RFC: Raw color fallback for PlatformColor - #1008
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Summary: Pull Request resolved: react#57556 An implementation for the RFC in react-native-community/discussions-and-proposals#1008 PlatformColor previously had no way to specify what color to use when none of the supplied native color tokens resolve on the device. On a miss the behavior was inconsistent across platforms and architectures (transparent, nil, or a thrown error), giving apps no control over the rendered result. This adds an optional trailing `{fallback: '<raw color string>'}` argument to `PlatformColor(...)`. The fallback is carried lazily to the native layer as a raw, unprocessed string and is only parsed when every provided token fails to resolve. When at least one token resolves the fallback is ignored, so existing call sites are completely unaffected and omitting the argument preserves today's exact behavior. Example: PlatformColor('someSystemToken', {fallback: '#FF0000'}) The change spans the JS entry points (all platform `PlatformColorValueTypes.*` files plus the Flow and TypeScript type declarations), the iOS (Paper and Fabric) and Android (Paper and Fabric) native color resolvers, a new "Lazy Fallback Colors" section in the RNTester PlatformColor example, and the regenerated C++ API snapshots. Changelog: [General][Added] - Support a lazy raw color fallback for PlatformColor when native tokens fail to resolve Differential Revision: D111837102
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…cOS (native) (react#57556) Summary: An implementation for the RFC in react-native-community/discussions-and-proposals#1008 This is the first diff in a stack that adds an optional trailing `{fallback: '<raw color string>'}` argument to `PlatformColor(...)`. The fallback is carried lazily to native and parsed only when every supplied color token fails to resolve. This diff wires up the iOS and macOS native color resolvers to honor that fallback; a later diff adds the JS argument that emits it, so on its own this change is a no-op for existing call sites. To distinguish a genuine miss (no token resolves) from a token that legitimately resolves to a transparent color, the semantic-color resolver gains an `OrNil` variant: - `RCTPlatformColorFromSemanticItemsOrNil` returns `nil` on a miss instead of collapsing to `clearColor`. `RCTPlatformColorFromSemanticItems` keeps its existing non-null contract by wrapping the `OrNil` variant. - On Fabric, `Color::createSemanticColor` returns the undefined-color sentinel (a null underlying `UIColor`) on a miss, so `PlatformColorParser.mm` can apply the fallback only on a true miss and otherwise render transparent exactly as before. - The fallback string is parsed with the shared CSS color parser (`parseCSSProperty<CSSColor>`), so `transparent`/`rgba(0,0,0,0)` are honored rather than mistaken for a parse failure. - On the iOS Paper (legacy) path, `RCTConvert.mm` parses the common hex forms (`#RGB`, `#RGBA`, `#RRGGBB`, `#RRGGBBAA`, alpha last) as the fallback when every semantic name misses. This spans the `xplat` iOS/macOS graphics resolvers and the vendored `third-party/react-native-macos` copies. Changelog: [Internal] - PlatformColor: iOS/macOS native support for a lazy raw-color fallback Differential Revision: D111837102
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…cOS (native) (react#57556) Summary: An implementation for the RFC in react-native-community/discussions-and-proposals#1008 This is the first diff in a stack that adds an optional trailing `{fallback: '<raw color string>'}` argument to `PlatformColor(...)`. The fallback is carried lazily to native and parsed only when every supplied color token fails to resolve. This diff wires up the iOS and macOS native color resolvers to honor that fallback; a later diff adds the JS argument that emits it, so on its own this change is a no-op for existing call sites. The fallback is supported on the new architecture (Fabric) only. To distinguish a genuine miss (no token resolves) from a token that legitimately resolves to a transparent color, the semantic-color resolver gains an `OrNil` variant: - `RCTPlatformColorFromSemanticItemsOrNil` returns `nil` on a miss instead of collapsing to `clearColor`. `RCTPlatformColorFromSemanticItems` keeps its existing non-null contract by wrapping the `OrNil` variant. - `Color::createSemanticColor` returns the undefined-color sentinel (a null underlying `UIColor`) on a miss, so `PlatformColorParser.mm` applies the fallback only on a true miss and otherwise renders transparent exactly as before. - The fallback string is parsed with the shared CSS color parser (`parseCSSProperty<CSSColor>`), so `transparent`/`rgba(0,0,0,0)` are honored rather than mistaken for a parse failure. This spans the `xplat` iOS and macOS graphics resolvers. Changelog: [Internal] - PlatformColor: iOS/macOS native support for a lazy raw-color fallback Reviewed By: javache Differential Revision: D111837102
