UltimaDark

This repository stores the source code for the UltimaDark Firefox extension The extension uses agressive techniques to get a dark mode everywhere on internet This is still highly experimental so it can also ruin your internet experience

UltimaDark stands out from other extensions in its category by altering colors even before the renderer (Gecko) processes them, which considerably improves performance. The UltimaDark code intercepts the page content at an early stage, right after it is fetched from the remote website. This preemptive editing prevents Gecko from displaying the default bright colors of the website before applying the dark theme, eliminating the jarring white flash during page loading.

During this initial edit, nothing has been parsed by Gecko yet — all values are still character strings. The challenge lies in identifying colors within these character strings and determining whether they will be used as background or foreground. This distinction is not an exact science, adding complexity to the process.

Once a color is detected, it undergoes the appropriate transformation, either darkening or brightening. After the transformation is complete, the original value is replaced in the character string, ready to be read by the renderer.

The adjustment of website colors, rather than implementing a dark theme, aims to preserve the authenticity of the website's intended design.

Let's focus specifically on the darkening transformation, as there are still refinements to be made in the brightening function.

² The darkening transformation begins by determining the lightness of the color. If it falls below a certain brightness threshold (B), it remains untouched, respecting the website's intended design.

For lightness values above B, the edit ensures it never exceeds a maximum lightness (A). The lightness scale ranges from 0 to 1, where 0 is black and 1 is fully white—unsuitable for a background.

• Lightness values from 0 to B are preserved as-is.
• Lightness values from B to 0.5 are scaled from B to A.
  • It might be a good option to shortcut this rule for lightness from B to A ( Do not edit site colors which are already under maximum lightness A, thus keeping exactly these intended colors as is)
• Lightness values from 0.5 to 1 are reversed and then scaled from A to B.
  • This implies lightness values of 1 (white) are then equals to B (not reversed to black !), ensuring good contrast with colors at point ².

You can review the transformation function here: Desmos Background Transformation Function and here Desmos Foreground Transformation Function.

UltimaDark also has the capability to edit pixels in images ("Image Edition" toggle), although this feature is currently experimental and not fully functional. An example of the broken functionality can be seen on the Apple support page: Broken Example. On the other hand, the feature works better on the Sushi Spirit website: Not-So-Bad Example.

Compatibility

• Currently running on Firefox 115.0.3 ESR and higher
• Mercury
• Waterfox G6.0.7 or higher
• LibreWolf
• Floorp

Versions

Currently on 1.5.x

Downloads

Download from AMO (Firefox's add-on repository)

How To Clone

git clone https://github.com/ThomazPom/Moz-Ext-UltimaDark

Prerequisite

• No script has to be executed
• Any Gecko based browser that maintains current Firefox WebExtension support on it's respective platform

Bug Reporting

Bug reports help developers to find out about issues they may not have experienced - it is impossible to test an extension synthetically in every way that users will.

• Please make sure you are testing on the latest verison of the extension by manually checking for updates from the "manage extensions" page or verifying the version number against the most recent merge.
• Search for the site name on the issue tracker to make sure it has not already been reported
• Disable other extensions that may be interfering with the layout of the site eg. content blockers before testing
• Take screenshots of the behavior and specify what Browser, Release Channel, and Version you are on along with providing a link to the offending site

Backporting

Without an unreasonable level of effort, this extension will not be compatible with Pre-Quantum versions of Firefox (56 and lower). However, it should be theoretically possible to get working on 57 and higher (excluding the ImageEdition rewrite which requires Firefox 105 or above). Contributions towards this broader compatibility would be greatly appreciated.