How to disconnect from one printer and reconnect to another?

[msandwidi]

Hello @Rajath4 Thank you for maintaining this package. I was glad that it is the one that fits my receipt printing needs. I have an issue when I tried disconnecting from the currently connected printer to connect to another one.

Let me give you more details about my use case

I have a restaurant point of sale app. After a sale is made, I would like to print a receipt for the customer with the printer at the cashier and print the order with the printer located in the kitchen so the cook can make the meal.

So I need to be able to print on both printer simultaneously. When I use this package, and tried the scenario, both the receipt and the order are getting printed from the same printer.. If I try one printer and switch to the other and print, the printing still goes to the previous printer.

Also I have no way of knowing what printer I is currently connected. Is there a way to know what printer is connected?

Is there a way to disconnect and reconnect to another printer on the fly?

like

await BluetoothThermalPrinter.connect(_receiptPrinter.mac);

//... more code here

//manually disconnect from receipt printer here 
await BluetoothThermalPrinter.disconnect();

//or the next .connect(mac) call would disconnect the currently connected printer 
///before connecting the new one

await BluetoothThermalPrinter.connect(_orderPrinter.mac);

//... more code here 

Thank you all

Doctor summary (to see all details, run flutter doctor -v):
[√] Flutter (Channel stable, 2.2.2, on Microsoft Windows [Version
    10.0.19042.1052], locale en-US)
[√] Android toolchain - develop for Android devices (Android SDK version
    30.0.3)

[msandwidi]

So I was able to add a .disconnect() methode that disconnects the currently connected device. It works as I want but I don't know what I am doing. I never wrote a single line of kotlin code before. If you look at the example, every time I setConnect, I disconnect the connected device. That way I can print the receipt, disconnect and connect to other printer, then print the order.

Another way of doing it also is to pass a parameter to .connect(mac, {bool dropPreviousConnection : false}) and drop the previous connection base on the dropPreviousConnection value.

I believe the following is what prevents the newly selected device to connect if there is already another one connect:

//.... more code
if (call.method == "connectPrinter") {
      var printerMAC = call.arguments.toString();
      if(printerMAC.length>0){
        mac = printerMAC;
      }else{
        result.success("false")
      }
      GlobalScope.launch(Dispatchers.Main) {
        if(outputStream == null) { //<= This may be preventing new device to connect 
          outputStream = connect()?.also {
            //result.success("true")
            //Toast.makeText(this@MainActivity, "Connected to printer", Toast.LENGTH_SHORT).show()
          }.apply {
            result.success(state)
            //Log.d(TAG, "finished: Connection state:$state")
          }
        }
      }
     }else if (call.method == "disconnectPrinter") {
//... more code 
}

This is what I added in the kotlin file

if (call.method == "disconnectPrinter") {
      GlobalScope.launch(Dispatchers.Main) {
        if(outputStream != null) {
          outputStream = disconnect()?.also {
            //result.success("true")
            //Toast.makeText(this@MainActivity, "Connected to printer", Toast.LENGTH_SHORT).show()
          }.apply {
            result.success("true")
            //Log.d(TAG, "finished: Connection state:$state")
          }
        }
      }
     } else if (call.method == "writeBytes") {
//...more code
}

Then in dart

//...more code

  /// Disconnect from device
  static Future<String?> disconnect() async {
    String? result = "false";
    try {
      result = await _channel.invokeMethod('disconnectPrinter');
    } on PlatformException catch (e) {
      print("Failed to disconnect: '${e.message}'.");
    }
    return result;
  }

//... more code

I hope this information is helpful to adding the feature.

Please checkout the disconnect branch

branch: https://github.com/msandwidi/BluetoothThermalPrinter/tree/disconnect

Thank you all

[JunioJsv]

@msandwidi thanks

[g14wx]

Thank you a lot @msandwidi !! 🎉, you are amazing!, it works like a charm! 🔥