Histogram: Add support for stacking mode (#84693)

.betterer.results

@@ -5716,8 +5716,8 @@ exports[`better eslint`] = {
       [0, 0, 0, "Do not use any type assertions.", "15"],
       [0, 0, 0, "Do not use any type assertions.", "16"]
     ],
-    "public/app/plugins/panel/histogram/Histogram.tsx:5381": [
-      [0, 0, 0, "Do not use any type assertions.", "0"]
+    "public/app/plugins/panel/histogram/migrations.ts:5381": [
+      [0, 0, 0, "Unexpected any. Specify a different type.", "0"]
     ],
     "public/app/plugins/panel/live/LiveChannelEditor.tsx:5381": [
       [0, 0, 0, "Unexpected any. Specify a different type.", "0"],

packages/grafana-schema/src/raw/composable/histogram/panelcfg/x/HistogramPanelCfg_types.gen.ts

@@ -36,7 +36,7 @@ export const defaultOptions: Partial<Options> = {
   bucketOffset: 0,
 };
 
-export interface FieldConfig extends common.AxisConfig, common.HideableFieldConfig {
+export interface FieldConfig extends common.AxisConfig, common.HideableFieldConfig, common.StackableFieldConfig {
   /**
    * Controls the fill opacity of the bars.
    */

public/app/plugins/panel/histogram/Histogram.tsx

@@ -24,6 +24,7 @@ import {
   measureText,
   UPLOT_AXIS_FONT_SIZE,
 } from '@grafana/ui';
+import { getStackingGroups, preparePlotData2 } from '@grafana/ui/src/components/uPlot/utils';
 
 import { defaultFieldConfig, FieldConfig, Options } from './panelcfg.gen';
 
@@ -207,6 +208,9 @@ const prepConfig = (frame: DataFrame, theme: GrafanaTheme2) => {
     },
   });
 
+  let stackingGroups = getStackingGroups(xMinOnlyFrame(frame));
+  builder.setStackingGroups(stackingGroups);
+
   let pathBuilder = uPlot.paths.bars!({ align: 1, size: [1, Infinity] });
 
   let seriesIndex = 0;
@@ -252,31 +256,32 @@ const prepConfig = (frame: DataFrame, theme: GrafanaTheme2) => {
   return builder;
 };
 
-const preparePlotData = (frame: DataFrame) => {
-  let data = [];
-
-  for (const field of frame.fields) {
-    if (field.name !== histogramFrameBucketMaxFieldName) {
-      data.push(field.values);
-    }
-  }
+// since we're reusing timeseries prep for stacking, we need to make a tmp frame where fields match the uplot data
+// by removing the x bucket max field to make sure stacking group series idxs match up
+const xMinOnlyFrame = (frame: DataFrame) => ({
+  ...frame,
+  fields: frame.fields.filter((f) => f.name !== histogramFrameBucketMaxFieldName),
+});
 
+const preparePlotData = (builder: UPlotConfigBuilder, xMinOnlyFrame: DataFrame) => {
   // uPlot's bars pathBuilder will draw rects even if 0 (to distinguish them from nulls)
   // but for histograms we want to omit them, so remap 0s -> nulls
-  for (let i = 1; i < data.length; i++) {
-    let counts = data[i];
+  for (let i = 1; i < xMinOnlyFrame.fields.length; i++) {
+    let counts = xMinOnlyFrame.fields[i].values;
+
     for (let j = 0; j < counts.length; j++) {
       if (counts[j] === 0) {
-        counts[j] = null;
+        counts[j] = null; // mutates!
       }
     }
   }
 
-  return data as AlignedData;
+  return preparePlotData2(xMinOnlyFrame, builder.getStackingGroups());
 };
 
 interface State {
   alignedData: AlignedData;
+  alignedFrame: DataFrame;
   config?: UPlotConfigBuilder;
 }
 
@@ -286,23 +291,17 @@ export class Histogram extends React.Component<HistogramProps, State> {
     this.state = this.prepState(props);
   }
 
-  prepState(props: HistogramProps, withConfig = true) {
-    let state: State = {
-      alignedData: [],
-    };
-
+  prepState(props: HistogramProps, withConfig = true): State {
     const { alignedFrame } = props;
-    if (alignedFrame) {
-      state = {
-        alignedData: preparePlotData(alignedFrame),
-      };
 
-      if (withConfig) {
-        state.config = prepConfig(alignedFrame, this.props.theme);
-      }
-    }
+    const config = withConfig ? prepConfig(alignedFrame, this.props.theme) : this.state.config!;
+    const alignedData = preparePlotData(config, xMinOnlyFrame(alignedFrame));
 
