smooth_image_viewer 0.2.0

A lightweight Flutter image viewer with gesture dismissal, paging, zoom, and Hero transitions.

smooth_image_viewer

A lightweight Flutter image viewer focused on smooth Hero transitions, a thumbnail-first first frame, and gesture-first interaction.

Why this package

• Two-way Hero transitions — enable or disable Hero independently for opening and returning to the source image.
• Thumbnail-first rendering — keep a lightweight image in the Hero flight, then mount the full-resolution image and gesture layer after the route settles.
• Natural image interaction — horizontal paging, pinch zoom, double-tap zoom, panning, and pull-down-to-dismiss with scale and background fade.
• Shape-aware return animation — rectangle, circle, uniform rounded corners, and four independently rounded corners.
• Preset motion speeds — fast, normal, and slow timings without exposing raw duration values in the public API.
• Small surface area — accepts ImageProviders and owns no networking, caching, state management, or platform-specific code.

Install

dependencies:
  smooth_image_viewer: ^0.1.0

Quick start

Wrap the image shown in your list or profile page with ImageViewerHero and reuse the same tag when opening the viewer:

ImageViewerHero(
  tag: 'photo-$id',
  shape: const ImageViewerShape.rounded(12),
  child: Image(
    image: thumbnailProvider,
    fit: BoxFit.cover,
  ),
)

ImageViewerRoute.open(
  context,
  images: <ImageProvider<Object>>[fullProvider],
  initialIndex: 0,
  heroTags: <Object?>['photo-$id'],
  previewProviders: <ImageProvider<Object>?>[thumbnailProvider],
);

For multiple images, pass matching lists to images, heroTags, and previewProviders. Missing Hero tags or previews simply disable that feature for the corresponding page.

Motion and callbacks

Hero opening and returning are enabled by default. The transition speed is a preset, with normal matching the default timing:

ImageViewerRoute.open(
  context,
  images: images,
  initialIndex: 1,
  enableEnterHero: true,
  enableExitHero: true,
  transitionSpeed: ImageViewerTransitionSpeed.normal,
  onPageChanged: (index) {
    debugPrint('Current image: $index'); // zero-based
  },
);

Use ImageViewerTransitionSpeed.fast or .slow for the other presets. Set either Hero flag to false to use the regular route fade for that direction.

Hero shapes

ImageViewerHero is rectangular by default. Declare the shape when the source image is clipped, especially when the child already uses a rounded Material or another clipping widget:

// Circle
shape: const ImageViewerShape.circle()

// Same radius on every corner
shape: const ImageViewerShape.rounded(16)

// Independent corner radii
shape: const ImageViewerShape.roundedCorners(
  BorderRadius.only(
    topLeft: Radius.circular(24),
    topRight: Radius.circular(8),
    bottomRight: Radius.circular(18),
    bottomLeft: Radius.circular(4),
  ),
)

Thumbnail-first previews

previewProviders is optional. When supplied, the preview provider is shown first and the full-resolution provider is mounted after the opening transition settles. For the most stable Hero flight, use the same thumbnail provider (or an equal ImageProvider) in the source ImageViewerHero and in previewProviders.

Without a preview provider, the full-resolution image is used as the static Hero layer.

API overview

API	Purpose
ImageViewerHero	Hero source widget with optional shape clipping
ImageViewerRoute.open	Opens a single-image or multi-image viewer
ImageViewerShape	Rectangle, circle, rounded, or per-corner shapes
ImageViewerTransitionSpeed	fast, normal, and slow presets
onPageChanged	Reports the zero-based page index after horizontal paging

Example

The package includes an interactive gallery covering multi-image previews, thumbnail-first rendering, Hero shapes, and all three transition speed presets:

cd example
flutter run

License

MIT