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Add flutter_web samples (#75)
This commit is contained in:
Kevin Moore
committed by
Andrew Brogdon
Andrew Brogdon
parent
42f2dce01b
commit
3fe927cb29
809
web/filipino_cuisine/lib/transformer_page_view.dart
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809
web/filipino_cuisine/lib/transformer_page_view.dart
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// Package transformer_page_view:
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// https://pub.dartlang.org/packages/transformer_page_view
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import 'dart:async';
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import 'package:flutter_web/foundation.dart';
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import 'package:flutter_web/widgets.dart';
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class IndexController extends ChangeNotifier {
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static const int NEXT = 1;
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static const int PREVIOUS = -1;
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static const int MOVE = 0;
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Completer _completer;
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int index;
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bool animation;
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int event;
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Future move(int index, {bool animation: true}) {
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this.animation = animation ?? true;
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this.index = index;
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this.event = MOVE;
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_completer = new Completer();
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notifyListeners();
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return _completer.future;
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}
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Future next({bool animation: true}) {
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this.event = NEXT;
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this.animation = animation ?? true;
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_completer = new Completer();
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notifyListeners();
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return _completer.future;
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}
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Future previous({bool animation: true}) {
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this.event = PREVIOUS;
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this.animation = animation ?? true;
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_completer = new Completer();
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notifyListeners();
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return _completer.future;
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}
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void complete() {
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if (!_completer.isCompleted) {
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_completer.complete();
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}
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}
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}
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typedef void PaintCallback(Canvas canvas, Size siz);
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class ColorPainter extends CustomPainter {
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final Paint _paint;
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final TransformInfo info;
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final List<Color> colors;
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ColorPainter(this._paint, this.info, this.colors);
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@override
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void paint(Canvas canvas, Size size) {
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int index = info.fromIndex;
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_paint.color = colors[index];
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canvas.drawRect(
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new Rect.fromLTWH(0.0, 0.0, size.width, size.height), _paint);
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if (info.done) {
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return;
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}
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int alpha;
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int color;
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double opacity;
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double position = info.position;
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if (info.forward) {
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if (index < colors.length - 1) {
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color = colors[index + 1].value & 0x00ffffff;
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opacity = (position <= 0
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? (-position / info.viewportFraction)
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: 1 - position / info.viewportFraction);
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if (opacity > 1) {
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opacity -= 1.0;
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}
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if (opacity < 0) {
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opacity += 1.0;
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}
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alpha = (0xff * opacity).toInt();
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_paint.color = new Color((alpha << 24) | color);
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canvas.drawRect(
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new Rect.fromLTWH(0.0, 0.0, size.width, size.height), _paint);
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}
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} else {
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if (index > 0) {
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color = colors[index - 1].value & 0x00ffffff;
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opacity = (position > 0
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? position / info.viewportFraction
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: (1 + position / info.viewportFraction));
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if (opacity > 1) {
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opacity -= 1.0;
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}
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if (opacity < 0) {
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opacity += 1.0;
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}
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alpha = (0xff * opacity).toInt();
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_paint.color = new Color((alpha << 24) | color);
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canvas.drawRect(
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new Rect.fromLTWH(0.0, 0.0, size.width, size.height), _paint);
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}
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}
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}
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@override
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bool shouldRepaint(ColorPainter oldDelegate) {
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return oldDelegate.info != info;
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}
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}
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class _ParallaxColorState extends State<ParallaxColor> {
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Paint paint = new Paint();
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@override
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Widget build(BuildContext context) {
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return new CustomPaint(
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painter: new ColorPainter(paint, widget.info, widget.colors),
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child: widget.child,
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);
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}
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}
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class ParallaxColor extends StatefulWidget {
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final Widget child;
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final List<Color> colors;
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final TransformInfo info;
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ParallaxColor({
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@required this.colors,
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@required this.info,
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@required this.child,
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});
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@override
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State<StatefulWidget> createState() {
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return new _ParallaxColorState();
