B4J Library SVGConverter – BMP/PNG to SVG

SVGConverter is a B4J library that allows you to convert any bitmap image (BMP, PNG, B4XBitmap, etc.) to vector SVG directly from your desktop applications.
It is based on Potrace but adds a complete layer of image processing, color quantization, PBM generation, and optimized SVG reconstruction.

The goal: to offer a simple, robust, and fully integrated solution for B4X to vectorize images, logos, icons, drawings, or signatures.

Main Features :

1. Monochrome Vectorization

• Converts an image to black and white SVG.
• Automatic ink detection (significant pixels).
• Optimized luminance threshold for drawings and signatures.

2. Single-Color Vectorization

• Automatic detection of the dominant color (excluding white).
• SVG path extraction and automatic recoloring.
• Generates a clean SVG, with transformation and scaling.

3. Multi-Color Vectorization (16-color palette)

• Color quantization in 32 levels - compact and stable palette.
• Layer-by-layer processing (1 PBM per color).
• Merging of SVG paths with individual fills.
• Accurate, clean, and optimized final result.

4. SVG to PNG Conversion

• Automatic handling of dimensions declared in the SVG.
• High-quality PNG export.

5. Integrated Error Handling

• Callback via SetErrorHandler.
• Detailed messages (Potrace, snapshot, missing files, etc.).
• No interruption of the main workflow.

Example of use :

Dim v As SVGConverter
v.Initialize(MainForm, "C:\Tools\potrace.exe")
v.SetErrorHandler(Me, "SVG_Error")

Dim svg As String = v.VectorizeColor(MyBitmap, True)
File.WriteString(C:\myFolder, "output.svg", svg)
 
....

Sub SVG_Error(Message As String)
    Log("SVG ERROR : " & Message)
End Sub

What the library brings to the B4X community

• A complete solution for vectorizing images without complex external dependencies.
• A simple, consistent API adapted to the B4X ecosystem.
• A direct bridge between the bitmap and vector worlds.
• A solid foundation for projects involving:
• dynamic logos,
• image processing,
• graphic tools,
• automation,
• UI asset generation.

Prerequisites

• B4J 10.30+
• Potrace (executable) https://potrace.sourceforge.net/
• Java 11+ recommended

Have fun