How to create a custom hook for handling responsive font sizes based on screen density in Next.js

Creating a custom hook for handling responsive font sizes based on screen density in a Next.js project involves utilizing the useEffect hook to calculate the appropriate font size based on the device's pixel density (window.devicePixelRatio). Here's a step-by-step guide on how to achieve this:

1. Create a Custom Hook: Start by creating a custom hook, let's name it useResponsiveFontSize.

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// hooks/useResponsiveFontSize.js
import { useEffect, useState } from 'react';

const useResponsiveFontSize = () => {
  const [fontSize, setFontSize] = useState(16); // Default font size

  useEffect(() => {
    const calculateFontSize = () => {
      const devicePixelRatio = window.devicePixelRatio || 1;
      const baseFontSize = 16; // Set your base font size
      const scaleFactor = 1.5; // Adjust this value as needed
      const calculatedFontSize = baseFontSize * devicePixelRatio * scaleFactor;

      setFontSize(calculatedFontSize);
    };

    calculateFontSize();

    window.addEventListener('resize', calculateFontSize);

    return () => {
      window.removeEventListener('resize', calculateFontSize);
    };
  }, []);

  return fontSize;
};

export default useResponsiveFontSize;

2. Use the Custom Hook: Now, you can use this custom hook in your components to set responsive font sizes.

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// components/MyComponent.js
import React from 'react';
import useResponsiveFontSize from '../hooks/useResponsiveFontSize';

const MyComponent = () => {
  const fontSize = useResponsiveFontSize();

  return (
    <div style={{ fontSize: `${fontSize}px` }}>
      {/* Your component content */}
    </div>
  );
};

export default MyComponent;

3. Adjust Scale Factor: The scaleFactor in the useResponsiveFontSize hook determines how much the font size scales based on the device's pixel density. You may need to adjust this value based on your design requirements and testing across different devices.

4. Usage Notes:

   • Ensure that the useResponsiveFontSize hook is used within a component that is mounted at the top level of your application to get the correct window object.
   • This approach calculates font sizes based on device pixel density. Adjust the scaleFactor and baseFontSize according to your design requirements.

5. Testing:

   • Test your application across various devices with different pixel densities to ensure that font sizes adjust correctly.

By following these steps, you can create a custom hook in Next.js for handling responsive font sizes based on screen density.