feat(partition): add 4.5 contrast for text in partition slices (#608)

Updates partition charts to allow for adaptive text color to meet acceptable color contrast ratio. For more information on text contrast see [docs](https://github.com/elastic/elastic-charts/blob/master/docs/0-Intro/1-Overview.mdx#background-colors-and-text-contrast).

BREAKING CHANGE
Adds `background` to the `Theme` object with the `BackgroundStyle` type that accepts a `color` value as a `string. Note text color might be different after changes from this PR, see docs on how to disable `textContrast` in the partition chart config.

Closes #606

.playground/playground.tsx

@@ -17,7 +17,7 @@
  * under the License. */
 
 import React from 'react';
-import { Example } from '../stories/treemap/6_custom_style';
+import { Example } from '../stories/stylings/20_partition_background';
 
 export class Playground extends React.Component {
   render() {

api/charts.api.md

@@ -176,6 +176,11 @@ export interface AxisStyle {
     tickLabelPadding?: number;
 }
 
+// @public
+export interface BackgroundStyle {
+    color: string;
+}
+
 // Warning: (ae-forgotten-export) The symbol "SpecRequiredProps" needs to be exported by the entry point index.d.ts
 // Warning: (ae-forgotten-export) The symbol "SpecOptionalProps" needs to be exported by the entry point index.d.ts
 // Warning: (ae-missing-release-tag) "BarSeries" is exported by the package, but it is missing a release tag (@alpha, @beta, @public, or @internal)
@@ -1403,6 +1408,7 @@ export interface Theme {
     areaSeriesStyle: AreaSeriesStyle;
     // (undocumented)
     axes: AxisConfig;
+    background: BackgroundStyle;
     barSeriesStyle: BarSeriesStyle;
     bubbleSeriesStyle: BubbleSeriesStyle;
     chartMargins: Margins;
@@ -1534,8 +1540,8 @@ export interface XYChartSeriesIdentifier extends SeriesIdentifier {
 
 // Warnings were encountered during analysis:
 //
-// src/chart_types/partition_chart/layout/types/config_types.ts:117:5 - (ae-forgotten-export) The symbol "TimeMs" needs to be exported by the entry point index.d.ts
-// src/chart_types/partition_chart/layout/types/config_types.ts:118:5 - (ae-forgotten-export) The symbol "AnimKeyframe" needs to be exported by the entry point index.d.ts
+// src/chart_types/partition_chart/layout/types/config_types.ts:120:5 - (ae-forgotten-export) The symbol "TimeMs" needs to be exported by the entry point index.d.ts
+// src/chart_types/partition_chart/layout/types/config_types.ts:121:5 - (ae-forgotten-export) The symbol "AnimKeyframe" needs to be exported by the entry point index.d.ts
 // src/chart_types/partition_chart/specs/index.ts:47:13 - (ae-forgotten-export) The symbol "NodeColorAccessor" needs to be exported by the entry point index.d.ts
 // src/commons/series_id.ts:37:3 - (ae-forgotten-export) The symbol "SeriesKey" needs to be exported by the entry point index.d.ts
 

docs/0-Intro/1-Overview.mdx

@@ -1,3 +1,17 @@
+import { Chart, Datum, Partition, PartitionLayout, Settings } from '../../src';
+import { mocks } from '../../src/mocks/hierarchical/index';
+import { config } from '../../src/chart_types/partition_chart/layout/config/config';
+import { ShapeTreeNode } from '../../src/chart_types/partition_chart/layout/types/viewmodel_types';
+import {
+  categoricalFillColor,
+  colorBrewerCategoricalStark9,
+  countryLookup,
+  indexInterpolatedFillColor,
+  interpolatorCET2s,
+  interpolatorTurbo,
+  productLookup,
+  regionLookup,
+} from '../../stories/utils/utils';
 import { Meta, Story } from "@storybook/addon-docs/blocks";
 
