56 lines
1.6 KiB
Dart
56 lines
1.6 KiB
Dart
// Copyright 2014 The Flutter Authors. All rights reserved.
|
|
// Use of this source code is governed by a BSD-style license that can be
|
|
// found in the LICENSE file.
|
|
|
|
import 'package:flutter/rendering.dart';
|
|
import 'package:flutter/widgets.dart';
|
|
|
|
class RenderDots extends RenderConstrainedBox {
|
|
RenderDots() : super(additionalConstraints: const BoxConstraints.expand());
|
|
|
|
// Makes this render box hittable so that we'll get pointer events.
|
|
@override
|
|
bool hitTestSelf(Offset position) => true;
|
|
|
|
final Map<int, Offset> _dots = <int, Offset>{};
|
|
|
|
@override
|
|
void handleEvent(PointerEvent event, BoxHitTestEntry entry) {
|
|
if (event is PointerDownEvent || event is PointerMoveEvent) {
|
|
_dots[event.pointer] = event.position;
|
|
markNeedsPaint();
|
|
} else if (event is PointerUpEvent || event is PointerCancelEvent) {
|
|
_dots.remove(event.pointer);
|
|
markNeedsPaint();
|
|
}
|
|
}
|
|
|
|
@override
|
|
void paint(PaintingContext context, Offset offset) {
|
|
final Canvas canvas = context.canvas;
|
|
canvas.drawRect(offset & size, Paint()..color = const Color(0xFF0000FF));
|
|
|
|
final paint = Paint()..color = const Color(0xFF00FF00);
|
|
for (final Offset point in _dots.values) {
|
|
canvas.drawCircle(point, 50.0, paint);
|
|
}
|
|
|
|
super.paint(context, offset);
|
|
}
|
|
}
|
|
|
|
class Dots extends SingleChildRenderObjectWidget {
|
|
const Dots({super.key, super.child});
|
|
|
|
@override
|
|
RenderDots createRenderObject(BuildContext context) => RenderDots();
|
|
}
|
|
|
|
void main() {
|
|
runApp(
|
|
const Directionality(
|
|
textDirection: TextDirection.ltr,
|
|
child: Dots(child: Center(child: Text('Touch me!'))),
|
|
),
|
|
);
|
|
}
|