React Hex Editor

View and edit binary data in React.

Install

yarn:

yarn add react-hex-editor

npm:

npm install --save react-hex-editor

Usage

This uses styled-components for ease of theming. It's a peer dependency, so don't forget to make sure it's installed!

import HexEditor from 'react-hex-editor';
import oneDarkPro from 'react-hex-editor/themes/oneDarkPro';

const YourApp = () => {
  // `data` contains the bytes to show. It can also be `Uint8Array`!
  const data = React.useMemo(() => new Array(100).fill(0), []);
  // If `data` is large, you probably want it to be mutable rather than cloning it over and over.
  // `nonce` can be used to update the editor when `data` is reference that does not change.
  const [nonce, setNonce] = useState(0);
  // The callback facilitates updates to the source data.
  const handleSetValue = React.useCallback((offset, value) => {
    data[offset] = value;
    setNonce(v => (v + 1));
  }, [data]);

  return (
    <HexEditor
      columns={0x10}
      data={data}
      nonce={nonce}
      onSetValue={handleSetValue}
      theme={{ hexEditor: oneDarkPro }}
    />
  )
};

Custom Styling

If you'd rather provide your own CSS and skip the styled-components depenency, that's okay too.

There are a few inline styles baked into the component for the basic functionality, but you're free to modify the fonts and colors to suit your tastes. If you'd like to disable the inline styles and use an all-CSS solution, pass an empty object for the inlineStyles prop.

import { UnstyleHexEditor } from 'react-hex-editor';

const YourApp = () => {
  /* ... */

  return (
    <UnstyleHexEditor
      className="your-hex-editor"
      columns={0x10}
      data={data.current}
      inlineStyles={{}} // Optional: override or disable inline styles
      nonce={nonce}
      onSetValue={handleSetValue}
    />
  )
};

Refer to styles.ts for an example of how to style. The permutations of combined classnames for each hex editor component really adds up, so you probably want to use a CSS preprocessor that supports nesting.

Explicit Sizing

The default HexEditor and UnstyledHexEditor components infer as much as necessary to calculate various dimensions based on the provided props. Underlying this is a BaseHexEditor component that needs everything spelled out.

import { BaseHexEditor /* ot UnstyledBaseHexEditor */ } from 'react-hex-editor';

const YourApp = () => {
  /* ... */

  return (
    <BaseHexEditor
      className="your-hex-editor"
      columns={0x10} // REQUIRED
      data={data.current}
      height={500} // REQUIRED
      nonce={nonce}
      rowHeight={22} // REQUIRED
      rows={0x10} // REQUIRED
      onSetValue={handleSetValue}
      width={600} // REQUIRED
    />
  )
};

You probably don't need to use this.

API

HexEditor

Standard Props

className

Classname applied to the Hex Editor's root element.

classNames

Classnames applied to various components of the Hex Editor that can be used for styling.

data (required)

Uint8Array or array of integerss (0-255) to display in the hex editor.

nonce

If data is mutable, update the nonce when there is a change so that the editor re-renders with the latest data.

onSetValue

Callback that is invoked with offset and value when attempting to write a value. Typically, you'd want to set data[offset] = value here.

Display Props

showAscii

Whether to show the ascii representation of the data.

showColumnLabels

Whether to show a fixed row at the top of the table for column offset labels.

showRowLabels

Whether to show row offset labels.

highlightColumn

Set to true to add a classname for the currently active column if you want to style it. Note: This can lead to degraded performance when there are a lot of rows visible.

formatValue

Function that takes the byte value and converts it to its ASCII representation. You can override it to change the ASCII output.

overscanCount

Controls the number of rows rendered outside of the viewport. Higher numbers will reduce blank areas when scrolling quickly, but may degrade performance.

Sizing Props (Can be inferred by auto-sizing component)

columns

Number of columns to display. (Can be inferred by auto-sizing component using width.)

rows

Number of rows to display. (Can be inferred by auto-sizing component using height.)

width

Pixel width of the overall hex editor.

height

Pixel height of the overall hex editor.

rowHeight

Pixel height of a single row.

byteWidth (auto-size only)

Pixel width of a single byte.

asciiWidth (auto-size only)

Pixel width of a single ASCII character.

gutterWidth (auto-size only)

Pixel width of the gutter between sections.

scrollbarWidth (auto-size only)

Pixel width of the scrollbar.

Styling Props

theme.hexEditor (styled-components only)

Includes various keys that are used for fonts and colors of the Hex Editor.

measureStyle (auto-size only)

Inline styles applied to the sample components used to infer size. Used for making them invisible and non-interactive.

Set to null to disable the default styles.

inputStyle

Did you know? There is an input that handles key events, focus, and copy/paste for the Hex Editor! These are the inline styles applied to that element that make it invisible and cover the editor.

Set to null to disable the default styles

style

Inline styles applied to the editor root.

inlineStyles

Inline styles for various editor components.

inlineStyles.ascii

Inline styles applied to a single ASCII character. Used for setting flexbox alignment.

inlineStyles.asciiValues

Inline styles applied to the ASCII section of a row. Used for setting flexbox alignment.

inlineStyles.body

Inline styles applied to Hex Editor body area. Used to force the scrollbar.

inlineStyles.byte

Inline styles applied to a single byte. Used for setting flexbox alignment.

inlineStyles.byteValues

Inline styles applied to the byte section of a row. Used for setting flexbox alignment.

inlineStyles.editor

Inline styles applied to the editor root. Used for setting position and the font-family.

inlineStyles.gutter

Inline styles applied to the gutter. Unstyled by default.

inlineStyles.header

Inline styles applied to Hex Editor header area. Used to force the scrollbar.

inlineStyles.offsetLabel

Inline styles applied to an offset label. Used for setting flexbox alignment.

inlineStyles.row

Inline styles applied to a single row. Used for setting flexbox alignment.

Input Behavior Props

autoFocus

Set to true to focus the Hex Editor on mount.

onBlur

Callback for when focus is lost.

onFocus

Callback for when focus is gained.

readOnly

Set to true if the Hex Editor is more of a Hex Viewer.

tabIndex

Set it, if you want!

Imperative Interface

The following functions are available is you use a ref on the Hex Editor.

blur

Drops focus from the Hex Editor.

focus

Takes focus for the Hex Editor.

scrollTo(scrollTop)

Scroll to the specified pixel offset.

scrollToItem(rowIndex, [align = 'auto'])

Scroll to the specified row offset. Align is from react-window and accepts 'auto', 'smart', 'center', 'end', or 'start'.

setSelectionRange(start, [end = start], [direction = null], [takeFocus = false])

Selects a range in the Hex Editor.

setValue(offset, value)

Sets a value in the Hex Editor.

@TODO

• Improve documentation
• Improve clipboard support
• Undo/redo history
• Text/byte search
• Demo page

Contributing

Thank you for your interest! If you find a bug or want to add a new feature, open an issue or create a pull request, and we'll figure it out from there.

License

ISC © Keith McKnight