Entity Classes

The Pixel Create application uses Room Database for local data persistence. The entity classes below represent the database schema and are mapped to SQLite tables. Each entity corresponds to a specific aspect of the pixel art creation workflow.

For a visual representation of how these entities relate to each other, see the Entity-Relationship Diagram and UML Class Diagram.

Core Entities

Entity Class	Description	Source Code
User	Stores user account information, OAuth authentication key (unique identifier from authentication provider), and personalized settings including default canvas dimensions, theme preferences, and tool settings.	User.java
Project	Represents a pixel art creation with metadata including project name, canvas dimensions, timestamps, thumbnail preview, and soft-delete flag. Central entity that ties together layers, snapshots, and export history.	Project.java
Layer	Individual drawing layers within a project supporting complex artwork with stacking order, visibility controls, lock state, and opacity settings.	Layer.java
Pixel	Stores individual pixel color data tied to a specific layer and position. Contains x/y coordinates, color value, and last modified timestamp.	Pixel.java

Color Management Entities

Entity Class	Description	Source Code
Palette	User-created color collections for consistent artwork styling. Contains palette name, default flag, and usage timestamps for sorting recently used palettes.	Palette.java
PaletteColor	Individual colors within a palette. Stores color value (ARGB/hex), display order, and optional user-defined color name.	PaletteColor.java

Data Persistence & History Entities

Entity Class	Description	Source Code
AutosaveSnapshot	Periodic backups of project state to prevent data loss. Contains serialized project data (JSON or binary), creation timestamp, and file size for storage tracking.	AutosaveSnapshot.java
ExportHistory	Logs every export operation for tracking and re-export functionality. Records file name, path, format (PNG, JPG, etc.), resolution, scale factor, and file size.	ExportHistory.java

Entity Relationships

The relationships between these entities follow standard database normalization principles:

User → Project: One-to-many (users create multiple projects)
User → Palette: One-to-many (users create multiple custom palettes)
Project → Layer: One-to-many (projects contain multiple layers)
Project → AutosaveSnapshot: One-to-many (projects have multiple snapshots)
Project → ExportHistory: One-to-many (projects generate multiple exports)
Layer → Pixel: One-to-many (layers contain multiple pixels)
Palette → PaletteColor: One-to-many (palettes contain multiple colors)

For detailed cardinality information and relationship constraints, see the ERD documentation.

Data Access Object (DAO) Interfaces

Each entity has a corresponding DAO interface that provides database operations (CRUD - Create, Read, Update, Delete). These interfaces are implemented by Room Database at compile time.

Core Entity DAOs

DAO Interface	Description	Source Code
UserDao	Data access operations for User entity. Provides methods to insert, update, delete users, and query by ID, username, or email. Returns LiveData for reactive UI updates.	UserDao.java
ProjectDao	Data access operations for Project entity. Manages project CRUD operations, queries projects by user, and supports filtering by deletion status.	ProjectDao.java
LayerDao	Data access operations for Layer entity. Handles layer management within projects, including ordering, visibility, and lock state queries.	LayerDao.java
PixelDao	Data access operations for Pixel entity. Manages individual pixel data with queries by layer, coordinate, and bulk operations for efficient canvas rendering.	PixelDao.java

Color Management DAOs

DAO Interface	Description	Source Code
PaletteDao	Data access operations for Palette entity. Manages custom palette collections, queries by user, and tracks recently used palettes.	PaletteDao.java
PaletteColorDao	Data access operations for PaletteColor entity. Handles individual colors within palettes, including ordering and color lookup operations.	PaletteColorDao.java

Data Persistence & History DAOs

DAO Interface	Description	Source Code
AutosaveSnapshotDao	Data access operations for AutosaveSnapshot entity. Manages project backup snapshots with retention policy support and timestamp-based queries.	AutosaveSnapshotDao.java
ExportHistoryDao	Data access operations for ExportHistory entity. Tracks export operations with queries by project, format, and date range for export analytics.	ExportHistoryDao.java

Database Implementation

These entities and DAOs are managed by the Room Database framework. For more information:

Database Schema: See SQL DDL for complete table definitions
Database Class: The LocalDatabase class coordinates all DAOs and entities
Type Converters: The LocalDatabase.Converters class handles conversion of Instant timestamps to SQLite-compatible types

Entity-Relationship Diagram - Visual representation of entity relationships
UML Class Diagram - Detailed class structure with methods and properties
SQL DDL - Database schema definition language
Javadocs - Complete API documentation