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}
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}
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class ParallaxContainer extends StatelessWidget {
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final Widget child;
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final double position;
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final double translationFactor;
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final double opacityFactor;
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ParallaxContainer(
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{@required this.child,
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@required this.position,
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this.translationFactor: 100.0,
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this.opacityFactor: 1.0})
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: assert(position != null),
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assert(translationFactor != null);
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@override
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Widget build(BuildContext context) {
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return Opacity(
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opacity: (1 - position.abs()).clamp(0.0, 1.0) * opacityFactor,
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child: new Transform.translate(
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offset: new Offset(position * translationFactor, 0.0),
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child: child,
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),
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);
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}
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}
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class ParallaxImage extends StatelessWidget {
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final Image image;
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final double imageFactor;
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ParallaxImage.asset(String name, {double position, this.imageFactor: 0.3})
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: assert(imageFactor != null),
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image = Image.asset(name,
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fit: BoxFit.cover,
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alignment: FractionalOffset(
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0.5 + position * imageFactor,
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0.5,
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));
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@override
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Widget build(BuildContext context) {
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return image;
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}
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}
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///
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/// NOTICE::
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///
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/// In order to make package smaller,currently we're not supporting any build-in page transformers
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/// You can find build in transforms here:
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///
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///
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///
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const int kMaxValue = 2000000000;
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const int kMiddleValue = 1000000000;
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/// Default auto play transition duration (in millisecond)
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const int kDefaultTransactionDuration = 300;
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class TransformInfo {
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/// The `width` of the `TransformerPageView`
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final double width;
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/// The `height` of the `TransformerPageView`
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final double height;
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/// The `position` of the widget pass to [PageTransformer.transform]
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/// A `position` describes how visible the widget is.
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/// The widget in the center of the screen' which is full visible, position is 0.0.
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/// The widge in the left ,may be hidden, of the screen's position is less than 0.0, -1.0 when out of the screen.
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/// The widge in the right ,may be hidden, of the screen's position is greater than 0.0, 1.0 when out of the screen
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///
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///
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final double position;
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/// The `index` of the widget pass to [PageTransformer.transform]
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final int index;
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/// The `activeIndex` of the PageView
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final int activeIndex;
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/// The `activeIndex` of the PageView, from user start to swipe
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/// It will change when user end drag
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final int fromIndex;
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/// Next `index` is greater than this `index`
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final bool forward;
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/// User drag is done.
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final bool done;
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/// Same as [TransformerPageView.viewportFraction]
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final double viewportFraction;
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/// Copy from [TransformerPageView.scrollDirection]
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final Axis scrollDirection;
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TransformInfo(
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{this.index,
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this.position,
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this.width,
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this.height,
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this.activeIndex,
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this.fromIndex,
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this.forward,
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this.done,
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this.viewportFraction,
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this.scrollDirection});
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}
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abstract class PageTransformer {
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///
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final bool reverse;
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PageTransformer({this.reverse: false});
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/// Return a transformed widget, based on child and TransformInfo
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Widget transform(Widget child, TransformInfo info);
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}
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typedef Widget PageTransformerBuilderCallback(Widget child, TransformInfo info);
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class PageTransformerBuilder extends PageTransformer {
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final PageTransformerBuilderCallback builder;
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PageTransformerBuilder({bool reverse: false, @required this.builder})
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: assert(builder != null),
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super(reverse: reverse);
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@override
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Widget transform(Widget child, TransformInfo info) {
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return builder(child, info);
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}
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}
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class TransformerPageController extends PageController {
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final bool loop;
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final int itemCount;
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final bool reverse;
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TransformerPageController({
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int initialPage = 0,
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bool keepPage = true,
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double viewportFraction = 1.0,
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this.loop: false,
