[beginner's question] How to rotate the ruler?

[rodrigo-morales-1]

Today I discovered the tool Ruler.

I was able to move it when the tool "Select" was enabled. However, I couldn't figure out how to rotate the Ruler.

Here's a video of me moving the Ruler in v2.4.1.

Screen_Recording_20251124_221036-convert.webm

What I tried

To figure that out, I decided to look at the source code. I found these two files which have the word "ruler" in its filename.

• https://github.com/LinwoodDev/Butterfly/blob/v2.4.1/app/lib/handlers/ruler.dart
• https://github.com/LinwoodDev/Butterfly/blob/v2.4.1/app/lib/selections/tools/ruler.dart

I pressed Ctrl+F in my web browser and I found some matches for "rotat" in https://github.com/LinwoodDev/Butterfly/blob/v2.4.1/app/lib/handlers/ruler.dart, so I guess it is possible to rotate the ruler, but I couldn't infer how to do it from reading the source code.

Suggestion

I think it would be helpful for some users if the documentation for the Ruler https://butterfly.linwood.dev/docs/v2/tools/ruler/ mentioned how to rotate it.

[CodeDoctorDE]

I think it's currently a bug, i will try to fix it in the next 2.4.2-rc.1

[rodrigo-morales-1]

@CodeDoctorDE Thanks for your quick attention.

I think an enhancement to the ruler would be to show the rotation angle in some part of the screen for the ruler while the ruler tool is enabled. This would be helpful for users that use Butterfly to take notes on geometry or trigonometry because drawing angles with given sizes is a common task while studying those topics.

This video shows how the rotation angle is shown for the ruler in the iOS notes app: https://youtu.be/0iHiMhjh00Y?t=33

Here are some sample images that students of geometry/trigonometry might want to draw in Butterfly:

Source: https://commons.wikimedia.org/wiki/File:Trigonometric_Functions_of_Any_Angle_Figure_1.svg

Source: https://commons.wikimedia.org/wiki/File:Triangle_30_30_120.svg

Source: https://commons.wikimedia.org/wiki/File:Hardest-easy-geometry-problem-langleys-adventitious-angles.png

Source: https://commons.wikimedia.org/wiki/File:Internal_and_external_angles.png

[CodeDoctorDE]

Im currently not sure: do you just want a label for the degree or a snapping system that snaps on whole numbers or also a protractor

[JerryMerweather]

Im currently not sure: do you just want a label for the degree or a snapping system that snaps on whole numbers or also a protractor

Why not both?

Tool settings for snapping ruler. And to modify the rotation using a slider and an input box just like the other tools.

And

While rotating, display the angle.

[rodrigo-morales-1]

I think @JerryMerweather's suggestion would cover most use cases. There would be 3 ways to rotate the ruler:

1. 2 finger gesture
   • The settings of the Ruler tool would show an option "Snap rotation to whole numbers" to set the behavior while using the 2 finger gesture.
   • While rotating
2. Modify the rotation using a slider that would be shown the settings of the Ruler tool
   • There might be some users that prefer setting the rotation through a slider than using the 2 finger gesture since Butterfly allow setting properties for some tools through a slider.
3. Input box to set the rotation to a specific value in the settings of the Ruler tool
   • The input box would be useful for people that want higher precision than whole numbers and don't want to use the 2 finger gesture since it would be too difficult to set it to an specific decimal value (e.g. 22.5, 7.5, etc.)

@CodeDoctorDE wrote: or also a protractor

In addition to the ruler, having a protractor would be useful too.

An advantage of the protractor is that it allows the user to compare all the rotation angles so that the user can choose the angle that is more suitable for her/him. The ruler doesn't have this advantage because the ruler only shows one rotation angle at a time. The protractor might be particularly useful for geometry students.

I found this video that shows the behavior of rulers in Zoomnotes (propietary note-taking software) https://youtu.be/zsXpaCjHDpI?t=23 Zoomnotes has an ordinary ruler, but also has a protractor triangle ruler and elliptical ruler.

Sidenote: In a previous edit of this message, I wrote that I haven't felt the need of using a protractor. I wrote that because I haven't seriously tried using Butterfly for solving geometry problems, since I'm currently exploring Butterfly (i.e. creating bug reports and feature requests), so I am solving them in paper for the time being.