Class: Image

Description: The Image component is a React component designed to display images with placeholder functionality. This ensures a better user experience by showing a placeholder before the image is fully loaded.

Methods

Method: onLoad

Description: The onLoad function is a callback triggered when the image has successfully finished loading. It sets the loaded state to true, signifying that the image is available for display.

Parameters:

  • None

Returns:

  • void

Example:

// Image component instance
const imageComponent = <Image src="image.jpg" />;

// When image loads successfully, `onLoad` callback is triggered
imageComponent.onLoad(); // sets the loaded state to true

Method: handlePlaceholder

Description: The handlePlaceholder function is responsible for managing the display of a placeholder image before the actual image is loaded. It creates a temporary SVG placeholder element, sets its size based on the target image's dimensions, and inserts it before the main image element. Once the image is loaded, the placeholder is removed.

Parameters:

  • img (HTMLImageElement): The actual image element that the placeholder is associated with.

Returns:

  • void

Example:

// Assuming `image` is the reference to the actual image element
handlePlaceholder(image.current);

// This will create an SVG placeholder, insert it before the image, and then remove it once the image loads

Method: placeholderSrc

Description: The placeholderSrc function generates a data URI for a simple SVG placeholder image based on the provided width and height. This placeholder image is displayed before the actual image is loaded.

Parameters:

  • w (number): The desired width of the placeholder image.
  • h (number): The desired height of the placeholder image.

Returns:

  • string: A data URI for an SVG image with the specified width and height.

Example:

// Get placeholder image URI
const placeholderUri = placeholderSrc(100, 100); // Returns a data URI for a 100x100 SVG

// This URI can be used as the `src` attribute for an image tag

Important Considerations:

  • The Image component relies on useEffect hook to manage the placeholder.
  • The useEffect hook ensures that the placeholder is handled when the component is mounted and that it remains updated when the image source changes.
  • The component is designed to handle image sources that can be either strings (URLs) or object-based (potentially for image data).
  • The placeholderSrc function generates a basic SVG placeholder. For more complex placeholder styles, you might need to use an alternative approach.
  • Consider using a dedicated library for lazy loading images in production environments.

Potential Pitfalls:

  • Ensure that the src prop for the Image component is provided correctly, as it's a required prop.
  • Be mindful of the dependencies passed to the useEffect hook. If you need to update the placeholder on different props, make sure those props are included in the dependency array.

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