1 files changed, 14 insertions, 0 deletions
diff --git a/solo-tool-project/src/solo_tool/handlers.py b/solo-tool-project/src/solo_tool/handlers.py
index 13e982b..0a4ee21 100644
--- a/solo-tool-project/src/solo_tool/handlers.py
+++ b/solo-tool-project/src/solo_tool/handlers.py
@@ -19,3 +19,17 @@ def positionToKeyPoint(st: SoloTool) -> Callable[[], None]:
     def f():
         st.keyPoint = st.position
     return f
+
+def changeKeyPoint(st: SoloTool, delta: int) -> Callable[[], None]:
+    from bisect import bisect_right, bisect_left
+    def f():
+        if delta > 0:
+            pivot = bisect_right(st.keyPoints, st.keyPoint) - 1
+        elif delta < 0:
+            pivot = bisect_left(st.keyPoints, st.keyPoint) - 1
+        else:
+            return
+        new = max(min(pivot + delta, len(st.keyPoints) - 1), 0)
+        st.keyPoint = st.keyPoints[new]
+    return f
+