Image Story Extension

The Image Story extension allows you to display rich HTML content (stories, descriptions, captions) below images in the lightbox. Content is loaded on-demand and cached for performance.

Installation

ESM (Module Bundlers)

import { vistaView } from 'vistaview';
import { imageStory } from 'vistaview/extensions/image-story';
import 'vistaview/style.css';
import 'vistaview/styles/extensions/image-story.css';

vistaView({
  elements: '#gallery a',
  extensions: [
    imageStory({
      getStory: async (index) => {
        const response = await fetch(`/api/stories/${index}`);
        const data = await response.json();
        return { content: data.html };
      },
    }),
  ],
});

UMD (CDN)

<link rel="stylesheet" href="https://unpkg.com/vistaview/dist/style.css" />
<link rel="stylesheet" href="https://unpkg.com/vistaview/dist/styles/extensions/image-story.css" />
<script src="https://unpkg.com/vistaview/dist/vistaview.umd.js"></script>
<script src="https://unpkg.com/vistaview/dist/extensions/image-story.umd.js"></script>

<script>
  VistaView.vistaView({
    elements: '#gallery a',
    extensions: [
      VistaView.imageStory({
        getStory: async (index) => {
          const response = await fetch(`/api/stories/${index}`);
          const data = await response.json();
          return { content: data.html };
        },
      }),
    ],
  });
</script>

Configuration

getStory (required)

A function that returns a promise resolving to a story object:

getStory: (imageIndex: number) => Promise<StoryResult>;

StoryResult interface:

interface StoryResult {
  content: string; // HTML content (will be sanitized)
  onLoad?: () => void; // Called when story is displayed
  onUnload?: () => void; // Called when navigating away
}

maxStoryCache (optional)

Maximum number of stories to keep in memory. Default: 5

imageStory({
  getStory: async (index) => {
    /* ... */
  },
  maxStoryCache: 10, // Keep 10 stories cached
});

Features

• Rich HTML content - Display formatted text, images, links, etc.
• On-demand loading - Stories are fetched only when needed
• Smart caching - Recently viewed stories are cached
• Auto-sanitization - HTML is automatically sanitized using DOMPurify
• Expandable panel - Users can expand/collapse the story
• Lifecycle hooks - onLoad/onUnload for custom behavior

Usage Examples

Basic Usage

import { imageStory } from 'vistaview/extensions/image-story';

vistaView({
  elements: '#gallery a',
  extensions: [
    imageStory({
      getStory: async (index) => ({
        content: `
          <h2>Image ${index + 1}</h2>
          <p>This is the story for image ${index + 1}.</p>
        `,
      }),
    }),
  ],
});

Fetching from API

imageStory({
  getStory: async (index) => {
    try {
      const response = await fetch(`/api/stories/${index}`);
      const data = await response.json();

      return {
        content: `
          <h2>${data.title}</h2>
          <p>${data.description}</p>
          <p><small>By ${data.author} on ${data.date}</small></p>
        `,
      };
    } catch (error) {
      return {
        content: '<p>Story could not be loaded.</p>',
      };
    }
  },
});

With Lifecycle Hooks

imageStory({
  getStory: async (index) => {
    const response = await fetch(`/api/stories/${index}`);
    const data = await response.json();

    return {
      content: data.html,
      onLoad: () => {
        console.log(`Story ${index} loaded`);
        // Track analytics
        gtag('event', 'story_view', { story_id: index });
      },
      onUnload: () => {
        console.log(`Story ${index} unloaded`);
        // Cleanup any event listeners
      },
    };
  },
});

With Static Stories

const stories = [
  {
    title: 'Sunset at the Beach',
    content: 'A beautiful evening captured at the coast...',
  },
  {
    title: 'Mountain Peak',
    content: 'Hiking adventure to the summit...',
  },
];

imageStory({
  getStory: async (index) => ({
    content: `
      <h2>${stories[index].title}</h2>
      <p>${stories[index].content}</p>
    `,
  }),
});

Styling

The extension includes default styles, but you can customize:

/* Story container */
.vvw-story {
  /* Positioned at bottom of lightbox */
}

/* Story text area */
.vvw-story-text {
  background: rgba(0, 0, 0, 0.8);
  backdrop-filter: blur(10px);
  color: white;
  padding: 16px;
  border-radius: 8px;
}

/* Expanded state */
.vvw-story-text.expanded {
  max-height: 400px;
  overflow-y: auto;
}

/* Expand/collapse button */
.vvw-story-button {
  background: rgba(255, 255, 255, 0.1);
  border: none;
  color: white;
  cursor: pointer;
}

Security

The extension automatically sanitizes HTML content using DOMPurify to prevent XSS attacks. However, you should still:

1. Validate input on your server
2. Use Content Security Policy (CSP) headers
3. Sanitize user-generated content before storing

Performance

Caching

Stories are cached in memory to avoid redundant API calls:

imageStory({
  getStory: async (index) => {
    // This is only called once per image (until cache eviction)
    return await fetchStory(index);
  },
  maxStoryCache: 10, // Adjust based on memory constraints
});

Lazy Loading

Stories are only fetched when the user navigates to an image, not during initialization.

Cache Eviction

When the cache exceeds maxStoryCache, the oldest entries are evicted (FIFO).

Bundle Size

• ESM: 33.60 KB (10.84 KB gzip)
• UMD: 25.28 KB (9.81 KB gzip)
• CSS: 2.52 KB (0.72 KB gzip)

Note: Includes DOMPurify for HTML sanitization.

Next Steps

• Learn about creating custom extensions
• Explore other extensions
• See configuration options