IosStreamConnector.js

//...

  tryRead = minicapClient => {
    this.log('tryRead')

    var outgoingImage
    for (var chunk; (chunk = minicapClient.read()); ) {
      //console.info('chunk(length=%d)', chunk.length)
      for (var cursor = 0, len = chunk.length; cursor < len; ) {
        if (this.readBannerBytes < this.bannerLength) {
          // parse minicap header (no longer used)
          switch (this.readBannerBytes) {
            case 0: // version
              this.banner.version = chunk[cursor]
              break
            case 1: // length
              if (this.banner.version == 2) {
                this.bannerLength = 252
                while (chunk.length < this.bannerLength) {
                  var extra = minicapClient.read()
                  if (!extra) continue

                  chunk = Buffer.concat([chunk, extra])
                  len = chunk.length
                }
                // first byte: version
                // second byte-25th byte: machine
                this.banner.machine = chunk.toString('utf8', 1, 25).replace(/\0+$/, '')
                this.banner.appname = chunk.toString('utf8', 25, 89).replace(/\0+$/, '')
                this.banner.appvers = chunk.toString('utf8', 89, 113).replace(/\0+$/, '')
                this.banner.hostname = chunk.toString('utf8', 113, 176).replace(/\0+$/, '')
                this.banner.scale = chunk.readFloatLE(176)
                this.banner.isIpad = chunk.readInt32LE(180)
                this.banner.protocolVersion = chunk.readInt32LE(184)
                cursor = this.readBannerBytes = this.banner.length = 252
                console.debug('header', chunk.length, this.banner)
                continue
              }
              this.banner.length = this.bannerLength = chunk[cursor]
              break
            
          }

          cursor += 1
          this.readBannerBytes += 1

          if (this.readBannerBytes === this.bannerLength) {
            this.addLineToConnectionLog('banner: \n' + JSON.stringify(this.banner, null, 2))
          }
        } else if (this.readFrameBytes < 4) {
          this.frameBodyLength += (chunk[cursor] << (this.readFrameBytes * 8)) >>> 0
          cursor += 1
          this.readFrameBytes += 1
          //          console.info('headerbyte%d(val=%d)', readFrameBytes, frameBodyLength)
        } else if (this.frameBodyLength > 1 << 30) {
          // absurd/-ve length interpreted as event coming from device
          console.log(`event ${this.frameBodyLength} ${cursor} ${len}`)
          var frameSize = 24,
            length,
            touches = []
          do {
            while (cursor + frameSize > len) {
              var extra = minicapClient.read()
              if (!extra) continue

              len = chunk.length
            }
            var frame = chunk.slice(cursor, cursor + frameSize)
            touches.push({
              timestamp: frame.readDoubleLE(0),
              x: frame.readFloatLE(8),
              y: frame.readFloatLE(12),
              phase: frame.readInt32LE(16)
            })
            length = frame.readInt32LE(20)
            cursor += frameSize
          } while (length < -1) // can be muti-touch
          console.log('touches: ', touches)
          this.frameBodyLength = this.readFrameBytes = 0
          this.frameBody = Buffer.alloc(0)
        } else {
          if (len - cursor >= this.frameBodyLength) {
            //console.info('bodyfin(len=%d,cursor=%d)', this.frameBodyLength, cursor)

            this.frameBody = Buffer.concat([this.frameBody, chunk.slice(cursor, cursor + this.frameBodyLength)])

            outgoingImage = this.frameBody
            cursor += this.frameBodyLength
            this.frameBodyLength = this.readFrameBytes = 0
            this.frameBody = Buffer.alloc(0)
          } else {
            //console.info('body(len=%d)', len - cursor)

            this.frameBody = Buffer.concat([this.frameBody, chunk.slice(cursor, len)])

            this.frameBodyLength -= len - cursor
            this.readFrameBytes += len - cursor
            cursor = len
          }
        }
      }
    }
    if (outgoingImage) {
      console.log('next frame ready: ' + (Date.now() - lastFrameTs) + 'ms')
      lastFrameTs = Date.now()
      this.publishData(outgoingImage)
    }
  }
  ///.