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…ative) (react#57655) Summary: An implementation for the RFC in react-native-community/discussions-and-proposals#1008 Wires up the Android native color resolver (Fabric) to honor the lazy `{fallback}` carried by `PlatformColor(...)`. A later diff adds the JS argument that emits it, so on its own this change is a no-op for existing call sites. To tell a genuine miss apart from a token that resolves to transparent black (ARGB 0): - `FabricUIManager.getColor` now returns a boxed `Nullable Integer` — `null` means no resource path resolved. The Fabric C++ `PlatformColorParser.h` reads that boxed result over JNI, caches the explicit-miss signal, and on a miss parses the raw fallback string with the shared CSS color parser (`parseCSSProperty<CSSColor>`), matching the iOS Fabric path. The color object is now read as a `map<string, RawValue>` because it mixes an array (`resource_paths`) with an optional string (`fallback`). - `NativeDrawable` carries an optional `colorFallback` alongside `resource_paths` so ripple drawables degrade to the fallback too. Generated files (`ReactAndroid.api` and the `ReactAndroid*Cxx.api` snapshots) are regenerated to match the new public signatures. Changelog: [Internal] - PlatformColor: Android native support for a lazy raw-color fallback Reviewed By: mdvacca Differential Revision: D113329136
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…cOS (native) (react#57556) Summary: An implementation for the RFC in react-native-community/discussions-and-proposals#1008 This is the first diff in a stack that adds an optional trailing `{fallback: '<raw color string>'}` argument to `PlatformColor(...)`. The fallback is carried lazily to native and parsed only when every supplied color token fails to resolve. This diff wires up the iOS and macOS native color resolvers to honor that fallback; a later diff adds the JS argument that emits it, so on its own this change is a no-op for existing call sites. The fallback is supported on the new architecture (Fabric) only. To distinguish a genuine miss (no token resolves) from a token that legitimately resolves to a transparent color, the semantic-color resolver gains an `OrNil` variant: - `RCTPlatformColorFromSemanticItemsOrNil` returns `nil` on a miss instead of collapsing to `clearColor`. `RCTPlatformColorFromSemanticItems` keeps its existing non-null contract by wrapping the `OrNil` variant. - `Color::createSemanticColor` returns the undefined-color sentinel (a null underlying `UIColor`) on a miss, so `PlatformColorParser.mm` applies the fallback only on a true miss and otherwise renders transparent exactly as before. - The fallback string is parsed with the shared CSS color parser (`parseCSSProperty<CSSColor>`), so `transparent`/`rgba(0,0,0,0)` are honored rather than mistaken for a parse failure. This spans the `xplat` iOS and macOS graphics resolvers. Changelog: [Internal] - PlatformColor: iOS/macOS native support for a lazy raw-color fallback Reviewed By: javache Differential Revision: D111837102
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…ative) (react#57655) Summary: An implementation for the RFC in react-native-community/discussions-and-proposals#1008 Wires up the Android native color resolver (Fabric) to honor the lazy `{fallback}` carried by `PlatformColor(...)`. A later diff adds the JS argument that emits it, so on its own this change is a no-op for existing call sites. To tell a genuine miss apart from a token that resolves to transparent black (ARGB 0): - `FabricUIManager.getColor` now returns a boxed `Nullable Integer` — `null` means no resource path resolved. The Fabric C++ `PlatformColorParser.h` reads that boxed result over JNI, caches the explicit-miss signal, and on a miss parses the raw fallback string with the shared CSS color parser (`parseCSSProperty<CSSColor>`), matching the iOS Fabric path. The color object is now read as a `map<string, RawValue>` because it mixes an array (`resource_paths`) with an optional string (`fallback`). - `NativeDrawable` carries an optional `colorFallback` alongside `resource_paths` so ripple drawables degrade to the fallback too. Generated files (`ReactAndroid.api` and the `ReactAndroid*Cxx.api` snapshots) are regenerated to match the new public signatures. Changelog: [Internal] - PlatformColor: Android native support for a lazy raw-color fallback Reviewed By: mdvacca, javache Differential Revision: D113329136
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Summary: An implementation for the RFC in react-native-community/discussions-and-proposals#1008 `PlatformColor` previously had no way to specify what color to use when none of the supplied native color tokens resolve on the device. On a miss the behavior was inconsistent across platforms and architectures (transparent, nil, or a thrown error), giving apps no control over the rendered result. This adds an optional trailing `{fallback: '<raw color string>'}` argument to `PlatformColor(...)` and updates the JS entry points to emit it. The fallback is carried lazily to native as a raw, unprocessed string and is only parsed when every provided token fails to resolve (the native side of that behavior landed earlier in this stack). When at least one token resolves the fallback is ignored, so existing call sites are completely unaffected and omitting the argument preserves today's exact behavior. Example: PlatformColor('someSystemToken', {fallback: '#FF0000'}) Each platform entry point (`PlatformColorValueTypes.{android,ios,macos,windows}.js`, plus the vendored macOS/Windows copies) collects the leading string tokens and, when a trailing `{fallback}` object is present, attaches its raw string to the native color object. Non-string arguments in a non-trailing position are filtered out consistently rather than being forwarded to native. The Flow (`.js.flow`), TypeScript (`.d.ts`), and generated (`ReactNativeApi.d.ts`) declarations widen the signature to `Array<string | {fallback: string}>`, which is backward compatible. Changelog: [General][Added] - Support a lazy raw color fallback for PlatformColor when native tokens fail to resolve Differential Revision: D113329139
