WPF C# POS 打印机，从下拉菜单中打开设备

Question

I'm trying to print a simple line of text using a POS printer. Currently i do not have an actual pos printer hooked up but i do have the microsoft pos printer simulator.

Currently i have a combobox control that will list all found posprinters. The idea is that in this combobox i select the printer that i want and then it will use that printer to print the text.

The code to get all the printers and add them to the combobox is the following code:

// Get available printers and add them to the combobox in the settings menu
        PosExplorer posExplorer = new PosExplorer();
        DeviceCollection printers = posExplorer.GetDevices("PosPrinter");
       for (int i = 0; i < printers.Count; i++)
        {
            settings_ComboBox_Printer.Items.Add(printers[i].ServiceObjectName);
        }

Then i have a button control to print a sample line of text, the code for the button press event is the following:

private void ButCart_PrintOrder_Click(object sender, RoutedEventArgs e)
    {
        PosExplorer posExplorer = new PosExplorer();

        // Get connected printer devices
        DeviceCollection printers = posExplorer.GetDevices("PosPrinter");
        for (int i = 0; i < printers.Count; i++)
        {
            if (printers[i].ServiceObjectName == settings_ComboBox_Printer.Text)
            {
                selectedPrinter = (PosPrinter)printers[i];
            }
        }

        try
        {
            string text = "test text";
            selectedPrinter.PrintNormal(PrinterStation.Receipt, text);
        } catch (Exception ae)
        {
            MessageBox.Show("An error occured: " + ae.ToString());
        }

    }

And lastely the selectedPrinter object is defined as this:

using Microsoft.PointOfService;
PosPrinter selectedPrinter;

The error that i get in the for loop in the button click event is that the printer[i] returns a DeviceInfo object rather than the device itself. So i would have to retreive the device and afterwards claim it and open it i assume. However i have no clue how to get the actual device and open it.

Thanks in advance!

Answer 1

I figured it out, u can initialize the printer using the posexplorer class by feeding it the device info. If anyone else ran into this issue, i changed the code and it works for me now :) I also added some checks to make sure that the printer is actually ready to print. Thanks for the replies and happy holidays!

private void ButCart_PrintOrder_Click(object sender, RoutedEventArgs e)
    {
        PosExplorer posExplorer = new PosExplorer();

        // Get connected printer devices
        DeviceCollection printers = posExplorer.GetDevices(DeviceType.PosPrinter);
        for (int i = 0; i < printers.Count; i++)
        {
            if (printers[i].ServiceObjectName == settings_ComboBox_Printer.Text)
            {
                selectedPrinter = posExplorer.CreateInstance(printers[i]) as PosPrinter;
            }
        }

        try
        {
            selectedPrinter.Open();
            if (!selectedPrinter.Claimed)
            {
                selectedPrinter.Claim(0);
                selectedPrinter.DeviceEnabled = true;
            }

            bool printerReady = true;
            if (selectedPrinter.CoverOpen)
            {
                MessageBox.Show("Printer cover is open.");
                printerReady = false;
            }
            if (selectedPrinter.PowerState == PowerState.OffOffline)
            {
                MessageBox.Show("Printer is has no power or is offline");
                printerReady = false;
            }
            if (selectedPrinter.State != ControlState.Idle)
            {
                MessageBox.Show("Printer is busy");
                printerReady = false;
            }

            if (printerReady)
            {
                string text = "test text";
                selectedPrinter.PrintNormal(PrinterStation.Receipt, text);
            }

        }
        catch (Exception ae)
        {
            MessageBox.Show("An error occured: " + ae.ToString());
        }
    }