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Rubén Norte
b1e8729f4d
Summary: Pull Request resolved: https://github.com/facebook/react-native/pull/51379 Changelog: [General][Fixed] Fix incorrect flattening / non-rendering of views with backgroundColor set to `rgba(255, 255, 255, 127/256)` Fixes #51378. ## Context When testing some unrelated things with Fantom is realized that the color for some text that I wasn't explicitly defining was being set to `rgba(255, 255, 255, 127)`, like here: https://github.com/facebook/react-native/blob/249a24ac756275eadbe3b4df1ff9c974af1671d2/packages/react-native-fantom/src/__tests__/Fantom-itest.js#L540-L542 When digging a bit more about why, I realized that was actually the value for `UndefinedColor`. When looking a bit deeper, I saw that the value for that constant was being set like this: ``` using Color = int32_t; namespace HostPlatformColor { static const facebook::react::Color UndefinedColor = std::numeric_limits<facebook::react::Color>::max(); } ``` I'm not sure what the logic could've been here: - Defining it as a value out of bounds for all valid colors? In this case, it's a 32 bit value so all the range of values are actually valid RGBA colors. - Defining it as a fully opaque white? Seems dangerous for a default because you wouldn't be able to distinguish a explicitly set white color from a non-set color, relevant if you're seeing a white background color in a view on top of another view with any other background color. The result of this existing logic was actually setting `UndefinedColor` to `rgba(255, 255, 255, 127)` because the alpha channel is defined in the first bits of the value, and `Color` being a signed int with 32 bits, the largest value is `01111....1`, so extracting the first 8 bits, you get 127. ## Changes This changes the value set for the `UndefinedColor` constant (which is used, among other things, to determine if a view sets a background color, or otherwise could potentially be flattened). The new value, instead of white with a 127/256 opacity, is black with 0% opacity (or simply the number 0 in `int32_t`). Reviewed By: javache Differential Revision: D74869311 fbshipit-source-id: 5582b4803b0b5c72cb3c1b33720c4542c5e3f1de