Merge pull request #1553 from abarth/child_view

Initial work to add Mozart child views

packages/flutter/lib/rendering.dart

@@ -10,6 +10,7 @@ export 'src/rendering/basic_types.dart';
 export 'src/rendering/binding.dart';
 export 'src/rendering/block.dart';
 export 'src/rendering/box.dart';
+export 'src/rendering/child_view.dart';
 export 'src/rendering/custom_layout.dart';
 export 'src/rendering/debug.dart';
 export 'src/rendering/editable_line.dart';

packages/flutter/lib/src/rendering/child_view.dart

+// Copyright 2016 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:async';
+
+import 'package:flutter/services.dart';
+import 'package:mojo_services/mojo/gfx/composition/scene_token.mojom.dart' as mojom;
+import 'package:mojo_services/mojo/ui/layouts.mojom.dart' as mojom;
+import 'package:mojo_services/mojo/ui/view_provider.mojom.dart' as mojom;
+import 'package:mojo_services/mojo/ui/views.mojom.dart' as mojom;
+import 'package:mojo/application.dart';
+import 'package:mojo/mojo/service_provider.mojom.dart' as mojom;
+
+import 'box.dart';
+import 'object.dart';
+
+// TODO(abarth): Populate the view host.
+final mojom.ViewHost _viewHost = null;
+
+class ChildViewConnection {
+  ChildViewConnection({ this.url }) {
+    mojom.ServiceProviderProxy incomingServices = new mojom.ServiceProviderProxy.unbound();
+    mojom.ServiceProviderStub outgoingServices = new mojom.ServiceProviderStub.unbound();
+    _connection = new ApplicationConnection(outgoingServices, incomingServices);
+    _unresolvedViewToken = _connectToView(incomingServices, outgoingServices);
+  }
+
+  final String url;
+
+  ApplicationConnection get connection => _connection;
+  ApplicationConnection _connection;
+
+  Future<mojom.ViewToken> _unresolvedViewToken;
+  mojom.ViewToken _viewToken;
+
+  Future<mojom.ViewToken> _connectToView(
+    mojom.ServiceProviderProxy incomingServices,
+    mojom.ServiceProviderStub outgoingServices
+  ) async {
+    assert(_viewToken == null);
+    mojom.ViewProviderProxy viewProvider = new mojom.ViewProviderProxy.unbound();
+    shell.connectToService(url, proxy);
+    mojom.ViewToken viewToken = (await viewProvider.ptr.createView(incomingServices, outgoingServices)).viewToken;
+    viewProvider.close();
+    assert(_viewToken == null);
+    _viewToken = viewToken;
+    assert(_viewKey == null);
+    if (_attached)
+      _addChildToViewHost();
+    return viewToken;
+  }
+
+  static int _nextViewKey = 1;
+  int _viewKey;
+
+  void _addChildToViewHost() {
+    assert(_attached);
+    assert(_viewToken != null);
+    assert(_viewKey == null);
+    _viewKey = _nextViewKey++;
+    _viewHost.addChild(_viewKey, _viewToken);
+  }
+
+  void _removeChildFromViewHost() {
+    assert(!_attached);
+    assert(_viewToken != null);
+    assert(_viewKey != null);
+    _viewHost.removeChild(_viewKey);
+    _viewKey = null;
+  }
+
+  // The number of render objects attached to this view. In between frames, we
+  // might have more than one connected if we get added to a new render object
+  // before we get removed from the old render object. By the time we get around
+  // to computing our layout, we must be back to just having one render object.
+  int _attachments = 0;
+  bool get _attached => _attachments > 0;
+
+  void _attach() {
+    assert(_attachments >= 0);
+    ++_attachments;
+    if (_viewToken != null && _viewKey == null)
+      _addChildToViewHost();
+  }
+
+  void _detach() {
+    assert(_attached);
+    --_attachments;
+    scheduleMicrotask(_removeChildFromViewHostIfNeeded);
+  }
+
