G2

Overview

The brushHighlight interaction targets chart elements. It highlights elements within the selected brush area and supports dragging and resizing the brush selection.

Trigger: Brush selection of elements.
End: Click on chart area.
Affected states:

Elements within the brush range change to active state.

Elements outside the brush range change to inactive state.

Built-in interaction states:

({
  // Define inactive state element opacity as 0.5
  state: { inactive: { opacity: 0.5 } },
});

example

import { Chart } from '@antv/g2';

const chart = new Chart({ container: 'container' });

chart.options({
  type: 'point',
  autoFit: true,
  data: {
    type: 'fetch',
    value:
      'https://gw.alipayobjects.com/os/basement_prod/6b4aa721-b039-49b9-99d8-540b3f87d339.json',
  },
  encode: { x: 'height', y: 'weight', color: 'gender' },
  state: { inactive: { stroke: 'gray' } },
  interaction: { brushHighlight: true },
});

chart.render();

Usage

There are two ways to configure the brushHighlight interaction:

First, pass a boolean to set whether to enable the interaction.

({
  type: 'interval',
  interaction: { brushHighlight: true }, // Use default configuration
});

Second, pass configuration options to configure the interaction.

({
  type: 'line',
  interaction: {
    brushHighlight: {
      series: true,
    },
  },
});

Configuration Level

Interaction can be configured at the Mark level:

({
  type: 'interval',
  interaction: { brushHighlight: true },
});

It can also be configured at the View level. Interactions declared on the view will be passed to marks declared in children. If the mark has declared the corresponding interaction, they will be merged; otherwise, it won’t be affected.

({
  type: 'view',
  interaction: { brushHighlight: true },
});

Configuration Options

Property	Description	Type	Default
reverse	Whether to reverse the brush	boolean	false
series	Whether brush affects series elements, controls the highlighting mode of selected elements	boolean	false
facet	Whether brush spans across facets, controls interaction behavior	boolean	false
selectedHandles	Directions of handles that can be resized	string[]	`['handle-n','handle-e','handle-s','handle-w','handle-nw','handle-ne','handle-se','handle-sw']`
brushRegion	Custom brush region, usually not configured, used internally by G2 for brushXHighlight and brushYHighlight	(x, y, x1, y1, extent) => any	`(x, y, x1, y1) => [x, y, x1, y1]`
mask	Mask style for brush area	mask	See mask
maskHandle	Handle style for brush area	maskHandle	See maskHandle

series

The series parameter is a key switch that controls the brush highlight mode, determining how to provide visual feedback for graphic elements. When configured as series: false, it’s more suitable for scatter plots, bar charts and other discrete elements, directly modifying element states (for continuous graphics like line charts, it changes the state of the entire line); when configured as series: true, continuous graphics like line charts and area charts will highlight local paths. Please enable or disable as needed.

series: false

import { Chart } from '@antv/g2';

const chart = new Chart({
  container: 'container',
});
const config = {
  type: 'line',
  interaction: { brushHighlight: { series: false } },
  data: [
    { year: '1991', value: 3 },
    { year: '1992', value: 4 },
    { year: '1993', value: 3.5 },
    { year: '1994', value: 5 },
    { year: '1995', value: 4.9 },
    { year: '1996', value: 6 },
    { year: '1997', value: 7 },
    { year: '1998', value: 9 },
    { year: '1999', value: 13 },
  ],
  encode: { x: 'year', y: 'value' },
  scale: { x: { range: [0, 1] }, y: { domainMin: 0, nice: true } },
  state: { active: { stroke: 'red' } },
  labels: [{ text: 'value', style: { dx: -10, dy: -12 } }],
};
chart.options(config);

chart.render();

series: true

import { Chart } from '@antv/g2';

const chart = new Chart({
  container: 'container',
});
const config = {
  type: 'line',
  interaction: { brushHighlight: { series: true } },
  data: [
    { year: '1991', value: 3 },
    { year: '1992', value: 4 },
    { year: '1993', value: 3.5 },
    { year: '1994', value: 5 },
    { year: '1995', value: 4.9 },
    { year: '1996', value: 6 },
    { year: '1997', value: 7 },
    { year: '1998', value: 9 },
    { year: '1999', value: 13 },
  ],
  encode: { x: 'year', y: 'value' },
  scale: { x: { range: [0, 1] }, y: { domainMin: 0, nice: true } },
  state: { active: { stroke: 'red' } },
  labels: [{ text: 'value', style: { dx: -10, dy: -12 } }],
};
chart.options(config);

chart.render();

mask

Configure the style of the brush area mask.