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this.itemCount,
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this.reverse: false,
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}) : super(
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initialPage: TransformerPageController._getRealIndexFromRenderIndex(
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initialPage ?? 0, loop, itemCount, reverse),
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keepPage: keepPage,
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viewportFraction: viewportFraction);
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int getRenderIndexFromRealIndex(num index) {
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return _getRenderIndexFromRealIndex(index, loop, itemCount, reverse);
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}
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int getRealItemCount() {
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if (itemCount == 0) return 0;
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return loop ? itemCount + kMaxValue : itemCount;
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}
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static _getRenderIndexFromRealIndex(
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num index, bool loop, int itemCount, bool reverse) {
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if (itemCount == 0) return 0;
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int renderIndex;
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if (loop) {
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renderIndex = index - kMiddleValue;
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renderIndex = renderIndex % itemCount;
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if (renderIndex < 0) {
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renderIndex += itemCount;
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}
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} else {
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renderIndex = index;
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}
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if (reverse) {
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renderIndex = itemCount - renderIndex - 1;
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}
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return renderIndex;
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}
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double get realPage {
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double page;
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if (position.maxScrollExtent == null || position.minScrollExtent == null) {
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page = 0.0;
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} else {
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page = super.page;
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}
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return page;
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}
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static _getRenderPageFromRealPage(
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double page, bool loop, int itemCount, bool reverse) {
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double renderPage;
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if (loop) {
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renderPage = page - kMiddleValue;
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renderPage = renderPage % itemCount;
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if (renderPage < 0) {
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renderPage += itemCount;
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}
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} else {
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renderPage = page;
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}
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if (reverse) {
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renderPage = itemCount - renderPage - 1;
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}
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return renderPage;
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}
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double get page {
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return loop
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? _getRenderPageFromRealPage(realPage, loop, itemCount, reverse)
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: realPage;
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}
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int getRealIndexFromRenderIndex(num index) {
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return _getRealIndexFromRenderIndex(index, loop, itemCount, reverse);
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}
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static int _getRealIndexFromRenderIndex(
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num index, bool loop, int itemCount, bool reverse) {
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int result = reverse ? (itemCount - index - 1) : index;
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if (loop) {
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result += kMiddleValue;
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}
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return result;
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}
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}
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class TransformerPageView extends StatefulWidget {
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/// Create a `transformed` widget base on the widget that has been passed to the [PageTransformer.transform].
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/// See [TransformInfo]
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///
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final PageTransformer transformer;
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/// Same as [PageView.scrollDirection]
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///
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/// Defaults to [Axis.horizontal].
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final Axis scrollDirection;
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/// Same as [PageView.physics]
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final ScrollPhysics physics;
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/// Set to false to disable page snapping, useful for custom scroll behavior.
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/// Same as [PageView.pageSnapping]
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final bool pageSnapping;
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/// Called whenever the page in the center of the viewport changes.
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/// Same as [PageView.onPageChanged]
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final ValueChanged<int> onPageChanged;
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final IndexedWidgetBuilder itemBuilder;
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// See [IndexController.mode],[IndexController.next],[IndexController.previous]
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final IndexController controller;
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/// Animation duration
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final Duration duration;
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/// Animation curve
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final Curve curve;
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final TransformerPageController pageController;
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/// Set true to open infinity loop mode.
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final bool loop;
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/// This value is only valid when `pageController` is not set,
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final int itemCount;
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/// This value is only valid when `pageController` is not set,
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final double viewportFraction;
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/// If not set, it is controlled by this widget.
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final int index;
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/// Creates a scrollable list that works page by page using widgets that are
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/// created on demand.
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///
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/// This constructor is appropriate for page views with a large (or infinite)
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/// number of children because the builder is called only for those children
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/// that are actually visible.
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///
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/// Providing a non-null [itemCount] lets the [PageView] compute the maximum
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/// scroll extent.
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///
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/// [itemBuilder] will be called only with indices greater than or equal to
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/// zero and less than [itemCount].
