Initial implementation of SnackBar

sky/sdk/lib/widgets/scaffold.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 'dart:math' as math;
+
 import '../rendering/box.dart';
 import '../rendering/object.dart';
 import '../theme/view_configuration.dart';
 import 'widget.dart';
 
+// Slots are painted in this order and hit tested in reverse of this order
 enum ScaffoldSlots {
-  toolbar,
   body,
   statusBar,
-  drawer,
-  floatingActionButton
+  toolbar,
+  snackBar,
+  floatingActionButton,
+  drawer
 }
 
 class RenderScaffold extends RenderBox {
 
   RenderScaffold({
-    RenderBox toolbar,
     RenderBox body,
     RenderBox statusBar,
-    RenderBox drawer,
-    RenderBox floatingActionButton
+    RenderBox toolbar,
+    RenderBox snackBar,
+    RenderBox floatingActionButton,
+    RenderBox drawer
   }) {
-    this[ScaffoldSlots.toolbar] = toolbar;
     this[ScaffoldSlots.body] = body;
     this[ScaffoldSlots.statusBar] = statusBar;
+    this[ScaffoldSlots.toolbar] = toolbar;
+    this[ScaffoldSlots.snackBar] = snackBar;
+    this[ScaffoldSlots.floatingActionButton] = floatingActionButton;
     this[ScaffoldSlots.drawer] = drawer;
-    this[ScaffoldSlots.floatingActionButton] = floatingActionButton;
   }
 
   Map<ScaffoldSlots, RenderBox> _slots = new Map<ScaffoldSlots, RenderBox>();
   RenderBox operator[] (ScaffoldSlots slot) => _slots[slot];
   void operator[]= (ScaffoldSlots slot, RenderBox value) {
     RenderBox old = _slots[slot];
     if (old == value)
       return;
     if (old != null)
       dropChild(old);
@@ skipping 40 matching lines @@
   }
 
   // TODO(eseidel): These change based on device size!
   // http://www.google.com/design/spec/layout/metrics-keylines.html#metrics-keylines-keylines-spacing
   static const kButtonX = 16.0; // left from right edge of body
   static const kButtonY = 16.0; // up from bottom edge of body
 
   void performLayout() {
     double bodyHeight = size.height;
     double bodyPosition = 0.0;
+    if (_slots[ScaffoldSlots.statusBar] != null) {
+      RenderBox statusBar = _slots[ScaffoldSlots.statusBar];
+      statusBar.layout(new BoxConstraints.tight(new Size(size.width, kStatusBarHeight)));
+      assert(statusBar.parentData is BoxParentData);
+      statusBar.parentData.position = new Point(0.0, size.height - kStatusBarHeight);
+      bodyHeight -= kStatusBarHeight;
+    }
     if (_slots[ScaffoldSlots.toolbar] != null) {
       RenderBox toolbar = _slots[ScaffoldSlots.toolbar];
       double toolbarHeight = kToolBarHeight + kNotificationAreaHeight;
       toolbar.layout(new BoxConstraints.tight(new Size(size.width, toolbarHeight)));
       assert(toolbar.parentData is BoxParentData);
       toolbar.parentData.position = Point.origin;
       bodyPosition += toolbarHeight;
       bodyHeight -= toolbarHeight;
     }
-    if (_slots[ScaffoldSlots.statusBar] != null) {
-      RenderBox statusBar = _slots[ScaffoldSlots.statusBar];
-      statusBar.layout(new BoxConstraints.tight(new Size(size.width, kStatusBarHeight)));
-      assert(statusBar.parentData is BoxParentData);
-      statusBar.parentData.position = new Point(0.0, size.height - kStatusBarHeight);
-      bodyHeight -= kStatusBarHeight;
-    }
     if (_slots[ScaffoldSlots.body] != null) {
       RenderBox body = _slots[ScaffoldSlots.body];
       body.layout(new BoxConstraints.tight(new Size(size.width, bodyHeight)));
       assert(body.parentData is BoxParentData);
       body.parentData.position = new Point(0.0, bodyPosition);
     }
+    double snackBarHeight = 0.0;
+    if (_slots[ScaffoldSlots.snackBar] != null) {
+      RenderBox snackBar = _slots[ScaffoldSlots.snackBar];
+      // TODO(jackson): On tablet/desktop, minWidth = 288, maxWidth = 568
+      snackBar.layout(new BoxConstraints(minWidth: size.width, maxWidth: size.width, minHeight: 0.0, maxHeight: size.height),
+                      parentUsesSize: true);
+      assert(snackBar.parentData is BoxParentData);
+      snackBar.parentData.position = new Point(0.0, size.height - snackBar.size.height);
+      snackBarHeight = snackBar.size.height;
+    }
+    if (_slots[ScaffoldSlots.floatingActionButton] != null) {
+      RenderBox floatingActionButton = _slots[ScaffoldSlots.floatingActionButton];
+      Size area = new Size(size.width - kButtonX, size.height - kButtonY - snackBarHeight);
+      floatingActionButton.layout(new BoxConstraints.loose(area), parentUsesSize: true);
+      assert(floatingActionButton.parentData is BoxParentData);
+      floatingActionButton.parentData.position = (area - floatingActionButton.size).toPoint();
+    }
     if (_slots[ScaffoldSlots.drawer] != null) {
       RenderBox drawer = _slots[ScaffoldSlots.drawer];
       drawer.layout(new BoxConstraints(minWidth: 0.0, maxWidth: size.width, minHeight: size.height, maxHeight: size.height));
       assert(drawer.parentData is BoxParentData);
       drawer.parentData.position = Point.origin;
     }
-    if (_slots[ScaffoldSlots.floatingActionButton] != null) {
-      RenderBox floatingActionButton = _slots[ScaffoldSlots.floatingActionButton];
-      Size area = new Size(size.width - kButtonX, size.height - kButtonY);
-      floatingActionButton.layout(new BoxConstraints.loose(area), parentUsesSize: true);
-      assert(floatingActionButton.parentData is BoxParentData);
-      floatingActionButton.parentData.position = (area - floatingActionButton.size).toPoint();
-    }
   }
 