Property	Description	Type	Default
maskFill	Mask fill color	string	`#777`
maskFillOpacity	Mask fill opacity	number	0.3
maskStroke	Mask stroke	string	`#fff`
maskStrokeOpacity	Stroke opacity	number
maskLineWidth	Mask stroke width	number
maskLineDash	Stroke dash configuration. First value is dash length, second is gap length. Setting to [0,0] means no stroke.	[number,number]
maskOpacity	Mask overall opacity	number
maskShadowColor	Mask shadow color	string
maskShadowBlur	Mask shadow Gaussian blur coefficient	number
maskShadowOffsetX	Set horizontal distance of shadow from mask	number
maskShadowOffsetY	Set vertical distance of shadow from mask	number
maskCursor	Mouse cursor style. Same as CSS cursor style	string	`default`

When configuring brush area mask style, it’s not configured as an object, but using the mask prefix with property names.

({
  interaction: {
    brushHighlight: {
      maskFill: '#000',
      maskFillOpacity: 0.2,
      maskStroke: 'red',
      maskStrokeOpacity: 0.9,
      maskLineWidth: 2,
      maskLineDash: [4, 8],
      maskOpacity: 0.2,
      maskShadowColor: '#d3d3d3',
      maskShadowBlur: 10,
      maskShadowOffsetX: 10,
      maskShadowOffsetY: 10,
      maskCursor: 'pointer',
    },
  },
});

maskHandle

The names of handles in eight directions are as follows (named according to north, south, east, west). Set corresponding properties in the format mask[handleName][styleAttribute], or set width through maskHandleSize.

custom-style

Property	Description	Type	Default
mask[handleName]Render	Custom mask handle rendering function	(g, options, document) => DisplayObject
mask[handleName]Size	Mask handle width	string
mask[handleName]Fill	Mask handle fill color	string
mask[handleName]FillOpacity	Mask handle fill opacity	number
mask[handleName]Stroke	Mask handle stroke	string
mask[handleName]StrokeOpacity	Stroke opacity	number
mask[handleName]LineWidth	Mask handle stroke width	number
mask[handleName]LineDash	Stroke dash configuration. First value is dash length, second is gap length. Setting to [0,0] means no stroke.	[number,number]
mask[handleName]Opacity	Mask handle overall opacity	number
mask[handleName]ShadowColor	Mask handle shadow color	string
mask[handleName]ShadowBlur	Mask handle shadow Gaussian blur coefficient	number
mask[handleName]ShadowOffsetX	Set horizontal distance of shadow from mask handle	number
mask[handleName]ShadowOffsetY	Set vertical distance of shadow from mask handle	number
mask[handleName]Cursor	Mouse cursor style. Same as CSS cursor style	string	`default`

chart.options({
  type: 'point',
  data: {
    type: 'fetch',
    value: 'data/penguins.csv',
  },
  encode: {
    color: 'species',
    x: 'culmen_length_mm',
    y: 'culmen_depth_mm',
  },
  state: {
    inactive: { stroke: 'gray', opacity: 0.5 },
  },
  interaction: {
    brushHighlight: {
      maskHandleNFill: 'blue',
      maskHandleEFill: 'red',
      maskHandleSFill: 'green',
      maskHandleWFill: 'yellow',
      maskHandleNWFill: 'black',
      maskHandleNEFill: 'steelblue',
      maskHandleSEFill: 'pink',
      maskHandleSWFill: 'orange',
    },
  },
});

Events

Listening to Events

The following events are supported:

brush:start - Triggered when starting to create brush
brush:end - Triggered when brush size and position update is complete
brush:remove - Triggered when brush is removed
brush:highlight - Triggered when brush changes size and position

chart.on('brush:highlight', (e) => {
  console.log(e.data.selection);
  console.log(e.nativeEvent);
});

Triggering Interaction

The following events are supported:

brush:highlight - Highlight data
brush:remove - Remove brush

chart.emit('brush:remove');
chart.emit('brush:highlight', { data: { selection } });

