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// Copyright 2014 The Flutter 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:flutter/rendering.dart';
import 'package:flutter/widgets.dart';
import 'package:flutter_test/flutter_test.dart';
void verifyPaintPosition(GlobalKey key, Offset ideal) {
final RenderObject target = key.currentContext!.findRenderObject()!;
expect(target.parent, isA<RenderViewport>());
final SliverPhysicalParentData parentData = target.parentData! as SliverPhysicalParentData;
final Offset actual = parentData.paintOffset;
expect(actual, ideal);
}
void main() {
testWidgets('Sliver protocol', (WidgetTester tester) async {
GlobalKey key1, key2, key3, key4, key5;
await tester.pumpWidget(
Directionality(
textDirection: TextDirection.ltr,
child: CustomScrollView(
slivers: <Widget>[
BigSliver(key: key1 = GlobalKey()),
OverlappingSliver(key: key2 = GlobalKey()),
OverlappingSliver(key: key3 = GlobalKey()),
BigSliver(key: key4 = GlobalKey()),
BigSliver(key: key5 = GlobalKey()),
],
),
),
);
final ScrollPosition position = tester.state<ScrollableState>(find.byType(Scrollable)).position;
const double max = RenderBigSliver.height * 3.0 + (RenderOverlappingSliver.totalHeight) * 2.0 - 600.0; // 600 is the height of the test viewport
assert(max < 10000.0);
expect(max, 1450.0);
expect(position.pixels, 0.0);
expect(position.minScrollExtent, 0.0);
expect(position.maxScrollExtent, max);
position.animateTo(10000.0, curve: Curves.linear, duration: const Duration(minutes: 1));
await tester.pumpAndSettle(const Duration(milliseconds: 10));
expect(position.pixels, max);
expect(position.minScrollExtent, 0.0);
expect(position.maxScrollExtent, max);
verifyPaintPosition(key1, Offset.zero);
verifyPaintPosition(key2, Offset.zero);
verifyPaintPosition(key3, Offset.zero);
verifyPaintPosition(key4, Offset.zero);
verifyPaintPosition(key5, const Offset(0.0, 50.0));
});
}
class RenderBigSliver extends RenderSliver {
static const double height = 550.0;
double get paintExtent => (height - constraints.scrollOffset).clamp(0.0, constraints.remainingPaintExtent);
@override
void performLayout() {
geometry = SliverGeometry(
scrollExtent: height,
paintExtent: paintExtent,
maxPaintExtent: height,
);
}
}
class BigSliver extends LeafRenderObjectWidget {
const BigSliver({ Key? key }) : super(key: key);
@override
RenderBigSliver createRenderObject(BuildContext context) {
return RenderBigSliver();
}
}
class RenderOverlappingSliver extends RenderSliver {
static const double totalHeight = 200.0;
static const double fixedHeight = 100.0;
double get paintExtent {
return math.min(
math.max(
fixedHeight,
totalHeight - constraints.scrollOffset,
),
constraints.remainingPaintExtent,
);
}
double get layoutExtent {
return (totalHeight - constraints.scrollOffset).clamp(0.0, constraints.remainingPaintExtent);
}
@override
void performLayout() {
geometry = SliverGeometry(
scrollExtent: totalHeight,
paintExtent: paintExtent,
layoutExtent: layoutExtent,
maxPaintExtent: totalHeight,
);
}
}
class OverlappingSliver extends LeafRenderObjectWidget {
const OverlappingSliver({ Key? key }) : super(key: key);
@override
RenderOverlappingSliver createRenderObject(BuildContext context) {
return RenderOverlappingSliver();
}
}