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InteractiveViewerOverlay
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import 'package:flutter/material.dart'; | |
class InteractiveViewerOverlay extends StatefulWidget { | |
final Widget child; | |
final double maxScale; | |
const InteractiveViewerOverlay({ | |
Key key, | |
@required this.child, | |
this.maxScale, | |
}) : super(key: key); | |
@override | |
_InteractiveViewerOverlayState createState() => | |
_InteractiveViewerOverlayState(); | |
} | |
class _InteractiveViewerOverlayState | |
extends State<InteractiveViewerOverlay> | |
with SingleTickerProviderStateMixin { | |
var viewerKey = GlobalKey(); | |
Rect placeholder; | |
OverlayEntry entry; | |
var controller = TransformationController(); | |
Matrix4Tween snapTween; | |
AnimationController snap; | |
@override | |
void initState() { | |
super.initState(); | |
snap = AnimationController(vsync: this); | |
snap.addListener(() { | |
if (snapTween == null) return; | |
controller.value = snapTween.evaluate(snap); | |
if (snap.isCompleted) { | |
entry.remove(); | |
entry = null; | |
setState(() { | |
placeholder = null; | |
}); | |
} | |
}); | |
} | |
@override | |
void dispose() { | |
snap.dispose(); | |
super.dispose(); | |
} | |
Widget buildViewer(BuildContext context) { | |
return InteractiveViewer( | |
key: viewerKey, | |
transformationController: controller, | |
panEnabled: false, | |
maxScale: widget.maxScale ?? 2.5, | |
child: widget.child, | |
onInteractionStart: (details) { | |
if (placeholder != null) return; | |
setState(() { | |
var renderObject = | |
viewerKey.currentContext.findRenderObject() as RenderBox; | |
placeholder = Rect.fromPoints( | |
renderObject.localToGlobal(Offset.zero), | |
renderObject | |
.localToGlobal(renderObject.size.bottomRight(Offset.zero)), | |
); | |
}); | |
entry = OverlayEntry( | |
builder: (context) { | |
return Positioned.fromRect( | |
rect: placeholder, | |
child: buildViewer(context), | |
); | |
}, | |
); | |
Overlay.of(context).insert(entry); | |
}, | |
onInteractionEnd: (details) { | |
snapTween = Matrix4Tween( | |
begin: controller.value, | |
end: Matrix4.identity(), | |
); | |
snap.value = 0; | |
snap.animateTo( | |
1, | |
duration: Duration(milliseconds: 250), | |
curve: Curves.ease, | |
); | |
}); | |
} | |
@override | |
Widget build(BuildContext context) { | |
var viewer = placeholder != null | |
? SizedBox.fromSize(size: placeholder.size) | |
: buildViewer(context); | |
return Card( | |
child: viewer, | |
clipBehavior: Clip.antiAlias, | |
); | |
} | |
} |
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