Video thumbnail not the correct size in PictureBox on 4K monitor.

[MPIon]

I have a PictureBox showing the thumbnail of a video using the following code :

boxData[boxNo].pictureBox.BackgroundImage = shellFile.Thumbnail.LargeBitmap;
boxData[boxNo].pictureBox.Image = Properties.Resources.Sprockets;

This shows correctly on a Full HD monitor at 100% scaling.
When I transfer to 4K monitor it is not correct (27" 4k at 200% scaling).
The Large Thumbnail is

On 4K is shows as :

When changing to ExtraLargeBitmap it shows as :

Neither is correct, but the Extra Large is better.
The sprockets around the image are from a resource file in the application.

Is there a way to adjust the thumbnail to fit?
I have tried Zoom and Stretch on the SizeMode, but they have no effect.

I won't change the monitor scaling from 200% as I need that for other reasons.

 

[Skydiver]

Did you read the documentation regarding how to use WinForms with High DPI?

High DPI support - Windows Forms .NET Framework

Learn about support in Windows Forms for common high DPI and dynamic DPI scenarios. Also learn how to configure Windows Forms applications for high DPI support.

learn.microsoft.com

 

[MPIon]

Thanks for the link Skydiver.
No I have not read this. I suppose I will have to wade through it to see if anything is relevant to thumbnails.
Actually, it is only the background image that seems to have a problem. If I remove this and just set the image to the thumbnail, it is the correct size.
Unfortunately it means that the sprockets that I was using to emphasise that the image is a video are not there.
I might have to find another way to do this if the documentation does not reveal anything.

 

[Skydiver]

You could make a custom control where there are two owner drawn panels docked to the left and right, and a picture box filling the middle. Draw the sprockets in the panels.