English

V Example

https://github.com/bobhyun/TS-ANPR/tree/main/examples/V/anpr

1. Copying the Engine Files

[Note] In this example, the engine file is extracted to the examples/bin/ directory to share it with other examples. However, for actual deployment, the engine file is typically copied to the directory where the application’s executable file is located.

For Windows x86 64-bit Extract the engine file to the examples/bin/windows-x86_64 directory
```
7z x tsanpr*-windows-x86_64.7z
```
For Windows x86 32-bit Extract the engine file to the examples/bin/windows-x86 directory
```
7z x tsanpr*-windows-x86.7z
```
For Linux x86 64-bit Extract the engine file to the examples/bin/linux-x86_64 directory
```
tar xvf tsanpr-linux-x86_64.tar.xz
```
For Linux arm 64-bit Extract the engine file to the examples/bin/linux-aarch64 directory
```
tar xvf tsanpr-linux-aarch64.tar.xz
```

Directory structure

examples/
├── bin/
│   ├── windows-x86_64/       # engine for Windows (x86_64)
│   │   ├── tsanpr.dll
│   │   ├── tsanpr-2505M.eon
│   │   └── tshelper.exe
│   ├── windows-x86/          # engine for Windows (x86)
│   │   └── ...
│   ├── linux-x86_64/         # engine for Linux (x86_64)
│   │   └── ...
│   └── linux-aarch64/        # engine for Linux (arm64)
│       └── ...
├── img/
└── V/
    └── anpr/                 # V module directory
        ├── v.mod             # module definition
        ├── anpr.v            # main example
        └── tsanpr.v          # TSANPR wrapper module

2. Prerequisites

Install V (latest version recommended)

Windows:

# Using Scoop
scoop install vlang

# Or download pre-built binary from:
# https://github.com/vlang/v/releases

Linux:

# Clone and build from source
git clone https://github.com/vlang/v
cd v
make
sudo ./v symlink

Verify installation
```
v version
```

3. How to Run

cd examples/V/anpr

# Run the ANPR example
v run .

Alternative methods:

# Compile and run separately
v .
./anpr        # Linux
anpr.exe      # Windows

# Compile with optimizations
v -prod .

4. Features

readImageFile: Process image files directly using anpr_read_file()
readEncodedImage: Process encoded image bytes using anpr_read_pixels() with ‘encoded’ format
readPixelBuffer: Process raw RGB pixel data using V’s stbi module (stb_image)
Dynamic loading: TSANPR library is loaded at runtime via V’s dl module
Cross-platform: Supports Windows and Linux (x86_64, x86, ARM64)

5. API Reference

TSANPR Module

The tsanpr module provides the following:

// Create TSANPR instance
pub fn new(library_path string) !TSANPR

// TSANPR methods
pub fn (mut t TSANPR) destroy()
pub fn (t &TSANPR) initialize(mode string) string
pub fn (t &TSANPR) read_file(img_file_name string, output_format string, options string) string
pub fn (t &TSANPR) read_pixels(pixels []u8, width u64, height u64, stride i64, pixel_format string, output_format string, options string) string

Recognition Options

Option	Description
`""`	Single license plate recognition (default)
`"vm"`	Recognize multiple license plates attached to vehicles
`"vmb"`	Recognize multiple license plates (including motorcycles)
`"vms"`	Recognize with surround detection
`"dms"`	Detect multiple surrounding objects (vehicles)
`"dmsr"`	Detect objects and recognize license plates
`"dmsri<coords>"`	Recognize within Region of Interest

Output Formats

"text", "json", "yaml", "xml", "csv"

6. Implementation Notes

This example uses V’s dl module for dynamic library loading:

Dynamic Library Loading:

Linux: Uses dlopen(), dlsym(), dlclose() via V’s dl module
Windows: Uses LoadLibrary(), GetProcAddress(), FreeLibrary() via V’s dl module

V Integration:

V’s C interop allows direct function pointer calls to native libraries
Automatic string conversion between V strings and C strings
Memory-safe with defer for cleanup

Pixel Buffer Processing: The readPixelBuffer function uses V’s built-in stbi module (stb_image wrapper) for image decoding. It loads the image, extracts raw RGB pixel data, and passes it to anpr_read_pixels() with the appropriate pixel format.

7. Troubleshooting

Compilation Issues:

Ensure V is properly installed and in PATH
Check V version: v version
Update V if needed: v up

Library Loading Issues:

Verify the TSANPR library exists in the expected location
On Linux, check LD_LIBRARY_PATH if needed
Ensure library architecture matches the V build (64-bit vs 32-bit)

Runtime Issues:

Check that engine files (.eon) are in the same directory as the library
Verify license is installed using tshelper