initial commit: LeafViewer, LeafZoomable, LeafContextMenu, LeafPopover, LeafImage, misc widgets + tests

example/lib/viewer_demo.dart

@@ -0,0 +1,131 @@
+import 'dart:io';
+import 'dart:ui' as ui;
+
+import 'package:flutter/foundation.dart';
+import 'package:flutter/material.dart';
+import 'package:leaf_widgets/leaf_widgets.dart';
+
+class _DemoImage {
+  const _DemoImage(this.url, this.size);
+  final String url;
+  final Size size;
+}
+
+const _demoImages = [
+  _DemoImage(
+    'https://file.pawchive.pw/data/82/91/829126892beebd0a7ff5b5a398e63a760b53162b15323ce900d944d126aa69ec.png?f=829126892beebd0a7ff5b5a398e63a760b53162b15323ce900d944d126aa69ec.png',
+    Size(1457, 2048),
+  ),
+  _DemoImage(
+    'https://file.pawchive.pw/data/09/f4/09f4e606de27786cf633282b8d3e194b62a0b6859368f8ac38d28300972f763c.jpeg?f=09f4e606de27786cf633282b8d3e194b62a0b6859368f8ac38d28300972f763c.jpeg',
+    Size(8500, 6000),
+  ),
+  _DemoImage(
+    'https://file.pawchive.pw/data/79/e9/79e996f02a2700dbc38c590057d027b7566608be8e87e49950cec165d6f8b525.png?f=79e996f02a2700dbc38c590057d027b7566608be8e87e49950cec165d6f8b525.png',
+    Size(3267, 1634),
+  ),
+];
+
+Size _containSize(Size viewport, Size image) {
+  final scale = viewport.width / image.width < viewport.height / image.height
+      ? viewport.width / image.width
+      : viewport.height / image.height;
+  return Size(image.width * scale, image.height * scale);
+}
+
+void openLeafViewerDemo(BuildContext context, {bool enableSwipeGestures = false}) {
+  Navigator.of(context).push(
+    PageRouteBuilder(
+      // Transparent route so the scrim fade reveals the gallery behind it,
+      // like the real app's fullscreen viewer.
+      opaque: false,
+      barrierColor: Colors.transparent,
+      barrierDismissible: true,
+      transitionDuration: const Duration(milliseconds: 200),
+      reverseTransitionDuration: const Duration(milliseconds: 200),
+      transitionsBuilder: (context, animation, secondaryAnimation, child) =>
+          FadeTransition(opacity: CurvedAnimation(parent: animation, curve: Curves.easeOut), child: child),
+      pageBuilder: (context, animation, secondaryAnimation) => Scaffold(
+        backgroundColor: Colors.transparent,
+        body: Stack(
+          children: [
+            LeafViewer(
+              pageCount: _demoImages.length,
+              enableSwipeGestures: enableSwipeGestures,
+              backgroundBuilder: (context, progress) =>
+                  Container(color: Colors.black.withValues(alpha: 0.87 * (1 - progress))),
+              pageBuilder: (context, index) {
+                final demo = _demoImages[index];
+                return LayoutBuilder(
+                  builder: (context, constraints) {
+                    return LeafZoomable(
+                      childSize: _containSize(constraints.biggest, demo.size),
+                      originalSize: demo.size,
+                      child: Image(
+                        image: _HeaderImageProvider(demo.url),
+                        fit: BoxFit.contain,
+                        filterQuality: FilterQuality.high,
+                        errorBuilder: (context, error, stackTrace) => const ColoredBox(
+                          color: Color(0xFF1A1A1A),
+                          child: Center(child: Icon(Icons.broken_image, color: Colors.white38)),
+                        ),
+                      ),
+                    );
+                  },
+                );
+              },
+            ),
+            Positioned(
+              top: 8,
+              right: 8,
+              child: IconButton(
+                icon: const Icon(Icons.close),
+                color: Colors.white70,
+                onPressed: () => Navigator.of(context).pop(),
+              ),
+            ),
+          ],
+        ),
+      ),
+    ),
+  );
+}
+
+/// ImageProvider for `file.pawchive.pw` (requires Referer + browser UA).
+class _HeaderImageProvider extends ImageProvider<_HeaderImageProvider> {
+  const _HeaderImageProvider(this.url);
+
+  final String url;
+
+  @override
+  bool operator ==(Object other) => other is _HeaderImageProvider && other.url == url;
+
+  @override
+  int get hashCode => url.hashCode;
+
+  @override
+  Future<_HeaderImageProvider> obtainKey(ImageConfiguration configuration) => SynchronousFuture(this);
+
+  @override
+  ImageStreamCompleter loadImage(_HeaderImageProvider key, ImageDecoderCallback decode) {
+    return MultiFrameImageStreamCompleter(codec: _loadAsync(decode), scale: 1.0);
+  }
+
+  Future<ui.Codec> _loadAsync(ImageDecoderCallback decode) async {
+    final client = HttpClient();
+    try {
+      final request = await client.getUrl(Uri.parse(url));
+      request.headers.set('Referer', 'https://pawchive.pw/');
+      request.headers.set('User-Agent',
+          'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36');
+      final response = await request.close();
+      if (response.statusCode != 200) {
+        throw HttpException('GET $url -> ${response.statusCode}', uri: Uri.parse(url));
+      }
+      final bytes = await consolidateHttpClientResponseBytes(response);
+      return await decode(await ui.ImmutableBuffer.fromUint8List(bytes));
+    } finally {
+      client.close();
+    }
+  }
+}