-    return state;
+    return {
+      alignedFrame,
+      alignedData,
+      config,
+    };
   }
 
   renderLegend(config: UPlotConfigBuilder) {
@@ -321,23 +320,18 @@ export class Histogram extends React.Component<HistogramProps, State> {
     const { structureRev, alignedFrame, bucketSize, bucketCount } = this.props;
 
     if (alignedFrame !== prevProps.alignedFrame) {
-      let newState = this.prepState(this.props, false);
+      const shouldReconfig =
+        this.state.config == null ||
+        bucketCount !== prevProps.bucketCount ||
+        bucketSize !== prevProps.bucketSize ||
+        this.props.options !== prevProps.options ||
+        this.state.config === undefined ||
+        structureRev !== prevProps.structureRev ||
+        !structureRev;
 
-      if (newState) {
-        const shouldReconfig =
-          bucketCount !== prevProps.bucketCount ||
-          bucketSize !== prevProps.bucketSize ||
-          this.props.options !== prevProps.options ||
-          this.state.config === undefined ||
-          structureRev !== prevProps.structureRev ||
-          !structureRev;
+      const newState = this.prepState(this.props, shouldReconfig);
 
-        if (shouldReconfig) {
-          newState.config = prepConfig(alignedFrame, this.props.theme);
-        }
-      }
-
-      newState && this.setState(newState);
+      this.setState(newState);
     }
   }
 

public/app/plugins/panel/histogram/config.ts

@@ -0,0 +1,10 @@
+import { StackingMode } from '@grafana/schema';
+
+import { FieldConfig } from './panelcfg.gen';
+
+export const defaultHistogramConfig: FieldConfig = {
+  stacking: {
+    mode: StackingMode.None,
+    group: 'A',
+  },
+};

public/app/plugins/panel/histogram/migrations.test.ts

@@ -1,4 +1,5 @@
 import { FieldConfigSource, PanelModel } from '@grafana/data';
+import { StackingMode } from '@grafana/ui';
 
 import { changeToHistogramPanelMigrationHandler } from './migrations';
 
@@ -12,7 +13,7 @@ describe('Histogram migrations', () => {
     };
   });
 
-  it('From old graph', () => {
+  it('Should migrate from old graph', () => {
     const old = {
       angular: {
         xaxis: {
@@ -23,6 +24,39 @@ describe('Histogram migrations', () => {
 
     const panel = {} as PanelModel;
     panel.options = changeToHistogramPanelMigrationHandler(panel, 'graph', old, prevFieldConfig);
-    expect(panel.options.combine).toBe(true);
+    expect(panel.options.combine).toBe(false);
+  });
+
+  it('Should migrate from old graph with percent stacking', () => {
+    const old = {
+      angular: {
+        xaxis: {
+          mode: 'histogram',
+        },
+        stack: true,
+        percentage: true,
+      },
+    };
+
+    const panel = {} as PanelModel;
+    panel.options = changeToHistogramPanelMigrationHandler(panel, 'graph', old, prevFieldConfig);
+    expect(panel.fieldConfig.defaults.custom.stacking.mode).toBe(StackingMode.Percent);
+    expect(panel.options.combine).toBe(false);
+  });
+
+  it('Should migrate from old graph with normal stacking', () => {
+    const old = {
+      angular: {
+        xaxis: {
+          mode: 'histogram',
+        },
+        stack: true,
+      },
+    };
+
+    const panel = {} as PanelModel;
+    panel.options = changeToHistogramPanelMigrationHandler(panel, 'graph', old, prevFieldConfig);
+    expect(panel.fieldConfig.defaults.custom.stacking.mode).toBe(StackingMode.Normal);
+    expect(panel.options.combine).toBe(false);
   });
 });

public/app/plugins/panel/histogram/migrations.ts

@@ -1,4 +1,15 @@
-import { PanelTypeChangedHandler } from '@grafana/data';
+import { isNil, omitBy } from 'lodash';
+
+import { FieldConfigSource, PanelTypeChangedHandler } from '@grafana/data';
+import {
+  LegendDisplayMode,
+  SortOrder,
+  StackingMode,
+  TooltipDisplayMode,
+} from '@grafana/schema/dist/esm/common/common.gen';
+
+import { defaultHistogramConfig } from './config';
+import { FieldConfig as HistogramFieldConfig, Options } from './panelcfg.gen';
 
