[Feature] Added enablePanAlways to allow the user pan any view with…

…out restrictions. (#427)

* allow pan even when the widget is smaller than the container

* Enable always pan widget.

.gitignore

@@ -72,3 +72,5 @@ build/
 !**/ios/**/default.pbxuser
 !**/ios/**/default.perspectivev3
 !/packages/flutter_tools/test/data/dart_dependencies_test/**/.packages
+.fvm/*
+.gitignore

example/pubspec.lock

@@ -7,7 +7,7 @@ packages:
       name: async
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "2.6.0"
+    version: "2.5.0"
   boolean_selector:
     dependency: transitive
     description:
@@ -127,7 +127,7 @@ packages:
       name: source_span
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.8.1"
+    version: "1.8.0"
   stack_trace:
     dependency: transitive
     description:
@@ -162,7 +162,7 @@ packages:
       name: test_api
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "0.3.0"
+    version: "0.2.19"
   typed_data:
     dependency: transitive
     description:

lib/photo_view.dart

@@ -257,6 +257,7 @@ class PhotoView extends StatefulWidget {
     this.filterQuality,
     this.disableGestures,
     this.errorBuilder,
+    this.enablePanAlways,
   })  : child = null,
         childSize = null,
         super(key: key);
@@ -290,6 +291,7 @@ class PhotoView extends StatefulWidget {
     this.tightMode,
     this.filterQuality,
     this.disableGestures,
+    this.enablePanAlways,
   })  : errorBuilder = null,
         imageProvider = null,
         gaplessPlayback = false,
@@ -388,6 +390,10 @@ class PhotoView extends StatefulWidget {
   // Useful when custom gesture detector is used in child widget.
   final bool? disableGestures;
 
+  /// Enable pan the widget even if it's smaller than the hole parent widget.
+  /// Useful when you want to drag a widget without restrictions.
+  final bool? enablePanAlways;
+
   bool get _isCustomChild {
     return child != null;
   }
@@ -505,6 +511,7 @@ class _PhotoViewState extends State<PhotoView> {
                 tightMode: widget.tightMode,
                 filterQuality: widget.filterQuality,
                 disableGestures: widget.disableGestures,
+                enablePanAlways: widget.enablePanAlways,
               )
             : ImageWrapper(
                 imageProvider: widget.imageProvider!,
@@ -530,6 +537,7 @@ class _PhotoViewState extends State<PhotoView> {
                 filterQuality: widget.filterQuality,
                 disableGestures: widget.disableGestures,
                 errorBuilder: widget.errorBuilder,
+                enablePanAlways: widget.enablePanAlways,
               );
       },
     );

lib/src/controller/photo_view_controller_delegate.dart

@@ -67,7 +67,9 @@ mixin PhotoViewControllerDelegate on State<PhotoViewCore> {
   }
 
   void _blindScaleListener() {
-    controller.position = clampPosition();
+    if (!widget.enablePanAlways) {
+      controller.position = clampPosition();
+    }
     if (controller.scale == controller.prevValue.scale) {
       return;
     }

lib/src/core/photo_view_core.dart

@@ -41,7 +41,8 @@ class PhotoViewCore extends StatefulWidget {
     required this.tightMode,
     required this.filterQuality,
     required this.disableGestures,
-  })  : customChild = null,
+    required this.enablePanAlways,
+  })   : customChild = null,
         super(key: key);
 
   const PhotoViewCore.customChild({
@@ -62,7 +63,8 @@ class PhotoViewCore extends StatefulWidget {
     required this.tightMode,
     required this.filterQuality,
     required this.disableGestures,
-  })  : imageProvider = null,
+    required this.enablePanAlways,
+  })   : imageProvider = null,
         gaplessPlayback = false,
         super(key: key);
 
@@ -86,6 +88,7 @@ class PhotoViewCore extends StatefulWidget {
   final HitTestBehavior? gestureDetectorBehavior;
   final bool tightMode;
   final bool disableGestures;
+  final bool enablePanAlways;
 
   final FilterQuality filterQuality;
 
@@ -151,10 +154,11 @@ class PhotoViewCoreState extends State<PhotoViewCore>
 
     updateScaleStateFromNewScale(newScale);
 
-    //
     updateMultiple(
       scale: newScale,
-      position: clampPosition(position: delta * details.scale),
+      position: widget.enablePanAlways
+          ? delta
+          : clampPosition(position: delta * details.scale),
       rotation:
           widget.enableRotation ? _rotationBefore! + details.rotation : null,
       rotationFocusPoint: widget.enableRotation ? details.focalPoint : null,

lib/src/core/photo_view_gesture_detector.dart

@@ -98,7 +98,7 @@ class PhotoViewGestureRecognizer extends ScaleGestureRecognizer {
   bool ready = true;
 
   @override
-  void addAllowedPointer(PointerDownEvent event) {
+  void addAllowedPointer(PointerEvent event) {
     if (ready) {
       ready = false;
       _pointerLocations = <int, Offset>{};

lib/src/photo_view_wrappers.dart

@@ -31,6 +31,7 @@ class ImageWrapper extends StatefulWidget {
     required this.filterQuality,
     required this.disableGestures,
     required this.errorBuilder,
+    required this.enablePanAlways,
   }) : super(key: key);
 
   final ImageProvider imageProvider;
@@ -56,6 +57,7 @@ class ImageWrapper extends StatefulWidget {
   final bool? tightMode;
   final FilterQuality? filterQuality;
   final bool? disableGestures;
+  final bool? enablePanAlways;
 
   @override
   _ImageWrapperState createState() => _ImageWrapperState();
@@ -187,6 +189,7 @@ class _ImageWrapperState extends State<ImageWrapper> {
       tightMode: widget.tightMode ?? false,
       filterQuality: widget.filterQuality ?? FilterQuality.none,
       disableGestures: widget.disableGestures ?? false,
+      enablePanAlways: widget.enablePanAlways ?? false,
     );
   }
 
@@ -236,6 +239,7 @@ class CustomChildWrapper extends StatelessWidget {
     required this.tightMode,
     required this.filterQuality,
     required this.disableGestures,
+    required this.enablePanAlways,
   }) : super(key: key);
 
   final Widget? child;
@@ -262,6 +266,7 @@ class CustomChildWrapper extends StatelessWidget {
   final bool? tightMode;
   final FilterQuality? filterQuality;
   final bool? disableGestures;
+  final bool? enablePanAlways;
 
   @override
   Widget build(BuildContext context) {
@@ -290,6 +295,7 @@ class CustomChildWrapper extends StatelessWidget {
       tightMode: tightMode ?? false,
       filterQuality: filterQuality ?? FilterQuality.none,
       disableGestures: disableGestures ?? false,
+      enablePanAlways: enablePanAlways ?? false,
     );
   }
 }

pubspec.lock

@@ -28,7 +28,7 @@ packages:
       name: async
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "2.6.0"
+    version: "2.6.1"
   boolean_selector:
     dependency: transitive
     description: