DataFrame: Add explicit histogram frame type (panel & transforms) (#61195)

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

@@ -175,7 +175,7 @@ const prepConfig = (frame: DataFrame, theme: GrafanaTheme2) => {
 
   let seriesIndex = 0;
 
-  // assumes BucketMax is [1]
+  // assumes xMin is [0], xMax is [1]
   for (let i = 2; i < frame.fields.length; i++) {
     const field = frame.fields[i];
 
@@ -209,10 +209,7 @@ const prepConfig = (frame: DataFrame, theme: GrafanaTheme2) => {
       softMax: customConfig.axisSoftMax,
 
       // The following properties are not used in the uPlot config, but are utilized as transport for legend config
-      dataFrameFieldIndex: {
-        fieldIndex: 1,
-        frameIndex: i - 2,
-      },
+      dataFrameFieldIndex: field.state.origin,
     });
   }
 
@@ -272,11 +269,12 @@ export class Histogram extends React.Component<HistogramProps, State> {
 
   renderLegend(config: UPlotConfigBuilder) {
     const { legend } = this.props;
-    if (!config || legend.showLegend === false || !this.props.rawSeries) {
+
+    if (!config || legend.showLegend === false) {
       return null;
     }
 
-    return <PlotLegend data={this.props.rawSeries} config={config} maxHeight="35%" maxWidth="60%" {...legend} />;
+    return <PlotLegend data={this.props.rawSeries!} config={config} maxHeight="35%" maxWidth="60%" {...legend} />;
   }
 
   componentDidUpdate(prevProps: HistogramProps) {

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

@@ -16,6 +16,20 @@ export const HistogramPanel = ({ data, options, width, height }: Props) => {
     if (!data?.series?.length) {
       return undefined;
     }
+
+    // stamp origins for legend's calcs (from raw values)
+    data.series.forEach((frame, frameIndex) => {
+      frame.fields.forEach((field, fieldIndex) => {
+        field.state = {
+          ...field.state,
+          origin: {
+            frameIndex,
+            fieldIndex,
+          },
+        };
+      });
+    });
+
     if (data.series.length === 1) {
       const info = getHistogramFields(data.series[0]);
       if (info) {

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

@@ -1,7 +1,7 @@
 import { DataFrame, FieldType } from '@grafana/data';
 import {
-  histogramFrameBucketMinFieldName,
-  histogramFrameBucketMaxFieldName,
+  isHistogramFrameBucketMinFieldName,
+  isHistogramFrameBucketMaxFieldName,
 } from '@grafana/data/src/transformations/transformers/histogram';
 
 export function originalDataHasHistogram(frames?: DataFrame[]): boolean {
@@ -14,8 +14,8 @@ export function originalDataHasHistogram(frames?: DataFrame[]): boolean {
   }
 
   if (
-    frame.fields[0].name !== histogramFrameBucketMinFieldName ||
-    frame.fields[1].name !== histogramFrameBucketMaxFieldName
+    !isHistogramFrameBucketMinFieldName(frame.fields[0].name) ||
+    !isHistogramFrameBucketMaxFieldName(frame.fields[1].name)
   ) {
     return false;
   }