Detect GUI rotation degree

Hi, I have a small project with genre fishing. Have a problem on detect rotation. I have a GUI texture like a reel that can be rotated.

How can i make the length decrease based on each 15 degree the reel rotated? Here is my Rotate code in C#:

 public class Rotate : MonoBehaviour {
 
     public Texture2D texture = null;
     public Vector2 size = new Vector2(0, 0);
  
     private float angle = 0;
     private Vector2 pos = new Vector2(0, 0);
     private Rect rect;
     private Vector2 pivot;
     public static bool rotating = false;
     public static bool rotating2 = false;
     private float initialMouseAngle;
     
     static float speed = 0.1f;
     
     float factor = Screen.width/800;
  
     void Start() {
         UpdateSettings();
     }
  
     void UpdateSettings() {
            pos = new Vector2(Screen.width-factor*700,Screen.height-factor*320+200);
         rect = new Rect(pos.x - size.x * 0.5f, pos.y - size.y * 0.5f, 150, 150);
            //Debug.Log ("Rect="+rect);
         pivot = new Vector2(rect.xMin + rect.width * 0.5f, rect.yMin + rect.height * 0.5f);
         //Debug.Log ("Pivot ="+pivot);
     }
  
     void OnGUI() {
            if (Application.isEditor){ 
             UpdateSettings(); 
         }
         
            Vector2 guiMouse = Input.mousePosition;
            guiMouse.y = Screen.height - guiMouse.y;
         
            if (Input.GetMouseButtonDown(0) && rect.Contains(guiMouse)) {
             Vector2 v2T = ((Vector2)guiMouse - pivot);
             initialMouseAngle = Mathf.Atan2(v2T.y, v2T.x) - angle * Mathf.Deg2Rad;
             rotating = true;
            }
            else if (Input.GetMouseButton(0) && rotating) {
              Vector2 v2T = ((Vector2)guiMouse - pivot);
             angle = (Mathf.Atan2 (v2T.y, v2T.x) - initialMouseAngle) * Mathf.Rad2Deg;
             //GetComponent<Length>().Jarak(speed);
             rotating2 = true;
             rect.ToString();
            }
            else if (Input.GetMouseButtonUp(0)) {
              rotating = false;
             rotating2 = false;
            }
         
         Matrix4x4 matrixBackup = GUI.matrix;
         GUIUtility.RotateAroundPivot(angle, pivot);
         
         if(FishingGUI.waktu == true){
             GUI.DrawTexture(rect, texture);
             animation.Play("idle");
             return;
         }
         
         GUI.matrix = matrixBackup;
     }
 }

I want to integrated with this want, so each 15 degree can decrease the length:

 public class Length : MonoBehaviour {
 
     [SerializeField]
     float MaxLength = 100f;
     float CurrentLength = 0f;
     
     void Start () {
         CurrentLength = MaxLength;
     }
     
     override public string ToString(){
         return CurrentLength + "";
     }
     
     public void Jarak(float tarikans){
         CurrentLength -= tarikans;
     }
     
     void Update(){
         if(CurrentLength <= 0){
             CurrentLength = 0;
         }
     }
 }

Please anyone can help or any other solution? Thanks