This change reverts https://github.com/flutter/engine/pull/15900. The
design of the expected consumer of the original PR changed, and the
feature ended up going unused. Since the unexpected difference in trace
event routing behavior has mostly ended up as a source of confusion,
change things back to route trace events to Fuchsia system tracing on
all configurations.
* `Image.toByteData()` was not implemented in either DomCanvas or CanvasKit. This PR covers **both.**
* `Picture.toImage()` was not implemented in either DomCanvas or CanvasKit. This PR covers **CanvasKit**
## Description
As the related issue refer, the application may be doing too much work on its main thread even in a simple hello_world demo.
That is because the creation of `Engine` on the ui thread takes a noticeable time, and it is blocking the platform thread in order to run `Shell::Setup` synchronously.
The cost of `Engine`'s constructor is mainly about the creating of root isolate. Actually, there used to be another time-consuming process, the default font manager setup, which was resolved by https://github.com/flutter/engine/pull/18225.
Similar to https://github.com/flutter/engine/pull/18225, this pr move the creation of root isolate out from creating `Engine`. After this action, the main thread blocking is quite an acceptable slice.
## Related Issues
https://github.com/flutter/flutter/issues/40563 could be resolved by this pr.
The C++ wrapper makes heavy use of templates to support arbitrary types
in the platform channel classes, but in practice EncodableValue is what
essentially all code will use. This defaults those template types to
reduce boilerplate in plugin code (e.g., allowing the use of
MethodChannel<> instead of MethodChannel<EncodableValue>).
If the InputConnectionAdaptor receives a key event that does not move
the caret or produce a text character (such as the back button), then
the event should be given to the EventResponder which will forward it
to the view.
Fixes https://github.com/flutter/flutter/issues/64864
Reduces errors caused by the loss of floating point precision when the
two extrema of the lerp differ significantly in magnitude. Previously,
we used the calculation:
a + (b - a) * t
When the difference in magnitude between `a` and `b` exceeds the
precision representable by double-precision floating point math, `b - a`
results in the larger-magnitude value of `a` or `b`. The error between
the value produced and the correct value is then scaled by t.
A simple example of the impact can be seen when `a` is significantly
larger in magnitude than `b`. In that case, `b - a` results in `a` and
when `t` is 1.0, the resulting value is `a - (a) * 1.0 == 0`.
The patch transforms the computation to the mathematically-equivalent
expression:
a * (1.0 - t) + b * t
By scaling each value independently, the behaviour is more accurate.
From the point of view of performance, this adds an extra
multiplication, but multiplication is relatively cheap and the behaviour
is significantly better.
This patch also adds a `precisionErrorTolerance` constant to
test_utils.dart and migrates existing tests to use `closeTo()` for
testing.
The tests themselves *do* currently use values that have an exact
floating-point representation, but we should allow for flexibility in
future implementation changes.
Previously, the behaviour of lerpDouble with respect to NaN and infinity
was relatively complex and difficult to reason about. This patch
simplifies the behaviour with respect to those conditions and adds
documentation and tests.
In general, if `a == b` or both values are null, infinite, or NaN, `a`
is returned. Otherwise we require `a` and `b` and `t` to be finite or
null and the result of the linear interpolation is returned.
This extracts a Dart test utilities library, containing
`expectAssertion` and `expectArgumentError` functions that simplify
running tests that test assertions across debug, profile, and release
configurations.
This change also restricts Dart unit tests to testing files whose
filename matches `*_test.dart` under `flutter/testing/dart`; previously
any file in that directory was run, but all files matched the above
pattern.
