Changed interfaces to abstract classes where possible in {lib,samples,pkg}

samples/swarm/Views.dart

 // Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 // This file contains View framework classes.
 // As it grows, it may need to be split into multiple files.
 
 /** A factory that creates a view from a data model. */
-interface ViewFactory<D> {
+abstract class ViewFactory<D> {
   View newView(D item);
 
   /** The width of the created view or null if the width is not fixed. */
   int get width;
 
   /** The height of the created view or null if the height is not fixed. */
   int get height;
 }
 
-interface VariableSizeViewFactory<D> {
+abstract class VariableSizeViewFactory<D> {
   View newView(D item);
 
   /** The width of the created view for a specific data model. */
   int getWidth(D item);
 
   /** The height of the created view for a specific data model. */
   int getHeight(D item);
 }
 
 /** A collection of event listeners. */
@@ skipping 21 matching lines @@
  */
 class _PlaceholderView extends View {
   _PlaceholderView() : super() {}
 
   Element render() => new Element.tag('div');
 }
 
 /**
  * Class providing all metrics required to layout a data driven list view.
  */
-interface ListViewLayout<D> {
+abstract class ListViewLayout<D> {
   void onDataChange();
 
   // TODO(jacobr): placing the newView member function on this class seems like
   // the wrong design.
   View newView(int index);
   /** Get the height of the view. Possibly expensive to compute. */
   int getHeight(int viewLength);
   /** Get the width of the view. Possibly expensive to compute. */
   int getWidth(int viewLength);
   /** Get the length of the view. Possible expensive to compute. */
@@ skipping 218 matching lines @@
   void onResize() {
     int lastViewLength = _viewLength;
     node.rect.then((ElementRect rect) {
       _viewLength = _vertical ? rect.offset.height : rect.offset.width;
       if (_viewLength != lastViewLength) {
         if (_scrollbar != null) {
           _scrollbar.refresh();
         }
         renderVisibleItems(true);
       }
-    }); 
+    });
   }
 
   void enterDocument() {
     if (scroller != null) {
       onResize();
 
       if (_scrollbar != null) {
         _scrollbar.initialize();
       }
     }
@@ skipping 12 matching lines @@
 
   void _decelStart() {
     num currentTarget = scroller.verticalEnabled ?
         scroller.currentTarget.y : scroller.currentTarget.x;
     num current = scroller.verticalEnabled ?
         scroller.contentOffset.y : scroller.contentOffset.x;
     num targetIndex = _layout.getSnapIndex(currentTarget, _viewLength);
     if (current != currentTarget) {
       // The user is throwing rather than statically releasing.
       // For this case, we want to move them to the next snap interval
-      // as long as they made at least a minimal throw gesture. 
+      // as long as they made at least a minimal throw gesture.
       num currentIndex = _layout.getSnapIndex(current, _viewLength);
-      if (currentIndex == targetIndex && 
+      if (currentIndex == targetIndex &&
         (currentTarget - current).abs() > SNAP_TO_NEXT_THROW_THRESHOLD &&
         -_layout.getOffset(targetIndex) != currentTarget) {
         num snappedCurrentPosition = -_layout.getOffset(targetIndex);
         targetIndex = getNextIndex(targetIndex, currentTarget < current);
       }
     }
     num targetPosition = -_layout.getOffset(targetIndex);
     if (currentTarget != targetPosition) {
       if (scroller.verticalEnabled) {
         scroller.throwTo(scroller.contentOffset.x, targetPosition);
@@ skipping 26 matching lines @@
       _throwTo(_layout.getOffset(
           _layout.getPageStartIndex(_pages.target.value, _viewLength)));
     }
   }
 
   num get _offset {
     return scroller.verticalEnabled ?
         scroller.getVerticalOffset() : scroller.getHorizontalOffset();
   }
 
-  /** 
+  /**
    * Calculates visible interval, based on the scroller position.
    */
   Interval getVisibleInterval() {
     return _layout.computeVisibleInterval(_offset, _viewLength, 0);
   }
 
   void renderVisibleItems(bool lengthChanged) {
     Interval targetInterval;
     if (scroller != null) {
       targetInterval = getVisibleInterval();
@@ skipping 64 matching lines @@
     return view;
   }
 
   View _addView(int index) {
     if (_itemViews.containsKey(index)) {
       final view = _itemViews[index];
       _addViewHelper(view, index);
       childViewAdded(view);
      return view;
     }
- 
+
     final view = _newView(index);
     _itemViews[index] = view;
     // TODO(jacobr): its ugly to put this here... but its needed
     // as typical even-odd css queries won't work as we only display some
     // children at a time.
     if (index == 0) {
       view.addClass('first-child');
     }
     _selectHelper(view, _data[index] == _lastSelectedItem);
     // The order of the child elements doesn't matter as we use absolute
     // positioning.
     _addViewHelper(view, index);
     childViewAdded(view);
     return view;
   }
- 
+
   void _addViewHelper(View view, int index) {
     _positionSubview(view.node, index);
     // The view might already be attached.
     if (view.node.parent != _containerElem) {
       _containerElem.nodes.add(view.node);
     }
   }
 
   /**
    * Detach a subview from the view replacing it with an empty placeholder view.
@@ skipping 121 matching lines @@
   void onDataChange() {}
 
   View newView(int index) {
     return itemViewFactory.newView(_data[index]);
   }
 
   int get _itemLength {
     return _vertical ? itemViewFactory.height : itemViewFactory.width;
   }
 
- 
+
   int getWidth(int viewLength) {
     return _vertical ? itemViewFactory.width : getLength(viewLength);
   }
- 
+
   int getHeight(int viewLength) {
     return _vertical ? getLength(viewLength) : itemViewFactory.height;
   }
 
   int getEstimatedHeight(int viewLength) {
     // Returns the exact height as it is trivial to compute for this layout.
     return getHeight(viewLength);
   }
 
   int getEstimatedWidth(int viewLength) {
@@ skipping 226 matching lines @@
     int start = _findFirstItemBefore(
         -offset - bufferLength,
         _lastVisibleInterval != null ? _lastVisibleInterval.start : 0);
     int end = _findFirstItemAfter(
         -offset + viewLength + bufferLength,
         _lastVisibleInterval != null ? _lastVisibleInterval.end : 0);
     _lastVisibleInterval = new Interval(start, Math.max(start, end));
     _lastOffset = offset;
     return _lastVisibleInterval;
   }
- 
+
   int _findFirstItemAfter(num target, int hint) {
     for (int i = 0; i < _data.length; i++) {
       if (getOffset(i) > target) {
         return i;
       }
     }
     return _data.length;
   }
 
   // TODO(jacobr): use hint.
@@ skipping 89 matching lines @@
 
     container = node.query('.dialog-body');
     container.nodes.add(_content.node);
 
     return node;
   }
 
   /** Override to handle dialog done. */
   void onDone() { }
 }