Virto Commerce Image Tools Module

Overview

The Image Tools Module provides comprehensive image processing capabilities for the Virto Commerce platform. It enables automatic thumbnail generation for product images, category banners, and other visual assets stored in blob storage.

The module features a format-agnostic architecture that supports both raster formats (JPEG, PNG, WebP) via SixLabors.ImageSharp and vector formats (SVG) with native XML manipulation, ensuring scalability without quality loss.

Key Features

• Multi-Format Support: Process raster images (JPEG, PNG, WebP, GIF, BMP, TIFF) and vector graphics (SVG)
• Flexible Resize Methods:
  • FixedSize - Proportional fit within specified dimensions with optional padding
  • FixedWidth - Maintain aspect ratio, resize to target width
  • FixedHeight - Maintain aspect ratio, resize to target height
  • Crop - Crop to exact dimensions using configurable anchor positions
• Background Processing: Batch thumbnail generation via Hangfire jobs with progress tracking
• Event-Driven Generation: Automatic thumbnail creation on blob upload events
• Incremental Processing: Only process new or modified images since last run
• Extensible Architecture: Plugin-based format handlers for easy addition of new formats

Configuration

Application Settings

Configure the module in appsettings.json:

{
  "ImageTools": {
    "Thumbnails": {
      "EnableImageProcessJob": false,
      "EventBasedThumbnailGeneration": true,
      "ImageProcessJobCronExpression": "0 0 * * *",
      "ProcessBatchSize": 50
    }
  }
}

Setting	Type	Default	Description
EnableImageProcessJob	Boolean	false	Enable scheduled background job for thumbnail processing
EventBasedThumbnailGeneration	Boolean	true	Generate thumbnails automatically when images are uploaded
ImageProcessJobCronExpression	String	0 0 * * *	Cron expression for scheduled job (daily at midnight)
ProcessBatchSize	Integer	50	Number of images to process before reporting progress

Allowed Image Formats

Formats can be enabled/disabled via Platform Settings UI:

• Raster: JPEG, PNG, WebP (default), GIF, BMP, TIFF, TGA, PBM
• Vector: SVG

Architecture

The module implements a Handler-Based Architecture for format-agnostic image processing:

┌─────────────────────────────────────────────────────────────────┐
│                  ThumbnailGenerationProcessor                    │
│                    (Orchestrates batch jobs)                     │
└─────────────────────────────┬───────────────────────────────────┘
                              │
┌─────────────────────────────▼───────────────────────────────────┐
│                   IThumbnailHandlerFactory                       │
│              (Routes to format-specific handler)                 │
└─────────────────────────────┬───────────────────────────────────┘
                              │
          ┌───────────────────┼───────────────────┐
          │                   │                   │
┌─────────▼─────────┐ ┌───────▼───────┐ ┌────────▼────────┐
│ RasterThumbnail   │ │ SvgThumbnail  │ │ Custom Format   │
│ Handler           │ │ Handler       │ │ Handler         │
│ (JPEG, PNG, WebP) │ │ (SVG, SVGZ)   │ │ (Extensible)    │
└─────────┬─────────┘ └───────┬───────┘ └─────────────────┘
          │                   │
┌─────────▼─────────┐ ┌───────▼───────┐
│ IThumbnailGen     │ │ ISvgService   │
│ (ImageSharp)      │ │ ISvgResizer   │
└───────────────────┘ └───────────────┘

Extension Points

To add support for a new format:

1. Implement IFormatThumbnailHandler:

public class PdfThumbnailHandler : IFormatThumbnailHandler
{
    public int Priority => 10;

    public Task<bool> CanHandleAsync(string imageUrl)
        => Task.FromResult(imageUrl.EndsWith(".pdf", StringComparison.OrdinalIgnoreCase));

    public Task<ThumbnailGenerationResult> GenerateThumbnailsAsync(
        string source, string destination, IList<ThumbnailOption> options, ICancellationToken token)
    {
        // Custom PDF thumbnail generation logic
    }
}

2. Register in DI:

serviceCollection.AddTransient<IFormatThumbnailHandler, PdfThumbnailHandler>();

Components

Core Interfaces

Interface	Description
IImageService	Load/save raster images from blob storage
IImageResizer	Raster image resize operations
ISvgService	Load/save SVG content from blob storage
ISvgResizer	SVG dimension manipulation
IAllowedImageFormatsService	Check if image format is in allowed formats list
IFormatThumbnailHandler	Format-specific thumbnail generation
IThumbnailHandlerFactory	Route to appropriate format handler
IThumbnailGenerator	Core thumbnail generation (obsolete - use handlers)
IThumbnailGenerationProcessor	Batch processing with progress tracking
IImagesChangesProvider	Detect new/modified images in blob storage

Services

Service	Description
ImageService	ImageSharp-based raster image I/O
ImageResizer	ImageSharp resize with multiple methods
SvgService	SVG blob storage operations
SvgResizer	SVG XML manipulation for resizing
AllowedImageFormatsService	Settings-based format validation
ThumbnailHandlerFactory	Priority-based handler selection
RasterThumbnailHandler	Raster format processing via IThumbnailGenerator
SvgThumbnailHandler	Vector format processing via ISvgService

Background Jobs

Job	Description
ThumbnailProcessJob	Hangfire job for scheduled/manual thumbnail generation

Domain Models

Model	Description
ThumbnailTask	Configuration for a thumbnail generation task (work path, options)
ThumbnailOption	Single thumbnail variant (size, method, quality, suffix)
SvgDimensions	SVG width, height, and viewBox attributes

Documentation

• Image Tools module user documentation
• REST API
• View on GitHub

References

• Deployment
• Installation
• Home
• Community
• Download latest release

License

Copyright (c) Virto Solutions LTD. All rights reserved.

Licensed under the Virto Commerce Open Software License (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://virtocommerce.com/opensourcelicense

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.