ImageHandler.js

Overview

The ImageHandler class is responsible for managing image processing and caching in a server site render system. It supports detecting image formats, handling external image downloads, caching images, and creating optimized versions of images in various sizes and formats (e.g., .webp).

Content

• ImageHandler.js
  • Overview
  • Content
  • Methods
    • detectImage
    • detectWebpImage
    • detectExternalImage
    • getFromCache
    • generateImages
    • prepareSources
    • downloadExternalImage

Methods

detectImage

• Purpose: Determines if a file path corresponds to an image file.
• Parameters:
  • path (string): The file path to check.
• Returns: true if the file is an image; otherwise, false.
• Supported Formats: .jpeg, .jpg, .tif, .tiff, .png, .webp, .bmp.

detectWebpImage

• Purpose: Checks if a file path corresponds to a .webp image.
• Parameters:
  • path (string): The file path to check.
• Returns: true if the file is a .webp image; otherwise, false.

detectExternalImage

• Purpose: Determines if a URL points to an external image by extracting the source query parameter.
• Parameters:
  • url (string): The URL path.
  • urlParams (string): Query parameters to append to the URL.
• Returns: The value of the source query parameter if present; otherwise, null.

getFromCache

• Purpose: Retrieves an image from the cache if it exists, or generates it if not.
• Parameters:
  • website (string): The website identifier.
  • url (string): The image URL path.
  • urlParams (string): Query parameters for the URL.
• Returns:
  • An object containing:
    • type ('asset' or 'error').
    • path (string): The path to the cached image or an error message.

generateImages

• Purpose: Handles the generation and caching of images, including external image downloads and .webp conversion.
• Parameters:
  • website (string): The website identifier.
  • url (string): The image URL path.
  • urlParams (string): Query parameters for the URL.
  • buildFolder (string, optional): The folder path where the site is being built.
• Returns: A promise resolving to an object containing:
  • type ('asset' or 'error').
  • path (string): The path to the cached image or an error message.
• Key Features:
  • Checks for existing cached or .webp files.
  • Creates missing directories if necessary.
  • Resizes images and generates .webp versions.

prepareSources

• Purpose: Creates resized versions of an image (600px and 1200px width) and converts them to .webp.
• Parameters:
  • path (string): The file path of the original image.
• Returns: true after the resized versions are created.
• Behavior:
  • Resizes images exceeding 600px and 1200px widths.
  • Saves resized images with suffixes -600 and -1200.

downloadExternalImage

• Purpose: Downloads an external image, caches it, and generates optimized versions.
• Parameters:
  • website (string): The website identifier.
  • url (string): The image URL path.
  • urlParams (string): Query parameters for the URL.
• Returns: The local path to the cached image.
• Behavior:
  • Constructs the full external URL using the source query parameter.
  • Downloads the image and saves it to the cache.
  • Creates .webp and resized versions of the image.