a0227cab15
Other changes in this patch:
- Make the 'flutter' tool say "Updating flutter tool..." when it calls
pub get, to avoid confusion about what the pub get output is about.
- Make the bash flutter tool call pub get when the revision has
changed. (This was already happening on Windows.)
- Fix a raft of bugs found by the analyzer.
- Fix some style nits in various bits of code that happened to be near
things the analyzer noticed.
- Remove the logic in "flutter test" that would run "pub get", since
upon further reflexion it was determined it didn't work anyway.
We'll probably have to add better diagnostics here and say to run the
updater script.
- Remove the native velocity tracker script, since it was testing code
that has since been removed.
Notes on ignored warnings:
- We ignore warnings in any packages that are not in the Flutter repo or
in the author's current directory.
- We ignore various irrelevant Strong Mode warnings. We still enable
strong mode because even though it's not really relevant to our needs,
it does (more or less accidentally) catch a few things that are
helpful to us.
- We allow CONSTANTS_LIKE_THIS, since we get some of those from other
platforms that we are copying for sanity and consistency.
- We allow one-member abstract classes since we have a number of them
where it's perfectly reasonable.
- We unfortunately still ignore warnings in mojom.dart autogenerated
files. We should really fix those but that's a separate patch.
- We verify the actual source file when we see the 'Name non-constant
identifiers using lowerCamelCase.' lint, to allow one-letter variables
that use capital letters (e.g. for physics expressions) and to allow
multiple-underscore variable names.
- We ignore all errors on lines that contain the following magic
incantation and a "#" character:
// analyzer doesn't like constructor tear-offs
- For all remaining errors, if the line contains a comment of the form
// analyzer says "..."
...then we ignore any errors that have that "..." string in them.
85 lines
2.8 KiB
Dart
85 lines
2.8 KiB
Dart
// Copyright (c) 2015 The Chromium Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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part of newton;
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class SpringDescription {
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/// The mass of the spring (m)
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final double mass;
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/// The spring constant (k)
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final double springConstant;
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/// The damping coefficient.
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/// Note: Not to be confused with the damping ratio. Use the separate
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/// constructor provided for this purpose
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final double damping;
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SpringDescription(
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{ this.mass, this.springConstant, this.damping }
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) {
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assert(mass != null);
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assert(springConstant != null);
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assert(damping != null);
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}
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/// Create a spring given the mass, spring constant and the damping ratio. The
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/// damping ratio is especially useful trying to determing the type of spring
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/// to create. A ratio of 1.0 creates a critically damped spring, > 1.0
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/// creates an overdamped spring and < 1.0 an underdamped one.
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SpringDescription.withDampingRatio(
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{double mass, double springConstant, double ratio: 1.0})
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: mass = mass,
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springConstant = springConstant,
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damping = ratio * 2.0 * math.sqrt(mass * springConstant);
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}
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enum SpringType { unknown, criticallyDamped, underDamped, overDamped, }
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/// Creates a spring simulation. Depending on the spring description, a
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/// critically, under or overdamped spring will be created.
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class SpringSimulation extends Simulation {
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final double _endPosition;
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final _SpringSolution _solution;
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/// A spring description with the provided spring description, start distance,
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/// end distance and velocity.
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SpringSimulation(
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SpringDescription desc, double start, double end, double velocity)
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: this._endPosition = end,
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_solution = new _SpringSolution(desc, start - end, velocity);
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SpringType get type => _solution.type;
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double x(double time) => _endPosition + _solution.x(time);
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double dx(double time) => _solution.dx(time);
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@override
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bool isDone(double time) =>
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_nearEqual(x(time), _endPosition, this.tolerance.distance) &&
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_nearZero(dx(time), this.tolerance.velocity);
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}
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/// A SpringSimulation where the value of x() is guaranteed to have exactly the
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/// end value when the simulation isDone().
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class ScrollSpringSimulation extends SpringSimulation {
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ScrollSpringSimulation(SpringDescription desc, double start, double end, double velocity)
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: super(desc, start, end, velocity);
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bool _isDone(double position, double velocity) {
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return _nearEqual(position, _endPosition, tolerance.distance) && _nearZero(velocity, tolerance.velocity);
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}
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@override
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double x(double time) {
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double xAtTime = super.x(time);
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return _isDone(xAtTime, dx(time)) ? _endPosition : xAtTime;
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}
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@override
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bool isDone(double time) => _isDone(x(time), dx(time));
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}
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