Examples

Custom Handle

You can specify the handle rendering function through mask[handleName]Render to render custom handles. The function signature is as follows:

function render(
  g, // Mount container
  options, // Style properties, set through mask[handleName][styleAttribute]
  document, // Canvas document, used to create sub-graphics
) {
  // Need to return the created graphic
}

Here’s an example of creating a path handle:

function renderPath(group, options, document) {
  // Creation logic
  // If it's the first render, create and mount the graphic
  if (!group.handle) {
    // Create graphics through document.createElement
    const path = document.createElement('path');
    group.handle = path;
    group.appendChild(group.handle);
  }

  // Update logic
  const { handle } = group;
  const { width, height, ...rest } = options;
  if (width === undefined || height === undefined) return handle;
  handle.attr(rest);

  // Return corresponding value
  return handle;
}

custom-brush

function createPathRender(path) {
  return (group, options, document) => {
    if (!group.handle) {
      const path = document.createElement('path');
      group.handle = path;
      group.appendChild(group.handle);
    }
    const { handle } = group;
    const { x, y, width, height, ...rest } = options;
    if (width === undefined || height === undefined) return handle;
    handle.style.d = path(x, y, width, height);
    handle.attr(rest);
    return handle;
  };
}

chart.options({
  type: 'point',
  data: {
    type: 'fetch',
    value: 'data/penguins.csv',
  },
  encode: {
    color: 'species',
    x: 'culmen_length_mm',
    y: 'culmen_depth_mm',
  },
  state: {
    inactive: { stroke: 'gray', opacity: 0.5 },
  },
  interaction: {
    brushHighlight: {
      maskHandleSize: 30,
      maskHandleNRender: createPathRender((x, y, width, height) => {
        return `M${x},${y + height / 2}L${x + width / 2},${y - height / 2}L${
          x + width
        },${y + height / 2},Z`;
      }),
      maskHandleERender: createPathRender(
        (x, y, width, height) =>
          `M${x + width / 2},${y}L${x + (width * 3) / 2},${y + height / 2}L${
            x + width / 2
          },${y + height},Z`,
      ),
      maskHandleSRender: createPathRender(
        (x, y, width, height) =>
          `M${x},${y + height / 2}L${x + width / 2},${y + (height / 2) * 3}L${
            x + width
          },${y + height / 2},Z`,
      ),
      maskHandleWRender: createPathRender(
        (x, y, width, height) =>
          `M${x + width / 2},${y}L${x - width},${y + height / 2}L${
            x + width / 2
          },${y + height},Z`,
      ),
      maskHandleNWRender: createPathRender(
        (x, y, width, height) =>
          `M${x},${y}L${x + width},${y + height / 2}L${x + width / 2},${
            y + height
          },Z`,
      ),
      maskHandleNERender: createPathRender(
        (x, y, width, height) =>
          `M${x},${y + height / 2}L${x + width},${y}L${x + width / 2},${
            y + height
          },Z`,
      ),
      maskHandleSERender: createPathRender(
        (x, y, width, height) =>
          `M${x + width / 2},${y}L${x + width},${y + height}L${x},${
            y + height / 2
          },Z`,
      ),
      maskHandleSWRender: createPathRender(
        (x, y, width, height) =>
          `M${x + width / 2},${y}L${x + width},${y + height / 2}L${x},${
            y + height
          },Z`,
      ),
      maskHandleNFill: 'blue',
      maskHandleEFill: 'red',
      maskHandleSFill: 'green',
      maskHandleWFill: 'yellow',
      maskHandleNWFill: 'black',
      maskHandleNEFill: 'steelblue',
      maskHandleSEFill: 'pink',
      maskHandleSWFill: 'orange',
    },
  },
});

Custom Interaction State

Some interactions change element states. We can change the interaction effect by configuring the appearance of element states.

import { Chart } from '@antv/g2';

const chart = new Chart({
  container: 'container',
});
chart.options({
  type: 'point',
  autoFit: true,
  data: {
    type: 'fetch',
    value:
      'https://gw.alipayobjects.com/os/basement_prod/6b4aa721-b039-49b9-99d8-540b3f87d339.json',
  },
  encode: { x: 'height', y: 'weight', color: 'gender' },
  state: {
    inactive: { stroke: 'gray', opacity: 0.5 },
    active: { lineWidth: 5 },
  },
  interaction: { brushHighlight: true },
});

chart.render();

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