 /*
  * This is called when the panel changes from another panel
@@ -13,16 +24,66 @@ export const changeToHistogramPanelMigrationHandler: PanelTypeChangedHandler = (
     const graphOptions: GraphOptions = prevOptions.angular;
 
     if (graphOptions.xaxis?.mode === 'histogram') {
-      return {
-        combine: true,
-      };
+      const { fieldConfig, options } = graphToHistogramOptions({
+        ...prevOptions.angular,
+        fieldConfig: prevFieldConfig,
+      });
+
+      panel.fieldConfig = fieldConfig; // Mutates the incoming panel
+
+      return options;
     }
   }
 
   return {};
 };
 
+function graphToHistogramOptions(angular: any): {
+  fieldConfig: FieldConfigSource;
+  options: Options;
+} {
+  const graphOptions: GraphOptions = angular;
+  let histogramFieldConfig: HistogramFieldConfig = {};
+  const options: Options = {
+    legend: {
+      displayMode: LegendDisplayMode.List,
+      showLegend: true,
+      placement: 'bottom',
+      calcs: [],
+    },
+    tooltip: {
+      mode: TooltipDisplayMode.Single,
+      sort: SortOrder.None,
+    },
+    combine: false,
+  };
+
+  if (graphOptions.stack) {
+    histogramFieldConfig.stacking = {
+      mode: graphOptions.percentage ? StackingMode.Percent : StackingMode.Normal,
+      group: defaultHistogramConfig.stacking!.group,
+    };
+
+    options.combine = false;
+  }
+
+  return {
+    fieldConfig: {
+      defaults: omitBy(
+        {
+          custom: histogramFieldConfig,
+        },
+        isNil
+      ),
+      overrides: [],
+    },
+    options,
+  };
+}
+
 interface GraphOptions {
+  stack?: boolean;
+  percentage?: boolean;
   xaxis: {
     mode: 'series' | 'time' | 'histogram';
     values?: string[];

public/app/plugins/panel/histogram/module.tsx

@@ -1,8 +1,16 @@
-import { FieldColorModeId, FieldConfigProperty, PanelPlugin } from '@grafana/data';
+import {
+  FieldColorModeId,
+  FieldConfigProperty,
+  FieldType,
+  identityOverrideProcessor,
+  PanelPlugin,
+} from '@grafana/data';
 import { histogramFieldInfo } from '@grafana/data/src/transformations/transformers/histogram';
 import { commonOptionsBuilder, graphFieldOptions } from '@grafana/ui';
+import { StackingEditor } from '@grafana/ui/src/options/builder';
 
 import { HistogramPanel } from './HistogramPanel';
+import { defaultHistogramConfig } from './config';
 import { changeToHistogramPanelMigrationHandler } from './migrations';
 import { FieldConfig, Options, defaultFieldConfig, defaultOptions } from './panelcfg.gen';
 import { originalDataHasHistogram } from './utils';
@@ -78,6 +86,21 @@ export const plugin = new PanelPlugin<Options, FieldConfig>(HistogramPanel)
       const cfg = defaultFieldConfig;
 
       builder
+        .addCustomEditor({
+          id: 'stacking',
+          path: 'stacking',
+          name: 'Stacking',
+          category: ['Histogram'],
+          defaultValue: defaultHistogramConfig.stacking,
+          editor: StackingEditor,
+          override: StackingEditor,
+          settings: {
+            options: graphFieldOptions.stacking,
+          },
+          process: identityOverrideProcessor,
+          shouldApply: (f) => f.type === FieldType.number,
+          showIf: (opts, data) => !originalDataHasHistogram(data),
+        })
         .addSliderInput({
           path: 'lineWidth',
           name: 'Line width',

public/app/plugins/panel/histogram/panelcfg.cue

@@ -42,6 +42,7 @@ composableKinds: PanelCfg: {
 				FieldConfig: {
 					common.AxisConfig
 					common.HideableFieldConfig
+					common.StackableFieldConfig
 
 					// Controls line width of the bars.
 					lineWidth?: uint32 & <=10 | *1

public/app/plugins/panel/histogram/panelcfg.gen.ts

@@ -34,7 +34,7 @@ export const defaultOptions: Partial<Options> = {
   bucketOffset: 0,
 };
 
-export interface FieldConfig extends common.AxisConfig, common.HideableFieldConfig {
+export interface FieldConfig extends common.AxisConfig, common.HideableFieldConfig, common.StackableFieldConfig {
   /**
    * Controls the fill opacity of the bars.
    */