openraster-go

openraster-go is a Go library for reading OpenRaster (ORA) files. OpenRaster is an open file format for storing layered raster graphics1.

Features

• 📂 Load and parse ORA files
• 🌲 Build and navigate the layer tree
• 🖼️ Access layer images and properties
• 🔍 Retrieve items by UUID
• 💫 Zero-dependencies

Installation

To install the openraster-go library, use the following command:

go get github.com/dmytrogajewski/openraster-go

Usage

Here's a quick example to get you started:

package main

import (
	"fmt"
	"image/color"
	"os"

	"github.com/dmytrogajewski/openraster-go/pkg/ora"
)

func colorEquals(c1, c2 color.Color) bool {
	r1, g1, b1, a1 := c1.RGBA()
	r2, g2, b2, a2 := c2.RGBA()
	return r1 == r2 && g1 == g2 && b1 == b2 && a1 == a2
}

func main() {
	f, err := os.Open("assets/map.ora")

	if err != nil {
		panic(err)
	}

	stats, err := f.Stat()

	if err != nil {
		panic(err)
	}

	o := ora.NewOra()
	err = o.Load(f, stats.Size())

	if err != nil {
		panic(err)
	}

	for _, oi := range o.Children {
		bounds := oi.Image.Bounds()

		for y := bounds.Min.Y; y < bounds.Max.Y; y++ {
			for x := bounds.Min.X; x < bounds.Max.X; x++ {
				c := oi.Image.At(x, y)
				if colorEquals(c, color.Black) {
					fmt.Print("█")
				} else {
					fmt.Print(" ")
				}
			}
			fmt.Println()
		}
		fmt.Printf("%v\n", oi.Name())
	}

}

API

Types

• Ora: Main struct representing the ORA file
• XMLElement: Struct representing an XML element
• Item: Represents a layer or group
• Group: Represents a group of layers

Methods

Ora

• *NewOra() Ora: Creates a new Ora instance
• *(o Ora) Load(reader io.ReaderAt, size int64) error: Loads and parses an ORA file
• (o *Ora) GetByUUID(uuid string) (*Item, error): Retrieves an item by its UUID

Item

• *(i Item) Name() string: Returns the name of the item
• *(i Item) Opacity() float64: Returns the opacity of the item
• *(i Item) Visible() bool: Returns the visibility status of the item

Development

Prerequisites

• Go 1.22 or later
• Make (for using the Makefile)

Running Tests

To run tests locally, use the following command:

make test

For more options, run:

make help

Continuous Integration

This project uses GitHub Actions for continuous integration. Two workflows are set up:

1. Run Tests: Automatically runs tests on every push to the main branch and for all pull requests.
2. Release: Runs tests and publishes the library to pkg.go.dev when a new release is created.

Contributing

We welcome contributions! Please see the CONTRIBUTING.md file for guidelines on how to contribute.

License

This project is licensed under the Apache 2.0 License. See the LICENSE file for details.

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Happy coding! 🎨🖌️