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…cOS (native) (react#57556) Summary: An implementation for the RFC in react-native-community/discussions-and-proposals#1008 This is the first diff in a stack that adds an optional trailing `{fallback: '<raw color string>'}` argument to `PlatformColor(...)`. The fallback is carried lazily to native and parsed only when every supplied color token fails to resolve. This diff wires up the iOS and macOS native color resolvers to honor that fallback; a later diff adds the JS argument that emits it, so on its own this change is a no-op for existing call sites. The fallback is supported on the new architecture (Fabric) only. To distinguish a genuine miss (no token resolves) from a token that legitimately resolves to a transparent color, the semantic-color resolver gains an `OrNil` variant: - `RCTPlatformColorFromSemanticItemsOrNil` returns `nil` on a miss instead of collapsing to `clearColor`. `RCTPlatformColorFromSemanticItems` keeps its existing non-null contract by wrapping the `OrNil` variant. - `Color::createSemanticColor` returns the undefined-color sentinel (a null underlying `UIColor`) on a miss, so `PlatformColorParser.mm` applies the fallback only on a true miss and otherwise renders transparent exactly as before. - The fallback string is parsed with the shared CSS color parser (`parseCSSProperty<CSSColor>`), so `transparent`/`rgba(0,0,0,0)` are honored rather than mistaken for a parse failure. This spans the `xplat` iOS and macOS graphics resolvers. Changelog: [Internal] - PlatformColor: iOS/macOS native support for a lazy raw-color fallback Reviewed By: javache Differential Revision: D111837102
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…ative) (react#57655) Summary: An implementation for the RFC in react-native-community/discussions-and-proposals#1008 Wires up the Android native color resolver (Fabric) to honor the lazy `{fallback}` carried by `PlatformColor(...)`. A later diff adds the JS argument that emits it, so on its own this change is a no-op for existing call sites. To tell a genuine miss apart from a token that resolves to transparent black (ARGB 0): - `FabricUIManager.getColor` now returns a boxed `Nullable Integer` — `null` means no resource path resolved. The Fabric C++ `PlatformColorParser.h` reads that boxed result over JNI, caches the explicit-miss signal, and on a miss parses the raw fallback string with the shared CSS color parser (`parseCSSProperty<CSSColor>`), matching the iOS Fabric path. The color object is now read as a `map<string, RawValue>` because it mixes an array (`resource_paths`) with an optional string (`fallback`). - `NativeDrawable` carries an optional `colorFallback` alongside `resource_paths` so ripple drawables degrade to the fallback too. Generated files (`ReactAndroid.api` and the `ReactAndroid*Cxx.api` snapshots) are regenerated to match the new public signatures. Changelog: [Internal] - PlatformColor: Android native support for a lazy raw-color fallback Reviewed By: mdvacca, javache Differential Revision: D113329136
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Summary: An implementation for the RFC in react-native-community/discussions-and-proposals#1008 `PlatformColor` previously had no way to specify what color to use when none of the supplied native color tokens resolve on the device. On a miss the behavior was inconsistent across platforms and architectures (transparent, nil, or a thrown error), giving apps no control over the rendered result. This adds an optional trailing `{fallback: '<raw color string>'}` argument to `PlatformColor(...)` and updates the JS entry points to emit it. The fallback is carried lazily to native as a raw, unprocessed string and is only parsed when every provided token fails to resolve (the native side of that behavior landed earlier in this stack). When at least one token resolves the fallback is ignored, so existing call sites are completely unaffected and omitting the argument preserves today's exact behavior. Example: PlatformColor('someSystemToken', {fallback: '#FF0000'}) Each platform entry point (`PlatformColorValueTypes.{android,ios,macos,windows}.js`, plus the vendored macOS/Windows copies) collects the leading string tokens and, when a trailing `{fallback}` object is present, attaches its raw string to the native color object. Non-string arguments in a non-trailing position are filtered out consistently rather than being forwarded to native. The Flow (`.js.flow`), TypeScript (`.d.ts`), and generated (`ReactNativeApi.d.ts`) declarations widen the signature to `Array<string | {fallback: string}>`, which is backward compatible. Changelog: [General][Added] - Support a lazy raw color fallback for PlatformColor when native tokens fail to resolve Differential Revision: D113329139
