Updated charted DEP to 0.4.X

packages/charted/lib/charts/cartesian_renderers/bar_chart_renderer.dart

 //
 // Copyright 2014 Google Inc. All rights reserved.
 //
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file or at
 // https://developers.google.com/open-source/licenses/bsd
 //
 
 part of charted.charts;
 
@@ skipping 29 matching lines @@
     var rows = new List()
       ..addAll(area.data.rows.map((e) => new List.generate(
           measuresCount, (i) => e[series.measures.elementAt(i)])));
 
     var dimensionVals = area.data.rows
         .map((row) => row.elementAt(area.config.dimensions.first))
         .toList();
 
     var bars = new OrdinalScale()
       ..domain = new Range(series.measures.length).toList()
-      ..rangeRoundBands([0, dimensionScale.rangeBand]);
+      ..rangeRoundBands([0, (dimensionScale as OrdinalScale).rangeBand]);
 
     // Create and update the bar groups.
 
     var groups = root.selectAll('.bar-rdr-rowgroup').data(rows);
     var animateBarGroups = alwaysAnimate || !groups.isEmpty;
 
     groups.enter.append('g')
       ..classed('bar-rdr-rowgroup')
       ..attrWithCallback(
           'transform',
@@ skipping 27 matching lines @@
     var bar =
         groups.selectAll('.bar-rdr-bar').dataWithCallback((d, i, c) => rows[i]),
         scaled0 = measureScale.scale(0).round();
 
     var getBarLength = (d) {
       var scaledVal = measureScale.scale(d).round(),
           ht = verticalBars
               ? (d >= 0 ? scaled0 - scaledVal : scaledVal - scaled0)
               : (d >= 0 ? scaledVal - scaled0 : scaled0 - scaledVal);
       ht = ht - strokeWidth;
-      return (ht < 0) ? 0 : ht;
+
+      // If bar would be scaled to 0 height but data is not 0, render bar
+      // at 1 pixel so user can see and hover over to see the data.
+      return (ht < 0) ? 1 : ht;
     };
     var getBarPos = (d) {
       var scaledVal = measureScale.scale(d).round();
+
+      // If bar would be scaled to 0 height but data is not 0, reserve 1 pixel
+      // height plus strokeWidthOffset to position the bar.
+      if (scaledVal == scaled0) {
+        return verticalBars
+            ? d > 0
+                ? scaled0 - 1 - strokeWidthOffset
+                : scaled0 + strokeWidthOffset
+            : d > 0
+                ? scaled0 + strokeWidthOffset
+                : scaled0 - 1 - strokeWidthOffset;
+      }
       return verticalBars
           ? (d >= 0 ? scaledVal : scaled0) + strokeWidthOffset
           : (d >= 0 ? scaled0 : scaledVal) + strokeWidthOffset;
     };
     var buildPath = (d, int i, bool animate) {
+      // If data is null or 0, an empty path for the bar is returned directly.
       if (d == null || d == 0) return '';
       if (verticalBars) {
         var fn = d > 0 ? topRoundedRect : bottomRoundedRect;
         return fn(
             bars.scale(i).toInt() + strokeWidthOffset,
             animate ? rect.height : getBarPos(d),
             barWidth,
             animate ? 0 : getBarLength(d),
             RADIUS);
       } else {
@@ skipping 114 matching lines @@
   }
 
   void _event(StreamController controller, data, int index, Element e) {
     if (controller == null) return;
     var rowStr = e.parent.dataset['row'];
     var row = rowStr != null ? int.parse(rowStr) : null;
     controller.add(new DefaultChartEventImpl(scope.event, area, series, row,
         series.measures.elementAt(index), data));
   }
 }