packages/flutter/test/gestures/transformed_double_tap_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/gestures.dart';
import 'package:flutter/material.dart';
import 'package:flutter_test/flutter_test.dart';

void main() {
  testWidgets('kTouchSlop is evaluated in the global coordinate space when scaled up', (WidgetTester tester) async {
    int doubleTapCount = 0;

    final Key redContainer = UniqueKey();
    await tester.pumpWidget(
        Center(
          child: Transform.scale(
            scale: 2.0,
            child: GestureDetector(
                onDoubleTap: () {
                  doubleTapCount++;
                },
                child: Container(
                  key: redContainer,
                  width: 100,
                  height: 150,
                  color: Colors.red,
                ),
            ),
          ),
        ),
    );

    // Move just below kTouchSlop should recognize tap.
    final Offset center = tester.getCenter(find.byKey(redContainer));
    TestGesture gesture = await tester.startGesture(center);
    await gesture.up();
    await tester.pump(kDoubleTapMinTime);
    gesture = await tester.startGesture(center + const Offset(kDoubleTapSlop - 1, 0));
    await gesture.up();

    expect(doubleTapCount, 1);

    doubleTapCount = 0;

    gesture = await tester.startGesture(center);
    await gesture.up();
    await tester.pump(kDoubleTapMinTime);
    gesture = await tester.startGesture(center + const Offset(kDoubleTapSlop + 1, 0));
    await gesture.up();

    expect(doubleTapCount, 0);
  });

  testWidgets('kTouchSlop is evaluated in the global coordinate space when scaled down', (WidgetTester tester) async {
    int doubleTapCount = 0;

    final Key redContainer = UniqueKey();
    await tester.pumpWidget(
        Center(
          child: Transform.scale(
            scale: 0.5,
            child: GestureDetector(
                onDoubleTap: () {
                  doubleTapCount++;
                },
                child: Container(
                  key: redContainer,
                  width: 500,
                  height: 500,
                  color: Colors.red,
                ),
            ),
          ),
        ),
    );

    // Move just below kTouchSlop should recognize tap.
    final Offset center = tester.getCenter(find.byKey(redContainer));
    TestGesture gesture = await tester.startGesture(center);
    await gesture.up();
    await tester.pump(kDoubleTapMinTime);
    gesture = await tester.startGesture(center + const Offset(kDoubleTapSlop - 1, 0));
    await gesture.up();

    expect(doubleTapCount, 1);

    doubleTapCount = 0;

    gesture = await tester.startGesture(center);
    await gesture.up();
    await tester.pump(kDoubleTapMinTime);
    gesture = await tester.startGesture(center + const Offset(kDoubleTapSlop + 1, 0));
    await gesture.up();

    expect(doubleTapCount, 0);
  });
}