📈 Dart Chart Generator API (HTTP Bar Chart Service)

This project is a simple, high-performance HTTP API built with Dart and the Shelf framework. It dynamically generates and serves customizable bar chart images (PNG format) based on data and optional color configurations passed in a JSON request body.

✨ Features

• Dynamic Bar Chart Generation: Creates PNG images from numerical data arrays.
• Fully Customizable Colors: Supports passing custom RGB values via the API for bars, background, grid lines, axes, and fonts.
• Simple REST Interface: Easy-to-use /chart POST endpoint for integration.
• High Performance: Built with Dart for fast, concurrent processing suitable for microservices.
• Dependencies: Uses the image package for efficient image manipulation.

🚀 Getting Started

Prerequisites

1. Dart SDK: Ensure you have the Dart SDK installed.
2. Dependencies: Make sure your pubspec.yaml is set up correctly (see below).

Installation

1. Clone the Repository:

   git clone https://github.com/C0dwiz/chart_server_dart
   cd chart_server_dart

2. Get Dependencies:

   dart pub get

Running the Server

Start the API server from the root directory:

dart run lib/server.dart

The console will display the URL: API start http://localhost:8080

📡 API Endpoint

The primary endpoint for chart generation is /chart, which requires a POST request with a JSON body.

POST /chart

Key	Type	Description	Required	Example
data	List<num>	The series of values to be plotted in the bar chart.	Yes	[500, 800, 1500, 1200, 700]
colors	Map<String, List<int>>	An optional object to override default chart colors.	No	See below

Request Example (JSON Body)

Send a POST request to http://localhost:8080/chart with Content-Type: application/json.

{
  "data": [50, 120, 90, 150, 60, 110],
  "colors": {
    "bar": [255, 69, 0],         
    "background": [20, 20, 30],  
    "font": [255, 255, 255],     
    "grid": [60, 60, 60]         
    // Other available keys: "axis", "barBorder", "axisLabel"
  }
}

Successful Response

A successful request will return:

• Status Code: 200 OK
• Content-Type: image/png (The response body is the raw PNG image data)

✅ Testing

To ensure the utility calculations and API routes are functioning correctly, you can run the unit tests provided in the test/ directory.

dart test

📝 Dependencies (pubspec.yaml)

This project relies on the following key dependencies:

dependencies:
  shelf: ^1.4.1        # Web server framework
  shelf_router: ^1.1.4  # Routing middleware
  image: ^4.1.3         # Image processing and drawing utilities
dev_dependencies:
  test: ^1.24.0         # Unit testing framework

🤝 Contributing

Feel free to open issues or submit pull requests if you have suggestions for features, performance improvements, or bug fixes!

⚖️ License

This project is licensed under the MIT License.

See the LICENSE file for more details.