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…cOS (native) (react#57556) Summary: An implementation for the RFC in react-native-community/discussions-and-proposals#1008 This is the first diff in a stack that adds an optional trailing `{fallback: '<raw color string>'}` argument to `PlatformColor(...)`. The fallback is carried lazily to native and parsed only when every supplied color token fails to resolve. This diff wires up the iOS and macOS native color resolvers to honor that fallback; a later diff adds the JS argument that emits it, so on its own this change is a no-op for existing call sites. The fallback is supported on the new architecture (Fabric) only. To distinguish a genuine miss (no token resolves) from a token that legitimately resolves to a transparent color, the semantic-color resolver gains an `OrNil` variant: - `RCTPlatformColorFromSemanticItemsOrNil` returns `nil` on a miss instead of collapsing to `clearColor`. `RCTPlatformColorFromSemanticItems` keeps its existing non-null contract by wrapping the `OrNil` variant. - `Color::createSemanticColor` returns the undefined-color sentinel (a null underlying `UIColor`) on a miss, so `PlatformColorParser.mm` applies the fallback only on a true miss and otherwise renders transparent exactly as before. - The fallback string is parsed with the shared CSS color parser (`parseCSSProperty<CSSColor>`), so `transparent`/`rgba(0,0,0,0)` are honored rather than mistaken for a parse failure. This spans the `xplat` iOS and macOS graphics resolvers. Changelog: [Internal] - PlatformColor: iOS/macOS native support for a lazy raw-color fallback Reviewed By: javache Differential Revision: D111837102
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…ative) (react#57655) Summary: An implementation for the RFC in react-native-community/discussions-and-proposals#1008 Wires up the Android native color resolver (Fabric) to honor the lazy `{fallback}` carried by `PlatformColor(...)`. A later diff adds the JS argument that emits it, so on its own this change is a no-op for existing call sites. To tell a genuine miss apart from a token that resolves to transparent black (ARGB 0): - `FabricUIManager.getColor` now returns a boxed `Nullable Integer` — `null` means no resource path resolved. The Fabric C++ `PlatformColorParser.h` reads that boxed result over JNI, caches the explicit-miss signal, and on a miss parses the raw fallback string with the shared CSS color parser (`parseCSSProperty<CSSColor>`), matching the iOS Fabric path. The color object is now read as a `map<string, RawValue>` because it mixes an array (`resource_paths`) with an optional string (`fallback`). - `NativeDrawable` carries an optional `colorFallback` alongside `resource_paths` so ripple drawables degrade to the fallback too. Generated files (`ReactAndroid.api` and the `ReactAndroid*Cxx.api` snapshots) are regenerated to match the new public signatures. Changelog: [Internal] - PlatformColor: Android native support for a lazy raw-color fallback Reviewed By: mdvacca, javache Differential Revision: D113329136
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Summary: An implementation for the RFC in react-native-community/discussions-and-proposals#1008 `PlatformColor` previously had no way to specify what color to use when none of the supplied native color tokens resolve on the device. On a miss the behavior was inconsistent across platforms and architectures (transparent, nil, or a thrown error), giving apps no control over the rendered result. This adds an optional trailing `{fallback: '<raw color string>'}` argument to `PlatformColor(...)` and updates the JS entry points to emit it. The fallback is carried lazily to native as a raw, unprocessed string and is only parsed when every provided token fails to resolve (the native side of that behavior landed earlier in this stack). When at least one token resolves the fallback is ignored, so existing call sites are completely unaffected and omitting the argument preserves today's exact behavior. Example: PlatformColor('someSystemToken', {fallback: '#FF0000'}) Each platform entry point (`PlatformColorValueTypes.{android,ios,macos,windows}.js`, plus the vendored macOS/Windows copies) collects the leading string tokens and, when a trailing `{fallback}` object is present, attaches its raw string to the native color object. Non-string arguments in a non-trailing position are filtered out consistently rather than being forwarded to native. The Flow (`.js.flow`), TypeScript (`.d.ts`), and generated (`ReactNativeApi.d.ts`) declarations widen the signature to `Array<string | {fallback: string}>`, which is backward compatible. Changelog: [General][Added] - Support a lazy raw color fallback for PlatformColor when native tokens fail to resolve Differential Revision: D113329139
