UI/Plot: Implement keyboard controls for plot cursor (#42244)

packages/grafana-ui/src/components/VizLayout/VizLayout.tsx

@@ -1,7 +1,11 @@
 import React, { FC, CSSProperties, ComponentType } from 'react';
 import { useMeasure } from 'react-use';
-import { CustomScrollbar } from '../CustomScrollbar/CustomScrollbar';
+import { css } from '@emotion/css';
 import { LegendPlacement } from '@grafana/schema';
+import { GrafanaTheme2 } from '@grafana/data';
+import { CustomScrollbar } from '../CustomScrollbar/CustomScrollbar';
+import { getFocusStyles } from '../../themes/mixins';
+import { useStyles2 } from '../../themes/ThemeContext';
 
 /**
  * @beta
@@ -24,6 +28,7 @@ export interface VizLayoutComponentType extends FC<VizLayoutProps> {
  * @beta
  */
 export const VizLayout: VizLayoutComponentType = ({ width, height, legend, children }) => {
+  const styles = useStyles2(getVizStyles);
   const containerStyle: CSSProperties = {
     display: 'flex',
     width: `${width}px`,
@@ -32,17 +37,17 @@ export const VizLayout: VizLayoutComponentType = ({ width, height, legend, child
   const [legendRef, legendMeasure] = useMeasure<HTMLDivElement>();
 
   if (!legend) {
-    return <div style={containerStyle}>{children(width, height)}</div>;
+    return (
+      <div tabIndex={0} style={containerStyle} className={styles.viz}>
+        {children(width, height)}
+      </div>
+    );
   }
 
   const { placement, maxHeight = '35%', maxWidth = '60%' } = legend.props;
 
   let size: VizSize | null = null;
 
-  const vizStyle: CSSProperties = {
-    flexGrow: 2,
-  };
-
   const legendStyle: CSSProperties = {};
 
   switch (placement) {
@@ -76,7 +81,9 @@ export const VizLayout: VizLayoutComponentType = ({ width, height, legend, child
 
   return (
     <div style={containerStyle}>
-      <div style={vizStyle}>{size && children(size.width, size.height)}</div>
+      <div tabIndex={0} className={styles.viz}>
+        {size && children(size.width, size.height)}
+      </div>
       <div style={legendStyle} ref={legendRef}>
         <CustomScrollbar hideHorizontalTrack>{legend}</CustomScrollbar>
       </div>
@@ -84,6 +91,15 @@ export const VizLayout: VizLayoutComponentType = ({ width, height, legend, child
   );
 };
 
+export const getVizStyles = (theme: GrafanaTheme2) => {
+  return {
+    viz: css({
+      flexGrow: 2,
+      borderRadius: theme.shape.borderRadius(1),
+      '&:focus-visible': getFocusStyles(theme),
+    }),
+  };
+};
 interface VizSize {
   width: number;
   height: number;

