Linteum

Linteum is a collaborative pixel canvas project built with Blazor, ASP.NET Core, SignalR, and PostgreSQL. You can open a canvas, place pixels, watch updates show up live, and even let bots join in.

Live site: linteum.ash-twin.com

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Features

• Live pixel updates across connected clients through SignalR.
• Multiple canvases, including public, private, and password-protected ones.
• Three canvas modes: Normal, FreeDraw, and Economy.
• Smoother freehand drawing with interpolated strokes.
• Canvas creation from either a blank board or a JPG starting image.
• Batch drawing support, plus bulk delete and queued text drawing on FreeDraw canvases.
• Lobby chat so people can talk before jumping into a canvas.
• Local accounts plus optional Google login.
• Canvas image export.
• Bot support for cleaning, painting, and image-based drawing.

Canvas modes

• Normal - the standard shared canvas mode. It keeps a daily pixel quota per user for each canvas (100 by default).
• FreeDraw - meant for faster editing. It supports batch pixel updates, batch delete, and queued text drawing.
• Economy - pixels have prices, balances matter, and subscribed users can earn hourly income based on what they own on that canvas.

By default, the app seeds a small starter set of canvases: home, home_FreeDraw, and home_Economy.

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Architecture and tech stack

Linteum is split into a few focused projects:

• Frontend: Blazor in interactive server mode.
• Backend: ASP.NET Core Web API.
• Realtime updates: SignalR.
• Database: PostgreSQL with Entity Framework Core.
• Containers: Docker and Docker Compose.

Project breakdown

• Linteum.Api - API endpoints, realtime hubs, and background services.
• Linteum.BlazorApp - the main web UI.
• Linteum.Bots - automated clients for cleanup, art bots, and image drawing.
• Linteum.Domain - entities and repository contracts.
• Linteum.Infrastructure - EF Core, repositories, and data access logic.
• Linteum.Shared - shared DTOs, enums, config, and helper utilities.

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Getting started

Prerequisites

• Docker Desktop
• .NET 10 SDK if you want to run the projects locally without Docker
• PowerShell if you want to use the helper script

Running with Docker

The simplest way to start the main services is:

docker compose up -d --build

There is also a small helper script in the repo:

.\build-and-up.ps1

If you want the bots too, start Compose with the bots profile:

docker compose --profile bots up -d --build

Environment variables

Set up your .env file or environment variables as described in docker-compose.yml. The main ones are:

• POSTGRES_USER, POSTGRES_PASSWORD, POSTGRES_DB
• MASTER_PASSWORD, MASTER_USER, MASTER_EMAIL
• GOOGLE_CLIENT_ID, GOOGLE_CLIENT_SECRET for Google login

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Bots

The repo includes a few bot clients:

• CleanerBot for clearing or tidying up a canvas.
• XeroxBot for drawing an image onto a canvas.

For bot commands and Docker examples, see DockerCheatsheet.md.

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Contributing

This project is still evolving, so issues and pull requests are welcome. If you want to try something, fix a rough edge, or add a feature, feel free to jump in.