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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 #

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.