Markdown Preview: Render Your .md Files!

Introduction

Hey guys! Let's talk about something super cool: implementing a markdown preview rendering feature. This is all about making life easier for you when you're working with markdown files. Imagine importing a .md file and instantly seeing a rendered preview that closely resembles the final PDF output. That's what we're aiming for! This preview, crafted with HTML and CSS, provides an immediate visual representation of your document. Here’s a deep dive into why and how we're bringing this feature to life.

Why a Markdown Preview?

Having a markdown preview is incredibly useful. First off, immediate feedback is a game-changer. Instead of exporting to PDF every time you make a small tweak, you see the changes in real-time. This speeds up your workflow and keeps you in the zone. Plus, it reduces errors. By visually confirming the formatting, hierarchy, and overall structure, you can catch mistakes early. For content creators, this is a lifesaver. Think about bloggers, technical writers, and anyone who uses markdown to draft documents. This feature lets them focus on content rather than constantly checking the output.

The preview also serves as a visual guide. While markdown is simple, the final look can depend on the rendering engine. Seeing a preview that approximates the final PDF gives you confidence that what you're writing is what you'll get. It’s a sanity check that ensures your document is on the right track. Ultimately, it makes the whole process smoother, faster, and less frustrating. No more guessing; just clear, visual feedback.

Description

Our main goal is to build a markdown parser and HTML renderer. This will display the imported .md file content in a preview pane with some basic styling. The idea is to give you a clear, immediate view of what your markdown will look like once it’s converted to PDF. It’s all about making the editing process smoother and more intuitive.

Key Features

So, what exactly will this feature bring to the table? Let’s break it down:

• Real-Time Rendering: As you load a markdown file, the preview pane will automatically display the rendered HTML.
• Hierarchical Headings: Headings (h1-h6) will be rendered with the appropriate hierarchy, making your document structure clear.
• List Support: Both ordered and unordered lists will be displayed correctly, ensuring your content flows as intended.
• Code Blocks: Code blocks will be displayed with a monospace font, making code snippets easy to read.
• Inline Code: Inline code will be styled distinctively, setting it apart from the rest of the text.
• Text Formatting: Bold and italic text will be properly formatted, adding emphasis where needed.
• Link Styling: Links will be styled (though not clickable in this initial version), giving you a sense of how they'll appear.
• Dynamic Updates: The preview will automatically update as the file content changes, providing a seamless editing experience.

Acceptance Criteria

To make sure we're on the right track, we have a few acceptance criteria. These are the benchmarks that will determine whether the feature is up to snuff.

• [ ] Markdown File Loading: When a markdown file is loaded, the preview pane displays the rendered HTML.
• [ ] Heading Hierarchy: When the markdown contains headings (h1-h6), they are rendered with appropriate hierarchy.
• [ ] List Display: When the markdown contains lists (ordered/unordered), they are displayed correctly.
• [ ] Code Block Styling: When the markdown contains code blocks, they are displayed with monospace font.
• [ ] Inline Code Styling: When the markdown contains inline code, it is styled distinctively.
• [ ] Text Formatting: When the markdown contains bold/italic text, then formatting is applied.
• [ ] Link Styling: When the markdown contains links, then they are styled (but not clickable in MVP).
• [ ] Dynamic Updates: When the file content changes, the preview updates accordingly.

These criteria ensure that the preview is accurate, functional, and provides a reliable representation of the final output. Meeting these standards means we're delivering a tool that you can depend on.

Technical Tasks

Under the hood, there are several technical tasks we need to tackle to bring this feature to life. These tasks span both the Rust backend and the Angular frontend, ensuring a cohesive and efficient implementation.

Rust Backend

• [ ] Markdown Parsing Library: Add a markdown parsing library to the Rust backend (either comrak or pulldown-cmark).

• [ ] Parse Markdown Command: Create a Rust command to parse markdown and return HTML.

  • This command will take the markdown content as a string and return the corresponding HTML.
  • Error handling will be implemented to manage parsing failures gracefully.

• [ ] HTML Sanitization: Ensure the returned HTML is sanitized to prevent security vulnerabilities (e.g., removing script tags).

Angular Frontend

• [ ] Preview Component: Create an Angular component for the preview pane.

  • This component will handle the display of the rendered HTML.
  • It will receive markdown content as an input and output the rendered HTML in a safe context.

• [ ] Basic CSS Styling: Add basic CSS styling for rendered HTML elements to match the UNV-1 template styling.

• [ ] Auto-Update Mechanism: Implement an auto-update mechanism to refresh the preview when the file changes.

Edge Case Handling

• [ ] Empty File: Handle the case where the markdown file is empty.
• [ ] Invalid Markdown: Manage scenarios with invalid markdown content.
• [ ] Large Files: Optimize performance for large markdown files.

Implementation Notes

Let’s dive a bit deeper into how we plan to implement this feature, focusing on both the Rust backend and the Angular frontend.

Rust Backend Details

• Parsing Library: We'll use either comrak or pulldown-cmark for parsing. Both are reliable and efficient.

• Command Structure: The command will look something like this:

  parse_markdown(content: String) -> Result<String, Error>
  

  It takes a string of markdown content and returns a Result containing either the HTML or an error.

• Sanitization: Ensuring the returned HTML is safe is crucial. We'll strip out any potentially harmful elements like script tags to prevent XSS attacks.

Angular Frontend Details

• Component Creation: We'll create a PreviewComponent with the following characteristics:

  • Input: Markdown content (using a signal or observable for reactivity).
  • Output: Rendered HTML in a safe context.

• DomSanitizer: We'll use Angular's DomSanitizer to safely render the HTML. This helps prevent security issues by ensuring the HTML is trusted.

• CSS Styling: The CSS should match the UNV-1 template styling. Here’s a basic version to get us started:

  /* minimal styling for mvp */
  

h1 font-size 2em; margin-bottom: 1em; h2 font-size 1.5em; margin-bottom: 0.75em; code font-family monospace; background: #f4f4f4; pre background #f4f4f4; padding: 1em; ```

Performance Considerations

Performance is key, especially with larger files. For files over 100KB, we’ll consider debouncing updates to prevent excessive re-rendering. Lazy rendering for very long documents is a future optimization we might explore.

Dependencies

This feature depends on the successful implementation of markdown file import, as tracked in issue #1. Before we can preview markdown, we need to be able to import it!

Additional Context

Remember, this is an approximate preview. It won't be a perfect 1:1 rendering with the final PDF right away. Our initial focus is on basic markdown elements to get the MVP up and running. We can always refine the rendering later to get it pixel-perfect.

So there you have it! A detailed plan to bring a markdown preview feature to life. Stay tuned for updates as we make progress. This is going to be awesome!