feat: Support drop-shadow filter utilities on native

[feri-irawan]

Proposal

Add support for Tailwind CSS v4's drop-shadow filter utilities on React Native.

Currently, drop-shadow-* classes are silently ignored on native because the drop-shadow function in the CSS processor returns undefined. Since React Native already supports filter: "drop-shadow(...)" as a string value (similar to how blur, grayscale, and other filters are already handled in Uniwind), this seems like a natural addition.

Context

Tailwind CSS v4 provides the following drop-shadow utilities:

Class	CSS Output
drop-shadow-sm	filter: drop-shadow(0 1px 2px var(--drop-shadow-color, ...))
drop-shadow-md	filter: drop-shadow(0 3px 3px var(--drop-shadow-color, ...))
drop-shadow-lg	filter: drop-shadow(0 4px 4px var(--drop-shadow-color, ...))
drop-shadow-xl	filter: drop-shadow(0 9px 7px var(--drop-shadow-color, ...))
drop-shadow-2xl	filter: drop-shadow(0 25px 25px var(--drop-shadow-color, ...))
drop-shadow-none	filter: drop-shadow(0 0 0 transparent)

These also support:

• Arbitrary values: drop-shadow-[0_10px_8px_rgba(0,0,0,0.5)]
• Color modifiers: drop-shadow-red-500, drop-shadow-indigo-500/50
• Combined filters: blur-md drop-shadow-md

React Native (0.76+) supports filter as a string prop, including drop-shadow(). Reference: React Native Shadow Props

Proposed Implementation

The change is minimal — a new processDropShadow method in packages/uniwind/src/bundler/css-processor/functions.ts that:

1. Filters out internal white-space tokens from the LightningCSS AST
2. Maps each argument (offsetX, offsetY, blurRadius, color) through processValue
3. Produces a JS template expression matching the existing filter pattern

This follows the exact same approach as processFilterFunction for blur, grayscale, etc.

I have a working implementation

I've already implemented this with comprehensive tests covering all variants (presets, arbitrary values, color modifiers, combined filters). All CI checks pass locally:

• ✅ bun run build
• ✅ bun run check:typescript / check:typescript:test
• ✅ bun run lint / check:format
• ✅ bun run circular:check
• ✅ bun run test:native (147 tests) / test:web (26 tests) / test:types
• ✅ bun run test:e2e (9 tests)

Happy to open a PR if this sounds good to the maintainers. Looking forward to feedback!

Update: PR submitted at #645

[Brentlok]

Closing this discussion in favor of original issue - #643
For the future - please wait before opening a new issue/discussion, after your initial issue was closed.
We have this action mainly to block AI agents from creating non sense issues without any reproduction, we're reopening all valid issues that were closed

[feri-irawan]

Thanks for the clarification! I understand the reasoning behind this action.

I’ll make sure to wait before opening a new issue/discussion if the initial one was closed. I appreciate you reopening valid issues as well. Thanks!