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Summary: An implementation for the RFC in react-native-community/discussions-and-proposals#1008 Rounds out the lazy `PlatformColor` fallback with tooling and a demo. - The `react-native/platform-colors` ESLint rule now permits an optional trailing `{fallback: <literal>}` options object so `PlatformColor('token', {fallback: '#RRGGBB'})` is lint-clean, while still requiring every other argument to be a literal. The options object must have exactly one `fallback` property whose value is a literal, so it stays statically analyzable. - A new "Lazy Fallback Colors" section in the RNTester `PlatformColor` example demonstrates valid tokens, misses with no fallback (transparent), and misses with hex / `rgb()` / `rgba()` / `#RRGGBBAA` fallbacks across `backgroundColor`, text `color`, and `borderColor`. Changelog: [Internal] - PlatformColor: ESLint support and RNTester example for the lazy raw-color fallback Differential Revision: D113329138
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…cOS (native) (#57556) Summary: Pull Request resolved: #57556 An implementation for the RFC in react-native-community/discussions-and-proposals#1008 This is the first diff in a stack that adds an optional trailing `{fallback: '<raw color string>'}` argument to `PlatformColor(...)`. The fallback is carried lazily to native and parsed only when every supplied color token fails to resolve. This diff wires up the iOS and macOS native color resolvers to honor that fallback; a later diff adds the JS argument that emits it, so on its own this change is a no-op for existing call sites. The fallback is supported on the new architecture (Fabric) only. To distinguish a genuine miss (no token resolves) from a token that legitimately resolves to a transparent color, the semantic-color resolver gains an `OrNil` variant: - `RCTPlatformColorFromSemanticItemsOrNil` returns `nil` on a miss instead of collapsing to `clearColor`. `RCTPlatformColorFromSemanticItems` keeps its existing non-null contract by wrapping the `OrNil` variant. - `Color::createSemanticColor` returns the undefined-color sentinel (a null underlying `UIColor`) on a miss, so `PlatformColorParser.mm` applies the fallback only on a true miss and otherwise renders transparent exactly as before. - The fallback string is parsed with the shared CSS color parser (`parseCSSProperty<CSSColor>`), so `transparent`/`rgba(0,0,0,0)` are honored rather than mistaken for a parse failure. This spans the `xplat` iOS and macOS graphics resolvers. Changelog: [Internal] - PlatformColor: iOS/macOS native support for a lazy raw-color fallback Reviewed By: javache, cipolleschi Differential Revision: D111837102 fbshipit-source-id: 20fd1d6e10b1ce953de3644752051843b51b230f
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…ative) (#57655) Summary: Pull Request resolved: #57655 An implementation for the RFC in react-native-community/discussions-and-proposals#1008 Wires up the Android native color resolver (Fabric) to honor the lazy `{fallback}` carried by `PlatformColor(...)`. A later diff adds the JS argument that emits it, so on its own this change is a no-op for existing call sites. To tell a genuine miss apart from a token that resolves to transparent black (ARGB 0): - `FabricUIManager.getColor` now returns a boxed `Nullable Integer` — `null` means no resource path resolved. The Fabric C++ `PlatformColorParser.h` reads that boxed result over JNI, caches the explicit-miss signal, and on a miss parses the raw fallback string with the shared CSS color parser (`parseCSSProperty<CSSColor>`), matching the iOS Fabric path. The color object is now read as a `map<string, RawValue>` because it mixes an array (`resource_paths`) with an optional string (`fallback`). - `NativeDrawable` carries an optional `colorFallback` alongside `resource_paths` so ripple drawables degrade to the fallback too. Generated files (`ReactAndroid.api` and the `ReactAndroid*Cxx.api` snapshots) are regenerated to match the new public signatures. Changelog: [Internal] - PlatformColor: Android native support for a lazy raw-color fallback Reviewed By: mdvacca, javache Differential Revision: D113329136 fbshipit-source-id: ee15aea8dfed66364e99d427825e1b9ebcbdc483
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Summary: An implementation for the RFC in react-native-community/discussions-and-proposals#1008 `PlatformColor` previously had no way to specify what color to use when none of the supplied native color tokens resolve on the device. On a miss the behavior was inconsistent across platforms and architectures (transparent, nil, or a thrown error), giving apps no control over the rendered result. This adds an optional trailing `{fallback: '<raw color string>'}` argument to `PlatformColor(...)` and updates the JS entry points to emit it. The fallback is carried lazily to native as a raw, unprocessed string and is only parsed when every provided token fails to resolve (the native side of that behavior landed earlier in this stack). When at least one token resolves the fallback is ignored, so existing call sites are completely unaffected and omitting the argument preserves today's exact behavior. Example: PlatformColor('someSystemToken', {fallback: '#FF0000'}) Each platform entry point (`PlatformColorValueTypes.{android,ios,macos,windows}.js`, plus the vendored macOS/Windows copies) collects the leading string tokens and, when a trailing `{fallback}` object is present, attaches its raw string to the native color object. Non-string arguments in a non-trailing position are filtered out consistently rather than being forwarded to native. The Flow (`.js.flow`), TypeScript (`.d.ts`), and generated (`ReactNativeApi.d.ts`) declarations widen the signature to `Array<string | {fallback: string}>`, which is backward compatible. Changelog: [General][Added] - Support a lazy raw color fallback for PlatformColor when native tokens fail to resolve Differential Revision: D113329139