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TransformerPageView({
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Key key,
|
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this.index,
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Duration duration,
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this.curve: Curves.ease,
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this.viewportFraction: 1.0,
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this.loop: false,
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this.scrollDirection = Axis.horizontal,
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this.physics,
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this.pageSnapping = true,
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this.onPageChanged,
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this.controller,
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this.transformer,
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this.itemBuilder,
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this.pageController,
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@required this.itemCount,
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}) : assert(itemCount != null),
|
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assert(itemCount == 0 || itemBuilder != null || transformer != null),
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this.duration =
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duration ?? new Duration(milliseconds: kDefaultTransactionDuration),
|
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super(key: key);
|
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factory TransformerPageView.children(
|
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{Key key,
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int index,
|
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Duration duration,
|
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Curve curve: Curves.ease,
|
||||
double viewportFraction: 1.0,
|
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bool loop: false,
|
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Axis scrollDirection = Axis.horizontal,
|
||||
ScrollPhysics physics,
|
||||
bool pageSnapping = true,
|
||||
ValueChanged<int> onPageChanged,
|
||||
IndexController controller,
|
||||
PageTransformer transformer,
|
||||
@required List<Widget> children,
|
||||
TransformerPageController pageController}) {
|
||||
assert(children != null);
|
||||
return new TransformerPageView(
|
||||
itemCount: children.length,
|
||||
itemBuilder: (BuildContext context, int index) {
|
||||
return children[index];
|
||||
},
|
||||
pageController: pageController,
|
||||
transformer: transformer,
|
||||
pageSnapping: pageSnapping,
|
||||
key: key,
|
||||
index: index,
|
||||
duration: duration,
|
||||
curve: curve,
|
||||
viewportFraction: viewportFraction,
|
||||
scrollDirection: scrollDirection,
|
||||
physics: physics,
|
||||
onPageChanged: onPageChanged,
|
||||
controller: controller,
|
||||
);
|
||||
}
|
||||
|
||||
@override
|
||||
State<StatefulWidget> createState() {
|
||||
return new _TransformerPageViewState();
|
||||
}
|
||||
|
||||
static int getRealIndexFromRenderIndex(
|
||||
{bool reverse, int index, int itemCount, bool loop}) {
|
||||
int initPage = reverse ? (itemCount - index - 1) : index;
|
||||
if (loop) {
|
||||
initPage += kMiddleValue;
|
||||
}
|
||||
return initPage;
|
||||
}
|
||||
|
||||
static PageController createPageController(
|
||||
{bool reverse,
|
||||
int index,
|
||||
int itemCount,
|
||||
bool loop,
|
||||
double viewportFraction}) {
|
||||
return new PageController(
|
||||
initialPage: getRealIndexFromRenderIndex(
|
||||
reverse: reverse, index: index, itemCount: itemCount, loop: loop),
|
||||
viewportFraction: viewportFraction);
|
||||
}
|
||||
}
|
||||
|
||||
class _TransformerPageViewState extends State<TransformerPageView> {
|
||||
Size _size;
|
||||
int _activeIndex;
|
||||
double _currentPixels;
|
||||
bool _done = false;
|
||||
|
||||
///This value will not change until user end drag.