packages/grafana-ui/src/components/uPlot/plugins/KeyboardPlugin.tsx

@@ -0,0 +1,160 @@
+import React, { useLayoutEffect } from 'react';
+import { clamp } from 'lodash';
+import uPlot from 'uplot';
+import { UPlotConfigBuilder } from '../config/UPlotConfigBuilder';
+
+interface KeyboardPluginProps {
+  config: UPlotConfigBuilder; // onkeypress, onkeyup, onkeydown (triggered by vizlayout handlers)
+}
+
+const PIXELS_PER_MS = 0.1 as const;
+const SHIFT_MULTIPLIER = 2 as const;
+const KNOWN_KEYS = new Set(['ArrowRight', 'ArrowLeft', 'ArrowUp', 'ArrowDown', 'Shift', ' ']);
+
+const initHook = (u: uPlot) => {
+  let vizLayoutViz: HTMLElement | null = u.root.closest('[tabindex]');
+  let pressedKeys = new Set<string>();
+  let dragStartX: number | null = null;
+  let keysLastHandledAt: number | null = null;
+
+  if (!vizLayoutViz) {
+    return;
+  }
+
+  const moveCursor = (dx: number, dy: number) => {
+    const { cursor } = u;
+    if (cursor.left === undefined || cursor.top === undefined) {
+      return;
+    }
+
+    const { width, height } = u.over.style;
+    const [maxX, maxY] = [Math.floor(parseFloat(width)), Math.floor(parseFloat(height))];
+
+    u.setCursor({
+      left: clamp(cursor.left + dx, 0, maxX),
+      top: clamp(cursor.top + dy, 0, maxY),
+    });
+  };
+
+  const handlePressedKeys = (time: number) => {
+    const nothingPressed = pressedKeys.size === 0;
+    if (nothingPressed || !u) {
+      keysLastHandledAt = null;
+      return;
+    }
+
+    const dt = time - (keysLastHandledAt ?? time);
+    const dx = dt * PIXELS_PER_MS;
+    let horValue = 0;
+    let vertValue = 0;
+
+    if (pressedKeys.has('ArrowUp')) {
+      vertValue -= dx;
+    }
+    if (pressedKeys.has('ArrowDown')) {
+      vertValue += dx;
+    }
+    if (pressedKeys.has('ArrowLeft')) {
+      horValue -= dx;
+    }
+    if (pressedKeys.has('ArrowRight')) {
+      horValue += dx;
+    }
+    if (pressedKeys.has('Shift')) {
+      horValue *= SHIFT_MULTIPLIER;
+      vertValue *= SHIFT_MULTIPLIER;
+    }
+
+    moveCursor(horValue, vertValue);
+
+    const { cursor } = u;
+    if (pressedKeys.has(' ') && cursor) {
+      const drawHeight = Number(u.over.style.height.slice(0, -2));
+
+      u.setSelect(
+        {
+          left: cursor.left! < dragStartX! ? cursor.left! : dragStartX!,
+          top: 0,
+          width: Math.abs(cursor.left! - (dragStartX ?? cursor.left!)),
+          height: drawHeight,
+        },
+        false
+      );
+    }
+
+    keysLastHandledAt = time;
+    window.requestAnimationFrame(handlePressedKeys);
+  };
+
+  vizLayoutViz.addEventListener('keydown', (e) => {
+    if (e.key === 'Tab') {
+      // Hide the cursor if the user tabs away
+      u.setCursor({ left: -5, top: -5 });
+      return;
+    }
+
+    if (!KNOWN_KEYS.has(e.key)) {
+      return;
+    }
+
+    e.preventDefault();
+    e.stopPropagation();
+
+    const newKey = !pressedKeys.has(e.key);
+    if (newKey) {
+      const initiateAnimationLoop = pressedKeys.size === 0;
+      pressedKeys.add(e.key);
+
+      dragStartX = e.key === ' ' && dragStartX === null ? u.cursor.left! : dragStartX;
+
+      if (initiateAnimationLoop) {
+        window.requestAnimationFrame(handlePressedKeys);
+      }
+    }
+  });
+
+  vizLayoutViz.addEventListener('keyup', (e) => {
+    if (!KNOWN_KEYS.has(e.key)) {
+      return;
+    }
+
+    pressedKeys.delete(e.key);
+
+    if (e.key === ' ') {
+      e.preventDefault();
+      e.stopPropagation();
+
+      // We do this so setSelect hooks get fired, zooming the plot
+      u.setSelect(u.select);
+      dragStartX = null;
+    }
+  });
+
+  vizLayoutViz.addEventListener('focus', (e) => {
+    // We only want to initialize the cursor if the user is using keyboard controls
+    if (!vizLayoutViz?.matches(':focus-visible')) {
+      return;
+    }
+
+    // Is there a more idiomatic way to do this?
+    const drawWidth = parseFloat(u.over.style.width);
+    const drawHeight = parseFloat(u.over.style.height);
+    u.setCursor({ left: drawWidth / 2, top: drawHeight / 2 });
+  });
+
+  vizLayoutViz.addEventListener('blur', (e) => {
+    keysLastHandledAt = null;
+    dragStartX = null;
+    pressedKeys.clear();
+    u.setSelect({ left: 0, top: 0, width: 0, height: 0 }, false);
+  });
+};
+
+/**
+ * @alpha
+ */
+export const KeyboardPlugin: React.FC<KeyboardPluginProps> = ({ config }) => {
+  useLayoutEffect(() => config.addHook('init', initHook), [config]);
+
+  return null;
+};

packages/grafana-ui/src/components/uPlot/plugins/TooltipPlugin.tsx

@@ -66,7 +66,15 @@ export const TooltipPlugin: React.FC<TooltipPluginProps> = ({
   useLayoutEffect(() => {
     let bbox: DOMRect | undefined = undefined;
 