 <Meta title="Introduction/Elastic Charts Overview" />
@@ -255,3 +269,155 @@ type PointStyleAccessor = (
 ```
 
 > Note: When overriding bar or point styles be mindful of performance and these accessor functions will be call on every bar/point is every series. Precomputing any expensive task before rendering.
+
+### Background Colors and Text Contrast
+You can provide the `backgroundColor` of the container that the chart will be placed onto. You can set the `textContrast` to a boolean value or a number. The default `textContrast` is set to 4.5 but you can always disable this or set your own numerical amount.
+
+> Note: This functionality is currently available for Partition charts. Please see the partition background and partition label stories.
+
+```js
+config: {
+  fillLabel: {
+    textInvertible: true,
+    textContrast: true, // can also be set to a number
+  }
+}
+```
+`textInvertible` will have to be set to true for `textContrast` to be set as well. To see an example of where this applies, please see the Partitions Background story within Stylings. Charts are included below but are static. 
+If you have `textInvertible` set to true, but do not have `textContrast` set to true, then the red slices, Europe, North America, and Asia, will have white text:
+
+<Chart className="story-chart">
+  <Settings theme={{background : {color: `rgba(155, 155, 155, 1)`}}} />
+  <Partition
+    id="spec_1"
+    data={mocks.miniSunburst}
+    valueAccessor={(d) => d.exportVal}
+    valueFormatter={(d) => `$${config.fillLabel.valueFormatter(Math.round(d / 1000000000))}\xa0Bn`}
+    layers={[
+      {
+        groupByRollup: (d) => d.sitc1,
+        nodeLabel: (d) => productLookup[d].name,
+        shape: {
+          fillColor: (d) => {
+            return categoricalFillColor(colorBrewerCategoricalStark9, 0.7)(d.sortIndex);
+          },
+        },
+      },
+      {
+        groupByRollup: (d) => countryLookup[d.dest].continentCountry.substr(0, 2),
+        nodeLabel: (d) => regionLookup[d].regionName,
+        shape: {
+          fillColor: (d) => {
+            return categoricalFillColor(colorBrewerCategoricalStark9, 0.5)(d.parent.sortIndex);
+          },
+        },
+      },
+      {
+        groupByRollup: (d) => d.dest,
+        nodeLabel: (d) => countryLookup[d].name,
+        shape: {
+          fillColor: (d) => {
+            return categoricalFillColor(colorBrewerCategoricalStark9, 0.3)(d.parent.parent.sortIndex);
+          },
+        },
+      },
+    ]}
+    config={{
+      partitionLayout: PartitionLayout.sunburst,
+      linkLabel: {
+        maxCount: 0,
+        fontSize: 14,
+      },
+      fontFamily: 'Arial',
+      fillLabel: {
+        valueFormatter: (d) => `$${config.fillLabel.valueFormatter(Math.round(d / 1000000000))}\xa0Bn`,
+        fontStyle: 'italic',
+        textInvertible: true,
+        textContrast: false,
+        fontWeight: 900,
+        valueFont: {
+          fontFamily: 'Menlo',
+          fontStyle: 'normal',
+          fontWeight: 100,
+        },
+      },
+      margin: { top: 0, bottom: 0, left: 0, right: 0 },
+      minFontSize: 1,
+      idealFontSizeJump: 1.1,
+      outerSizeRatio: 1,
+      emptySizeRatio: 0,
+      circlePadding: 4,
+      backgroundColor: 'rgba(229,229,229,1)',
+    }}
+  />
+</Chart>
+
+
+
+Now if you set the `textContrast` to true as well, these slices also become black in text color: 
+
+<Chart className="story-chart">
+  <Settings theme={{background : {color: `rgba(155, 155, 155, 1)`}}} />
+  <Partition
+    id="spec_1"
+    data={mocks.miniSunburst}
