Use useCallback.

src/hooks/crosshair.tsx

@@ -1,4 +1,4 @@
-import { useEffect, useState, useRef } from "react";
+import { useEffect, useState, useRef, useCallback } from "react";
 import type { Dispatch, SetStateAction } from "react";
 import type { CartesianSpace } from "../types";
 import { minmax } from "../util";
@@ -12,6 +12,22 @@ function isTouchEvent(event: Event): event is TouchEvent {
   return "touches" in event;
 }
 
+function extractEventCoordinates(event: MouseEvent | TouchEvent): {
+  clientX: number;
+  clientY: number;
+} {
+  if (isTouchEvent(event)) {
+    return {
+      clientX: event.touches[0].clientX,
+      clientY: event.touches[0].clientY,
+    };
+  }
+  return {
+    clientX: event.clientX,
+    clientY: event.clientY,
+  };
+}
+
 export function useCrosshair({
   origin,
   dimensions,
@@ -26,19 +42,6 @@ export function useCrosshair({
   const [isDragging, setIsDragging] = useState(false);
   const crosshairRef = useRef<HTMLDivElement>(null);
 
-  // Construct event handler refs
-  // Prevents unnecessary function recreation
-  const calculatePositionsRef = useRef((_: MouseEvent | TouchEvent) => {});
-  const startCrosshairInteractionRef = useRef(
-    (_: MouseEvent | TouchEvent) => {},
-  );
-  const processCrosshairInteractionRef = useRef(
-    (_: MouseEvent | TouchEvent) => {},
-  );
-  const endCrosshairInteractionRef = useRef((_: MouseEvent | TouchEvent) => {});
-
-  // Store dependencies as refs
-  // Always use latest values
   const originRef = useRef(origin);
   const dimensionsRef = useRef(dimensions);
 
@@ -47,121 +50,92 @@ export function useCrosshair({
     dimensionsRef.current = dimensions;
   }, [origin, dimensions]);
 
-  // Update handler functions when dependencies change via reference
+  const calculatePositions = useCallback(
-
+    (event: MouseEvent | TouchEvent) => {
-  useEffect(() => {
-    calculatePositionsRef.current = (event: MouseEvent | TouchEvent) => {
       const orig = originRef.current;
       const dims = dimensionsRef.current;
 
-      const clientX = isTouchEvent(event)
+      const { clientX, clientY } = extractEventCoordinates(event);
-        ? event.touches[0].clientX
-        : event.clientX;
-      const clientY = isTouchEvent(event)
-        ? event.touches[0].clientY
-        : event.clientY;
 
       const xPos = minmax(clientX - orig.x, 0, dims.x - 1);
       const yPos = minmax(clientY - orig.y, 0, dims.y - 1);
       setXPosition(xPos);
       setYPosition(yPos);
-    };
+    },
+    [setXPosition, setYPosition],
+  );
 
-    startCrosshairInteractionRef.current = (event: MouseEvent | TouchEvent) => {
+  const processCrosshairInteraction = useCallback(
+    (event: MouseEvent | TouchEvent) => {
       event.preventDefault();
-      calculatePositionsRef.current(event);
+      calculatePositions(event);
+    },
+    [calculatePositions],
+  );
+
+  const endCrosshairInteraction = useCallback(
+    (event: MouseEvent | TouchEvent) => {
+      setIsDragging(false);
+      if (!isTouchEvent(event)) {
+        document.removeEventListener("mousemove", processCrosshairInteraction);
+        document.removeEventListener("mouseup", endCrosshairInteraction);
+      } else {
+        document.removeEventListener("touchmove", processCrosshairInteraction);
+        document.removeEventListener("touchend", endCrosshairInteraction);
+        document.removeEventListener("touchcancel", endCrosshairInteraction);
+      }
+    },
+    [processCrosshairInteraction],
+  );
+
+  const startCrosshairInteraction = useCallback(
+    (event: MouseEvent | TouchEvent) => {
+      event.preventDefault();
+      calculatePositions(event);
       setIsDragging(true);
 
