印表機模組

調用流程

使用 APOLLO 中內置的打印機打印收據或報告很簡單。

---

設置

創建一個實例，並通過 getControllerInstance() and connectController() 連接到終端。

如果發生任何錯誤，應通過 onError 通知應用程序。

abstract class ApolloPrinter(private val context: Context) : PrinterDelegate {

    private var printerController: PrinterController? = null
    private val printerFixedWidth = 384
    private lateinit var printData: ByteArray

    fun connect(): Boolean {
        try {
            if (printerController == null) {
                // get instance
                printerController = getControllerInstance(context, this)

                // enable debug log display in console
                SPDeviceController.enableDebugLog(true)
            }
            // establish the communication channel with terminal
            printerController?.connectController()
        } catch (ex: Exception) {
            return false
        }
        return true
    }

    fun disconnect() {
        printerController?.disconnectController()
        printerController?.releaseControllerInstance()
    }

    override fun onError(errorType: ControllerError.Error?, message: String?) {
        // handle error here
    }

}

---

打印流程

準備打印數據

APOLLO 熱打印機有 384 點/行。在發送到打印機之前，應用程序應將收據或報告轉換為 byte array 字節數組。

一種簡單的方法是首先使用 HTML 創建收據或報告並將其轉換為 bitmap 位圖。在應用程序的 build.gradle，添加 html2bitMap。

dependencies {
  //HTML to bitmap library
  implementation 'com.izettle:html2bitmap:1.6'
}

在 ApolloPrinter 类中，有一个将位图转换为 ByteArray 的示例。

/**
 * Input bitmap can be any size but preferred use APOLLO printer width or scaling is needed
 */
private fun bitmapTo1bppByteArray(bitmap: Bitmap): ByteArray {
    val bFilter = true
    val bmpResult: Bitmap

    var width = bitmap.width
    var height = bitmap.height
    val widthNew = printerFixedWidth
    val dataLen = ceil((width * height).toDouble() / 8).toInt()
    val paddedData = ByteArray(dataLen)

    /* First do a scale to make sure width match apollo criteria */
    if (widthNew != bitmap.width) {
        val scaleWidthFactor = widthNew.toDouble() / width
        val dstHeight = (height * scaleWidthFactor).toInt()
        bmpResult = Bitmap.createScaledBitmap(bitmap, widthNew, dstHeight, bFilter)
    } else {
        bmpResult = bitmap
    }

    //Change to B&W and RGB565
    val convertedBitmap = Bitmap.createBitmap(bmpResult.width, bmpResult.height, Bitmap.Config.RGB_565)
    val canvas = Canvas(convertedBitmap)
    val ma = ColorMatrix()
    ma.setSaturation(0f)
    val paint = Paint()
    paint.colorFilter = ColorMatrixColorFilter(ma)
    canvas.drawBitmap(bitmap, 0f, 0f, paint)

    width = convertedBitmap.width
    height = convertedBitmap.height

    val bb: ByteBuffer = ByteBuffer.allocate(convertedBitmap.byteCount)
    convertedBitmap.copyPixelsToBuffer(bb)

    val byteStream = ByteArrayInputStream(bb.array())

    var bitPosition = 0
    var bytePosition = 0

    for (y in 0 until height) {
        for (x in 0 until width) {
            //Read 2 bytes from byte stream, beware of endian
            val rgb565 = byteStream.read() or (byteStream.read() shl 8)

            //Here for simplicity just use Red value (5bits) and threshold set to 16 which assume the input bitmap already in Grey scale
            val red = (rgb565 shr 11)

            //get binary value
            var value: Byte

            value = if (red <= 16) {
                0x01.toByte()
            } else {
                0x00.toByte()
            }

            paddedData[bytePosition] = paddedData[bytePosition] or (value.toInt() shl bitPosition).toByte()
            bitPosition++

            if (bitPosition == 8) {
                bitPosition = 0
                bytePosition++
            }
        }
    }

    return paddedData
}

您可以通過 bitmapTo1bppByteArray 將位圖轉換為 byteArray。

// data that feed to the printer later
private lateinit var printData: ByteArray

// pass your html string
fun preparePrintData(html: String) {
    val bitmap = Html2Bitmap.Builder()
        .setContext(context)
        .setBitmapWidth(printerFixedWidth) // 384
        .setContent(WebViewContent.html(html))
        .build().bitmap

    printData = bitmapTo1bppByteArray(bitmap)
}

---

發送打印數據

應用程序應在 getControllerInstance() 和 connectController() 之後接收 onPrintDataRequested。應用程序應通過 sendPrinterData 將字節數組格式的 printData 傳遞給打印機。

override fun onPrintDataRequested() {
    printerController?.sendPrinterData(printData)
}

---

打印狀態

應用程序應接收 onPrinterStatus 和 onPrinterCompleted 以獲取打印機狀態。

override fun onPrinterStatus(p0: PrintStatus?) {
    when (p0) {
        PrintStatus.OVERHEAT -> {
            // printer overheat, please wait
        }
        PrintStatus.NO_PAPER_OR_COVER_OPENED -> {
            // no paper or the cover is opened, please re-fill the paper roll and close the cover properly
        }
        PrintStatus.PRINTER_LOWBATTERY -> {
            // battery is low, please charge the APOLLO
        }
        PrintStatus.SUCCESS -> {
            // print success
        }
        else -> {
        }
    }
}

override fun onPrinterCompleted() {
    // do something
}

---