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Summary: An implementation for the RFC in react-native-community/discussions-and-proposals#1008 `PlatformColor` previously had no way to specify what color to use when none of the supplied native color tokens resolve on the device. On a miss the behavior was inconsistent across platforms and architectures (transparent, nil, or a thrown error), giving apps no control over the rendered result. This adds an optional trailing `{fallback: '<raw color string>'}` argument to `PlatformColor(...)` and updates the JS entry points to emit it. The fallback is carried lazily to native as a raw, unprocessed string and is only parsed when every provided token fails to resolve (the native side of that behavior landed earlier in this stack). When at least one token resolves the fallback is ignored, so existing call sites are completely unaffected and omitting the argument preserves today's exact behavior. Example: PlatformColor('someSystemToken', {fallback: '#FF0000'}) Each platform entry point (`PlatformColorValueTypes.{android,ios,macos,windows}.js`, plus the vendored macOS/Windows copies) collects the leading string tokens and, when a trailing `{fallback}` object is present, attaches its raw string to the native color object. Non-string arguments in a non-trailing position are filtered out consistently rather than being forwarded to native. The Flow (`.js.flow`), TypeScript (`.d.ts`), and generated (`ReactNativeApi.d.ts`) declarations widen the signature to `Array<string | {fallback: string}>`, which is backward compatible. Changelog: [General][Added] - Support a lazy raw color fallback for PlatformColor when native tokens fail to resolve Differential Revision: D113329139
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Summary: An implementation for the RFC in react-native-community/discussions-and-proposals#1008 `PlatformColor` previously had no way to specify what color to use when none of the supplied native color tokens resolve on the device. On a miss the behavior was inconsistent across platforms and architectures (transparent, nil, or a thrown error), giving apps no control over the rendered result. This adds an optional trailing `{fallback: '<raw color string>'}` argument to `PlatformColor(...)` and updates the JS entry points to emit it. The fallback is carried lazily to native as a raw, unprocessed string and is only parsed when every provided token fails to resolve (the native side of that behavior landed earlier in this stack). When at least one token resolves the fallback is ignored, so existing call sites are completely unaffected and omitting the argument preserves today's exact behavior. Example: PlatformColor('someSystemToken', {fallback: '#FF0000'}) Each platform entry point (`PlatformColorValueTypes.{android,ios,macos,windows}.js`, plus the vendored macOS/Windows copies) collects the leading string tokens and, when a trailing `{fallback}` object is present, attaches its raw string to the native color object. Non-string arguments in a non-trailing position are filtered out consistently rather than being forwarded to native. The Flow (`.js.flow`), TypeScript (`.d.ts`), and generated (`ReactNativeApi.d.ts`) declarations widen the signature to `Array<string | {fallback: string}>`, which is backward compatible. Changelog: [General][Added] - Support a lazy raw color fallback for PlatformColor when native tokens fail to resolve Reviewed By: javache, huntie Differential Revision: D113329139
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Summary: An implementation for the RFC in react-native-community/discussions-and-proposals#1008 Rounds out the lazy `PlatformColor` fallback with tooling and a demo. - The `react-native/platform-colors` ESLint rule now permits an optional trailing `{fallback: <literal>}` options object so `PlatformColor('token', {fallback: '#RRGGBB'})` is lint-clean, while still requiring every other argument to be a literal. The options object must have exactly one `fallback` property whose value is a literal, so it stays statically analyzable. - A new "Lazy Fallback Colors" section in the RNTester `PlatformColor` example demonstrates valid tokens, misses with no fallback (transparent), and misses with hex / `rgb()` / `rgba()` / `#RRGGBBAA` fallbacks across `backgroundColor`, text `color`, and `borderColor`. Changelog: [Internal] - PlatformColor: ESLint support and RNTester example for the lazy raw-color fallback Reviewed By: christophpurrer Differential Revision: D113329138
Abbondanzo
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Aug 5, 2026
