2fa8ddcea66de378dd2b3effa46b7080(c48b3fdd1c915
6f9901cdeee6911ffe6e c709ceac15c918fc392a6d51df8089edc)
   at MindFusion.Diagramming.ShapeNode.caf4474dadf19b15a82502e8142e562c6(IGraphics c6c92d7b0a001e45905428290158c2b17, RectangleF ce628c69113f2f8808f36872bc2738966, Boolean c9ad6e71c98bc3301de210ef60cbebaf6, Brush cfe6c9db5410bcfcba1e5ef84f3723807, Pen c70516b352fa4534e29f3eea90837a640, RenderOptions ccf51cc94bd4a2fb3622e3aa9f3d15511)
   at MindFusion.Diagramming.ShapeNode.DrawLocal(IGraphics graphics, RenderOptions options)
   at MindFusion.Diagramming.DiagramNode.Draw(IGraphics graphics, RenderOptions options)
   at MindFusion.Diagramming.Diagram.c36c1fca3b267b5451f759c0295c2805a(IGraphics c6c92d7b0a001e45905428290158c2b17, DiagramItem ca6e827fc07fcc9e1bcb0b1fce21834e2, Boolean c1e4be7b4a08ee92d4d8160fe7cdf183b, Nullable`1 cba5fe945e4bbdbc1273efda679d7f4fe)
   at MindFusion.Diagramming.Diagram.c85c9fb5f1477600f0b8e47a76b97a8a7(IGraphics c6c92d7b0a001e45905428290158c2b17, RectangleF cba5fe945e4bbdbc1273efda679d7f4fe, Boolean c4f62962e65ed617349113106456b7633)
   at MindFusion.Diagramming.Diagram.Draw(IGraphics graphics, RenderOptions options, RectangleF clipRect, Boolean noModifiedItems)
   at MindFusion.Diagramming.WinForms.DiagramView.cbdcbabce8bb735d287c1c0e3584d6497(IG
raphics c6c92d7b0a001e45905428290158c2b17, RectangleF c9261db5050cfcb2acba21bce194905d7, Boolean cdca9e96975ed25325aeab09ccb659e27)
   at MindFusion.Diagramming.WinForms.DiagramView.OnPaint(PaintEventArgs pe)
   at System.Windows.Forms.Control.PaintWithErrorHandling(PaintEventArgs e, Int16 layer)
   at System.Windows.Forms.Control.WmPaint(Message& m)
   at System.Windows.Forms.Control.WndProc(Message& m)
   at MindFusion.Diagramming.WinForms.DiagramView.WndProc(Message& m)
   at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)

Is there anything we can do about this?
DavidL

I restrict the diagram's zoom level to 50% to 200%, so I don't think that it's a zoom-level problem.

DavidL

This was a one-off report from a customer. I can't reproduce it, so let's leave it for now. Thanks for your help.
DavidL

I will have a look at the code and report what I find.
Thanks for you help.
DavidL