mirror of
https://github.com/flutter/flutter
synced 2024-10-13 19:52:53 +00:00
51 lines
1.5 KiB
Dart
51 lines
1.5 KiB
Dart
// Copyright 2015 The Chromium 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(Point position) => true;
|
|
|
|
final Map<int, Point> _dots = <int, Point>{};
|
|
|
|
@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, new Paint()..color = new Color(0xFF0000FF));
|
|
|
|
Paint paint = new Paint()..color = new Color(0xFF00FF00);
|
|
for (Point point in _dots.values)
|
|
canvas.drawCircle(point, 50.0, paint);
|
|
|
|
super.paint(context, offset);
|
|
}
|
|
}
|
|
|
|
class Dots extends SingleChildRenderObjectWidget {
|
|
Dots({ Key key, Widget child }) : super(key: key, child: child);
|
|
|
|
@override
|
|
RenderDots createRenderObject(BuildContext context) => new RenderDots();
|
|
}
|
|
|
|
void main() {
|
|
runApp(new Dots(child: new Center(child: new Text('Touch me!'))));
|
|
}
|