   void paint(PaintingCanvas canvas, Offset offset) {
-    for (ScaffoldSlots slot in [ScaffoldSlots.body, ScaffoldSlots.statusBar, ScaffoldSlots.toolbar, ScaffoldSlots.floatingActionButton, ScaffoldSlots.drawer]) {
+    for (ScaffoldSlots slot in ScaffoldSlots.values) {
       RenderBox box = _slots[slot];
       if (box != null) {
         assert(box.parentData is BoxParentData);
         canvas.paintChild(box, box.parentData.position + offset);
       }
     }
   }
 
   void hitTestChildren(HitTestResult result, { Point position }) {
-    for (ScaffoldSlots slot in [ScaffoldSlots.drawer, ScaffoldSlots.floatingActionButton, ScaffoldSlots.toolbar, ScaffoldSlots.statusBar, ScaffoldSlots.body]) {
+    for (ScaffoldSlots slot in ScaffoldSlots.values.reversed) {
       RenderBox box = _slots[slot];
       if (box != null) {
         assert(box.parentData is BoxParentData);
         if ((box.parentData.position & box.size).contains(position)) {
           if (box.hitTest(result, position: (position - box.parentData.position).toPoint()))
             return;
         }
       }
     }
   }
 
   String debugDescribeChildren(String prefix) {
     return _slots.keys.map((slot) => '${prefix}${slot}: ${_slots[slot].toString(prefix)}').join();
   }
 }
 
 class Scaffold extends RenderObjectWrapper {
 
-  // static final Style _style = new Style('''
-  //   ${typography.typeface};
-  //   ${typography.black.body1};''');
-
   Scaffold({
     String key,
-    Widget toolbar,
     Widget body,
     Widget statusBar,
-    Widget drawer,
-    Widget floatingActionButton
-  }) : _toolbar = toolbar,
-       _body = body,
-       _statusBar = statusBar,
-       _drawer = drawer,
-       _floatingActionButton = floatingActionButton,
-       super(key: key);
+    Widget toolbar,
+    Widget snackBar,
+    Widget floatingActionButton,
+    Widget drawer
+  }) : super(key: key) {
+    this[ScaffoldSlots.body] = body;
+    this[ScaffoldSlots.statusBar] = statusBar;
+    this[ScaffoldSlots.toolbar] = toolbar;
+    this[ScaffoldSlots.snackBar] = snackBar;
+    this[ScaffoldSlots.floatingActionButton] = floatingActionButton;
+    this[ScaffoldSlots.drawer] = drawer;
+  }
 
-  Widget _toolbar;
-  Widget _body;
-  Widget _statusBar;
-  Widget _drawer;
-  Widget _floatingActionButton;
+  Map<ScaffoldSlots, Widget> _slots = new Map<ScaffoldSlots, Widget>();
+  Widget operator[] (ScaffoldSlots slot) => _slots[slot];
+  void operator[]= (ScaffoldSlots slot, Widget value) {
+    _slots[slot] = value;
+  }
 
   RenderScaffold get root => super.root;
   RenderScaffold createNode() => new RenderScaffold();
 
   void walkChildren(WidgetTreeWalker walker) {
-    if (_toolbar != null)
-      walker(_toolbar);
-    if (_body != null)
-      walker(_body);
-    if (_statusBar != null)
-      walker(_statusBar);
-    if (_drawer != null)
-      walker(_drawer);
-    if (_floatingActionButton != null)
-      walker(_floatingActionButton);
+    for (ScaffoldSlots slot in ScaffoldSlots.values) {
+      Widget widget = _slots[slot];
+      if (widget != null)
+        walker(widget);
+    }
   }
 
   void insertChildRoot(RenderObjectWrapper child, ScaffoldSlots slot) {
     root[slot] = child != null ? child.root : null;
   }
 
   void detachChildRoot(RenderObjectWrapper child) {
     final root = this.root; // TODO(ianh): Remove this once the analyzer is cleverer
     assert(root is RenderScaffold);
     assert(root == child.root.parent);
     root.remove(child.root);
     assert(root == this.root); // TODO(ianh): Remove this once the analyzer is cleverer
   }
 
   void remove() {
     walkChildren((Widget child) => removeChild(child));
     super.remove();
   }
 
   void syncRenderObject(Widget old) {
     super.syncRenderObject(old);
-    _toolbar = syncChild(_toolbar, old is Scaffold ? old._toolbar : null, ScaffoldSlots.toolbar);
-    _body = syncChild(_body, old is Scaffold ? old._body : null, ScaffoldSlots.body);
-    _statusBar = syncChild(_statusBar, old is Scaffold ? old._statusBar : null, ScaffoldSlots.statusBar);
-    _drawer = syncChild(_drawer, old is Scaffold ? old._drawer : null, ScaffoldSlots.drawer);
-    _floatingActionButton = syncChild(_floatingActionButton, old is Scaffold ? old._floatingActionButton : null, ScaffoldSlots.floatingActionButton);
+    for (ScaffoldSlots slot in ScaffoldSlots.values) {
+      Widget widget = this[slot];
+      this[slot] = syncChild(widget, old is Scaffold ? old[slot] : null, slot);
+    }
   }
 
 }