rectangle edge smoothness fix

[Vinci10]

Description:

(Based on #5830)
Fixed an issue where rounded edge was not rendered correctly.

Before

After

Checklist:

• Tests included.
• Lint and formatter run with no errors.
• Tests all pass.

[andydotxyz]

This is a great looking improvement thanks so much.

Unfortunately it has broken the ability to draw thin borders on rectangles...

See ere how the file save dialog input in fyne_demo has a significantly wider outline:

[coveralls]

coverage: 62.38% (-0.01%) from 62.392%
when pulling 86418bf on Vinci10:rectangle_edge_smoothness_fix
into c23b700 on fyne-io:develop.

[Vinci10]

Good point. Fortunately, if there is added border then sharp edge is not visible, what about changing edge_softness to 0 when border is added ? edge_softness has already been added as a shader parameter

IMO significantly wider outline looks better but I understand that someone may want to draw thin border

[andydotxyz]

Good point. Fortunately, if there is added border then sharp edge is not visible, what about changing edge_softness to 0 when border is added ? edge_softness has already been added as a shader parameter

I'm not certain of the details but if the edge is only used when it is fill to background then that sounds like a fine approach.

[Vinci10]

Maybe we should add edge_softness as a new rectangle parameter to allow user to change it? High edge_softness value may create something looking like drop shadow

[andydotxyz]

Maybe we should add edge_softness as a new rectangle parameter to allow user to change it? High edge_softness value may create something looking like drop shadow

No.

The Fyne API is a semantic API - the parameters do what they mean. Something called "EdgeSoftness" that can create a shadow-like effect makes no sense IMHO.

[andydotxyz]

This is looking excellent now thanks.
Unfortunately a tidy in how shaders are loaded ("embed" package) is blocking this now.
Could you re-base on latest develop and we can get this merged?

Thanks!

[Vinci10]

I updated the PR with a different implementation of the stroke and fill colors via smoothstep to make the thin border look smooth for rounded corners . Please check if it works as expected. Thanks.

[andydotxyz]

I updated the PR with a different implementation of the stroke and fill colors via smoothstep to make the thin border look smooth for rounded corners . Please check if it works as expected. Thanks.

Thanks so much for going back and looking at it again :)

[andydotxyz]

Thanks - this version looks cool.
The comment style is pretty weird though - if it's needed try to limit it to the content.

[Vinci10]

I removed that comment. I think it is not needed. I tested the code only on WSL Ubuntu 20.04. I am not able to perform tests on other platforms and I am not sure about performance impact. Could you please verify correctness of this new code ? Thanks.

[Vinci10]

I had to update PR because I found out that edges were cropped so I expanded frame without changing rectangle size

[andydotxyz]

Excellent, thanks so much for pulling this together, loving the smoothness

[andydotxyz]

Congratulations on landing your first Fyne PR and thanks so much!