[Doc] Document charts plugin (opensearch-project#2695)

- Update README with full capabilities
- Add `current_usage` to track current usage

Signed-off-by: Josh Romero <rmerqg@amazon.com>

CHANGELOG.md

@@ -77,6 +77,7 @@ Inspired from [Keep a Changelog](https://keepachangelog.com/en/1.0.0/)
 - Add the release runbook to RELEASING.md ([#2533](https://github.com/opensearch-project/OpenSearch-Dashboards/pull/2533))
 - [MD] Add design documents of multiple data source feature [#2538](https://github.com/opensearch-project/OpenSearch-Dashboards/pull/2538)
 - [MD] Tweak multiple data source design doc [#2724](https://github.com/opensearch-project/OpenSearch-Dashboards/pull/2724)
+- Add `current-usage.md` and more details to `README.md` of `charts` plugin ([#2695](https://github.com/opensearch-project/OpenSearch-Dashboards/pull/2695))
 
 ### 🛠 Maintenance
 

docs/charts/current_usage.md

@@ -0,0 +1,184 @@
+# Usage
+
+The purpose of this doc is to keep track of the current (as of 2022-11-14) usage of the [charts plugin](../../src/plugins/charts/), as well as other packages and tools with similar purposes. See https://github.com/opensearch-project/OpenSearch-Dashboards/issues/2830 for more information on future plans.
+
+## Lifecycle methods/services
+
+### `ChartsPluginStart`
+
+1. `ChartsPluginStart['theme']` used by `discover` plugin to fetch `chartsTheme` and `chartsBaseTheme` for use in styling the histogram.
+
+### `ChartsPluginSetup`
+
+1. `ChartsPluginSetup` declared as one of `MetricVisPluginSetupDependencies` in the `vis_type_metric` plugin, but isn't actually used.
+2. `ChartsPluginSetup['colors']` used by `vis_type_tagcloud` plugin. Only the seed colors are used via `d3.scale.ordinal().range(colors.seedColors)`
+3. `ChartsPluginSetup.colors` and `ChartsPluginSetup.theme` used by the `vis_type_timeseries` plugin.
+	1. `themeService.useChartsBaseTheme()` is used only as a fallback; otherwise theme (dark or light) is calculated from the user-specified background color
+	2. `colors.mappedColors` used to fetch mapped colors only if user has not specified a color for a particular series label (and there's no color specified from the server).
+4. `ChartsPluginSetup.colors.createColorLookupFunction()` is used by the `vis_type_vislib` plugin, ultimately, as part of `getColorFunc()` and `getPieColorFunc()`; the former also uses fallback for default and overwritten colors from `uiState`.
+5. Set as a dependency in stub plugin `vis_type_xy`, but not actually used.
+
+## `uiSettings` in advanced settings `visualization:colorMapping`
+
+Appears to only be used by the telemetry plugin: https://github.com/opensearch-project/OpenSearch-Dashboards/blob/95f4fd5c6a6cd59bd555bf0ec120843ef6a93566/src/plugins/telemetry/schema/oss_plugins.json#L1363
+
+## Static functions and components
+
+### Color Maps
+
+#### `ColorMap` interface
+
+1. `region_map` plugin
+2. `tile_map` plugin
+3. `timeline` plugin
+4. `vis_type_metric` plugin
+5. `vis_type_timeline` plugin
+
+#### `ColorSchema` interface
+
+1. `maps_legacy` plugin
+2. `region_map` plugin
+3. `tile_map` plugin
+4. `vis_type_metric` plugin
+5. `vis_type_vislib` plugin
+6. `visualizations` plugin
+7. `visualize` plugin
+8. `vis_builder` plugin
+
+#### `ColorSchemas` enum
+
+1. `region_map` plugin
+2. `tile_map` plugin
+3. `vis_type_metric` plugin
+4. `vis_type_vislib` plugin
+5. `vis_builder` plugin
+
+#### `RawColorSchema` interface
+
+Not used by any core plugins
+
+#### `colorSchemas` array of objects
+
+1. `region_map` plugin
+2. `tile_map` plugin
+3. `vis_type_metric` plugin
+4. `vis_type_vislib` plugin
+5. `vis_builder` plugin
+
+#### `getHeatmapColors` function
+
+1. `vis_type_metric` plugin
+2. `vis_type_vislib` plugin
+
+#### `truncatedColorMaps` object
+
+1. `region_map` plugin
+2. `tile_map` plugin
+
+#### `truncatedColorSchemas` array of objects
+
+1. `region_map` plugin
+2. `tile_map` plugin
+
+#### `vislibColorMaps` object
+
+1. `vis_type_metric` plugin
+
+### React components
+
+These components may eventually make more sense elsewhere. See https://github.com/opensearch-project/OpenSearch-Dashboards/issues/2832 for one such proposal.
+
+#### `ColorModes` object
+
+1. `vis_type_metric` plugin
+2. `vis_type_vislib` plugin
+3. `vis_builder` plugin
+
+#### `Rotates` object
+
+1. `vis_type_vislib` plugin
+
+#### `BasicOptions` component
+
+1. `tile_map` plugin
+2. `vis_type_vislib` plugin
+3. `vis_builder` plugin
+
+#### `ColorRanges` component
+
+1. `vis_type_metric` plugin
+2. `vis_type_vislib` plugin
+3. `vis_builder` plugin
+
+#### `ColorSchemaOptions` component
+
+Accounts for customized `vis.colors` in the `uiState`. Supports setting custom colors via legend, and resetting.
+
+1. `vis_type_metric` plugin. Doesn't actually support custom colors
+2. `vis_type_vislib` plugin
+3. `vis_builder` plugin (metric visualization). Doesn't support custom colors
+
+#### `NumberInputOption` component
+
+1. `region_map` plugin
+2. `vis_type_table` plugin
+3. `vis_type_vislib` plugin
+
+#### `RangeOption` component
+
+1. `tile_map` plugin
+2. `vis_type_markdown` plugin
+3. `vis_type_metric` plugin
+4. `vis_type_timeseries` plugin
+5. `vis_builder` plugin
+
+#### `RequiredNumberInputOption` component
+
+1. `vis_type_vislib` plugin
+
+#### `SelectOption` component
+
+1. `index_pattern_management` plugin
+2. `maps_legacy` plugin
+3. `region_map` plugin
+4. `tile_map` plugin
+5. `vis_type_table` plugin
+6. `vis_type_tagcloud` plugin
+7. `vis_type_timeseries` plugin
+8. `vis_type_vislib` plugin
+9. `vis_builder` plugin
+
+#### `SwitchOption` component
+
+1. `maps_legacy` plugin
+2. `region_map` plugin
+3. `tile_map` plugin
+4. `vis_type_markdown` plugin
+5. `vis_type_metric` plugin
+6. `vis_type_table` plugin
+7. `vis_type_tagcloud` plugin
+8. `vis_type_vislib` plugin
+9. `vis_builder` plugin
+
+#### `TextInputOption` component
+
+1. `maps_legacy` plugin
+2. `vis_type_vislib` plugin
+
+# OUI chart colors
+
+An alternative to using color schemas and maps provided by the `charts` plugin is to use [color palettes from OUI](https://github.com/opensearch-project/oui/blob/main/src/services/color/oui_palettes.ts).
+
+## `ouiPaletteColorBlind()`
+
+1. `index_pattern_management` plugin
+2. `vis_type_vega` plugin
+3. `vis_type_vislib` plugin
+
+## Other quantitative palettes
+
+Not currently used
+
+## `colorPalette`
+
+Not currently used