|
||||
int _fromIndex;
|
||||
|
||||
PageTransformer _transformer;
|
||||
|
||||
TransformerPageController _pageController;
|
||||
|
||||
Widget _buildItemNormal(BuildContext context, int index) {
|
||||
int renderIndex = _pageController.getRenderIndexFromRealIndex(index);
|
||||
Widget child = widget.itemBuilder(context, renderIndex);
|
||||
return child;
|
||||
}
|
||||
|
||||
Widget _buildItem(BuildContext context, int index) {
|
||||
return new AnimatedBuilder(
|
||||
animation: _pageController,
|
||||
builder: (BuildContext c, Widget w) {
|
||||
int renderIndex = _pageController.getRenderIndexFromRealIndex(index);
|
||||
Widget child;
|
||||
if (widget.itemBuilder != null) {
|
||||
child = widget.itemBuilder(context, renderIndex);
|
||||
}
|
||||
if (child == null) {
|
||||
child = new Container();
|
||||
}
|
||||
if (_size == null) {
|
||||
return child ?? new Container();
|
||||
}
|
||||
|
||||
double position;
|
||||
|
||||
double page = _pageController.realPage;
|
||||
|
||||
if (_transformer.reverse) {
|
||||
position = page - index;
|
||||
} else {
|
||||
position = index - page;
|
||||
}
|
||||
position *= widget.viewportFraction;
|
||||
|
||||
TransformInfo info = new TransformInfo(
|
||||
index: renderIndex,
|
||||
width: _size.width,
|
||||
height: _size.height,
|
||||
position: position.clamp(-1.0, 1.0),
|
||||
activeIndex:
|
||||
_pageController.getRenderIndexFromRealIndex(_activeIndex),
|
||||
fromIndex: _fromIndex,
|
||||
forward: _pageController.position.pixels - _currentPixels >= 0,
|
||||
done: _done,
|
||||
scrollDirection: widget.scrollDirection,
|
||||
viewportFraction: widget.viewportFraction);
|
||||
return _transformer.transform(child, info);
|
||||
});
|
||||
}
|
||||
|
||||
double _calcCurrentPixels() {
|
||||
_currentPixels = _pageController.getRenderIndexFromRealIndex(_activeIndex) *
|
||||
_pageController.position.viewportDimension *
|
||||
widget.viewportFraction;
|
||||
|
||||
// print("activeIndex:$_activeIndex , pix:$_currentPixels");
|
||||
|
||||
return _currentPixels;
|
||||
}
|
||||
|
||||
@override
|
||||
Widget build(BuildContext context) {
|
||||
IndexedWidgetBuilder builder =
|
||||
_transformer == null ? _buildItemNormal : _buildItem;
|
||||
Widget child = new PageView.builder(
|
||||
itemBuilder: builder,
|
||||
itemCount: _pageController.getRealItemCount(),
|
||||
onPageChanged: _onIndexChanged,
|
||||
controller: _pageController,
|
||||
scrollDirection: widget.scrollDirection,
|
||||
physics: widget.physics,
|
||||
pageSnapping: widget.pageSnapping,
|
||||
reverse: _pageController.reverse,
|
||||
);
|
||||
if (_transformer == null) {
|
||||
return child;
|
||||
}
|
||||
return new NotificationListener(
|
||||
onNotification: (ScrollNotification notification) {
|
||||
if (notification is ScrollStartNotification) {
|
||||
_calcCurrentPixels();
|
||||
_done = false;
|
||||
_fromIndex = _activeIndex;
|
||||
} else if (notification is ScrollEndNotification) {
|
||||
_calcCurrentPixels();
|
||||
_fromIndex = _activeIndex;
|
||||
_done = true;
|
||||
}
|
||||
|
||||
return false;
|
||||
},
|
||||
child: child);
|
||||
}
|
||||
|
||||
void _onIndexChanged(int index) {
|
||||
_activeIndex = index;
|
||||
if (widget.onPageChanged != null) {
|
||||
widget.onPageChanged(_pageController.getRenderIndexFromRealIndex(index));
|
||||
}
|
||||
}
|
||||
|
||||
void _onGetSize(_) {
|
||||
Size size;
|
||||
if (context == null) {
|
||||
onGetSize(size);
|
||||
return;
|
||||
}
|
||||
RenderObject renderObject = context.findRenderObject();
|
||||
if (renderObject != null) {
|
||||
Rect bounds = renderObject.paintBounds;
|
||||
if (bounds != null) {
|
||||
size = bounds.size;
|
||||
}
|
||||
}
|
||||
_calcCurrentPixels();
|
||||
onGetSize(size);
|
||||
}
|
||||
|
||||
void onGetSize(Size size) {
|
||||
if (mounted) {
|
||||
setState(() {
|
||||
_size = size;
|
||||
});
|
||||
}
|
||||
}
|
||||
|
||||
@override
|
||||
void initState() {
|
||||
_transformer = widget.transformer;
|
||||
// int index = widget.index ?? 0;
|
||||
_pageController = widget.pageController;
|
||||
if (_pageController == null) {
