Support mixed color spaces in Color.lerp#182934
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Instead of asserting that both colors must share the same color space, Color.lerp now converts both colors to the wider gamut color space before interpolating. For example, lerping between an sRGB color and a Display P3 color produces a Display P3 result.
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This pull request updates Color.lerp to support interpolation between colors in different color spaces by converting them to a wider gamut color space before interpolating. The changes are applied to both native and web platforms, and new tests are added to verify the new behavior. The implementation is functionally correct, but I've provided a few suggestions to refactor the code for better maintainability and readability by reducing code duplication.
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gaaclarke
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Hi @spydon! I considered this when the wide gamut code was introduced and this was an explicit design decision to omit. I didn't want people to accidentally slip into a colorspace they didn't intend. If someone wants this behavior they can write the following one line function instead:
Color? colorSpaceLerp(Color? x, Color? y, delta t, ColorSpace cs) =>
lerp(x?.withValues(colorSpace: cs),
y?.withValues(colorSpace: cs),
t);Doing it like this, developers can be much more intentional about what colorspace they are working in and reason about it better statically. A smaller consideration is we're trying to limit the size of dart:ui and someone can add this functionality at the app level pretty easily. That considered, I don't recommend this for an addition to dart:ui, sorry.
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Hey @gaaclarke! But doesn't that that mean that nobody will be able to use the wide color space with any material theming, that can surely not be intentional? |
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What scenario are you thinking about? Someone could just do this, no? final ButtonStyle raisedButtonStyle = ElevatedButton.styleFrom(
foregroundColor: Color.from(alpha: 1, red: 1, green: 0, blue: 0, colorSpace: ColorSpace.displayP3),
backgroundColor: Colors.red.withValues(colorSpace: ColorSpace.displayP3),
minimumSize: Size(88, 36),
padding: EdgeInsets.symmetric(horizontal: 16),
shape: const RoundedRectangleBorder(
borderRadius: BorderRadius.all(Radius.circular(2)),
),
);
ElevatedButton(
style: raisedButtonStyle,
onPressed: () { },
child: Text('Looks like a RaisedButton'),
)Are you saying there is a lerp under the covers and it's tricky that someone has to know to convert to displayp3? |
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Check the repro in the linked issue, it should clarify things: #182777 |
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Ahh, okay. You are saying not only are there lerps under the covers but sometimes you don't even have access to one of the colors that is being lerp'd.
I agree this is probably the best path forward then. The only alternative would be to modify every single lerp call in the framework (and potentially users' widgets).
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@dkwingsmt can you give me a secondary review, please? |
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Roll Flutter from 46fb7210422d to d3dd7744e81f (33 revisions) flutter/flutter@46fb721...d3dd774 2026-03-04 [email protected] Show warning when plugins do not support SwiftPM (flutter/flutter#182506) 2026-03-04 [email protected] Give guided message when project is not compatible with SwiftPM (flutter/flutter#182394) 2026-03-04 [email protected] Pass --web-define through to web runner when using --machine mode (flutter/flutter#183228) 2026-03-04 [email protected] Improve SwiftPM minimum platform mismatch diagnostics (flutter/flutter#182375) 2026-03-04 [email protected] Use dart::bin::SetupDartIo to setup dart:io (flutter/flutter#176714) 2026-03-04 [email protected] Roll Skia from 3197848b14ad to ada0b7628c79 (5 revisions) (flutter/flutter#183221) 2026-03-04 [email protected] Roll Skia from fe9e9f22c531 to 3197848b14ad (15 revisions) (flutter/flutter#183198) 2026-03-04 [email protected] refactor: remove material in reorderable_list_test, scroll_notification_test, scroll_physics_test, shortcuts_test, sliver_floating_header_test, snapshot_widget_test (flutter/flutter#182698) 2026-03-04 [email protected] refactor: remove material in pop_scope_test, route_notification_message_test, two_dimensional_utils, two_dimensional_viewport_test (flutter/flutter#182699) 2026-03-04 [email protected] Add dev/benchmarks/README.md (flutter/flutter#182976) 2026-03-03 [email protected] Roll RapidJSON to a branch based on the current upstream