       if (!isTouchEvent(event)) {
-        document.addEventListener(
+        document.addEventListener("mousemove", processCrosshairInteraction);
-          "mousemove",
+        document.addEventListener("mouseup", endCrosshairInteraction, {
-          processCrosshairInteractionRef.current,
+          passive: true,
-        );
+        });
-        document.addEventListener(
-          "mouseup",
-          endCrosshairInteractionRef.current,
-          { passive: true },
-        );
       } else {
-        document.addEventListener(
+        document.addEventListener("touchmove", processCrosshairInteraction);
-          "touchmove",
+        document.addEventListener("touchend", endCrosshairInteraction, {
-          processCrosshairInteractionRef.current,
+          passive: true,
-        );
+        });
-        document.addEventListener(
+        document.addEventListener("touchcancel", endCrosshairInteraction, {
-          "touchend",
+          passive: true,
-          endCrosshairInteractionRef.current,
+        });
-          { passive: true },
-        );
-        document.addEventListener(
-          "touchcancel",
-          endCrosshairInteractionRef.current,
-          { passive: true },
-        );
       }
-    };
+    },
+    [calculatePositions, processCrosshairInteraction, endCrosshairInteraction],
+  );
 
-    processCrosshairInteractionRef.current = (
-      event: MouseEvent | TouchEvent,
-    ) => {
-      event.preventDefault();
-      calculatePositionsRef.current(event);
-    };
-
-    endCrosshairInteractionRef.current = (event: MouseEvent | TouchEvent) => {
-      setIsDragging(false);
-      if (!isTouchEvent(event)) {
-        document.removeEventListener(
-          "mousemove",
-          processCrosshairInteractionRef.current,
-        );
-        document.removeEventListener(
-          "mouseup",
-          endCrosshairInteractionRef.current,
-        );
-      } else {
-        document.removeEventListener(
-          "touchmove",
-          processCrosshairInteractionRef.current,
-        );
-        document.removeEventListener(
-          "touchend",
-          endCrosshairInteractionRef.current,
-        );
-        document.removeEventListener(
-          "touchcancel",
-          endCrosshairInteractionRef.current,
-        );
-      }
-    };
-  }, []);
-
-  // Set up entry listeners
   useEffect(() => {
     const currentRef = crosshairRef.current;
     if (currentRef) {
-      currentRef.addEventListener(
+      currentRef.addEventListener("mousedown", startCrosshairInteraction);
-        "mousedown",
+      currentRef.addEventListener("touchstart", startCrosshairInteraction);
-        startCrosshairInteractionRef.current,
-      );
-      currentRef.addEventListener(
-        "touchstart",
-        startCrosshairInteractionRef.current,
-      );
     }
 
     return () => {
       if (currentRef) {
-        currentRef.removeEventListener(
+        currentRef.removeEventListener("mousedown", startCrosshairInteraction);
-          "mousedown",
+        currentRef.removeEventListener("touchstart", startCrosshairInteraction);
-          startCrosshairInteractionRef.current,
-        );
-        currentRef.removeEventListener(
-          "touchstart",
-          startCrosshairInteractionRef.current,
-        );
       }
+
+      document.removeEventListener("mousemove", processCrosshairInteraction);
+      document.removeEventListener("mouseup", endCrosshairInteraction);
+      document.removeEventListener("touchmove", processCrosshairInteraction);
+      document.removeEventListener("touchend", endCrosshairInteraction);
+      document.removeEventListener("touchcancel", endCrosshairInteraction);
     };
-  }, []);
+  }, [
+    startCrosshairInteraction,
+    processCrosshairInteraction,
+    endCrosshairInteraction,
+  ]);
 