+  void _removeChildFromViewHostIfNeeded() {
+    assert(_attachments >= 0);
+    if (_attachments == 0)
+      _removeChildFromViewHost();
+  }
+
+  Future<mojom.ViewLayoutInfo> _layout({ Size size, double scale }) async {
+    assert(_attached);
+    assert(_attachments == 1);
+    assert(_viewKey != null);
+    int width = (size.width * scale).round();
+    int height = (size.height * scale).round();
+    // TODO(abarth): Ideally we would propagate our actually constraints to be
+    // able to support rich cross-app layout. For now, we give the child tight
+    // constraints for simplicity.
+    mojom.BoxConstraints childConstraints = new mojom.BoxConstraints()
+      ..minWidth = width
+      ..maxWidth = width
+      ..minHeight = height
+      ..maxHeight = height;
+    mojom.ViewLayoutParams layoutParams = new mojom.ViewLayoutParams()
+      ..constraints = childConstraints
+      ..devicePixelRatio = scale;
+    return (await _viewHost.layoutChild(_viewKey, layoutParams)).info;
+  }
+
+  String toString() {
+    return '$runtimeType(url: $url)';
+  }
+}
+
+class RenderChildView extends RenderBox {
+  RenderChildView({
+    ChildViewConnection child,
+    double scale
+  }) : _child = child, _scale = scale;
+
+  ChildViewConnection get child => _child;
+  ChildViewConnection _child;
+  void set child (ChildViewConnection value) {
+    if (value == _child)
+      return;
+    if (attached)
+      _child?._detach();
+    _child = value;
+    _layoutInfo = null;
+    if (attached)
+      _child?._attach();
+
+    if (_child == null) {
+      markNeedsPaint();
+    } else if (_child._viewToken != null) {
+      // We've already connected to the view, so we're ready to invalidate our
+      // layout immediately.
+      markNeedsLayout();
+    } else {
+      // Otherwise, we're still in the process of connecting, so we need to
+      // repaint now (to remove any old child view), and we need to watch for
+      // the view token resolving before attempting layout.
+      markNeedsPaint();
+      _child._unresolvedViewToken.then(_handleViewTokenResolved);
+    }
+  }
+
+  double get scale => _scale;
+  double _scale;
+  void set scale (double value) {
+    if (value == _scale)
+      return;
+    _scale = value;
+    if (_child != null)
+      markNeedsLayout();
+  }
+
+  void attach() {
+    super.attach();
+    _child?._attach();
+  }
+
+  void detach() {
+    _child?._detach();
+    super.detach();
+  }
+
+  bool get alwaysNeedsCompositing => true;
+  bool get sizedByParent => true;
+
+  void performResize() {
+    size = constraints.biggest;
+  }
+
+  void performLayout() {
+    if (_child != null)
+      _child._layout(size: size, scale: scale).then(_handleLayoutInfoChanged);
+  }
+
+  mojom.ViewLayoutInfo _layoutInfo;
+
+  void _handleLayoutInfoChanged(mojom.ViewLayoutInfo layoutInfo) {
+    _layoutInfo = layoutInfo;
+    markNeedsPaint();
+  }
+
+  void _handleViewTokenResolved(mojom.ViewToken viewToken) {
+    // The _viewToken might not match viewToken if _child changed between the
+    // time we started waiting for the future and the time it resolved.
+    if (attached && _child?._viewToken == viewToken)
+      markNeedsLayout();
+  }
+
+  void paint(PaintingContext context, Offset offset) {
+    assert(needsCompositing);
+    if (_layoutInfo != null)
+      context.pushChildScene(offset, _layoutInfo);
+  }
+
+  void debugDescribeSettings(List<String> settings) {
+    super.debugDescribeSettings(settings);
+    settings.add('child: $child');
+    settings.add('scale: $scale');
+  }
+}

