948ae15ca5
Our examples have been growing organically over time. This patch cleans them up to illustrate specific aspects of Flutter.
45 lines
1.5 KiB
Dart
45 lines
1.5 KiB
Dart
// Copyright 2016 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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import 'dart:math' as math;
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import 'package:flutter/animation.dart';
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import 'package:flutter/rendering.dart';
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void main() {
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// A green box...
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RenderBox green = new RenderDecoratedBox(
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decoration: const BoxDecoration(backgroundColor: const Color(0xFF00FF00))
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);
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// of a certain size...
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RenderBox square = new RenderConstrainedBox(
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additionalConstraints: const BoxConstraints.tightFor(width: 200.0, height: 200.0),
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child: green
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);
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// With a given rotation (starts off as the identity transform)...
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RenderTransform spin = new RenderTransform(
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transform: new Matrix4.identity(),
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alignment: const FractionalOffset(0.5, 0.5),
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child: square
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);
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// centered...
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RenderBox root = new RenderPositionedBox(
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alignment: const FractionalOffset(0.5, 0.5),
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child: spin
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);
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// on the screen.
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new RenderingFlutterBinding(root: root);
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// A repeating animation every 1800 milliseconds...
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AnimationController animation = new AnimationController(
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duration: const Duration(milliseconds: 1800)
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)..repeat();
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// From 0.0 to math.PI.
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Tween<double> tween = new Tween<double>(begin: 0.0, end: math.PI);
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animation.addListener(() {
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// Each frame of the animation, set the rotation of the square.
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spin.transform = new Matrix4.rotationZ(tween.evaluate(animation));
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});
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}
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