How do you implement a custom transition between screens in Flutter?

Implementing a custom transition between screens in Flutter involves leveraging the `PageRouteBuilder` class to define a custom page route with a specified transition animation. Here’s a step-by-step guide:

1. Create a Custom Page Route:

   Start by creating a custom page route using the `PageRouteBuilder` class. Define the `pageBuilder` to return the widget for the new screen and set the `transitionsBuilder` to handle the animation between screens.

```dart
PageRouteBuilder(
  pageBuilder: (context, animation, secondaryAnimation) => MyCustomScreen(),
  transitionsBuilder: (context, animation, secondaryAnimation, child) {
    const begin = Offset(1.0, 0.0);
    const end = Offset.zero;
    const curve = Curves.easeInOut;

    var tween = Tween(begin: begin, end: end).chain(CurveTween(curve: curve));

    var offsetAnimation = animation.drive(tween);
    return SlideTransition(position: offsetAnimation, child: child);
  },
);
```

2. Define Custom Screen:

   Create the custom screen, in this case, `MyCustomScreen`, which will be displayed when the transition occurs.

```dart
class MyCustomScreen extends StatelessWidget {
  // Your custom screen implementation
}
```

3. Specify Transition Parameters:

   Customize the transition parameters, such as the offset, curve, and duration, based on your design preferences. These parameters determine the direction and style of the transition animation.

```dart
const begin = Offset(1.0, 0.0);
const end = Offset.zero;
const curve = Curves.easeInOut;

var tween = Tween(begin: begin, end: end).chain(CurveTween(curve: curve));
```

4. Apply Transition:

   Apply the transition to the child widget using the `SlideTransition` widget. This widget animates the position of the child based on the specified transition animation.

```dart
return SlideTransition(position: offsetAnimation, child: child);
```

5. Integrate in Navigator:

   Finally, use the custom page route when navigating to the new screen using the `Navigator`.

```dart
Navigator.of(context).push(
  PageRouteBuilder(
    pageBuilder: (context, animation, secondaryAnimation) => MyCustomScreen(),
    transitionsBuilder: (context, animation, secondaryAnimation, child) {
      // ... (as shown in the first step)
    },
  ),
);
```

By following these steps, you can implement a custom transition effect that adds a unique visual appeal to the navigation between screens in your Flutter application.