packages/flutter/lib/src/rendering/layer.dart

@@ -5,6 +5,7 @@
 import 'dart:ui' as ui;
 
 import 'package:vector_math/vector_math_64.dart';
+import 'package:mojo_services/mojo/ui/layouts.mojom.dart' as mojom;
 
 import 'basic_types.dart';
 import 'debug.dart';
@@ -107,6 +108,30 @@ class PictureLayer extends Layer {
   }
 }
 
+class ChildSceneLayer extends Layer {
+  ChildSceneLayer({ this.offset, this.layoutInfo });
+
+  Offset offset;
+  mojom.ViewLayoutInfo layoutInfo;
+
+  void addToScene(ui.SceneBuilder builder, Offset layerOffset) {
+    builder.addChildScene(
+      offset + layerOffset,
+      layoutInfo.size.width,
+      layoutInfo.size.height,
+      layoutInfo.sceneToken.value
+    );
+  }
+
+  void debugDescribeSettings(List<String> settings) {
+    super.debugDescribeSettings(settings);
+    settings.add('offset: $offset');
+    settings.add('physicalWidth: ${layoutInfo.size.width}');
+    settings.add('physicalHeight: ${layoutInfo.size.height}');
+    settings.add('sceneToken.value: ${layoutInfo.sceneToken.value}');
+  }
+}
+
 /// A layer that indicates to the compositor that it should display
 /// certain performance statistics within it.
 class PerformanceOverlayLayer extends Layer {

packages/flutter/lib/src/rendering/object.dart

@@ -9,6 +9,7 @@ import 'package:flutter/gestures.dart';
 import 'package:flutter/painting.dart';
 import 'package:flutter/scheduler.dart';
 import 'package:flutter/services.dart';
+import 'package:mojo_services/mojo/ui/layouts.mojom.dart' as mojom;
 import 'package:vector_math/vector_math_64.dart';
 
 import 'debug.dart';
@@ -189,12 +190,16 @@ class PaintingContext {
   /// compositor.
   void pushPerformanceOverlay(Offset offset, int optionsMask, int rasterizerThreshold, Size size) {
     _stopRecordingIfNeeded();
-    PerformanceOverlayLayer performanceOverlayLayer = new PerformanceOverlayLayer(
+    _appendLayer(new PerformanceOverlayLayer(
       overlayRect: new Rect.fromLTWH(offset.dx, offset.dy, size.width, size.height),
       optionsMask: optionsMask,
       rasterizerThreshold: rasterizerThreshold
-    );
-    _appendLayer(performanceOverlayLayer);
+    ));
+  }
+
+  void pushChildScene(Offset offset, mojom.ViewLayoutInfo layoutInfo) {
+    _stopRecordingIfNeeded();
+    _appendLayer(new ChildSceneLayer(offset: offset, layoutInfo: layoutInfo));
   }
 
   /// Push a rectangular clip rect.

packages/flutter/lib/src/widgets/child_view.dart

+// Copyright 2016 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 'media_query.dart';
+import 'framework.dart';
+
+export 'package:flutter/rendering.dart' show ChildViewConnection;
+
+class ChildView extends StatelessComponent {
+  ChildView({ Key key, this.child }) : super(key: key);
+
+  final ChildViewConnection child;
+
+  Widget build(BuildContext context) {
+    return new _ChildViewWidget(
+      child: child,
+      scale: MediaQuery.of(context).devicePixelRatio
+    );
+  }
+}
+
+class _ChildViewWidget extends LeafRenderObjectWidget {
+  _ChildViewWidget({
+    ChildViewConnection child,
+    this.scale
+  }) : child = child, super(key: new GlobalObjectKey(child));
+
+  final ChildViewConnection child;
+  final double scale;
+
+  RenderChildView createRenderObject() => new RenderChildView(child: child, scale: scale);
+
+  void updateRenderObject(RenderChildView renderObject, _ChildViewWidget oldWidget) {
+    renderObject
+      ..child = child
+      ..scale = scale;
+  }
+}

packages/flutter/lib/widgets.dart

@@ -8,6 +8,7 @@ library widgets;
 export 'src/widgets/asset_vendor.dart';
 export 'src/widgets/basic.dart';
 export 'src/widgets/binding.dart';
+export 'src/widgets/child_view.dart';
 export 'src/widgets/dismissable.dart';
 export 'src/widgets/drag_target.dart';
 export 'src/widgets/editable.dart';
@@ -35,9 +36,9 @@ export 'src/widgets/placeholder.dart';
 export 'src/widgets/raw_keyboard_listener.dart';
 export 'src/widgets/routes.dart';
 export 'src/widgets/scroll_behavior.dart';
-export 'src/widgets/scrollable.dart';
 export 'src/widgets/scrollable_grid.dart';
 export 'src/widgets/scrollable_list.dart';
+export 'src/widgets/scrollable.dart';
 export 'src/widgets/semantics_debugger.dart';
 export 'src/widgets/status_transitions.dart';
 export 'src/widgets/title.dart';