src/plugins/charts/README.md

@@ -1,29 +1,88 @@
 # Charts
 
-The Charts plugin is a way to create easier integration of shared colors, themes, types and other utilities across all OpenSearch Dashboards charts and visualizations.
+The Charts plugin provides utility services for accessing shared colors and themes for visual consistency across all OpenSearch Dashboards charts and visualizations. It also provides a number of static utility functions and standard components for user-specified chart configuration.
 
-## Static methods
+## Services
 
-### `vislibColorMaps`
+### Theme service
 
-Color mappings related to vislib visualizations
+A utility service for fetching `chartsTheme` and `chartsBaseTheme`.
 
-### `truncatedColorMaps`
+For more, see Theme service [docs](public/services/theme/README.md)
 
-Color mappings subset of `vislibColorMaps`
+### Color service
+#### Static properties
+##### `seedColors`
+
+A list of colors chosen for visual appeal.
+
+#### Static methods
+##### `mappedColors`
 
-### `colorSchemas`
+Get a value-based mapping of colors.
+
+##### `createColorLookupFunction`
+
+Factory for color mapping function.
+
+## Static functions and components
+### Color maps
+#### `colorSchemas`
 
 Color mappings in `value`/`text` form
 
-### `getHeatmapColors`
+#### `getHeatmapColors`
 
 Function to retrieve heatmap related colors based on `value` and `colorSchemaName`
 
-### `truncatedColorSchemas`
+#### `truncatedColorMaps`
+
+Color mappings subset of `vislibColorMaps`
+
+#### `truncatedColorSchemas`
 
 Truncated color mappings in `value`/`text` form
 
-## Theme
+#### `vislibColorMaps`
+
+Color mappings related to vislib visualizations
+
+### Components
+
+Standardized React input UI components which can be used by visualization editors to specify various visualization options.
+
+#### `BasicOptions`
+
+Components for specifying legend and tooltip
+
+#### `ColorRanges`
+
+Component for specifying color range thresholds
+
+#### `ColorSchemaOptions`
+
+Component for specifying color schemas (palettes)
+
+#### `NumberInputOption`
+
+Deprecated in favor of `RequiredNumberInputOption`
+
+#### `RangeOption`
+
+Component for specifying a numerical value with a slider
+
+#### `RequiredNumberInputOption`
+
+Component for specifying numerical values, such as a threshold.
+
+#### `SelectOption`
+
+Basic select component
+
+#### `SwitchOption`
+
+Basic toggle component
+
+#### `TextInputOption`
 
-See Theme service [docs](public/services/theme/README.md)
+Basic text input component