Flutter Mobile Development · 강의

Hero 전환 및 공유 요소 모션

정교한 화면 전환을 위해 Hero 위젯과 사용자 지정 비행 셔틀을 조정합니다.

Hero 전환 및 공유 요소 모션은(는) CoddyKit의 무료 Flutter Mobile Development 강의입니다. 이것은 4개 중 3번째 강의입니다. 아래에서 전체 강의를 무료로 읽을 수 있으며, 내장 코드 에디터와 24/7 AI 튜터와 함께 브라우저에서 직접 실습할 수 있습니다. 이 강의는 Flutter Mobile Development 학습 경로의 일부이며, 진행 상황이 웹과 CoddyKit 앱에 동기화됩니다. Flutter Mobile Development 강의에는 총 4개의 강의가 포함되어 있습니다.

이 강의의 일부는 아직 번역되지 않았으며 영어로 표시됩니다.

What Shared Element Motion Means

A Hero transition animates a single widget so it appears to fly from one screen to another during a route push or pop. Instead of the user losing track of an element across screens, the same visual object morphs in place.

Think of a thumbnail in a list that expands into a full-screen detail image.
Flutter computes the start and end rectangles and tweens the widget between them.
This continuity is what designers call shared element motion.

In this lesson you will coordinate Hero widgets and customize the flight shuttle that actually renders during the in-between frames.

The Hero Widget Contract

To create a Hero animation you wrap the source and destination widgets in a Hero widget and give both the same tag. The tag is how Flutter pairs them across routes.

Tags must be unique per screen but identical between the two screens.
If two Heroes on the same screen share a tag, Flutter throws an assertion at navigation time.

Below, a product thumbnail on the list screen uses the product id as its tag.

Hero(
  tag: 'product-${product.id}',
  child: Image.network(
    product.thumbnailUrl,
    width: 80,
    height: 80,
    fit: BoxFit.cover,
  ),
)

Matching the Destination Hero

The detail screen must wrap its large image in a Hero with the exact same tag. When you push the detail route, Flutter detects both Heroes and starts the flight automatically.

The child widgets do not have to be identical — only the tag must match.
Here the destination is a full-width image, while the source was an 80x80 thumbnail.

Hero(
  tag: 'product-${product.id}',
  child: Image.network(
    product.imageUrl,
    width: double.infinity,
    height: 320,
    fit: BoxFit.cover,
  ),
)

How Tags Drive Pairing

During a route transition Flutter scans both the outgoing and incoming routes for Heroes, then builds a map keyed by tag. Only tags present on both routes animate; an unmatched Hero simply fades with its page.

Because tags are matched by equality, you can use any object as a tag — strings, ints, or enums — as long as == and hashCode behave correctly.

bool heroesMatch(Object tagA, Object tagB) {
  return tagA == tagB;
}

void main() {
  print(heroesMatch('product-7', 'product-7')); // true -> flies
  print(heroesMatch('product-7', 'product-9')); // false -> fades
  print(heroesMatch(42, 42));                    // true
}

The Default Flight Shuttle

The widget rendered during the flight is called the flight shuttle. By default Flutter uses the destination Hero's child for the entire flight, cross-fading where needed.

This works well when the two children look alike. But when the source and destination have very different shapes — for example a square avatar becoming a rounded banner — the default can look like an abrupt swap. That is when you supply a custom flightShuttleBuilder.

Customizing the Flight Shuttle

The flightShuttleBuilder lets you control exactly what is painted mid-flight. Its signature gives you the animation, the direction (push or pop), and both Hero contexts.

flightDirection is HeroFlightDirection.push or .pop.
Return any widget; it will be positioned inside the interpolated rectangle for you.

Here we rotate the child slightly as it flies to add polish.

Hero(
  tag: 'product-${product.id}',
  flightShuttleBuilder: (
    BuildContext flightContext,
    Animation<double> animation,
    HeroFlightDirection direction,
    BuildContext fromContext,
    BuildContext toContext,
  ) {
    return RotationTransition(
      turns: Tween<double>(begin: 0, end: 0.05).animate(animation),
      child: toContext.widget,
    );
  },
  child: Image.network(product.imageUrl, fit: BoxFit.cover),
)

Cross-Fading Between Two Children

A common shuttle pattern is cross-fading from the source child to the destination child so the morph reads smoothly. You can drive a FadeTransition from the same flight animation.

On push, fade the source out and the destination in.
On pop, reverse the roles using flightDirection.

Widget buildShuttle(
  BuildContext flightContext,
  Animation<double> animation,
  HeroFlightDirection direction,
  BuildContext fromContext,
  BuildContext toContext,
) {
  final Widget fromHero = (fromContext.widget as Hero).child;
  final Widget toHero = (toContext.widget as Hero).child;
  final bool isPush = direction == HeroFlightDirection.push;
  return Stack(
    fit: StackFit.expand,
    children: [
      FadeTransition(
        opacity: Tween<double>(begin: isPush ? 1 : 0, end: isPush ? 0 : 1)
            .animate(animation),
        child: fromHero,
      ),
      FadeTransition(
        opacity: Tween<double>(begin: isPush ? 0 : 1, end: isPush ? 1 : 0)
            .animate(animation),
        child: toHero,
      ),
    ],
  );
}

Shaping the Flight Path

By default the Hero moves along a straight line. You can bend that path with createRectTween, which controls how the bounding rectangle is interpolated.

