// Copyright 2015 The Chromium Authors. All rights reserved. // Use of this source code is governed by a BSD-style license that can be // found in the LICENSE file. import 'dart:math' as math; import 'package:vector_math/vector_math_64.dart' show Matrix4; import 'basic.dart'; import 'framework.dart'; export 'package:flutter/animation.dart' show AnimationDirection; export 'package:flutter/rendering.dart' show RelativeRect; /// A component that rebuilds when the given animation changes value. /// /// AnimatedComponent is most useful for stateless animated widgets. To use /// AnimatedComponent, simply subclass it and implement the build function. /// /// For more complex case involving additional state, consider using /// [AnimatedBuilder]. abstract class AnimatedComponent extends StatefulComponent { AnimatedComponent({ Key key, this.animation }) : super(key: key) { assert(animation != null); } /// The animation to which this component is listening. final Animation<Object> animation; /// Override this function to build widgets that depend on the current value /// of the animation. Widget build(BuildContext context); /// Subclasses typically do not override this method. _AnimatedComponentState createState() => new _AnimatedComponentState(); void debugFillDescription(List<String> description) { super.debugFillDescription(description); description.add('animation: $animation'); } } class _AnimatedComponentState extends State<AnimatedComponent> { void initState() { super.initState(); config.animation.addListener(_handleTick); } void didUpdateConfig(AnimatedComponent oldConfig) { if (config.animation != oldConfig.animation) { oldConfig.animation.removeListener(_handleTick); config.animation.addListener(_handleTick); } } void dispose() { config.animation.removeListener(_handleTick); super.dispose(); } void _handleTick() { setState(() { // The animation's state is our build state, and it changed already. }); } Widget build(BuildContext context) { return config.build(context); } } /// Animates the position of a widget relative to its normal position. class SlideTransition extends AnimatedComponent { SlideTransition({ Key key, Animation<FractionalOffset> position, this.transformHitTests: true, this.child }) : position = position, super(key: key, animation: position) { assert(position != null); } /// The animation that controls the position of the child. /// /// If the current value of the position animation is (dx, dy), the child will /// be translated horizontally by width * dx and vertically by height * dy. final Animation<FractionalOffset> position; /// Whether hit testing should be affected by the slide animation. /// /// If false, hit testing will proceed as if the child was not translated at /// all. Setting this value to false is useful for fast animations where you /// expect the user to commonly interact with the child widget in its final /// location and you want the user to benefit from "muscle memory". final bool transformHitTests; final Widget child; Widget build(BuildContext context) { return new FractionalTranslation( translation: position.value, transformHitTests: transformHitTests, child: child ); } } /// Animates the size of a widget. class ScaleTransition extends AnimatedComponent { ScaleTransition({ Key key, Animation<double> scale, this.alignment: const FractionalOffset(0.5, 0.5), this.child }) : scale = scale, super(key: key, animation: scale); /// The animation that controls the scale of the child. /// /// If the current value of the scale animation is v, the child will be /// painted v times its normal size. final Animation<double> scale; /// The alignment of the origin of the coordainte system in which the scale /// takes place, relative to the size of the box. /// /// For example, to set the origin of the scale to bottom middle, you can use /// an alignment of (0.5, 1.0). final FractionalOffset alignment; final Widget child; Widget build(BuildContext context) { double scaleValue = scale.value; Matrix4 transform = new Matrix4.identity() ..scale(scaleValue, scaleValue); return new Transform( transform: transform, alignment: alignment, child: child ); } } /// Animates the rotation of a widget. class RotationTransition extends AnimatedComponent { RotationTransition({ Key key, Animation<double> turns, this.child }) : turns = turns, super(key: key, animation: turns); /// The animation that controls the rotation of the child. /// /// If the current value of the turns animation is v, the child will be /// rotated v * 2 * pi radians before being painted. final Animation<double> turns; final Widget child; Widget build(BuildContext context) { double turnsValue = turns.value; Matrix4 transform = new Matrix4.rotationZ(turnsValue * math.PI * 2.0); return new Transform( transform: transform, alignment: const FractionalOffset(0.5, 0.5), child: child ); } } /// Animates the opacity of a widget. class FadeTransition extends AnimatedComponent { FadeTransition({ Key key, Animation<double> opacity, this.child }) : opacity = opacity, super(key: key, animation: opacity); /// The animation that controls the opacity of the child. /// /// If the current value of the opacity animation is v, the child will be /// painted with an opacity of v. For example, if v is 0.5, the child will be /// blended 50% with its background. Similarly, if v is 0.0, the child will be /// completely transparent. final Animation<double> opacity; final Widget child; Widget build(BuildContext context) { return new Opacity(opacity: opacity.value, child: child); } } /// An interpolation between two relative rects. /// /// This class specializes the interpolation of Tween<RelativeRect> to be /// appropriate for rectangles that are described in terms of offsets from /// other rectangles. class RelativeRectTween extends Tween<RelativeRect> { RelativeRectTween({ RelativeRect begin, RelativeRect end }) : super(begin: begin, end: end); RelativeRect lerp(double t) => RelativeRect.lerp(begin, end, t); } /// Animated version of [Positioned] which takes a specific /// [Animation<RelativeRect>] to transition the child's position from a start /// position to and end position over the lifetime of the animation. /// /// Only works if it's the child of a [Stack]. class PositionedTransition extends AnimatedComponent { PositionedTransition({ Key key, Animation<RelativeRect> rect, this.child }) : rect = rect, super(key: key, animation: rect) { assert(rect != null); } /// The animation that controls the child's size and position. final Animation<RelativeRect> rect; final Widget child; Widget build(BuildContext context) { return new Positioned( top: rect.value.top, right: rect.value.right, bottom: rect.value.bottom, left: rect.value.left, child: child ); } } /// A builder that builds a widget given a child. typedef Widget TransitionBuilder(BuildContext context, Widget child); /// A general-purpose widget for building animations. /// /// AnimatedBuilder is useful for more complex components that wish to include /// an animation as part of a larger build function. To use AnimatedBuilder, /// simply construct the widget and pass it a builder function. /// /// If your [builder] function contains a subtree that does not depend on the /// animation, it's more efficient to build that subtree once instead of /// rebuilding it on every animation tick. /// /// If you pass the pre-built subtree as the [child] parameter, the /// AnimatedBuilder will pass it back to your builder function so that you /// can incorporate it into your build. /// /// Using this pre-built child is entirely optional, but can improve /// performance significantly in some cases and is therefore a good practice. /// /// For simple cases without additional state, consider using /// [AnimatedComponent]. class AnimatedBuilder extends AnimatedComponent { AnimatedBuilder({ Key key, Animation<Object> animation, this.builder, this.child }) : super(key: key, animation: animation); /// Called every time the animation changes value. final TransitionBuilder builder; /// If your builder function contains a subtree that does not depend on the /// animation, it's more efficient to build that subtree once instead of /// rebuilding it on every animation tick. /// /// If you pass the pre-built subtree as the [child] parameter, the /// AnimatedBuilder will pass it back to your builder function so that you /// can incorporate it into your build. /// /// Using this pre-built child is entirely optional, but can improve /// performance significantly in some cases and is therefore a good practice. final Widget child; Widget build(BuildContext context) { return builder(context, child); } }