I hope the video will be enough.

No. Please always add example code so we can replicate the issue.

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It is possible that there is a delay in painting so when you ask for the image to display it does not happen immediately.
Are you by any chance writing the image to be white and reusing it?

Important note is that when you call Refresh it is not actually painting to canvas, it is queueing the change to be reflected in next redraw - which will happen asynchronously.

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andydotxyz:

I read a file and then write the content to the image. I do not explictly Refresh although I have done so as a test, but the flashes remained.

Jaclz:

I'll put together a demo package - all the code, plus a file to 'play'. Do I just drop that in this box?

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demo-fits-folder.zip
main.zip

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I changed the theme to dark and now it flashes black. With white theme it flashes white.

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I went to go.mod and updated all available modules as image was mentioned in two of them. Sadly, now I get:

fyne.io/fyne/v2/internal/painter

..\pkg\mod\fyne.io\fyne\[email protected]\internal\painter\font.go:209:65: out.LineBounds.LineHeight undefined (type shaping.Bounds has no field or method LineHeight)

Where do I go from here?

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I was trying to build a simple demo of the flashing. Now I can't use Fyne at all because of the above error. I do not know enough to be able to rollback to something that does work.

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I have built a simple demo that repeatedly shows the same image using the same mechanisms that are in my "video player".

It does not "flash", so I'm closing this thread.

I got Fyne to work again in my demo program by NOT accepting any of the updates shown to be available in go.mod

I'm new to Golang and probably haven't learned that updates come with risks. Plus, there's the old maxim: If it's not broken, don't fix it. I should have followed it, but the presence of references to image in two of the updates seduced me.

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I went to go.mod and updated all available modules as image was mentioned in two of them. Sadly, now I get:

fyne.io/fyne/v2/internal/painter

..\pkg\mod\fyne.io\fyne\[email protected]\internal\painter\font.go:209:65: out.LineBounds.LineHeight undefined (type shaping.Bounds has no field or method LineHeight)

Where do I go from here?

You can always upgrade Fyne safely but it looks like you upgraded all dependencies and sadly one library we use pushed a breaking change.

In the future you can do just a single library upgrade like "go get fyne.io/fyne/v2@latest" to avoid this.

We are preparing an update to fyne that hides the go-text breakage but I've been too busy to release it the last week sorry.

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Ah. File operations are slow and expensive compared to the graphical operations, so perhaps it was blanking the image when load started and what you were seeing was the delay in load time.
You workaround seems sensible, though you may need to move that to a worker goroutine for larger directories.

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