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Point#>>scaleTo:

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Aliaksei Syrel

Point#>>scaleTo:

scaleTo: anExtent
"Return a Point scalefactor for shrinking a thumbnail of the receiver's extent to fit within anExtent."

5@5 scaleTo: 10@10 => 2.0@2.0

10@10 scaleTo: 5@5 => 0.5@0.5

10@10 scaleTo: 5@10 => 1.0@1.0 (wat)

5@10 scaleTo: 10@0 => 0.6666666666666666@0.0 (wat?)

5@0 scaleTo: 10@0 => ZeroDivide (still, wat?)

The idea of the method is nice, especially result as float point, so it can be nicely used for UI. I just don't understand why by contract it does not work with zeros.

Imagine we have two UI elements of arbitrary extent, meaning that 5@0 is completely valid extent. Then imagine we have another UI element with extent 10@0. I would expect to have at least any valid scaling factor that would give correct result if applied.

For example for corner cases result could be:

5@10 scaleTo: 10@0 => 2.0@0.0 (to scale 10 to 0 we need to multiply by 0)

5@0 scaleTo: 10@10 => ZeroDivide

5@0 scaleTo: 10@0 => 2.0@1.0 (when scaling factor is 1.0 it means that scaled arguments are equal, so the same rule can be applied when scaling 0 to 0. Please realize, scaling is not a division!)

Otherwise this method is completely useless (no senders, btw)

So, let's discuss. :)

Cheers,

Alex

Aliaksei Syrel

Re: Point#>>scaleTo:

opened an issue

https://pharo.fogbugz.com/f/cases/17753/Point-scaleTo-is-broken

Nicolai Hess-3-2

Re: Point#>>scaleTo:

In reply to this post by Aliaksei Syrel

2016-03-04 11:48 GMT+01:00 Aliaksei Syrel <[hidden email]>:

scaleTo: anExtent
"Return a Point scalefactor for shrinking a thumbnail of the receiver's extent to fit within anExtent."

5@5 scaleTo: 10@10 => 2.0@2.0
10@10 scaleTo: 5@5 => 0.5@0.5

10@10 scaleTo: 5@10 => 1.0@1.0 (wat)
5@10 scaleTo: 10@0 => 0.6666666666666666@0.0 (wat?)
5@0 scaleTo: 10@0 => ZeroDivide (still, wat?)

The idea of the method is nice, especially result as float point, so it can be nicely used for UI. I just don't understand why by contract it does not work with zeros.

Imagine we have two UI elements of arbitrary extent, meaning that 5@0 is completely valid extent. Then imagine we have another UI element with extent 10@0. I would expect to have at least any valid scaling factor that would give correct result if applied.

For example for corner cases result could be:

5@10 scaleTo: 10@0 => 2.0@0.0 (to scale 10 to 0 we need to multiply by 0)
5@0 scaleTo: 10@10 => ZeroDivide
5@0 scaleTo: 10@0 => 2.0@1.0 (when scaling factor is 1.0 it means that scaled arguments are equal, so the same rule can be applied when scaling 0 to 0. Please realize, scaling is not a division!)

As it scales to fit with preserving the aspect ration, I would expect:

5@10 scaleTo: 10@0 => Some error, as an extent with aspect ratio 1/2 can not fit in something with zero height.

5@0 scaleTo: 10@10 => Although it is a bit strange, I would expect 2@0

5@0 scaleTo: 10@0 => Again, 2@0 would work, it scales an 5@0 extent to fit in 10@0

Otherwise this method is completely useless (no senders, btw)
So, let's discuss. :)

Cheers,
Alex