fascinating-lantern-0546

readme.md

fascinating-lantern-0546

Created with <3 with dartpad.dev.

main.dart

import 'package:flutter/material.dart';

import '../common/logging.dart';
import 'dimension_preview.dart';

const _logTarget = "widget::scalable_dimension_wrapper";

class ScalableDimensionWrapper extends StatefulWidget {
  final DimensionPreview child;

  const ScalableDimensionWrapper({super.key, required this.child});

  @override
  _ScalableDimensionWrapperState createState() =>
      _ScalableDimensionWrapperState();
}

class _ScalableDimensionWrapperState extends State<ScalableDimensionWrapper> {
  double _scale = 1.0;
  double _initialScale = 1.0; // Initial scale factor
  Offset _position = const Offset(0.0, 0.0);
  Offset _initialFocalPoint = const Offset(0.0, 0.0);
  Offset _initialPosition = const Offset(0.0, 0.0);

  // Define the bounding box for your containing area
  double boundingBoxWidth = 200.0;
  double boundingBoxHeight = 200.0;

  @override
  Widget build(BuildContext context) {
    return Positioned(
      left: _position.dx,
      top: _position.dy,
      child: Transform.scale(
        scale: _scale,
        child: GestureDetector(
          onScaleStart: (details) {
            _initialFocalPoint = details.localFocalPoint;
            _initialPosition = _position;
          },
          onScaleUpdate: (ScaleUpdateDetails details) {
            setState(() {
              var key = widget.child.key as GlobalKey;
              var box = key.currentContext!.findRenderObject() as RenderBox;

              // Calculate the new scale based on the initial scale and the zoom factor
              double newScale = _initialScale * details.scale;
              // Ensure the scaling stays within a reasonable range
              newScale = newScale.clamp(0.2, 2.0);

              // Calculate the new position
              Offset newPosition = _initialPosition +
                  (details.localFocalPoint - _initialFocalPoint);

              // Calculate the effective size of the box considering scaling
              double boxWidth = box.size.width * newScale;
              double boxHeight = box.size.height * newScale;

              // Ensure the item does not move outside the bounding box
              newPosition = Offset(
                newPosition.dx.clamp(0.0, boundingBoxWidth - boxWidth),
                newPosition.dy.clamp(0.0, boundingBoxHeight - boxHeight),
              );

              // Update the scale factor and position
              _scale = newScale;
              _position = newPosition;
            });
          },
          onScaleEnd: (details) {
            logger.finest("$_logTarget updating position: '$_position'");
            logger.finest("$_logTarget updating scale: '$_initialScale'");
            // Save the current scale factor as the initial scale for the next interaction
            _initialScale = _scale;
          },
          child: widget.child,
        ),
      ),
    );
  }
}