A tool to generate Markdown file QuickLook previews for macOS Catalina and up

Latest Release: 1.4.0

 

How to Use PreviewMarkdown

Install the app and run it. This will register the availability of the app’s QuickLook extensions, Previewer and Thumbnailer. You can now quit the app: just click OK:

Using QuickLook in Finder — select a Markdown file (.md, .mdown or .markdown, for example) and press space — will pop up a rendered image of file:

You can disable or re-enable Previewer and Thumbnailer in System Preferences > Extensions:

For some background information on how Catalina delivers QuickLook previews, please see this blog post.

From version 1.3.0, PreviewMarkdown will optionally preview YAML front matter at the start of your Markdown files. YAML is often used this way to hold metadata that will be read by static website generators when they read the Markdown content for page rendering.

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Customise the Preview

The app’s Preferences panel allows you to adjust some of the key elements of the preview:

• The colour of code blocks.
• The colour of headlines.
• The base text size, from 10pt to 28pt.
• The primary text font and style.
• Code blocks’ monospace font and style.
• Whether YAML front matter should be included in previews.
• Whether previews should be displayed white-on-black even in macOS Dark Mode.
• Whether thumbnails should should feature an MD file type tag.

Choose your preferred text size — headings are scaled up from this value in even steps — using the slider, then pick the fonts you want regular text and code to be presented in. You can also choose each font’s style:

Choose your preferred heading and code colours by clicking the appropriate colour well to pop up macOS’ colour picker. As you make your colour selection, the colour well will be updated:

Click Save to apply your choices.

Changing these settings will affect previews immediately, but may not affect thumbnails until you open a folder that has not been previously opened during the current login session. Thumbnails are always presented dark-on-light, even under macOS’ Dark Mode. This is a Finder convention.

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Feedback and Bug Reports

You can use the in-app UI to submit feedback or contact me. Just click in the Send Feedback button in the main window, or select Report a Bug… from the Help menu:

Please include your email address if you would like a response. I can’t respond without one. Please see the privacy policy for details of email address usage.

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Troubleshooting

If it appears that either Previewer or Thumbnailer are not working after you have run the host app, please log out of your Mac and then log back in.

Some applications which can edit Markdown files may register a non-standard, proprietary Uniform Type Identifier (UTI) for Markdown files. PreviewMarkdown may not be aware of these UTIs and therefore may not be able to preview and thumbnail these files on your system. If you encounter this issue — typically, previews of markdown files will show the raw formatting text — please run utitool to see your system’s registered Markdown file UTI. This UTI will automatically be included in any message you send using PreviewMarkdown’s feedback facility.

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Enjoyed Using PreviewMarkdown?

If you have found PreviewMarkdown to be useful, please consider writing a positive review on the Mac App Store, or simply give it a rating.

Thank you!

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Acknowledgements

PreviewMarkdown makes use of code from the following sources:

• SwiftyMarkdown — Markdown-to-NSAttributedString conversion.
• YamlSwift — YAML-to-NSAttributedString conversion.

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Source Code

You can view PreviewMarkdown’s source code at GitHub.

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Release Notes

• 1.4.0 28 July 2021
  • Allow any installed font to be selected.
  • Allow the heading colour to be selected.
  • Allow any colour to be chosen using macOS’ colour picker.
  • Tighten the thumbnailer code.
  • Fixed a rare bug in the previewer error reporting code.
• 1.3.1 17 June 2021
  • Add links to other PreviewApps.
  • Support macOS 11 Big Sur’s UTType API.
  • Stability improvements.
• 1.3.0 9 May 2021
  • Add optional presentation of YAML front matter to previews.
  • Recode Thumbnailer to make it thread safe: this should prevent crashes leading to generic or editor-specific thumbnail icons being seen.
  • Update user-agent string.
  • Minor code and UI improvements.
• 1.2.0 4 February 2021
  • Add preview display preferences (requested by various anonymous feedback senders).
  • Add file type ident tag to thumbnails (requested by @chamiu).
  • Add What’s New sheet to be shown with new major/minor versions.
  • Include local markdown UTI with user-submitted feedback.
  • Add link for app reviews.
• 1.1.4 16 January 2021
  • Add UTI net.ia.markdown.
• 1.1.3 13 January 202
  • Add UTI writer.pro.markdown.
• 1.1.2 18 November 2020
  • Apple Silicon support.
• 1.1.1 1 October 2020
  • Add report bugs/send feedback mechanism.
  • Add further usage advice to the main window.
  • Handle markdown formatting not yet rendered by SwiftyMarkdown: three-tick code blocks; HTML symbols; space-inset lists.
• 1.1.0 25 September 2020
  • Add macOS Big Sur support.
  • Better macOS dark/light mode support.
  • Migrate engine to SwiftyMarkdown 1.2.3.
• 1.0.5 9 April 2020
  • Mac App Store version.
• 1.0.4 Not Released
  • No user-visible changes.
• 1.0.3 10 December 2019
  • Add the version number to the app info dialog.
• 1.0.2 4 December 2019
  • Fix random crash (string index out of range in SwiftyMarkdown).
• 1.0.1 20 November 2019
  • Correct thumbnail styling.
• 1.0.0 8 November 2019
  • Initial public release.

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Related Software

• ASCII
• HighlighterSwift
• MNU
• PreviewCode
• PreviewYaml

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