Without twoTouchOnly set to true in Column, CastError appears

[LevinGermann]

Describe the bug
I have the ZoomOverlay used in a Column widget, and when I don't set the twoTouchOnly property to true, the widget glitches quickly, bounces back to the original location and produces an error:

I/flutter (23218): ══╡ EXCEPTION CAUGHT BY ANIMATION LIBRARY ╞═════════════════════════════════════════════════════════
I/flutter (23218): The following _CastError was thrown while notifying listeners for AnimationController:
I/flutter (23218): Null check operator used on a null value
I/flutter (23218):
I/flutter (23218): When the exception was thrown, this was the stack:
I/flutter (23218): #0 _ZoomOverlayState.initState. (package:zoom_pinch_overlay/zoom_pinch_overlay.dart:92:36)
I/flutter (23218): #1 AnimationLocalListenersMixin.notifyListeners (package:flutter/src/animation/listener_helpers.dart:136:19)
I/flutter (23218): #2 AnimationController.value= (package:flutter/src/animation/animation_controller.dart:366:5)
I/flutter (23218): #3 AnimationController.reset (package:flutter/src/animation/animation_controller.dart:385:5)
I/flutter (23218): #4 _ZoomOverlayState.onScaleEnd (package:zoom_pinch_overlay/zoom_pinch_overlay.dart:176:22)
I/flutter (23218): #5 ScaleGestureRecognizer._reconfigure. (package:flutter/src/gestures/scale.dart:465:53)
I/flutter (23218): #6 GestureRecognizer.invokeCallback (package:flutter/src/gestures/recognizer.dart:182:24)
I/flutter (23218): #7 ScaleGestureRecognizer._reconfigure (package:flutter/src/gestures/scale.dart:465:11)
I/flutter (23218): #8 ScaleGestureRecognizer.handleEvent (package:flutter/src/gestures/scale.dart:388:36)
I/flutter (23218): #9 PointerRouter._dispatch (package:flutter/src/gestures/pointer_router.dart:93:12)
I/flutter (23218): #10 PointerRouter._dispatchEventToRoutes. (package:flutter/src/gestures/pointer_router.dart:138:9)
I/flutter (23218): #11 _LinkedHashMapMixin.forEach (dart:collection-patch/compact_hash.dart:397:8)
I/flutter (23218): #12 PointerRouter._dispatchEventToRoutes (package:flutter/src/gestures/pointer_router.dart:136:18)
I/flutter (23218): #13 PointerRouter.route (package:flutter/src/gestures/pointer_router.dart:122:7)
I/flutter (23218): #14 GestureBinding.handleEvent (package:flutter/src/gestures/binding.dart:439:19)
I/flutter (23218): #15 GestureBinding.dispatchEvent (package:flutter/src/gestures/binding.dart:419:22)
I/flutter (23218): #16 RendererBinding.dispatchEvent (package:flutter/src/rendering/binding.dart:287:11)
I/flutter (23218): #17 GestureBinding._handlePointerEventImmediately (package:flutter/src/gestures/binding.dart:374:7)
I/flutter (23218): #18 GestureBinding.handlePointerEvent (package:flutter/src/gestures/binding.dart:338:5)
I/flutter (23218): #19 GestureBinding._flushPointerEventQueue (package:flutter/src/gestures/binding.dart:296:7)
I/flutter (23218): #20 GestureBinding._handlePointerDataPacket (package:flutter/src/gestures/binding.dart:279:7)
I/flutter (23218): #24 _invoke1 (dart:ui/hooks.dart:182:10)
I/flutter (23218): #25 PlatformDispatcher._dispatchPointerDataPacket (dart:ui/platform_dispatcher.dart:282:7)
I/flutter (23218): #26 _dispatchPointerDataPacket (dart:ui/hooks.dart:96:31)
I/flutter (23218): (elided 3 frames from dart:async)
I/flutter (23218):
I/flutter (23218): The AnimationController notifying listeners was:
I/flutter (23218): AnimationController#e9df8(⏮ 0.000; paused)
I/flutter (23218): ════════════════════════════════════════════════════════════════════════════════════════════════════

A workaround is to set this field to true; but the same error will appear if you then try to use 3 fingers instead of just 2.

To Reproduce

Column(
      crossAxisAlignment: CrossAxisAlignment.start,
      children: [
        Padding(
          padding: const EdgeInsets.only(top: 16.0),
          child: Center(
            child: AspectRatio(
              aspectRatio: kImageAspectRatio,
              child: ZoomOverlay(
                minScale: 0.5,
                maxScale: 3.0,
                child: ClipRRect(
                  borderRadius: BorderRadius.circular(6),
                  child: CachedNetworkImage(
                    imageUrl: imageUrl!,
                    fadeInCurve: Curves.easeInOutSine,
                    placeholder: (context, _) =>
                        const ImageLoadingPlaceholder(),
                  ),
                ),
              ),
            ),
          ),
        ),
        caption,
      ],
    );

Expected behavior
The widget should zoom without an error, no matter if I set the twoTouchOnly property.

Smartphone (please complete the following information):

• Flutter (Channel stable, 2.2.3, on macOS 11.5 20G71 darwin-arm)
• zoom_pinch_overlay: 1.1.2
• Device: Samsung S21
• OS: Android 11

[pishguy]

+1

[Mayb3Nots]

I have fixed the Null assertion error. However for your glitching problem you just have to make the ZoomOverlay above the AspectRatio like this:

Column(
      crossAxisAlignment: CrossAxisAlignment.start,
      children: [
        Padding(
          padding: const EdgeInsets.only(top: 16.0),
          child: Center(
            child: ZoomOverlay(
              minScale: 0.5,
              maxScale: 3.0,
              child: AspectRatio(
                aspectRatio: kImageAspectRatio,
                child: ClipRRect(
                  borderRadius: BorderRadius.circular(6),
                  child: CachedNetworkImage(
                    imageUrl: imageUrl!,
                    fadeInCurve: Curves.easeInOutSine,
                    placeholder: (context, _) =>
                        const ImageLoadingPlaceholder(),
                  ),
                ),
              ),
            ),
          ),
        ),
        caption,
      ],
    );

Let me know if that fixes you problem.