Why is this method ineffective?

[peakedshout]

type Unit struct {
wStart, wEnd float32
hStart, hEnd float32
fyne.CanvasObject
}

Like this, I made a combinatory, but it doesn't show up in use? This looks like the method should be implemented

[Jacalz]

It is just a data, it doesn't contain any logic. What are you trying to do? Extending fyne.CanvasObject basically doesn't do anything because it is just an interface, not a concrete implementation.

[peakedshout]

I want to implement a display aspect ratio for any object, so that the layout can be resized according to these proportions, and not limited to a certain component object.

[andydotxyz]

You should look at layouts for this functionality, not extending the generic concept of a canvas object.
It may seem counter-intuitive at first, but the position and size of widgets is controlled by the layout of the container they are in.
With this method we can adapt UI much more easily to the variety of output devices we support.
See https://docs.fyne.io/extend/custom-layout

[peakedshout]

I did implement a custom layout that I expected to be displayed according to the scale, so that the properties of each scale should not be bound to the layout object?

[peakedshout]

In the custom layout, I get the extended layout object, and the layout will be resized according to the extended properties of the layout object, I don't think this idea should be too much of a problem?

[andydotxyz]

I don't understand what an extended layout object is... A layout is any type that implements the two methods of the Layout interface. No extension and no extra objects should be needed.

[andydotxyz]

I did implement a custom layout that I expected to be displayed according to the scale, so that the properties of each scale should not be bound to the layout object?

I don't fully understand this, but perhaps you can see how Border container uses a layout with extra properties to influence the layout. Or check out the responsive layout in fyne-x repo https://github.com/fyne-io/fyne-x/blob/master/layout/responsive.go for inspiration.

[andydotxyz]

Not really. You seem to be asking the widgets where they would like to appear - that's not really what layouts do.
I may be missing something - but can't your layout make the decision based on available space?

[peakedshout]

I just want to show it proportionally based on the total size of the current layout.
Perhaps, I could extend a widget to wrap this unidentified object, and expand the information in this new component. Alternatively, append a map to the layout to do so.
However, in the case of golang, it is not uncommon to extend the approach of the interface (language features). As defined by the API, it accepts the CanvasObject interface as a parameter, and the external implementation of the interface does not play a role, which is undoubtedly very confusing. For a golang programmer who is new to fyne, there is a high probability that this trap will be triggered, especially those who like to design abstractly with interfaces.

[andydotxyz]

As Jacob mentioned you can provide custom widgets - but not custom canvas objects, because the painter will not understand how to paint them.

Going back to the original point the widgets should not control layout - it's not how Fyne is designed so you will be constantly fighting the API features.
Consider instead using the responsive layout from fyne-x https://github.com/fyne-io/fyne-x

[peakedshout]

Well, I don't want to argue about anything anymore, I can only hope that Fyne will get better and have fewer pitfalls like that.

[andydotxyz]

I'm closing out this discussion - but I hope you can see that in the answers above we have shown how to do each of the things you desired, and explained why the API is designed the way it is.