   return { crosshairRef, isDragging };
 }

src/hooks/scroll.ts

@@ -1,4 +1,4 @@
-import { useState, useRef, useEffect } from "react";
+import { useState, useRef, useEffect, useCallback } from "react";
 import type { RefObject } from "react";
 
 export function handleScroll(
@@ -6,7 +6,7 @@ export function handleScroll(
   scrollDelta: number,
   handleIncrement: () => void,
   handleDecrement: () => void,
-) {
+): number {
   const newLength = prevLength + scrollDelta;
 
   if (Math.abs(newLength) > 50) {
@@ -47,10 +47,7 @@ export function useScroll<T extends HTMLElement>({
     deltaYMultiplierRef.current = deltaYMultiplier;
   }, [onScrollUp, onScrollDown, deltaYMultiplier]);
 
-  const handleWheelEventRef = useRef((_: WheelEvent) => {});
+  const handleWheelEvent = useCallback((event: WheelEvent) => {
-
-  useEffect(() => {
-    handleWheelEventRef.current = (event: WheelEvent) => {
     event.preventDefault();
 
     setScrollLength((prev) =>
@@ -61,28 +58,27 @@ export function useScroll<T extends HTMLElement>({
         onScrollUpRef.current,
       ),
     );
-    };
   }, []);
 
-  function addScrollListener() {
+  const addScrollListener = useCallback(() => {
     const currentRef = targetRef.current;
     if (currentRef) {
-      currentRef.addEventListener("wheel", handleWheelEventRef.current);
+      currentRef.addEventListener("wheel", handleWheelEvent);
-    }
     }
+  }, [handleWheelEvent, targetRef]);
 
-  function removeScrollListener() {
+  const removeScrollListener = useCallback(() => {
     const currentRef = targetRef.current;
     if (currentRef) {
-      currentRef.removeEventListener("wheel", handleWheelEventRef.current);
+      currentRef.removeEventListener("wheel", handleWheelEvent);
-    }
     }
+  }, [handleWheelEvent, targetRef]);
 
   useEffect(() => {
     return () => {
       removeScrollListener();
     };
-  }, []);
+  }, [removeScrollListener]);
 
   return {
     addScrollListener,

src/hooks/slider.tsx

@@ -1,5 +1,5 @@
-import { useState, useRef, useEffect } from "react";
+import { useState, useRef, useEffect, useCallback } from "react";
-import type { Dispatch, SetStateAction, RefObject } from "react";
+import type { Dispatch, SetStateAction } from "react";
 import { minmax } from "../util";
 import type { CartesianSpace } from "../types";
 import { useScroll } from "./scroll";
@@ -26,6 +26,20 @@ function chooseValueByDirection(
   return direction === Direction.HORIZONTAL ? xValue : yValue;
 }
 
+function extractEventCoordinate(
+  event: MouseEvent | TouchEvent,
+  direction: Direction,
+): number {
+  if (isTouchEvent(event)) {
+    return chooseValueByDirection(
+      direction,
+      event.touches[0].clientX,
+      event.touches[0].clientY,
+    );
+  }
+  return chooseValueByDirection(direction, event.clientX, event.clientY);
+}
+
 export function useSlider({
   direction,
   origin,
@@ -36,21 +50,10 @@ export function useSlider({
   origin: CartesianSpace;
   dimensions: CartesianSpace;
   setPosition: Dispatch<SetStateAction<number>>;
-}): { sliderRef: RefObject<HTMLDivElement | null>; isDragging: boolean } {
+}) {
   const [isDragging, setIsDragging] = useState(false);
   const sliderRef = useRef<HTMLDivElement>(null);
 
