131 lines
4.3 KiB
Markdown
131 lines
4.3 KiB
Markdown
# leaf_widgets
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Leaf UI widgets — zero external dependencies.
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- `LeafViewer` — a self-contained, photo_view-style fullscreen viewer:
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clamped zoom + pan, swipe-to-dismiss, double-tap zoom, mouse-wheel zoom,
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native keyboard controls and tap-outside dismissal. Desktop + mobile
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behaviour out of the box.
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- `LeafZoomable` — opt-in per-page zoom wrapper for `LeafViewer` (also usable
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standalone); auto-sizes itself from an image's pixel dimensions via
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`LeafZoomable.image`.
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- `LeafZoomController` — the zoom/pan state machine behind both (clamped,
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fling, double-tap staging, wheel zoom).
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- Plus: `LeafContextMenu`, `LeafPopover`, `LeafImage`, `AnimatedFavoriteButton`,
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`AnimatedStar`.
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## Features
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- Clamped zoom (1x–maxScale) and pan (corners cannot escape the viewport)
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- Edge-release: a drag at a fully zoomed-out, fully clamped position pages or
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dismisses instead of panning (gesture-arena based, no raw pointer routing)
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- Mobile: swipe to page, drag perpendicular to dismiss, double-tap zooms
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(1x → contained → 1:1 when dimensions are known)
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- Desktop (Windows/Linux/macOS): mouse-wheel zoom (cursor-anchored), no drag
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paging/dismiss/double-tap by default, default on-screen controls
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(previous/next, close, page counter) — or your own via `controlsBuilder`
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- Keyboard when focused: ←/→ (or ↑/↓ for vertical paging) + Esc dismiss
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(opt-out with `enableKeyboard: false`)
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- Tap outside the active image fires `onTapOutside`
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- `LeafZoomable.image`: pixel dimensions extracted from the image stream at
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load time — contained size and 1:1 double-tap step work without passing
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anything (falls back to viewport clamping until decoded)
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## Getting started
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Add to `pubspec.yaml`:
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```yaml
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dependencies:
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leaf_widgets:
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path: ../leaf_widgets
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```
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## Usage
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```dart
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import 'package:flutter/material.dart';
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import 'package:leaf_widgets/leaf_widgets.dart';
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class PostViewer extends StatelessWidget {
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const PostViewer({super.key, required this.posts});
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final List<String> urls;
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@override
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Widget build(BuildContext context) {
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return Scaffold(
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backgroundColor: Colors.black,
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body: LeafViewer(
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pageCount: urls.length,
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onDismissed: () => Navigator.of(context).maybePop(),
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pageBuilder: (context, index) => LeafZoomable.image(
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image: Image.network(
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urls[index],
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fit: BoxFit.contain,
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errorBuilder: (context, error, stackTrace) =>
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const Center(child: Icon(Icons.broken_image, color: Colors.white38)),
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),
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),
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),
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);
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}
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}
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```
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That is the full viewer: paging, clamped zoom/pan, swipe-dismiss, double-tap
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(1:1 included — the pixel dimensions are resolved automatically), wheel zoom,
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keyboard, tap-outside, and desktop controls.
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### Sizing control
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`LeafZoomable` sizes the zoom clamp itself when possible:
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- `LeafZoomable.image` resolves the image's pixel dimensions from its stream
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(no second download — the image cache dedupes) and uses them for the
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contained size and the 1:1 stage.
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- Plain `LeafZoomable(child: ...)` clamps against the viewport until you pass
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explicit sizes:
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```dart
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// Contained (fit-to-screen) render size + full-resolution size.
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LeafZoomable(
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childSize: myContainedSize, // optional — defaults to the viewport
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originalSize: myFullSize, // optional — null disables the 1:1 stage
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child: myWidget,
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)
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```
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### Custom chrome
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```dart
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LeafViewer(
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pageCount: urls.length,
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controlsBuilder: (context, controls) => Row(
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children: [
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IconButton(
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onPressed: controls.canGoPrevious ? () => controls.goToPage(controls.currentIndex - 1) : null,
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icon: const Icon(Icons.chevron_left),
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),
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Text('${controls.currentIndex + 1} / ${controls.pageCount}'),
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],
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),
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pageBuilder: (context, index) => /* ... */,
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)
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```
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### Platforms
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- Touch: swipe paging, perpendicular drag dismiss, double-tap zoom.
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- Desktop: wheel zoom, keyboard, default controls; swipe gestures are off
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unless `enableSwipeGestures: true` forces them on.
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- `scrollDirection` flips paging to vertical; the dismiss gesture then runs
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along the other axis.
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## Additional information
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- Example: `example/lib/viewer_demo.dart`
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- All viewer code lives in `lib/src/viewer/` — zoom math in
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`leaf_zoom_controller.dart` (property-tested), gesture arbitration in
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`leaf_pan_zoom_recognizer.dart` (ported from photo_view, MIT).
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