From 45f2c589875444a2767f280a69fbb947c620689d Mon Sep 17 00:00:00 2001
From: Adam Barth <abarth@chromium.org>
Date: Thu, 27 Aug 2015 15:02:35 -0700
Subject: [PATCH] Add PointerRouter

This patch is the first step towards implementing gestures. The pointer router
allows the gesture detectors to hook in at the end of the pointer event
propagation chain.

Related to #145
---
 packages/flutter/lib/base/pointer_router.dart | 40 +++++++++++++++++++
 .../flutter/lib/rendering/sky_binding.dart    |  4 ++
 packages/flutter/lib/widgets/drag_target.dart |  3 ++
 packages/flutter/lib/widgets/framework.dart   |  2 +
 4 files changed, 49 insertions(+)
 create mode 100644 packages/flutter/lib/base/pointer_router.dart

diff --git a/packages/flutter/lib/base/pointer_router.dart b/packages/flutter/lib/base/pointer_router.dart
new file mode 100644
index 0000000000..5b12864d62
--- /dev/null
+++ b/packages/flutter/lib/base/pointer_router.dart
@@ -0,0 +1,40 @@
+// 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 'dart:sky' as sky;
+
+import 'package:sky/base/hit_test.dart';
+
+typedef void _Route(sky.PointerEvent event);
+
+class PointerRouter extends HitTestTarget {
+  final Map<int, List<_Route>> _routeMap = new Map<int, List<_Route>>();
+
+  void addRoute(int pointer, _Route route) {
+    List<_Route> routes = _routeMap.putIfAbsent(pointer, () => new List<_Route>());
+    assert(!routes.contains(route));
+    routes.add(route);
+  }
+
+  void removeRoute(int pointer, _Route route) {
+    assert(_routeMap.containsKey(pointer));
+    List<_Route> routes = _routeMap[pointer];
+    assert(routes.contains(route));
+    routes.remove(route);
+    if (routes.isEmpty)
+      _routeMap.remove(pointer);
+  }
+
+  EventDisposition handleEvent(sky.Event e, HitTestEntry entry) {
+    if (e is! sky.PointerEvent)
+      return EventDisposition.ignored;
+    sky.PointerEvent event = e;
+    List<_Route> routes = _routeMap[event.pointer];
+    if (routes == null)
+      return EventDisposition.ignored;
+    for (_Route route in new List<_Route>.from(routes))
+      route(event);
+    return EventDisposition.processed;
+  }
+}
diff --git a/packages/flutter/lib/rendering/sky_binding.dart b/packages/flutter/lib/rendering/sky_binding.dart
index 5eca6e8f34..0a4b0f689e 100644
--- a/packages/flutter/lib/rendering/sky_binding.dart
+++ b/packages/flutter/lib/rendering/sky_binding.dart
@@ -4,6 +4,7 @@
 
 import 'dart:sky' as sky;
 
+import 'package:sky/base/pointer_router.dart';
 import 'package:sky/base/hit_test.dart';
 import 'package:sky/base/scheduler.dart' as scheduler;
 import 'package:sky/rendering/box.dart';
@@ -92,6 +93,8 @@ class SkyBinding {
     }
   }
 
+  final PointerRouter pointerRouter = new PointerRouter();
+
   Map<int, PointerState> _stateForPointer = new Map<int, PointerState>();
 
   PointerState _createStateForPointer(sky.PointerEvent event, Point position) {
@@ -127,6 +130,7 @@ class SkyBinding {
 
   HitTestResult hitTest(Point position) {
     HitTestResult result = new HitTestResult();
+    result.add(new HitTestEntry(pointerRouter));
     _renderView.hitTest(result, position: position);
     return result;
   }
diff --git a/packages/flutter/lib/widgets/drag_target.dart b/packages/flutter/lib/widgets/drag_target.dart
index d7d6d5d1c3..63e8c1ec95 100644
--- a/packages/flutter/lib/widgets/drag_target.dart
+++ b/packages/flutter/lib/widgets/drag_target.dart
@@ -5,6 +5,7 @@
 import 'dart:collection';
 
 import 'package:sky/base/hit_test.dart';
+import 'package:sky/rendering/object.dart';
 import 'package:sky/rendering/sky_binding.dart';
 import 'package:sky/widgets/basic.dart';
 import 'package:sky/widgets/framework.dart';
@@ -80,6 +81,8 @@ class DragController {
 
   DragTarget _getDragTarget(List<HitTestEntry> path) {
     for (HitTestEntry entry in path.reversed) {
+      if (entry.target is! RenderObject)
+        continue;
       for (Widget widget in RenderObjectWrapper.getWidgetsForRenderObject(entry.target)) {
         if (widget is DragTarget)
           return widget;
diff --git a/packages/flutter/lib/widgets/framework.dart b/packages/flutter/lib/widgets/framework.dart
index 5859650745..9617933d27 100644
--- a/packages/flutter/lib/widgets/framework.dart
+++ b/packages/flutter/lib/widgets/framework.dart
@@ -1282,6 +1282,8 @@ class WidgetSkyBinding extends SkyBinding {
     if (disposition == EventDisposition.consumed)
       return EventDisposition.consumed;
     for (HitTestEntry entry in result.path.reversed) {
+      if (entry.target is! RenderObject)
+        continue;
       for (Widget target in RenderObjectWrapper.getWidgetsForRenderObject(entry.target)) {
         if (target is Listener) {
           EventDisposition targetDisposition = target._handleEvent(event);