Summary: An implementation for the RFC in react-native-community/discussions-and-proposals#1008 `PlatformColor` previously had no way to specify what color to use when none of the supplied native color tokens resolve on the device. On a miss the behavior was inconsistent across platforms and architectures (transparent, nil, or a thrown error), giving apps no control over the rendered result. This adds an optional trailing `{fallback: '<raw color string>'}` argument to `PlatformColor(...)` and updates the JS entry points to emit it. The fallback is carried lazily to native as a raw, unprocessed string and is only parsed when every provided token fails to resolve (the native side of that behavior landed earlier in this stack). When at least one token resolves the fallback is ignored, so existing call sites are completely unaffected and omitting the argument preserves today's exact behavior. Example: PlatformColor('someSystemToken', {fallback: '#FF0000'}) Each platform entry point (`PlatformColorValueTypes.{android,ios,macos,windows}.js`, plus the vendored macOS/Windows copies) collects the leading string tokens and, when a trailing `{fallback}` object is present, attaches its raw string to the native color object. Non-string arguments in a non-trailing position are filtered out consistently rather than being forwarded to native. The Flow (`.js.flow`), TypeScript (`.d.ts`), and generated (`ReactNativeApi.d.ts`) declarations widen the signature to `Array<string | {fallback: string}>`, which is backward compatible. Changelog: [General][Added] - Support a lazy raw color fallback for PlatformColor when native tokens fail to resolve Reviewed By: javache, huntie Differential Revision: D113329139
Abbondanzo
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Aug 5, 2026
Summary: An implementation for the RFC in react-native-community/discussions-and-proposals#1008 Rounds out the lazy `PlatformColor` fallback with tooling and a demo. - The `react-native/platform-colors` ESLint rule now permits an optional trailing `{fallback: <literal>}` options object so `PlatformColor('token', {fallback: '#RRGGBB'})` is lint-clean, while still requiring every other argument to be a literal. The options object must have exactly one `fallback` property whose value is a literal, so it stays statically analyzable. - A new "Lazy Fallback Colors" section in the RNTester `PlatformColor` example demonstrates valid tokens, misses with no fallback (transparent), and misses with hex / `rgb()` / `rgba()` / `#RRGGBBAA` fallbacks across `backgroundColor`, text `color`, and `borderColor`. Changelog: [Internal] - PlatformColor: ESLint support and RNTester example for the lazy raw-color fallback Reviewed By: christophpurrer Differential Revision: D113329138
Abbondanzo
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Aug 5, 2026
Summary: An implementation for the RFC in react-native-community/discussions-and-proposals#1008 Adds unit and integration coverage for the PlatformColor raw-color fallback introduced in the parent diff: - CSSColorTest.cpp: additional CSS `<color>` parse cases pinning the shared parser used on the native fallback path - PlatformColorFallback-itest.js: JS integration test for token-miss -> fallback Changelog: [Internal] Reviewed By: christophpurrer Differential Revision: D111917092
Abbondanzo
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Aug 5, 2026
Summary: An implementation for the RFC in react-native-community/discussions-and-proposals#1008 `PlatformColor` previously had no way to specify what color to use when none of the supplied native color tokens resolve on the device. On a miss the behavior was inconsistent across platforms and architectures (transparent, nil, or a thrown error), giving apps no control over the rendered result. This adds an optional trailing `{fallback: '<raw color string>'}` argument to `PlatformColor(...)` and updates the JS entry points to emit it. The fallback is carried lazily to native as a raw, unprocessed string and is only parsed when every provided token fails to resolve (the native side of that behavior landed earlier in this stack). When at least one token resolves the fallback is ignored, so existing call sites are completely unaffected and omitting the argument preserves today's exact behavior. Example: PlatformColor('someSystemToken', {fallback: '#FF0000'}) Each platform entry point (`PlatformColorValueTypes.{android,ios,macos,windows}.js`, plus the vendored macOS/Windows copies) collects the leading string tokens and, when a trailing `{fallback}` object is present, attaches its raw string to the native color object. Non-string arguments in a non-trailing position are filtered out consistently rather than being forwarded to native. The Flow (`.js.flow`), TypeScript (`.d.ts`), and generated (`ReactNativeApi.d.ts`) declarations widen the signature to `Array<string | {fallback: string}>`, which is backward compatible. Changelog: [General][Added] - Support a lazy raw color fallback for PlatformColor when native tokens fail to resolve Reviewed By: javache, huntie Differential Revision: D113329139
Abbondanzo
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Aug 5, 2026