+    valueAccessor={(d) => d.exportVal}
+    valueFormatter={(d) => `$${config.fillLabel.valueFormatter(Math.round(d / 1000000000))}\xa0Bn`}
+    layers={[
+      {
+        groupByRollup: (d) => d.sitc1,
+        nodeLabel: (d) => productLookup[d].name,
+        shape: {
+          fillColor: (d) => {
+            return categoricalFillColor(colorBrewerCategoricalStark9, 0.7)(d.sortIndex);
+          },
+        },
+      },
+      {
+        groupByRollup: (d) => countryLookup[d.dest].continentCountry.substr(0, 2),
+        nodeLabel: (d) => regionLookup[d].regionName,
+        shape: {
+          fillColor: (d) => {
+            return categoricalFillColor(colorBrewerCategoricalStark9, 0.5)(d.parent.sortIndex);
+          },
+        },
+      },
+      {
+        groupByRollup: (d) => d.dest,
+        nodeLabel: (d) => countryLookup[d].name,
+        shape: {
+          fillColor: (d) => {
+            return categoricalFillColor(colorBrewerCategoricalStark9, 0.3)(d.parent.parent.sortIndex);
+          },
+        },
+      },
+    ]}
+    config={{
+      partitionLayout: PartitionLayout.sunburst,
+      linkLabel: {
+        maxCount: 0,
+        fontSize: 14,
+      },
+      fontFamily: 'Arial',
+      fillLabel: {
+        valueFormatter: (d) => `$${config.fillLabel.valueFormatter(Math.round(d / 1000000000))}\xa0Bn`,
+        fontStyle: 'italic',
+        textInvertible: true,
+        textContrast: true,
+        fontWeight: 900,
+        valueFont: {
+          fontFamily: 'Menlo',
+          fontStyle: 'normal',
+          fontWeight: 100,
+        },
+      },
+      margin: { top: 0, bottom: 0, left: 0, right: 0 },
+      minFontSize: 1,
+      idealFontSizeJump: 1.1,
+      outerSizeRatio: 1,
+      emptySizeRatio: 0,
+      circlePadding: 4,
+      backgroundColor: 'rgba(229,229,229,1)',
+    }}
+  />
+</Chart>

package.json

@@ -83,7 +83,9 @@
     "@storybook/react": "5.2.8",
     "@storybook/source-loader": "^5.3.9",
     "@storybook/theming": "^5.2.8",
+    "@types/chroma-js": "^2.0.0",
     "@types/classnames": "^2.2.7",
+    "@types/color": "^3.0.1",
     "@types/core-js": "^2.5.2",
     "@types/d3-array": "^1.2.6",
     "@types/d3-collection": "^1.0.8",
@@ -170,6 +172,7 @@
     "webpack-dev-server": "^3.3.1"
   },
   "dependencies": {
+    "chroma-js": "^2.1.0",
     "@popperjs/core": "^2.4.0",
     "classnames": "^2.2.6",
     "d3-array": "^1.2.4",

src/chart_types/partition_chart/layout/config/config.ts

@@ -173,8 +173,9 @@ export const configMetadata = {
   fillLabel: {
     type: 'group',
     values: {
-      textColor: { dflt: '#000000', type: 'color' },
+      textColor: { type: 'color', dflt: '#000000' },
       textInvertible: { dflt: false, type: 'boolean' },
+      textContrast: { dflt: false, type: 'boolean' || 'number' },
       ...fontSettings,
       valueGetter: {
         dflt: sumValueGetter,
@@ -221,6 +222,7 @@ export const configMetadata = {
       },
       textColor: { dflt: '#000000', type: 'color' },
       textInvertible: { dflt: false, type: 'boolean' },
+      textContrast: { dflt: false, type: 'boolean' || 'number' },
       textOpacity: { dflt: 1, min: 0, max: 1, type: 'number' },
       minimumStemLength: {
         dflt: 0,

src/chart_types/partition_chart/layout/types/config_types.ts

@@ -33,9 +33,12 @@ export type PerSidePadding = PerSideDistance;
 
 export type Padding = Pixels | Partial<PerSidePadding>;
 
+export type TextContrast = boolean | number;
+
 interface LabelConfig extends Font {
   textColor: Color;
   textInvertible: boolean;
+  textContrast: TextContrast;
