codifyiq_image_viewer 2.0.0

A full-screen image viewer with swipe paging, pinch-to-zoom, and custom actions, powered by photo_view.

codifyiq_image_viewer

A full-screen image viewer with swipe paging, pinch-to-zoom, and custom actions, built on photo_view. Images may come from the network, assets, a local file, or any custom ImageProvider.

Installation

dependencies:
  codifyiq_image_viewer: ^2.0.0

Usage

import 'package:codifyiq_image_viewer/codifyiq_image_viewer.dart';

ImageViewerWidget(
  items: [
    ImageViewerItem.network('https://example.com/a.jpg'),
    ImageViewerItem.asset('assets/b.png'),
  ],
);

Thumbnails and placeholders

When a grid or list already shows a small version of each image, pass it as the item's placeholder. The viewer shows it straight away and swaps in the full image once it has downloaded, instead of showing a spinner:

ImageViewerItem.network(
  photo.url,
  placeholder: NetworkImage(photo.thumbnailUrl), // the provider the grid used
  heroTag: photo.id,
);

Give the placeholder the same aspect ratio as the full image. One that fails to load is ignored.

Layout

The viewer follows the Material 3 breakpoints:

• Phones (windows narrower than 600dp, or shorter than 480dp as in landscape): the image fills the screen and the header and footer float over it on a dark gradient. Tapping the image hides or shows them.
• Tablets, desktop and most browser windows: the header and footer sit above and below the image, which fits between them with the 24dp Material margin, so they never cover it.

Override either choice:

ImageViewerWidget(
  items: items,
  controlsLayout: ImageViewerControlsLayout.inset, // or .overlay
  contentPadding: const EdgeInsets.all(16),        // space around the image
  controlsHideOnTap: false,                         // keep overlay controls up
);

Header and footer

The header shows the image's title (or its filename) above the page indicator, and the footer shows its caption with a row of page dots (for 2 to 20 images). Replace either with your own:

ImageViewerWidget(
  items: [
    ImageViewerItem.network(
      photo.url,
      title: photo.name,
      caption: photo.description,
    ),
  ],
  titleBuilder: (context, item, index, total) => Text(item.title ?? ''),
  footerBuilder: (context, item, index, total) =>
      item.caption == null ? null : Text(item.caption!), // null: no footer
);

pageIndicatorBuilder still changes the "1 / 5" text on its own.

Actions

Share, Download and Delete appear when you supply their callbacks. Give items an id and filename so the callbacks know which record to act on, and add your own actions with actions, as overflow menu entries or, with showInAppBar, header buttons. isVisible offers an action only for some images:

ImageViewerWidget(
  items: [
    for (final photo in photos)
      ImageViewerItem.network(photo.url, id: photo.id, filename: photo.filename),
  ],
  onDownload: (item, index) => download(item.id!, item.filename!),
  onDelete: (item, index) => delete(item.id!),
  actions: [
    ImageViewerAction(
      label: 'Set as featured',
      icon: Icons.star_outline,
      showInAppBar: true,
      isVisible: (item, index) => item.id != featuredId,
      onSelected: (item, index) => setFeatured(item.id!),
    ),
  ],
);

The viewer reads isVisible each time it rebuilds. If the viewer is its own route, rebuild it when the answer changes, for example with a ValueListenableBuilder around it in the route's builder, so the button disappears as soon as the image becomes featured.

items can change while the viewer is open. After a delete, rebuild with the shorter list and the viewer moves to the neighbouring image. Removing from the list you passed in works just as well as passing a new one.

• Give every item an id when the list can change. It is how the viewer recognises the image being viewed after the change.
• items must never be empty. When the last image is deleted, close the viewer (Navigator.of(context).pop()) instead of rebuilding it with an empty list.
• Zoom returns to fit-to-screen when images are removed, reordered or inserted ahead of others.

Web note: ImageViewerItem.file is not supported on Flutter web. Use .network, .asset, or a custom ImageProvider on the web target.

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Part of the CodifyIQ component family · pub.dev/publishers/codifyiq.com