Summary: An implementation for the RFC in react-native-community/discussions-and-proposals#1008 `PlatformColor` previously had no way to specify what color to use when none of the supplied native color tokens resolve on the device. On a miss the behavior was inconsistent across platforms and architectures (transparent, nil, or a thrown error), giving apps no control over the rendered result. This adds an optional trailing `{fallback: '<raw color string>'}` argument to `PlatformColor(...)` and updates the JS entry points to emit it. The fallback is carried lazily to native as a raw, unprocessed string and is only parsed when every provided token fails to resolve (the native side of that behavior landed earlier in this stack). When at least one token resolves the fallback is ignored, so existing call sites are completely unaffected and omitting the argument preserves today's exact behavior. Example: PlatformColor('someSystemToken', {fallback: '#FF0000'}) Each platform entry point (`PlatformColorValueTypes.{android,ios,macos,windows}.js`, plus the vendored macOS/Windows copies) collects the leading string tokens and, when a trailing `{fallback}` object is present, attaches its raw string to the native color object. Non-string arguments in a non-trailing position are filtered out consistently rather than being forwarded to native. The Flow (`.js.flow`), TypeScript (`.d.ts`), and generated (`ReactNativeApi.d.ts`) declarations widen the signature to `Array<string | {fallback: string}>`, which is backward compatible. Changelog: [General][Added] - Support a lazy raw color fallback for PlatformColor when native tokens fail to resolve Reviewed By: javache, huntie Differential Revision: D113329139
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Aug 6, 2026
Summary: Pull Request resolved: #57701 An implementation for the RFC in react-native-community/discussions-and-proposals#1008 `PlatformColor` previously had no way to specify what color to use when none of the supplied native color tokens resolve on the device. On a miss the behavior was inconsistent across platforms and architectures (transparent, nil, or a thrown error), giving apps no control over the rendered result. This adds an optional trailing `{fallback: '<raw color string>'}` argument to `PlatformColor(...)` and updates the JS entry points to emit it. The fallback is carried lazily to native as a raw, unprocessed string and is only parsed when every provided token fails to resolve (the native side of that behavior landed earlier in this stack). When at least one token resolves the fallback is ignored, so existing call sites are completely unaffected and omitting the argument preserves today's exact behavior. Example: PlatformColor('someSystemToken', {fallback: '#FF0000'}) Each platform entry point (`PlatformColorValueTypes.{android,ios,macos,windows}.js`, plus the vendored macOS/Windows copies) collects the leading string tokens and, when a trailing `{fallback}` object is present, attaches its raw string to the native color object. Non-string arguments in a non-trailing position are filtered out consistently rather than being forwarded to native. The Flow (`.js.flow`), TypeScript (`.d.ts`), and generated (`ReactNativeApi.d.ts`) declarations widen the signature to `Array<string | {fallback: string}>`, which is backward compatible. Changelog: [General][Added] - Support a lazy raw color fallback for PlatformColor when native tokens fail to resolve Reviewed By: javache, huntie Differential Revision: D113329139 fbshipit-source-id: b6eb16e34d708bf8c14f8a8e3b9eb70547245447
meta-codesync Bot
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Aug 6, 2026
Summary: Pull Request resolved: #57705 An implementation for the RFC in react-native-community/discussions-and-proposals#1008 Rounds out the lazy `PlatformColor` fallback with tooling and a demo. - The `react-native/platform-colors` ESLint rule now permits an optional trailing `{fallback: <literal>}` options object so `PlatformColor('token', {fallback: '#RRGGBB'})` is lint-clean, while still requiring every other argument to be a literal. The options object must have exactly one `fallback` property whose value is a literal, so it stays statically analyzable. - A new "Lazy Fallback Colors" section in the RNTester `PlatformColor` example demonstrates valid tokens, misses with no fallback (transparent), and misses with hex / `rgb()` / `rgba()` / `#RRGGBBAA` fallbacks across `backgroundColor`, text `color`, and `borderColor`. Changelog: [Internal] - PlatformColor: ESLint support and RNTester example for the lazy raw-color fallback Reviewed By: christophpurrer Differential Revision: D113329138 fbshipit-source-id: 7d38a8d55b54615d1b131591e99d13e6299eb5cb
meta-codesync Bot
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Aug 6, 2026
Summary: Pull Request resolved: #57708 An implementation for the RFC in react-native-community/discussions-and-proposals#1008 Adds unit and integration coverage for the PlatformColor raw-color fallback introduced in the parent diff: - CSSColorTest.cpp: additional CSS `<color>` parse cases pinning the shared parser used on the native fallback path - PlatformColorFallback-itest.js: JS integration test for token-miss -> fallback Changelog: [Internal] Reviewed By: christophpurrer Differential Revision: D111917092 fbshipit-source-id: 412387d0d598b5556cf7a3eafbc0da60ceaf2725
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This adds a short RFC for introducing an API change to
PlatformColorthat allows fallbacks, rather than rendering transparentlyRFC Document