-    const plotMouseLeave = () => {
+    const plotEnter = () => {
+      if (!isMounted()) {
+        return;
+      }
+      setIsActive(true);
+      plotInstance.current?.root.classList.add('plot-active');
+    };
+
+    const plotLeave = () => {
       if (!isMounted()) {
         return;
       }
@@ -75,22 +83,17 @@ export const TooltipPlugin: React.FC<TooltipPluginProps> = ({
       plotInstance.current?.root.classList.remove('plot-active');
     };
 
-    const plotMouseEnter = () => {
-      if (!isMounted()) {
-        return;
-      }
-      setIsActive(true);
-      plotInstance.current?.root.classList.add('plot-active');
-    };
-
     // cache uPlot plotting area bounding box
     config.addHook('syncRect', (u, rect) => (bbox = rect));
 
     config.addHook('init', (u) => {
       plotInstance.current = u;
 
-      u.over.addEventListener('mouseleave', plotMouseLeave);
+      u.root.parentElement?.addEventListener('focus', plotEnter);
-      u.over.addEventListener('mouseenter', plotMouseEnter);
+      u.over.addEventListener('mouseenter', plotEnter);
+
+      u.root.parentElement?.addEventListener('blur', plotLeave);
+      u.over.addEventListener('mouseleave', plotLeave);
 
       if (sync === DashboardCursorSync.Crosshair) {
         u.root.classList.add('shared-crosshair');
@@ -157,8 +160,10 @@ export const TooltipPlugin: React.FC<TooltipPluginProps> = ({
     return () => {
       setCoords(null);
       if (plotInstance.current) {
-        plotInstance.current.over.removeEventListener('mouseleave', plotMouseLeave);
+        plotInstance.current.over.removeEventListener('mouseleave', plotLeave);
-        plotInstance.current.over.removeEventListener('mouseenter', plotMouseEnter);
+        plotInstance.current.over.removeEventListener('mouseenter', plotEnter);
+        plotInstance.current.root.parentElement?.removeEventListener('focus', plotEnter);
+        plotInstance.current.root.parentElement?.removeEventListener('blur', plotLeave);
       }
     };
   }, [config, setCoords, setIsActive, setFocusedPointIdx, setFocusedPointIdxs]);

packages/grafana-ui/src/components/uPlot/plugins/index.ts

@@ -1,2 +1,3 @@
 export { ZoomPlugin } from './ZoomPlugin';
 export { TooltipPlugin } from './TooltipPlugin';
+export { KeyboardPlugin } from './KeyboardPlugin';

public/app/plugins/panel/timeseries/TimeSeriesPanel.tsx

@@ -1,7 +1,7 @@
 import React, { useMemo } from 'react';
 import { Field, PanelProps } from '@grafana/data';
 import { TooltipDisplayMode } from '@grafana/schema';
-import { usePanelContext, TimeSeries, TooltipPlugin, ZoomPlugin } from '@grafana/ui';
+import { usePanelContext, TimeSeries, TooltipPlugin, ZoomPlugin, KeyboardPlugin } from '@grafana/ui';
 import { getFieldLinksForExplore } from 'app/features/explore/utils/links';
 import { AnnotationsPlugin } from './plugins/AnnotationsPlugin';
 import { ContextMenuPlugin } from './plugins/ContextMenuPlugin';
@@ -54,6 +54,7 @@ export const TimeSeriesPanel: React.FC<TimeSeriesPanelProps> = ({
       {(config, alignedDataFrame) => {
         return (
           <>
+            <KeyboardPlugin config={config} />
             <ZoomPlugin config={config} onZoom={onChangeTimeRange} />
             {options.tooltip.mode === TooltipDisplayMode.None || (
               <TooltipPlugin