|
||||
_pageController = new TransformerPageController(
|
||||
initialPage: widget.index,
|
||||
itemCount: widget.itemCount,
|
||||
loop: widget.loop,
|
||||
reverse:
|
||||
widget.transformer == null ? false : widget.transformer.reverse);
|
||||
}
|
||||
// int initPage = _getRealIndexFromRenderIndex(index);
|
||||
// _pageController = new PageController(initialPage: initPage,viewportFraction: widget.viewportFraction);
|
||||
_fromIndex = _activeIndex = _pageController.initialPage;
|
||||
|
||||
_controller = getNotifier();
|
||||
if (_controller != null) {
|
||||
_controller.addListener(onChangeNotifier);
|
||||
}
|
||||
super.initState();
|
||||
}
|
||||
|
||||
@override
|
||||
void didUpdateWidget(TransformerPageView oldWidget) {
|
||||
_transformer = widget.transformer;
|
||||
int index = widget.index ?? 0;
|
||||
bool created = false;
|
||||
if (_pageController != widget.pageController) {
|
||||
if (widget.pageController != null) {
|
||||
_pageController = widget.pageController;
|
||||
} else {
|
||||
created = true;
|
||||
_pageController = new TransformerPageController(
|
||||
initialPage: widget.index,
|
||||
itemCount: widget.itemCount,
|
||||
loop: widget.loop,
|
||||
reverse: widget.transformer == null
|
||||
? false
|
||||
: widget.transformer.reverse);
|
||||
}
|
||||
}
|
||||
|
||||
if (_pageController.getRenderIndexFromRealIndex(_activeIndex) != index) {
|
||||
_fromIndex = _activeIndex = _pageController.initialPage;
|
||||
if (!created) {
|
||||
int initPage = _pageController.getRealIndexFromRenderIndex(index);
|
||||
_pageController.animateToPage(initPage,
|
||||
duration: widget.duration, curve: widget.curve);
|
||||
}
|
||||
}
|
||||
if (_transformer != null)
|
||||
WidgetsBinding.instance.addPostFrameCallback(_onGetSize);
|
||||
|
||||
if (_controller != getNotifier()) {
|
||||
if (_controller != null) {
|
||||
_controller.removeListener(onChangeNotifier);
|
||||
}
|
||||
_controller = getNotifier();
|
||||
if (_controller != null) {
|
||||
_controller.addListener(onChangeNotifier);
|
||||
}
|
||||
}
|
||||
super.didUpdateWidget(oldWidget);
|
||||
}
|
||||
|
||||
@override
|
||||
void didChangeDependencies() {
|
||||
if (_transformer != null)
|
||||
WidgetsBinding.instance.addPostFrameCallback(_onGetSize);
|
||||
super.didChangeDependencies();
|
||||
}
|
||||
|
||||
ChangeNotifier getNotifier() {
|
||||
return widget.controller;
|
||||
}
|
||||
|
||||
int _calcNextIndex(bool next) {
|
||||
int currentIndex = _activeIndex;
|
||||
if (_pageController.reverse) {
|
||||
if (next) {
|
||||
currentIndex--;
|
||||
} else {
|
||||
currentIndex++;
|
||||
}
|
||||
} else {
|
||||
if (next) {
|
||||
currentIndex++;
|
||||
} else {
|
||||
currentIndex--;
|
||||
}
|
||||
}
|
||||
|
||||
if (!_pageController.loop) {
|
||||
if (currentIndex >= _pageController.itemCount) {
|
||||
currentIndex = 0;
|
||||
} else if (currentIndex < 0) {
|
||||
currentIndex = _pageController.itemCount - 1;
|
||||
}
|
||||
}
|
||||
|
||||
return currentIndex;
|
||||
}
|
||||
|
||||
void onChangeNotifier() {
|
||||
int event = widget.controller.event;
|
||||
int index;
|
||||
switch (event) {
|
||||
case IndexController.MOVE:
|
||||
{
|
||||
index = _pageController
|
||||
.getRealIndexFromRenderIndex(widget.controller.index);
|
||||
}
|
||||
break;
|
||||
case IndexController.PREVIOUS:
|
||||
case IndexController.NEXT:
|
||||
{
|
||||
index = _calcNextIndex(event == IndexController.NEXT);
|
||||
}
|
||||
break;
|
||||
default:
|
||||
//ignore this event
|
||||
return;
|
||||
}
|
||||
if (widget.controller.animation) {
|
||||
_pageController
|
||||
.animateToPage(index,
|
||||
duration: widget.duration, curve: widget.curve ?? Curves.ease)
|
||||
.whenComplete(widget.controller.complete);
|
||||
} else {
|
||||
_pageController.jumpToPage(index);
|
||||
widget.controller.complete();
|
||||
}
|
||||
}
|
||||
|
||||
ChangeNotifier _controller;
|
||||
|
||||
void dispose() {
|
||||
super.dispose();
|
||||
if (_controller != null) {
|
||||
_controller.removeListener(onChangeNotifier);
|
||||
}
|
||||
}
|
||||
}
|
||||
Reference in New Issue
Block a user