-  // Construct event handler refs
-  // Prevents unnecessary function recreation
-  const calculatePositionRef = useRef((_: MouseEvent | TouchEvent) => {});
-  const startSliderInteractionRef = useRef((_: MouseEvent | TouchEvent) => {});
-  const processSliderInteractionRef = useRef(
-    (_: MouseEvent | TouchEvent) => {},
-  );
-  const endSliderInteractionRef = useRef((_: MouseEvent | TouchEvent) => {});
-
-  // Store dependencies as refs
-  // Always use latest values
   const directionRef = useRef(direction);
   const originRef = useRef(origin);
   const dimensionsRef = useRef(dimensions);
@@ -61,147 +64,125 @@ export function useSlider({
     dimensionsRef.current = dimensions;
   }, [direction, origin, dimensions]);
 
-  // Setup scroll handlers
+  // Setup drag handlers
-  const handleScrollUp = () => {
+  const calculatePosition = useCallback(
-    const dir = directionRef.current;
+    (event: MouseEvent | TouchEvent) => {
-    const dims = dimensionsRef.current;
-
-    setPosition((prev: number) =>
-      minmax(prev - 1, 0, chooseValueByDirection(dir, dims.x, dims.y)),
-    );
-  };
-
-  const handleScrollDown = () => {
-    const dir = directionRef.current;
-    const dims = dimensionsRef.current;
-
-    setPosition((prev: number) =>
-      minmax(prev + 1, 0, chooseValueByDirection(dir, dims.x, dims.y)),
-    );
-  };
-
-  // Initialize scroll handling
-  const { addScrollListener, removeScrollListener } = useScroll({
-    targetRef: sliderRef,
-    onScrollUp: handleScrollUp,
-    onScrollDown: handleScrollDown,
-  });
-
-  // Update handler functions when dependencies change via reference
-  useEffect(() => {
-    calculatePositionRef.current = (event: MouseEvent | TouchEvent) => {
       const dir = directionRef.current;
       const orig = originRef.current;
       const dims = dimensionsRef.current;
 
-      const clientCoord = isTouchEvent(event)
+      const clientCoord = extractEventCoordinate(event, dir);
-        ? chooseValueByDirection(
-            dir,
-            event.touches[0].clientX,
-            event.touches[0].clientY,
-          )
-        : chooseValueByDirection(dir, event.clientX, event.clientY);
       const positionValue = minmax(
         clientCoord - chooseValueByDirection(dir, orig.x, orig.y),
         0,
         chooseValueByDirection(dir, dims.x, dims.y),
       );
       setPosition(positionValue);
-    };
+    },
+    [setPosition],
+  );
 
-    startSliderInteractionRef.current = (event: MouseEvent | TouchEvent) => {
+  const processSliderInteraction = useCallback(
+    (event: MouseEvent | TouchEvent) => {
       event.preventDefault();
-      calculatePositionRef.current(event);
+      calculatePosition(event);
+    },
+    [calculatePosition],
+  );
+
+  const endSliderInteraction = useCallback(
+    (event: MouseEvent | TouchEvent) => {
+      setIsDragging(false);
+      if (!isTouchEvent(event)) {
+        document.removeEventListener("mousemove", processSliderInteraction);
+        document.removeEventListener("mouseup", endSliderInteraction);
+      } else {
+        document.removeEventListener("touchmove", processSliderInteraction);
+        document.removeEventListener("touchend", endSliderInteraction);
+        document.removeEventListener("touchcancel", endSliderInteraction);
+      }
+    },
+    [processSliderInteraction],
+  );
+
+  const startSliderInteraction = useCallback(
+    (event: MouseEvent | TouchEvent) => {
+      event.preventDefault();
+      calculatePosition(event);
       setIsDragging(true);
 
