packages/flutter/test/widgets/gesture_detector_test.dart

// 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 'package:flutter_test/flutter_test.dart';
import 'package:flutter/widgets.dart';
import 'package:flutter/rendering.dart';
import 'package:flutter/gestures.dart';

void main() {
  testWidgets('Uncontested scrolls start immediately', (WidgetTester tester) async {
    bool didStartDrag = false;
    double updatedDragDelta;
    bool didEndDrag = false;

    final Widget widget = GestureDetector(
      onVerticalDragStart: (DragStartDetails details) {
        didStartDrag = true;
      },
      onVerticalDragUpdate: (DragUpdateDetails details) {
        updatedDragDelta = details.primaryDelta;
      },
      onVerticalDragEnd: (DragEndDetails details) {
        didEndDrag = true;
      },
      child: Container(
        color: const Color(0xFF00FF00),
      ),
    );

    await tester.pumpWidget(widget);
    expect(didStartDrag, isFalse);
    expect(updatedDragDelta, isNull);
    expect(didEndDrag, isFalse);

    const Offset firstLocation = Offset(10.0, 10.0);
    final TestGesture gesture = await tester.startGesture(firstLocation, pointer: 7);
    expect(didStartDrag, isTrue);
    didStartDrag = false;
    expect(updatedDragDelta, isNull);
    expect(didEndDrag, isFalse);

    const Offset secondLocation = Offset(10.0, 9.0);
    await gesture.moveTo(secondLocation);
    expect(didStartDrag, isFalse);
    expect(updatedDragDelta, -1.0);
    updatedDragDelta = null;
    expect(didEndDrag, isFalse);

    await gesture.up();
    expect(didStartDrag, isFalse);
    expect(updatedDragDelta, isNull);
    expect(didEndDrag, isTrue);
    didEndDrag = false;

    await tester.pumpWidget(Container());
  });

  testWidgets('Match two scroll gestures in succession', (WidgetTester tester) async {
    int gestureCount = 0;
    double dragDistance = 0.0;

    const Offset downLocation = Offset(10.0, 10.0);
    const Offset upLocation = Offset(10.0, 50.0); // must be far enough to be more than kTouchSlop

    final Widget widget = GestureDetector(
      onVerticalDragUpdate: (DragUpdateDetails details) { dragDistance += details.primaryDelta; },
      onVerticalDragEnd: (DragEndDetails details) { gestureCount += 1; },
      onHorizontalDragUpdate: (DragUpdateDetails details) { fail('gesture should not match'); },
      onHorizontalDragEnd: (DragEndDetails details) { fail('gesture should not match'); },
      child: Container(
        color: const Color(0xFF00FF00),
      ),
    );
    await tester.pumpWidget(widget);

    TestGesture gesture = await tester.startGesture(downLocation, pointer: 7);
    await gesture.moveTo(upLocation);
    await gesture.up();

    gesture = await tester.startGesture(downLocation, pointer: 7);
    await gesture.moveTo(upLocation);
    await gesture.up();

    expect(gestureCount, 2);
    expect(dragDistance, 40.0 * 2.0); // delta between down and up, twice

    await tester.pumpWidget(Container());
  });

  testWidgets('Pan doesn\'t crash', (WidgetTester tester) async {
    bool didStartPan = false;
    Offset panDelta;
    bool didEndPan = false;

    await tester.pumpWidget(
      GestureDetector(
        onPanStart: (DragStartDetails details) {
          didStartPan = true;
        },
        onPanUpdate: (DragUpdateDetails details) {
          panDelta = details.delta;
        },
        onPanEnd: (DragEndDetails details) {
          didEndPan = true;
        },
        child: Container(
          color: const Color(0xFF00FF00),
        ),
      ),
    );

    expect(didStartPan, isFalse);
    expect(panDelta, isNull);
    expect(didEndPan, isFalse);

    await tester.dragFrom(const Offset(10.0, 10.0), const Offset(20.0, 30.0));

    expect(didStartPan, isTrue);
    expect(panDelta.dx, 20.0);
    expect(panDelta.dy, 30.0);
    expect(didEndPan, isTrue);
  });

  testWidgets('Translucent', (WidgetTester tester) async {
    bool didReceivePointerDown;
    bool didTap;

