MouseCapture - Electric UI

MouseCapture provides access to mouse position data when positioned over a ChartContainer, intended for drawing interactive annotations.

Usage

Using MouseCapture is simple, but usage often complicates the Chart structure.

For maximum flexibility, we create a mouseData Signal with the useMouseSignal hook which interacts with MouseCapture component through the use of captureRef.

Using the mouseDataSource with accessor syntax then allows use of the x, y, hovered and id members.

Screenshot of component MouseCapture crosshair

import { 
  ChartContainer, 
  LineChart, 
  RealTimeDomain, 
  TimeAxis,  
  VerticalAxis,
  MouseCapture,
  useMouseSignal,
  VerticalLineAnnotation,
  HorizontalLineAnnotation
} from '@electricui/components-desktop-charts'
import { useMessageDataSource } from '@electricui/core-timeseries'
 
const OverviewPage = () => {
  const temperatureDS = useMessageDataSource('temp_ptc')
 
  const [mouseSignal, captureRef] = useMouseSignal()
 
  return (
    <React.Fragment>
      <ChartContainer>
        <LineChart dataSource={temperatureDS} />
        <RealTimeDomain window={1000} />
        <TimeAxis />
        <VerticalAxis />
 
        <MouseCapture captureRef={captureRef} />
 
        <VerticalLineAnnotation
          dataSource={mouseSignal}
          accessor={data => data.x}
        />
        <HorizontalLineAnnotation
          dataSource={mouseSignal}
          accessor={data => data.y}
        />
      </ChartContainer>
    </React.Fragment>
  )
}

Finding nearby data

Screenshot of component MouseCapture basicsearch

The cursor position by itself won't usually be enough for helpful annotations. The search DataTransformers were designed to help find data near the cursor's position.

This example code finds the the point on the curve closest in time (x axis) and displays a PointAnnotation at that point.

import { useMouseSignal, 
         MouseCapture,
         ChartContainer, 
         LineChart, 
         PointAnnotation,
         RealTimeDomain,
         TimeAxis,
         VerticalAxis,
} from '@electricui/components-desktop-charts'
import { useMessageDataSource } from '@electricui/core-timeseries'
import { useDataTransformer } from '@electricui/timeseries-react'
import { closestTemporally } from '@electricui/dataflow'
 
import { Colors } from '@blueprintjs/core'
 
const OverviewPage = () => {
  const dataSource = useMessageDataSource<number>('sensor')
  const [mouseSignal, captureRef] = useMouseSignal()
 
  const closestEvent = useDataTransformer(() => {
    return closestTemporally(dataSource, mouseSignal, data => data.x)
  })
 
  return (
    <React.Fragment>
      <ChartContainer>
        <LineChart dataSource={dataSource} />
 
        <PointAnnotation
          dataSource={closestEvent}
          accessor={event => ({ x: event.time, y: event.data })}
          color={Colors.BLUE3}
          size={10}
        />
      
        <MouseCapture captureRef={captureRef} />
        <RealTimeDomain window={1000} />
        <TimeAxis />
        <VerticalAxis />
      </ChartContainer>
    </React.Fragment>
  )
}