   textOpacity: Ratio;
   valueFormatter: ValueFormatter;
   valueFont: PartialFont;

src/chart_types/partition_chart/layout/types/types.ts

@@ -43,6 +43,8 @@ export interface Font {
   fontVariant: FontVariant;
   fontWeight: FontWeight;
   fontFamily: FontFamily;
+  textColor: string;
+  textOpacity: number;
 }
 
 export type PartialFont = Partial<Font>;

src/chart_types/partition_chart/layout/types/viewmodel_types.ts

@@ -22,20 +22,19 @@ import { Font } from './types';
 import { config, ValueGetterName } from '../config/config';
 import { ArrayNode, HierarchyOfArrays } from '../utils/group_by_rollup';
 import { Color } from '../../../../utils/commons';
+import { LinkLabelsViewModelSpec } from '../viewmodel/link_text_layout';
 import { VerticalAlignments } from '../viewmodel/viewmodel';
 
 /** @internal */
 export type LinkLabelVM = {
-  link: PointTuples;
+  linkLabels: PointTuples;
   translate: PointTuple;
   textAlign: CanvasTextAlign;
   text: string;
   valueText: string;
   width: Distance;
   valueWidth: Distance;
   verticalOffset: Distance;
-  labelFontSpec: Font;
-  valueFontSpec: Font;
 };
 
 /** @internal */
@@ -95,19 +94,33 @@ export type ShapeViewModel = {
   config: Config;
   quadViewModel: QuadViewModel[];
   rowSets: RowSet[];
-  linkLabelViewModels: LinkLabelVM[];
+  linkLabelViewModels: LinkLabelsViewModelSpec;
   outsideLinksViewModel: OutsideLinksViewModel[];
   diskCenter: PointObject;
   pickQuads: PickFunction;
   outerRadius: number;
 };
 
+const defaultFont: Font = {
+  fontStyle: 'normal',
+  fontVariant: 'normal',
+  fontFamily: '',
+  fontWeight: 'normal',
+  textColor: 'black',
+  textOpacity: 1,
+};
+
 /** @internal */
 export const nullShapeViewModel = (specifiedConfig?: Config, diskCenter?: PointObject): ShapeViewModel => ({
   config: specifiedConfig || config,
   quadViewModel: [],
   rowSets: [],
-  linkLabelViewModels: [],
+  linkLabelViewModels: {
+    linkLabels: [],
+    labelFontSpec: defaultFont,
+    valueFontSpec: defaultFont,
+    strokeColor: '',
+  },
   outsideLinksViewModel: [],
   diskCenter: diskCenter || { x: 0, y: 0 },
   pickQuads: () => [],

src/chart_types/partition_chart/layout/utils/__mocks__/calcs.ts

@@ -0,0 +1,21 @@
+/*
+ * Licensed to Elasticsearch B.V. under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch B.V. licenses this file to you 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. */
+const module = jest.requireActual('../calcs.ts');
+
+export const getBackgroundWithContainerColorFromUser = jest.fn(module.getBackgroundWithContainerColorFromUser);
+export const makeHighContrastColor = jest.fn(module.makeHighContrastColor);

src/chart_types/partition_chart/layout/utils/__mocks__/d3_utils.ts → src/chart_types/partition_chart/layout/utils/__mocks__/color_library_wrappers.ts

@@ -16,7 +16,7 @@
  * specific language governing permissions and limitations
  * under the License. */
 
-const module = jest.requireActual('../d3_utils.ts');
+const module = jest.requireActual('../color_library_wrappers.ts');
 
 export const defaultColor = module.defaultColor;
 export const transparentColor = module.transparentColor;

src/chart_types/partition_chart/layout/utils/__mocks__/fill_text_layout.ts

@@ -0,0 +1,20 @@
+/*
+ * Licensed to Elasticsearch B.V. under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch B.V. licenses this file to you 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. */
+const module = jest.requireActual('../../viewmodel/fill_text_layout.ts');
+
+export const getTextColorIfTextInvertible = jest.fn(module.getTextColorIfTextInvertible);