Update web/ samples to work with Flutter SDK (#134)

* add package:http dependency in dad_jokes

* add package:http dependency in filipino_cuisine

* don't build package:http demos until flutter/flutter#34858 is resolved

* update gallery

* update github_dataviz

* update particle_background

* don't build github_dataviz (uses package:http)

* update slide_puzzle

* update spinning_square

* update timeflow

* update vision_challenge

* update charts

* update dad_jokes

* update filipino cuisine

* ignore build output

* update timeflow and vision_challenge

* update slide_puzzle

* don't commit build/ directory

* move preview.png images to assets

* fix path url join

* update readme

* update web/readme.md

web/charts/lib/line_chart/range_annotation_margin.dart

@@ -0,0 +1,141 @@
+// Copyright 2018 the Charts project authors. Please see the AUTHORS file
+// for details.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+/// Example of a line chart with range annotations configured to render labels
+/// in the chart margin area.
+// EXCLUDE_FROM_GALLERY_DOCS_START
+import 'dart:math';
+// EXCLUDE_FROM_GALLERY_DOCS_END
+import 'package:charts_flutter/flutter.dart' as charts;
+import 'package:flutter/material.dart';
+
+class LineRangeAnnotationMarginChart extends StatelessWidget {
+  final List<charts.Series> seriesList;
+  final bool animate;
+
+  LineRangeAnnotationMarginChart(this.seriesList, {this.animate});
+
+  /// Creates a [LineChart] with sample data and range annotations.
+  ///
+  /// The second annotation extends beyond the range of the series data,
+  /// demonstrating the effect of the [Charts.RangeAnnotation.extendAxis] flag.
+  /// This can be set to false to disable range extension.
+  factory LineRangeAnnotationMarginChart.withSampleData() {
+    return new LineRangeAnnotationMarginChart(
+      _createSampleData(),
+      // Disable animations for image tests.
+      animate: false,
+    );
+  }
+
+  // EXCLUDE_FROM_GALLERY_DOCS_START
+  // This section is excluded from being copied to the gallery.
+  // It is used for creating random series data to demonstrate animation in
+  // the example app only.
+  factory LineRangeAnnotationMarginChart.withRandomData() {
+    return new LineRangeAnnotationMarginChart(_createRandomData());
+  }
+
+  /// Create random data.
+  static List<charts.Series<LinearSales, num>> _createRandomData() {
+    final random = new Random();
+
+    final data = [
+      new LinearSales(0, random.nextInt(100)),
+      new LinearSales(1, random.nextInt(100)),
+      new LinearSales(2, random.nextInt(100)),
+      // Fix one of the points to 100 so that the annotations are consistently
+      // placed.
+      new LinearSales(3, 100),
+    ];
+
+    return [
+      new charts.Series<LinearSales, int>(
+        id: 'Sales',
+        domainFn: (LinearSales sales, _) => sales.year,
+        measureFn: (LinearSales sales, _) => sales.sales,
+        data: data,
+      )
+    ];
+  }
+  // EXCLUDE_FROM_GALLERY_DOCS_END
+
+  @override
+  Widget build(BuildContext context) {
+    return new charts.LineChart(seriesList,
+        animate: animate,
+
+        // Allow enough space in the left and right chart margins for the
+        // annotations.
+        layoutConfig: new charts.LayoutConfig(
+            leftMarginSpec: new charts.MarginSpec.fixedPixel(60),
+            topMarginSpec: new charts.MarginSpec.fixedPixel(20),
+            rightMarginSpec: new charts.MarginSpec.fixedPixel(60),
+            bottomMarginSpec: new charts.MarginSpec.fixedPixel(20)),
+        behaviors: [
+          // Define one domain and two measure annotations configured to render
+          // labels in the chart margins.
+          new charts.RangeAnnotation([
+            new charts.RangeAnnotationSegment(
+                0.5, 1.0, charts.RangeAnnotationAxisType.domain,
+                startLabel: 'D1 Start',
+                endLabel: 'D1 End',
+                labelAnchor: charts.AnnotationLabelAnchor.end,
+                color: charts.MaterialPalette.gray.shade200,
+                // Override the default vertical direction for domain labels.
+                labelDirection: charts.AnnotationLabelDirection.horizontal),
+            new charts.RangeAnnotationSegment(
+                15, 20, charts.RangeAnnotationAxisType.measure,
+                startLabel: 'M1 Start',
+                endLabel: 'M1 End',
+                labelAnchor: charts.AnnotationLabelAnchor.end,
+                color: charts.MaterialPalette.gray.shade300),
+            new charts.RangeAnnotationSegment(
+                35, 65, charts.RangeAnnotationAxisType.measure,
+                startLabel: 'M2 Start',
+                endLabel: 'M2 End',
+                labelAnchor: charts.AnnotationLabelAnchor.start,
+                color: charts.MaterialPalette.gray.shade400),
+          ], defaultLabelPosition: charts.AnnotationLabelPosition.margin),
+        ]);
+  }
+
+  /// Create one series with sample hard coded data.
+  static List<charts.Series<LinearSales, int>> _createSampleData() {
+    final data = [
+      new LinearSales(0, 5),
+      new LinearSales(1, 25),
+      new LinearSales(2, 100),
+      new LinearSales(3, 75),
+    ];
+
+    return [
+      new charts.Series<LinearSales, int>(
+        id: 'Sales',
+        domainFn: (LinearSales sales, _) => sales.year,
+        measureFn: (LinearSales sales, _) => sales.sales,
+        data: data,
+      )
+    ];
+  }
+}
+
+/// Sample linear data type.
+class LinearSales {
+  final int year;
+  final int sales;
+
+  LinearSales(this.year, this.sales);
+}