packages/flutter/test/cupertino/scrollbar_test.dart

// 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 'package:flutter/cupertino.dart';
import 'package:flutter/services.dart';
import 'package:flutter_test/flutter_test.dart';

import '../rendering/mock_canvas.dart';

const CupertinoDynamicColor _kScrollbarColor = CupertinoDynamicColor.withBrightness(
  color: Color(0x59000000),
  darkColor: Color(0x80FFFFFF),
);

void main() {
  const Duration _kScrollbarTimeToFade = Duration(milliseconds: 1200);
  const Duration _kScrollbarFadeDuration = Duration(milliseconds: 250);
  const Duration _kScrollbarResizeDuration = Duration(milliseconds: 100);

  testWidgets('Scrollbar never goes away until finger lift', (WidgetTester tester) async {
    await tester.pumpWidget(
      const Directionality(
        textDirection: TextDirection.ltr,
        child: MediaQuery(
          data: MediaQueryData(),
          child: CupertinoScrollbar(
            child: SingleChildScrollView(child: SizedBox(width: 4000.0, height: 4000.0)),
          ),
        ),
      ),
    );
    final TestGesture gesture = await tester.startGesture(tester.getCenter(find.byType(SingleChildScrollView)));
    await gesture.moveBy(const Offset(0.0, -10.0));
    await tester.pump();
    // Scrollbar fully showing
    await tester.pump(const Duration(milliseconds: 500));
    expect(find.byType(CupertinoScrollbar), paints..rrect(
      color: _kScrollbarColor.color,
    ));

    await tester.pump(const Duration(seconds: 3));
    await tester.pump(const Duration(seconds: 3));
    // Still there.
    expect(find.byType(CupertinoScrollbar), paints..rrect(
      color: _kScrollbarColor.color,
    ));

    await gesture.up();
    await tester.pump(_kScrollbarTimeToFade);
    await tester.pump(_kScrollbarFadeDuration * 0.5);

    // Opacity going down now.
    expect(find.byType(CupertinoScrollbar), paints..rrect(
      color: _kScrollbarColor.color.withAlpha(69),
    ));
  });

  testWidgets('Scrollbar dark mode', (WidgetTester tester) async {
    Brightness brightness = Brightness.light;
    StateSetter setState;
    await tester.pumpWidget(
      Directionality(
        textDirection: TextDirection.ltr,
        child: StatefulBuilder(
          builder: (BuildContext context, StateSetter setter) {
            setState = setter;
            return MediaQuery(
              data: MediaQueryData(platformBrightness: brightness),
              child: const CupertinoScrollbar(
                child: SingleChildScrollView(child: SizedBox(width: 4000.0, height: 4000.0)),
              ),
            );
          },
        ),
      ),
    );

    final TestGesture gesture = await tester.startGesture(tester.getCenter(find.byType(SingleChildScrollView)));
    await gesture.moveBy(const Offset(0.0, 10.0));
    await tester.pump();
    // Scrollbar fully showing
    await tester.pumpAndSettle();
    expect(find.byType(CupertinoScrollbar), paints..rrect(
      color: _kScrollbarColor.color,
    ));

    setState(() { brightness = Brightness.dark; });
    await tester.pump();

    expect(find.byType(CupertinoScrollbar), paints..rrect(
      color: _kScrollbarColor.darkColor,
    ));
  });

  testWidgets('Scrollbar thumb can be dragged with long press', (WidgetTester tester) async {
    final ScrollController scrollController = ScrollController();
    await tester.pumpWidget(
      Directionality(
        textDirection: TextDirection.ltr,
        child: MediaQuery(
          data: const MediaQueryData(),
          child: PrimaryScrollController(
            controller: scrollController,
            child: const CupertinoScrollbar(
              child: SingleChildScrollView(child: SizedBox(width: 4000.0, height: 4000.0)),
            ),
          ),
        ),
      ),
    );

    expect(scrollController.offset, 0.0);

    // Scroll a bit.
    const double scrollAmount = 10.0;
    final TestGesture scrollGesture = await tester.startGesture(tester.getCenter(find.byType(SingleChildScrollView)));
    // Scroll down by swiping up.
    await scrollGesture.moveBy(const Offset(0.0, -scrollAmount));
    await tester.pump();
    await tester.pump(const Duration(milliseconds: 500));
    // Scrollbar thumb is fully showing and scroll offset has moved by
    // scrollAmount.
    expect(find.byType(CupertinoScrollbar), paints..rrect(
      color: _kScrollbarColor.color,
    ));
    expect(scrollController.offset, scrollAmount);
    await scrollGesture.up();
    await tester.pump();

    int hapticFeedbackCalls = 0;
    SystemChannels.platform.setMockMethodCallHandler((MethodCall methodCall) async {
      if (methodCall.method == 'HapticFeedback.vibrate') {
        hapticFeedbackCalls++;
      }
    });

    // Longpress on the scrollbar thumb and expect a vibration after it resizes.
    expect(hapticFeedbackCalls, 0);
    final TestGesture dragScrollbarGesture = await tester.startGesture(const Offset(796.0, 50.0));
    await tester.pump(const Duration(milliseconds: 100));
    expect(hapticFeedbackCalls, 0);
    await tester.pump(_kScrollbarResizeDuration);
    // Allow the haptic feedback some slack.
    await tester.pump(const Duration(milliseconds: 1));
    expect(hapticFeedbackCalls, 1);

    // Drag the thumb down to scroll down.
    await dragScrollbarGesture.moveBy(const Offset(0.0, scrollAmount));
    await tester.pump(const Duration(milliseconds: 100));
    await dragScrollbarGesture.up();
    await tester.pumpAndSettle();

    // The view has scrolled more than it would have by a swipe gesture of the
    // same distance.
    expect(scrollController.offset, greaterThan(scrollAmount * 2));
    // The scrollbar thumb is still fully visible.
    expect(find.byType(CupertinoScrollbar), paints..rrect(
      color: _kScrollbarColor.color,
    ));

    // Let the thumb fade out so all timers have resolved.
    await tester.pump(_kScrollbarTimeToFade);
    await tester.pump(_kScrollbarFadeDuration);
  });
}