Prerequisite
Hi! I’m Anointing, your friendly neighborhood software engineer. I’m an Outreachy GNOME intern currently working on the project titled “Implement the SVG2 Text Layout Algorithm in Librsvg.”
In a previous blog post, I briefly introduced my project and tasks. If you missed it, don’t worry—this article dives deeper into the project and the specific task I’m working on.
What is Librsvg?
Librsvg is a lightweight library used to render Scalable Vector Graphics (SVGs), primarily within GNOME projects. It has been around since 2001, initially developed to handle SVG icons and graphical assets for GNOME desktops. Over the years, it has evolved into a versatile tool used for various SVG rendering needs.
What is SVG2?
Before understanding SVG2, let’s break down SVG (Scalable Vector Graphics):
- SVG is an XML-based format for creating two-dimensional graphics.
- Unlike raster images (e.g., JPEG or PNG), SVG images are scalable, meaning they retain quality regardless of size.
- They are widely used for web graphics, illustrations, icons, and more because of their scalability and efficiency.
SVG2 (Scalable Vector Graphics, version 2) is the latest update to the SVG standard, developed by the World Wide Web Consortium (W3C). It builds upon SVG 1.1 with new features, bug fixes, and enhancements to make SVG more powerful and consistent across modern browsers.
Librsvg’s Current State
Librsvg supports some parts of the SVG 1.1 specifications for text, including bidirectional text. However, advanced features like per-glyph positioning or text-on-path are not yet implemented.
The SVG2 specification introduces significant improvements in text layout, such as:
- Fine-grained glyph positioning
- Support for right-to-left and bidirectional text
- Vertical text layout
- Text-on-path
- Automatic text wrapping
Currently, librsvg does not fully implement SVG2’s comprehensive text layout algorithm. My role is to help improve this functionality.
My Role: Implementing the SVG2 Text Layout Algorithm
If the above sounds technical, don’t worry—I’ll explain the key tasks in simpler terms.
1. Support for Basic Text Layout
This involves ensuring that text in SVG images appears correctly. Imagine a digital poster: every word and letter must be precisely positioned. My task is to make sure librsvg can handle this properly.
2. Whitespace Handling
Whitespace refers to the blank space between words and lines. In SVG, whitespace is standardized—extra spaces should not disrupt the layout. I’m implementing an algorithm to handle whitespace effectively.
3. Left-to-Right (LTR) and Right-to-Left (RTL) Languages
Languages like English are read from left to right, while Arabic or Hebrew are read from right to left. Librsvg must handle both correctly using a process called the Bidi (Bidirectional) algorithm.
4. Inter-Glyph Spacing
In SVG, attributes like x, y, dx, and dy allow precise control over letter spacing. This ensures text looks balanced and beautiful. Additionally, this task involves handling ligatures (e.g., combining characters in Arabic) to ensure the output is correct.
5. Text-on-Path Handling (If Time Permits)
This feature allows text to follow a specific shape, like a circle or wave. It’s a fancy but useful way to add artistic effects to SVGs.
Why Does This Matter?
Improving librsvg’s text layout makes it more powerful and accessible for designers, developers, and artists. Whether creating infographics, digital posters, or interactive charts, these enhancements ensure that text renders beautifully in every language and style.
Tips for Newbies
If you’re new to SVG, text layout algorithms, or even Rust (the programming language used in librsvg), here’s what you need to know:
- Skills Needed: Communication, basic Rust programming, and familiarity with terms like shaping, bidi algorithm, glyphs, ligatures, and baselines.
- Start Small: Focus on one concept at a time—there’s no need to know everything at once.
- Resources: The GNOME librsvg project is beginner-friendly and a great way to dive into open-source contributions.
Resources for Learning and Contributing
- SVG2 Text Specification: Learn the official details of SVG2’s text features.
- GNOME Librsvg Repository: Explore the codebase and start contributing.
- Core Text and SVG Learning Resources: Find guides and tutorials to help you understand SVG and text layout concepts.
Wrapping Up
These tasks may seem technical, but they boil down to making librsvg a better tool for rendering SVGs. Whether it’s neat text placement, handling multiple languages, or adding artistic text effects, we’re improving SVG rendering for everyone.
So far, this project has been a journey of immense learning for me—both in technical skills like Rust programming and soft skills like clear communication.
Feel free to ask questions or share your thoughts. I’d love to hear from you! 😊