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87 lines
2.4 KiB
Dart
87 lines
2.4 KiB
Dart
// Copyright 2015 The Chromium Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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import 'package:flutter/material.dart';
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import 'package:flutter/rendering.dart';
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import 'package:flutter/gestures.dart';
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// Material design colors. :p
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List<Color> kColors = <Color>[
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Colors.teal[500],
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Colors.amber[500],
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Colors.purple[500],
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Colors.lightBlue[500],
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Colors.deepPurple[500],
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Colors.lime[500],
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];
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class Dot {
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final Paint _paint;
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Point position = Point.origin;
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double radius = 0.0;
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Dot({ Color color }) : _paint = new Paint()..color = color;
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void update(PointerInputEvent event) {
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position = new Point(event.x, event.y);
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radius = 5 + (95 * event.pressure);
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}
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void paint(PaintingContext context, Offset offset) {
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context.canvas.drawCircle(position + offset, radius, _paint);
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}
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}
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class RenderTouchDemo extends RenderBox {
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final Map<int, Dot> dots = <int, Dot>{};
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void handleEvent(InputEvent event, BoxHitTestEntry entry) {
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if (event is PointerInputEvent) {
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switch (event.type) {
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case 'pointerdown':
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Color color = kColors[event.pointer.remainder(kColors.length)];
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dots[event.pointer] = new Dot(color: color)..update(event);
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break;
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case 'pointerup':
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dots.remove(event.pointer);
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break;
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case 'pointercancel':
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dots.clear();
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break;
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case 'pointermove':
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dots[event.pointer].update(event);
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break;
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}
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markNeedsPaint();
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}
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}
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void performLayout() {
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size = constraints.biggest;
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}
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void paint(PaintingContext context, Offset offset) {
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final PaintingCanvas canvas = context.canvas;
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Paint white = new Paint()
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..color = const Color(0xFFFFFFFF);
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canvas.drawRect(offset & size, white);
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for (Dot dot in dots.values)
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dot.paint(context, offset);
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}
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}
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void main() {
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RenderParagraph paragraph = new RenderParagraph(new PlainTextSpan("Touch me!"));
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RenderStack stack = new RenderStack(children: <RenderBox>[
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new RenderTouchDemo(),
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paragraph,
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]);
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// Prevent the RenderParagraph from filling the whole screen so
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// that it doesn't eat events.
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final StackParentData paragraphParentData = paragraph.parentData;
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paragraphParentData..top = 40.0
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..left = 20.0;
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new FlutterBinding(root: stack);
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}
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