       if (!isTouchEvent(event)) {
-        document.addEventListener(
+        document.addEventListener("mousemove", processSliderInteraction);
-          "mousemove",
+        document.addEventListener("mouseup", endSliderInteraction, {
-          processSliderInteractionRef.current,
-        );
-        document.addEventListener("mouseup", endSliderInteractionRef.current, {
           passive: true,
         });
       } else {
-        document.addEventListener(
+        document.addEventListener("touchmove", processSliderInteraction);
-          "touchmove",
+        document.addEventListener("touchend", endSliderInteraction, {
-          processSliderInteractionRef.current,
-        );
-        document.addEventListener("touchend", endSliderInteractionRef.current, {
           passive: true,
         });
-        document.addEventListener(
+        document.addEventListener("touchcancel", endSliderInteraction, {
-          "touchcancel",
-          endSliderInteractionRef.current,
-          {
           passive: true,
+        });
+      }
     },
+    [calculatePosition, processSliderInteraction, endSliderInteraction],
   );
-      }
-    };
 
-    processSliderInteractionRef.current = (event: MouseEvent | TouchEvent) => {
+  // Setup scroll handlers
-      event.preventDefault();
+  const handleScrollUp = useCallback(() => {
-      calculatePositionRef.current(event);
+    const dir = directionRef.current;
-    };
+    const dims = dimensionsRef.current;
 
-    endSliderInteractionRef.current = (event: MouseEvent | TouchEvent) => {
+    setPosition((prev: number) =>
-      setIsDragging(false);
+      minmax(prev - 1, 0, chooseValueByDirection(dir, dims.x, dims.y)),
-      if (!isTouchEvent(event)) {
-        document.removeEventListener(
-          "mousemove",
-          processSliderInteractionRef.current,
     );
-        document.removeEventListener(
+  }, [setPosition]);
-          "mouseup",
+
-          endSliderInteractionRef.current,
+  const handleScrollDown = useCallback(() => {
+    const dir = directionRef.current;
+    const dims = dimensionsRef.current;
+
+    setPosition((prev: number) =>
+      minmax(prev + 1, 0, chooseValueByDirection(dir, dims.x, dims.y)),
     );
-      } else {
+  }, [setPosition]);
-        document.removeEventListener(
+
-          "touchmove",
+  const { addScrollListener, removeScrollListener } = useScroll({
-          processSliderInteractionRef.current,
+    targetRef: sliderRef,
-        );
+    onScrollUp: handleScrollUp,
-        document.removeEventListener(
+    onScrollDown: handleScrollDown,
-          "touchend",
+  });
-          endSliderInteractionRef.current,
-        );
-        document.removeEventListener(
-          "touchcancel",
-          endSliderInteractionRef.current,
-        );
-      }
-    };
-  }, []);
 
   // Set up entry listeners
   useEffect(() => {
     const currentRef = sliderRef.current;
     if (currentRef) {
       addScrollListener();
-      currentRef.addEventListener(
+      currentRef.addEventListener("mousedown", startSliderInteraction);
-        "mousedown",
+      currentRef.addEventListener("touchstart", startSliderInteraction);
-        startSliderInteractionRef.current,
-      );
-      currentRef.addEventListener(
-        "touchstart",
-        startSliderInteractionRef.current,
-      );
     }
 
     return () => {
       if (currentRef) {
         removeScrollListener();
-        currentRef.removeEventListener(
+        currentRef.removeEventListener("mousedown", startSliderInteraction);
-          "mousedown",
+        currentRef.removeEventListener("touchstart", startSliderInteraction);
-          startSliderInteractionRef.current,
-        );
-        currentRef.removeEventListener(
-          "touchstart",
-          startSliderInteractionRef.current,
-        );
       }
+
+      document.removeEventListener("mousemove", processSliderInteraction);
+      document.removeEventListener("mouseup", endSliderInteraction);
+      document.removeEventListener("touchmove", processSliderInteraction);
+      document.removeEventListener("touchend", endSliderInteraction);
+      document.removeEventListener("touchcancel", endSliderInteraction);
     };
-  }, []);
+  }, [
+    addScrollListener,
+    removeScrollListener,
+    startSliderInteraction,
+    processSliderInteraction,
+    endSliderInteraction,
+  ]);
 
   return { sliderRef, isDragging };
 }