Resolving Local SVG Image Rendering Issues in Astro

What We Were Trying to Do and Why

We were attempting to display local SVG images stored in the public directory of our Astro project. Specifically, we had SVG files located at /Users/mpstaton/code/lossless-monorepo/site/public/visuals/ that we wanted to reference in our JSON data files and render in our components.

The specific use case was updating the featureSideImage.json file to use a local SVG file instead of a placeholder:

json

{
  "label": "Collaborative Coding",
  "title": "Real-time Team Collaboration",
  "details": "Work together seamlessly with your team in real-time. Changes sync instantly across all devices, with smart conflict resolution and version history. Boost productivity and keep everyone on the same page with our collaborative notebook environment.",
  "imageSide": "left",
  "ctaText": "Try It Now",
  "ctaUrl": "#",
  "imageUrl": "/visuals/Convey__Picto__Assembly-Line.svg"
}

Despite the SVG file existing in the correct location and the path being correctly specified, the image wasn't rendering on the site.

Incorrect Attempts

We spent hours trying various approaches, including:

Checking file paths and permissions:
- Verified the SVG file existed in the public directory
- Confirmed the path was correctly specified in the JSON
- Checked file permissions and content
Inspecting component rendering:
- Examined the FeatureSideImage.astro component to ensure it was correctly handling the image prop
- Verified the component was receiving the correct data from the JSON file
Debugging image loading:
- Used browser dev tools to check network requests
- Confirmed the SVG file was accessible via direct URL

Despite all these checks, the image still wasn't rendering, and we couldn't figure out why.

The "Aha!" Moment

After examining the codebase more carefully, we discovered the issue was in the getImageForPath utility function in /Users/mpstaton/code/lossless-monorepo/site/src/utils/imageMapping.ts.

This function was responsible for processing image paths from JSON data before passing them to components. The function had logic to handle remote URLs (starting with "http") and one specific local image, but it was missing logic to handle local paths that start with a slash.

Here's the problematic code:

typescript

export function getImageForPath(imagePath: string, title: string = ''): { src: string; alt: string } {
  // Check if it's a remote URL
  if (imagePath.startsWith('http')) {
    return {
      src: imagePath,
      alt: title
    };
  }
  
  // For the specific Warp Notebooks image, use a direct mapping
  if (imagePath.includes('Screenshot 2025-03-30 at 11.42.35 AM_Warp--Notebooks.png')) {
    // Using a relative path that works in the browser
    return {
      src: '/assets/Representations/Screenshot 2025-03-30 at 11.42.35 AM_Warp--Notebooks.png',
      alt: title
    };
  }
  
  // For other local images, use a placeholder for now
  console.warn(`Using placeholder for local image: ${imagePath}`);
  return getPlaceholderImage(imagePath, title);
}

The key issue was that any local path starting with a slash (like /visuals/Convey__Picto__Assembly-Line.svg) would fall through to the default case, which replaced it with a placeholder image rather than using the actual path.

The Solution

The fix was simple but non-obvious: add a specific condition to handle local paths that start with a slash, returning them directly instead of using a placeholder:

typescript

export function getImageForPath(imagePath: string, title: string = ''): { src: string; alt: string } {
  // Check if it's a remote URL
  if (imagePath.startsWith('http')) {
    return {
      src: imagePath,
      alt: title
    };
  }
  
  // Handle local paths that start with a slash (from the public directory)
  if (imagePath.startsWith('/')) {
    return {
      src: imagePath,
      alt: title
    };
  }
  
  // For the specific Warp Notebooks image, use a direct mapping
  if (imagePath.includes('Screenshot 2025-03-30 at 11.42.35 AM_Warp--Notebooks.png')) {
    // Using a relative path that works in the browser
    return {
      src: '/assets/Representations/Screenshot 2025-03-30 at 11.42.35 AM_Warp--Notebooks.png',
      alt: title
    };
  }
  
  // For other local images, use a placeholder for now
  console.warn(`Using placeholder for local image: ${imagePath}`);
  return getPlaceholderImage(imagePath, title);
}

This change ensures that paths starting with a slash (which typically reference files in the public directory) are passed through directly to the browser, which can then correctly resolve them relative to the site root.

Key Takeaways

Path Resolution Logic: In Astro (and many web frameworks), paths starting with a slash (/) are resolved relative to the site root, which maps to the public directory.
Utility Function Completeness: When creating utility functions for handling different types of inputs (like image paths), ensure all valid input formats are handled correctly.
Debug with Console Logs: The console warning in the original code (console.warn(Using placeholder for local image: ${imagePath});) was a clue that our local image paths were being caught by the fallback case.
Public Directory Convention: Files in the public directory should be referenced with paths starting from the site root (e.g., /visuals/image.svg), not relative paths.

This issue highlights the importance of thoroughly understanding how path resolution works in your framework and ensuring that utility functions handle all valid input formats correctly.