use-move-note.ts

Overview

use-move-note.ts defines a custom React hook named useMoveNote that manages the visibility and positioning of an SVG element (presumably a "note" or tooltip) based on the current mouse position. This hook is designed to facilitate dynamic UI behavior where an SVG element follows the mouse cursor with an offset and can be shown or hidden programmatically.

The hook internally uses the useMouse hook from ahooks to track mouse coordinates, React's useState for managing visibility state, and useRef to directly manipulate the SVG element's CSS positioning in the DOM.

Detailed Explanation

useMoveNote() Hook

Purpose

Provides reactive logic and references to control an SVG note's visibility and position relative to the mouse pointer.

Returns

An object containing:

• ref: React ref object attached to the SVG element that should follow the mouse.

• showImage: Function to make the SVG element visible.

• hideImage: Function to hide the SVG element.

• mouse: Mouse position data from useMouse hook.

• imgVisible: Boolean state indicating whether the SVG element is visible.

Internal Logic and Implementation Details

• Mouse Tracking:
  Uses useMouse from ahooks to get the current mouse position (clientX and clientY).

• Visibility State:
  Manages visibility of the SVG element using React's useState.

• Positioning:
  An effect hook (useEffect) updates the position of the referenced SVG element whenever the mouse moves. It sets the element's CSS top and left properties to position it relative to the mouse with an offset of -70px vertically and +10px horizontally. This offset likely helps position the note slightly above and to the right of the cursor.

• Visibility Handlers:
  The hook exposes showImage and hideImage functions to toggle visibility externally. These use useCallback to memoize and prevent unnecessary re-renders.

Parameters

• None. This hook is self-contained.

Usage Example

import React from 'react';
import { useMoveNote } from './use-move-note';

export function MoveNoteExample() {
  const { ref, showImage, hideImage, imgVisible } = useMoveNote();

  return (
    <div>
      <button 
        onMouseEnter={showImage} 
        onMouseLeave={hideImage}
      >
        Hover me to show note
      </button>

      {imgVisible && (
        <svg 
          ref={ref} 
          style={{ 
            position: 'absolute', 
            pointerEvents: 'none' 
          }} 
          width="100" 
          height="50"
        >
          <rect width="100" height="50" fill="lightyellow" stroke="black" />
          <text x="10" y="25" fill="black">Note content</text>
        </svg>
      )}
    </div>
  );
}

Interaction with Other Parts of the Application

• Integration Point:
  This hook is intended to be used inside React components that render an SVG element acting as a "move note" or tooltip following the mouse pointer.

• Dependency:
  Relies on useMouse from the ahooks library to obtain live mouse cursor coordinates.

• DOM Manipulation:
  Directly manipulates the style.top and style.left properties of the referenced SVG element to update its position.

• Visibility Control:
  Provides externally callable functions to control the note's visibility, enabling integration with UI events like mouse enter/leave.

Important Implementation Details and Algorithms

• Position Calculation:
  The note's position is updated on every mouse movement by setting the SVG element's CSS properties. The vertical offset of -70px ensures the note appears above the cursor, while a horizontal offset of +10px places it slightly to the right, preventing overlap with the mouse pointer.

• Performance Considerations:
  The position update runs inside a useEffect hook that depends on mouse.clientX and mouse.clientY, ensuring updates only occur when the mouse moves.

• Ref Usage:
  The hook uses useRef to access the underlying DOM node for direct style manipulation, which is necessary because CSS positioning cannot be controlled via React props alone when the position depends on real-time mouse coordinates.

Mermaid Diagram: Flowchart of Functions and Relationships in useMoveNote

flowchart TD
    A[useMoveNote Hook] --> B[ref (SVGSVGElement)]
    A --> C[mouse (from useMouse)]
    A --> D[imgVisible (state)]
    A --> E[showImage()]
    A --> F[hideImage()]
    E --> D
    F --> D
    C --> G[useEffect to update ref.current.style.top/left]

Summary

The useMoveNote hook is a reusable utility designed to manage an SVG element that tracks the mouse position and can be shown or hidden on demand. It combines mouse tracking, state management, and direct DOM manipulation to achieve this behavior with minimal setup required by the consuming component.

This hook is particularly useful in UI scenarios such as custom tooltips, floating notes, or interactive annotations that need to follow the cursor dynamically.