Currently the framework uses fairly large "hit slop" values to disambiguate taps from drags/pans. This makes sense on touch devices where the interaction is not very precise, on mice however it can feel as if the UI is lagging. This is immediately noticeable on our infra dashboard, where it takes almost half of a grid square of drag before the actual drag kicks in.

One potential solution is to always use smaller constants depending on whether the interaction is mouse or touch based. The only reasonable choice is to use the pointer device kind and not target platform - same platform can have different input sources. This requires exposing the pointer device kind in a few new places in several of the gesture detectors, and using the enum to compute the correct hit slop from an expanded set of constants.

This almost works, however there are a few places (notably ListViews) which uses the touch hit slop as a default value in scroll physics. It does not seem like it will be easy to disambiguate a user provided scroll physics constant from the default and/or adjust it somehow - this might require significant changes to scroll physics which I have left out of this PR.

This PR does not adjust:

kTouchSlop used in scroll_physics.dart's minFlingDistance
kTouchSlop used in PrimaryPointerGestureRecognizer/LongPressGestureRecognizer

Previously, the CPU/GPU measurement using gauge happened after the
driver test is done. Now, the measurement happens within the driver
test. So we need to properly increase the delay and duration to get a
comparable reading as the old gauge measurements.

Those 2 tests have been green for the last 10 runs

This reverts commit 5e0aa8b9.

This reverts commit 4fde217d.

They appear to be passing now.

Fix typo.

This reverts commit df833986.

* synthetic packages by default in gen_l10n tool

* Refactor default path for synthetic package

* Remove unused import

* Code cleanup

* Further improvements to help text

* Refactor synthetic package path

* Remove newlines

* Test cleanup

* clean up logic in inputs and outputs list function

* Update l10n.yaml usage

* only add option if value is non-null

* Update stocks app as proof of concept for synthetic package usage

* Address nits

* print pubspec contents

* add print statements

* Do not allow null value for useSyntheticPackage

* +

* +

* +

* +

* Cleanup

* Add test

* Fix text

* Dont parse pubspec directly

* Test using context

* WIP: generate synthetic packages on pub get -- needs tests

* Allow null value

* Update null handling

* Refactor to properly handle null case

* Fix yamlMap condition

* Fix yaml node for real

* WIP: struggling to write tests

* WIP - take absolute path as an option

* Add tests

* Use environment project directory for synthetic package generation pathway

* Fix typo

* Improve help text

* Update defaults

* Remove unauthorized path import

* Fix pathing issues at synthetic package generation

* Fix typo in test

* Use path.join so projectDir matches up based on OS

* Fix Windows pathing in test

* Remove unnecessary replaceApp code for projectDir.path

* Use globals.fs.currentDirectory.path in resident_runner_test.dart

* Fix merge conflict

* Add test to ensure that synthetic package is generated on pub get

* Fix resident_runner_test.dart tests

* Fix tests

* Use package:file instead of dart:io

* WIP - exploration

* Remove synthetic package use from stocks example

* Update integration test to not use synthetic packages

* Remove trailing whitespace

* flutter pub get runs synth package generation

* Remove more print statements

* Add license header

* WIP - minimally working pub.get

* Use own MockBuildSystem

* Modify test and implementation to be a little cleaner

* Fix flutter pub get invocation

* Use synthetic packages in stocks app

* Revert "Use synthetic packages in stocks app"

This reverts commit 45bf24903c3d4a2a5fd5481d7d6bc36c4a348703.

* Add environment and buildSystem params to flutter test

* Address code review feedback

* +

* Isolate codegen into its own API

* Fix imports

* Slight refactor

* Add one more test for no l10n.yaml file

* Remove unneeded mock class and import in pub_get_test.dart

* More code review feedback

* Remove unnecessary imports

* Remove `return await`s that I missed

* use arrow functions instead

This reverts commit 12b7355d.

This reverts commit ce9cde8c.

This reverts commit e8252817.

Because the test bed's CPU is too hot.

Bug: https://github.com/flutter/flutter/issues/64723

* Use Pixel4 for better wait times

According to the firebase team, these have lower wait times for tests.

To allow tests to begin migrating to null safety, sound null safety needs to be disabled. Also removes the experiment flag that is unnecessary since the framework is on the SDK allowlist.

Added instructions on how to regenerate certificate too.