head (flutter/flutter#183048) 2026-03-03 [email protected] [Impeller] Update comments to reflect new info about 2-pass rendering (flutter/flutter#183050) 2026-03-03 [email protected] Add vmservices for accessibilityEvaluation (flutter/flutter#182791) 2026-03-03 [email protected] Roll Fuchsia Linux SDK from 0dCDM2oORHwDf_pyb... to JJw5EJ87vLGqFVl4h... (flutter/flutter#183177) 2026-03-03 [email protected] Support mixed color spaces in `Color.lerp` (flutter/flutter#182934) 2026-03-03 [email protected] Add warning when there is a widget with color between `Material` and `ListTile` (flutter/flutter#181402) 2026-03-03 [email protected] [ios]uitest for admob banner in scrollable list gesture issue (flutter/flutter#183128) 2026-03-03 [email protected] Roll Packages from faa4e22 to 9083bc9 (4 revisions) (flutter/flutter#183164) 2026-03-03 [email protected] Build App and native asset frameworks for Add to App FlutterPluginRegistrant (flutter/flutter#183136) 2026-03-03 [email protected] Roll Skia from f886711f180d to fe9e9f22c531 (4 revisions) (flutter/flutter#183155) 2026-03-03 [email protected] Roll Dart SDK from e86dbe9aa742 to c597ef90d2dc (2 revisions) (flutter/flutter#183147) 2026-03-03 [email protected] fix: bump matcher (flutter/flutter#183167) 2026-03-02 [email protected] Use isA to test for exceptions (flutter/flutter#183129) 2026-03-02 [email protected] [two_dimensional_scrollables] Fix tableview janks when first row/column pinned (flutter/flutter#180563) 2026-03-02 [email protected] Add await to callsites of BasicMessageChannel.send (flutter/flutter#182868) 2026-03-02 [email protected] Roll pub packages (flutter/flutter#183133) 2026-03-02 [email protected] Improve FFI code for windowing (flutter/flutter#183098) 2026-03-02 [email protected] [workflow] Update the changelog merge action to fetch the stable branch (flutter/flutter#183132) 2026-03-02 [email protected] Roll Skia from e180358b7a7a to f886711f180d (2 revisions) (flutter/flutter#183130) 2026-03-02 [email protected] Merge changelog from 3.41.3. (flutter/flutter#183131) 2026-03-02 [email protected] Make TextDecoration final and unify maskValue across platforms (flutter/flutter#183070) 2026-03-02 [email protected] Roll pub packages (flutter/flutter#182640) 2026-03-02 [email protected] Enable SwiftPM by default on master and beta (flutter/flutter#182923) If this roll has caused a breakage, revert this CL and stop the roller using the controls here: https://autoroll.skia.org/r/flutter-packages Please CC [email protected],[email protected] on the revert to ensure that a human is aware of the problem. To file a bug in Packages: https://github.com/flutter/flutter/issues/new/choose To report a problem with the AutoRoller itself, please file a bug: https://issues.skia.org/issues/new?component=1389291&template=1850622 Documentation for the AutoRoller is here: ...
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Instead of asserting that both colors must share the same color space, Color.lerp now converts both colors to the wider gamut color space before interpolating. For example, lerping between an sRGB color and a Display P3 color produces a Display P3 result. Instead of asserting that both colors must share the same color space, Color.lerp now converts both colors to the wider gamut color space before interpolating. For example, lerping between an sRGB color and a Display P3 color produces a Display P3 result. Fixes: flutter#182777 ## Pre-launch Checklist - [x] I read the [Contributor Guide] and followed the process outlined there for submitting PRs. - [x] I read the [Tree Hygiene] wiki page, which explains my responsibilities. - [x] I read and followed the [Flutter Style Guide], including [Features we expect every widget to implement]. - [x] I signed the [CLA]. - [x] I listed at least one issue that this PR fixes in the description above. - [x] I updated/added relevant documentation (doc comments with `///`). - [x] I added new tests to check the change I am making, or this PR is [test-exempt]. - [x] I followed the [breaking change policy] and added [Data Driven Fixes] where supported. - [x] All existing and new tests are passing. --------- Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>
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Instead of asserting that both colors must share the same color space, Color.lerp now converts both colors to the wider gamut color space before interpolating. For example, lerping between an sRGB color and a Display P3 color produces a Display P3 result.
Instead of asserting that both colors must share the same color space, Color.lerp now converts both colors to the wider gamut color space before interpolating. For example, lerping between an sRGB color and a Display P3 color produces a Display P3 result.
Fixes: #182777
Pre-launch Checklist
///).