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import 'package:flutter/material.dart';
// https://api.flutter.dev/flutter/dart-ui/ColorFilter/ColorFilter.matrix.html
const ColorFilter _identity = ColorFilter.matrix(<double>[
1, 0, 0, 0, // identity matrix
0, 0, 1, 0,
0, 0, 0, 0,
1, 0, 0, 0,
0, 0, 1, 0,
]);
const ColorFilter _greyscale = ColorFilter.matrix(<double>[
0.2126, 0.7152, 0.0722, 0, 0, // greyscale filter
0.2126, 0.7152, 0.0722, 0, 0,
0.2126, 0.7152, 0.0722, 0, 0,
0, 0, 0, 1, 0,
]);
// This class is used to implement enabled/disabled icons with only one image:
// when the widget is disabled (value==false) the image is displayed in
// greyscale and at 50% opacity.
class SwitchableImage extends StatelessWidget {
final bool value;
final String imageAssetId;
final double width, height;
const SwitchableImage({
Key? key,
required this.value,
required this.imageAssetId,
required this.width,
required this.height,
}) : super(key: key);
@override
Widget build(BuildContext context) {
return Container(
child: Opacity(
opacity: value ? 1.0 : 0.5,
child: ColorFiltered(
colorFilter: value ? _identity : _greyscale,
child: Image.asset(
imageAssetId,
width: width,
height: height,
fit: BoxFit.contain,
),
),
),
);
}
}
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