window-capture

Captures parts of application windows at an interval as a png image.

Capturing entire Slack Window

const getWindowCapturer = require('window-capturer')

let id = 0
const saveImage = require('../test/util/save-image')
const appFilter = /Slack/
const capturer = getWindowCapturer({ interval: 1000, appFilter })
capturer
  .on('error', console.error)
  .on('png', png => {
    saveImage('slack-' + (id++), png)
    if (id > 10) capturer.stop()
  })
  .start()

Capturing part of Slack Window

const getWindowCapturer = require('window-capturer')

function crop(bounds) {
  // crop upper left third with margin
  const x = bounds.x + 10
  const y = bounds.y + 5
  const w = bounds.w / 3
  const h = bounds.h / 3
  return { x, y, w, h }
}

let id = 0
const saveImage = require('../test/util/save-image')
const appFilter = /Slack/
const capturer = getWindowCapturer({ interval: 1000, appFilter, crop })
capturer
  .on('error', console.error)
  .on('png', png => {
    saveImage('slackpartial-' + (id++), png)
    if (id > 10) capturer.stop()
  })
  .start()

Installation

npm install window-capture

API

window-capture

Returns an instance of a WindowCapturer.

arguments

• @param {Object} opts specifies how/which windows should be tracked, @see thlorenz/window-tracker and cropped
• @param {Number} interval how often are windows queried
• @param {RegExp} appFilter if supplied only windows whose owning app title matches this filter will be captured
• @param {RegExp} windowilter if supplied only windows whose title matches this filter will be captured
• @param {function} crop if supplied, only part of the window will be captured, otherwise the entire window
  • crop is called with (bounds, window)
  • bounds is { x, y, w, h }
  • window includes all metadata about the window
  • if crop returns null no capture is made, otherwise the bounds that it returns are used for the capture

WindowCapturer#start()

Starts capturing windows.

WindowCapturer#stop()

Stops capturing windows.

Lower level capture API

windowCapturer.captureBounds

Captures the specified bounds of the screen.

arguments

• @name captureBounds
• @param {Object} bounds { x, y, w, h }
• @param {function} cb called back with (err, pngBuffer)

windowCapturer.captureWindow

Captures the entire specified window.

arguments

• @name captureWindow
• @param {Number} winid id of the window to be captured
• @param {function} cb called back with (err, pngBuffer)

License

MIT