How to get rotation angle applied to a line segment?

[poortip87]

Hi All,

I am developing a C++ plugin for AI CC 2017. I need to get the rotation angle applied to a line segment.

I found this method in the AIRealMathSuite which might give what I need,

AIAPI void(* AIRealMathSuite::AIRealMatrixGetRotate) (const AIRealMatrix *m, AIReal *angle)

But for this I need the AIRealMatrix parameter which is the transformation matrix of the line segment.

I am not sure how to get that.

Any ideas where I might start on this?

Thanks!

[sergey_ak]

It seems that there is no way, to get it. I have similiar problem, trying to get rotation/transformation matrix of kGroupArt object. As documentation for AITransformArtSuite::TransformArt says:

• Text art, raster art, and placed art objects have associated transformation matrices. Functions such as AIRasterSuite::GetRasterMatrix() in the related suites provide access to the matrices. TransformArt() does not use the associated matrix, but instead uses a matrix that you pass to the function.
• Path art objects are simple collections of connected line segments, and do not have an associated transformation matrix. For these, you must use the TransformArt() function.

[LeoTaro]

What are you trying to achieve? Do you want to distinguish between when a user draws a horizontal line and rotates it 90 degrees and when they draw a vertical line? I don't think that is possible. When you rotate a line, Illustrator just moves the points, it doesn't store the original points and the rotation. If you want to know the angle of a line segment, you can work this out from the start and end points.

[poortip87]

I want to find if the user has transformed the line by rotating it. So, finding the angle through the coordinates won't be much useful to me.

I was going through the Scripting forum to find some answers there, and I got a breakthrough..

AI adds a tag to an item if it has been rotated. The tag is 'BBAccumRotation'.

I used the object's dictionary to find the tag and get it's value. The value is stored as a string in radians.

Convert it to degrees and you get the rotation angle.

[poortip87 · Accepted solution]

Okay.. So, I was able to do it..

I was going through the Scripting forum to find some answers there, and I got a breakthrough..

AI adds a tag to an item if it has been rotated. The tag is 'BBAccumRotation'.

I used the object's dictionary to find the tag and get it's value. The value is stored as a string in radians.

Convert it to degrees and you get the rotation angle.