    Future<Null> pumpWidgetTree(HitTestBehavior behavior) {
      return tester.pumpWidget(
        Directionality(
          textDirection: TextDirection.ltr,
          child: Stack(
            children: <Widget>[
              Listener(
                onPointerDown: (_) {
                  didReceivePointerDown = true;
                },
                child: Container(
                  width: 100.0,
                  height: 100.0,
                  color: const Color(0xFF00FF00),
                ),
              ),
              Container(
                width: 100.0,
                height: 100.0,
                child: GestureDetector(
                  onTap: () {
                    didTap = true;
                  },
                  behavior: behavior,
                ),
              ),
            ],
          ),
        ),
      );
    }

    didReceivePointerDown = false;
    didTap = false;
    await pumpWidgetTree(null);
    await tester.tapAt(const Offset(10.0, 10.0));
    expect(didReceivePointerDown, isTrue);
    expect(didTap, isTrue);

    didReceivePointerDown = false;
    didTap = false;
    await pumpWidgetTree(HitTestBehavior.deferToChild);
    await tester.tapAt(const Offset(10.0, 10.0));
    expect(didReceivePointerDown, isTrue);
    expect(didTap, isFalse);

    didReceivePointerDown = false;
    didTap = false;
    await pumpWidgetTree(HitTestBehavior.opaque);
    await tester.tapAt(const Offset(10.0, 10.0));
    expect(didReceivePointerDown, isFalse);
    expect(didTap, isTrue);

    didReceivePointerDown = false;
    didTap = false;
    await pumpWidgetTree(HitTestBehavior.translucent);
    await tester.tapAt(const Offset(10.0, 10.0));
    expect(didReceivePointerDown, isTrue);
    expect(didTap, isTrue);

  });

  testWidgets('Empty', (WidgetTester tester) async {
    bool didTap = false;
    await tester.pumpWidget(
      Center(
        child: GestureDetector(
          onTap: () {
            didTap = true;
          },
        ),
      ),
    );
    expect(didTap, isFalse);
    await tester.tapAt(const Offset(10.0, 10.0));
    expect(didTap, isTrue);
  });

  testWidgets('Only container', (WidgetTester tester) async {
    bool didTap = false;
    await tester.pumpWidget(
      Center(
        child: GestureDetector(
          onTap: () {
            didTap = true;
          },
          child: Container(),
        ),
      ),
    );
    expect(didTap, isFalse);
    await tester.tapAt(const Offset(10.0, 10.0));
    expect(didTap, isFalse);
  });

  testWidgets('cache unchanged callbacks', (WidgetTester tester) async {
    final GestureTapCallback inputCallback = () {};

    await tester.pumpWidget(
      Center(
        child: GestureDetector(
          onTap: inputCallback,
          child: Container(),
        ),
      ),
    );

    final RenderSemanticsGestureHandler renderObj1 = tester.renderObject(find.byType(GestureDetector));
    final GestureTapCallback actualCallback1 = renderObj1.onTap;

    await tester.pumpWidget(
      Center(
        child: GestureDetector(
          onTap: inputCallback,
          child: Container(),
        ),
      ),
    );

    final RenderSemanticsGestureHandler renderObj2 = tester.renderObject(find.byType(GestureDetector));
    final GestureTapCallback actualCallback2 = renderObj2.onTap;

    expect(renderObj1, same(renderObj2));
    expect(actualCallback1, same(actualCallback2)); // Should be cached.
  });

  testWidgets('Tap down occurs after kPressTimeout', (WidgetTester tester) async {
    int tapDown = 0;
    int tap = 0;
    int tapCancel = 0;
    int longPress = 0;

    await tester.pumpWidget(
      Container(
        alignment: Alignment.topLeft,
        child: Container(
          alignment: Alignment.center,
          height: 100.0,
          color: const Color(0xFF00FF00),
          child: GestureDetector(
            onTapDown: (TapDownDetails details) {
              tapDown += 1;
            },
            onTap: () {
              tap += 1;
            },
            onTapCancel: () {
              tapCancel += 1;
            },
            onLongPress: () {
              longPress += 1;
            },
          ),
        ),
      ),
    );

    // Pointer is dragged from the center of the 800x100 gesture detector
    // to a point (400,300) below it. This always causes onTapCancel to be
    // called; onTap should never be called.
    Future<Null> dragOut(Duration timeout) async {
      final TestGesture gesture = await tester.startGesture(const Offset(400.0, 50.0));
      // If the timeout is less than kPressTimeout the recognizer will just trigger
      // the onTapCancel callback. If the timeout is greater than kLongPressTimeout
      // then onTapDown, onLongPress, and onCancel will be called.
      await tester.pump(timeout);
      await gesture.moveTo(const Offset(400.0, 300.0));
      await gesture.up();
    }

    await dragOut(kPressTimeout * 0.5); // generates tapCancel
    expect(tapDown, 0);
    expect(tapCancel, 1);
    expect(tap, 0);
    expect(longPress, 0);

    await dragOut(kPressTimeout); // generates tapDown, tapCancel
    expect(tapDown, 1);
    expect(tapCancel, 2);
    expect(tap, 0);
    expect(longPress, 0);

    await dragOut(kLongPressTimeout); // generates tapDown, longPress, tapCancel
    expect(tapDown, 2);
    expect(tapCancel, 3);
    expect(tap, 0);
    expect(longPress, 1);
  });
}