Material's MaterialRectArcTween gives a curved, more natural arc — the same motion Material Design recommends for shared element transitions.

import 'package:flutter/material.dart';

RectTween arcTween(Rect? begin, Rect? end) {
  return MaterialRectArcTween(begin: begin, end: end);
}

// Usage on the Hero:
// Hero(
//   tag: 'product-7',
//   createRectTween: arcTween,
//   child: ...,
// )

Avoiding Tag Collisions in Lists

The most frequent Hero bug is a duplicate tag on a single screen. In a ListView of items, every Hero needs a tag unique to its data row.

Never use a constant string like 'hero' for all items.
Derive the tag from a stable identity such as the model id.

This helper guarantees uniqueness when building list rows.

String heroTagFor(String screen, Object id) {
  return '$screen::$id';
}

void main() {
  final ids = [1, 2, 2, 3];
  final tags = <String>{};
  for (final id in ids) {
    final tag = heroTagFor('list', id);
    if (!tags.add(tag)) {
      print('Collision on $tag');
    } else {
      print('OK $tag');
    }
  }
}

Wrapping Heroes in Material

When a Hero's child has elevation, rounded corners, or ink — like a Card or Material surface — the flight can show clipped or square corners because the in-flight widget is detached from its original ancestors.

Wrap the shuttle (or the children) in a Material with type: MaterialType.transparency so text, shadows, and clipping render correctly mid-flight.

Hero(
  tag: 'card-${item.id}',
  flightShuttleBuilder: (ctx, anim, dir, from, to) {
    return Material(
      type: MaterialType.transparency,
      child: (to.widget as Hero).child,
    );
  },
  child: Material(
    type: MaterialType.transparency,
    child: ProductCard(item: item),
  ),
)

Coordinating Hero with Rive

In this track we pair Hero transitions with Rive animations for richer motion. A clean approach is to let the Hero handle position and size, while a Rive state machine plays a micro-animation on arrival.

Drive a Rive SMITrigger when the destination route finishes its transition.
Use animation.addStatusListener on the flight to fire the trigger at AnimationStatus.completed.

Keep the Hero shuttle simple; let Rive own the expressive part so the two systems do not fight over the same frames.

void fireOnArrival(Animation<double> animation, void Function() onArrived) {
  animation.addStatusListener((status) {
    if (status == AnimationStatus.completed) {
      onArrived(); // e.g. riveTrigger.fire();
    }
  });
}

Quick Check

You have a grid of avatars; tapping one pushes a profile screen. The avatar is a 56x56 circle, and the destination is a 200-tall rounded banner. The default flight looks like an abrupt swap and the corners flicker square during motion. Which combination best fixes this?

Recap

You now know how to build polished shared element transitions:

Matching tags on source and destination Heroes drive the pairing; tags must be unique per screen and identical across screens.
The flight shuttle is what renders mid-flight; customize it with flightShuttleBuilder to cross-fade differing children.
Wrap shuttle content in a transparent Material to keep shadows, text, and rounded corners correct.
Bend the path with createRectTween and MaterialRectArcTween for a natural arc.
Let Hero own position and hand expressive micro-motion to a Rive state machine, fired on AnimationStatus.completed.

Combine these to make screen changes feel continuous and intentional.

자주 묻는 질문

“Hero 전환 및 공유 요소 모션” 강의는 무료인가요?

네 — “Hero 전환 및 공유 요소 모션” 전체 내용을 이 웹사이트에서 무료로 읽을 수 있습니다. 인터랙티브하게 실습하려면(내장 코드 에디터와 24/7 AI 튜터), CoddyKit PRO로 업그레이드하면 Flutter Mobile Development 강의 전체를 잠금 해제할 수 있습니다. Flutter Mobile Development 강의에는 총 4개의 강의가 포함되어 있습니다.

“Hero 전환 및 공유 요소 모션”에서 뭘 배우나요?

정교한 화면 전환을 위해 Hero 위젯과 사용자 지정 비행 셔틀을 조정합니다. 브라우저에서 직접 실행하는 실습 코드로 Flutter Mobile Development을(를) 배우며, 24/7 AI 튜터가 강의를 진행하면서 질문에 답변해줍니다.

Flutter Mobile Development을(를) 시작하는 데 경험이 필요한가요?

사전 경험은 필요하지 않습니다. CoddyKit의 Flutter Mobile Development은(는) 초급자부터 고급 학습자까지를 위해 구성되어 있으므로, 여기서 시작하거나 처음부터 시작할 수 있으며 자신의 속도대로 진행할 수 있습니다. 이것은 4개 중 3번째 강의입니다.

“Hero 전환 및 공유 요소 모션” 강의는 얼마나 걸리나요?

대부분의 CoddyKit 강의는 약 5~10분이 소요됩니다. 각 강의는 간결하고 인터랙티브하여 꾸준한 진행이 가능하며, 웹과 앱에서 중단한 부분부터 바로 시작할 수 있습니다.

이 Flutter Mobile Development 강의에서 코드를 작성하고 실행할 수 있나요?

네. 모든 Flutter Mobile Development 강의에는 내장 코드 에디터가 포함되어 있으므로, 브라우저에서 바로 실제 코드를 작성하고 실행한 후 즉시 AI 피드백을 받을 수 있습니다 — 로컬 설정이 필요 없습니다.

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