Exemplo de manipulador de eventos (documentação do SDK do PDV para .NET v1.14)

Este exemplo demonstra como os aplicativos podem registrar manipuladores para qualquer um dos cinco tipos de evento suportados pelo Microsoft Point of Service for .NET (POS for .NET):

• DataEvent
• ErrorEvent
• StatusUpdateEvent
• OutputCompleteEvent
• DirectIOEvent

Ele também mostra como um aplicativo gerencia solicitações de saída assíncronas para um PosPrinter dispositivo.

Para criar o projeto de exemplo

1. Compile e instale o código de exemplo de objeto de serviço do exemplo de saída assíncrona.

2. Crie um projeto de aplicativo do Windows Forms no Microsoft Visual Studio 2013.

3. A seção de código abaixo inclui dois arquivos, AsyncApp.cs e AsyncApp.Designer.cs.

4. No projeto recém-criado, substitua Form1.cs por AsyncApp.cs e Form1.Designer.cs por AsyncApp.Designer.cs.

5. Se ainda não existir, adicione uma referência de assembly a Microsoft.PointOfService.dll. Em uma instalação padrão, você pode encontrar esse arquivo em Arquivos de programas (x86)\Microsoft Point Of Service\SDK.

6. Compile e execute.

Para executar o exemplo

1. Este exemplo exibe uma interface de usuário GUI que permite ao usuário enviar solicitações de impressão assíncronas e síncronas para o objeto de serviço de exemplo de saída assíncrona.

2. O objeto de serviço aguarda por vários segundos antes de retornar de uma solicitação, seja ela síncrona ou assíncrona.

3. A interface do usuário exibe o status de cada solicitação na caixa de texto.

Exemplo

Este código de exemplo demonstra vários pontos-chave:

• Usando um evento OutputCompleteEvent para notificar o aplicativo de que o objeto de serviço concluiu uma solicitação de saída.
• Registrando manipuladores de eventos, incluindo o uso de reflexão para fazer isso.
• Usando PosExplorer para procurar objetos de serviço específicos.

Para demonstrar como a reflexão pode ser usada para descobrir quais eventos estão disponíveis em um determinado objeto, esse código usa o PosCommon objeto retornado sem CreateInstance(DeviceInfo) primeiro transmiti-lo para um PosPrinter. Na maioria dos casos, um aplicativo não precisa ser genérico dessa maneira e, portanto, lançaria o objeto conforme apropriado.

// ASYNCAPP.CS
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Threading;
using System.Windows.Forms;
using System.Reflection;
using Microsoft.PointOfService;

namespace AsyncOutputApp
{
    public partial class AsyncApp : Form
    {
        PosCommon posCommon;
        PosExplorer posExplorer;

        public AsyncApp()
        {
            InitializeComponent();

            btnPrintAsync.Enabled = true;
            btnPrintSync.Enabled = true;

            posExplorer = new PosExplorer(this);
            posCommon = null;

            string SOName = "AsyncOutputPrinter";

            try
            {
                OpenDevice(SOName);
                SetupEvents();
            }
            catch
            {
                MessageBox.Show("The Service Object '" +
                        SOName + "' failed to load",
                        "Service Object Error",
                        MessageBoxButtons.OK,
                        MessageBoxIcon.Exclamation);

                btnPrintAsync.Enabled = false;
                btnPrintSync.Enabled = false;
            }
        }

        private void OpenDevice(string SOName)
        {
            string str = txtPrintResults.Text;
            DeviceInfo device = null;

            txtPrintResults.Clear();

            {
                // Retrieve the list of PosPrinter Service Objects.
                DeviceCollection devices =
                        posExplorer.GetDevices(
                        DeviceType.PosPrinter);

                // Iterate through the list looking for the one
                // needed for this sample.
                foreach(DeviceInfo d in devices)
                {
                    if(d.ServiceObjectName == SOName)
                    {
                        device = d;
                        break;
                    }
                }

                if (device == null)
                {
                    throw new Exception("Service Object not found");
                }

                txtPrintResults.Text = "Opening device: " +
                        device.ServiceObjectName + ", type: " +
                        device.Type + "\r\n";

                posCommon =
                        (PosCommon)posExplorer.CreateInstance(device);

                posCommon.Open();
                posCommon.Claim(0);
                posCommon.DeviceEnabled = true;
            }
        }

        // When this button is pressed, AsyncMode is turned off,
        // and the application waits for each print request
        // to complete before regaining control.
        private void btnPrintSync_Click(object sender, EventArgs e)
        {
            PosPrinter posPrinter = posCommon as PosPrinter;
            posPrinter.AsyncMode = false;

            txtPrintResults.AppendText(
                        "Printing will take place " +
                        "synchronously.\r\n");

            StartPrinting();
        }

        // When this button is pressed, AsyncMode is turned on. Print
        // requests will be queued and delivered on a
        // first-in-first-out basis.
        private void btnPrintAsync_Click(object sender, EventArgs e)
        {
            PosPrinter posPrinter = posCommon as PosPrinter;
            posPrinter.AsyncMode = true;

            txtPrintResults.AppendText(
                        "Printing will take place " +
                        "asynchronously.\r\n");

            StartPrinting();
        }

        private void StartPrinting()
        {
            PosPrinter posPrinter = posCommon as PosPrinter;

            txtPrintResults.AppendText(
                        "Calling PrintNormal to start " +
                        "printing...\r\n");

            // Notice that calling PrintNormal() here may not result
            // in a print request being sent immediately to the
            // printer. In asynchronous mode, the requested is
            // placed in a first-in-first-out queue managed by
            // POS for .NET.
            try
            {
                posPrinter.PrintNormal(
                            PrinterStation.Receipt,
                            "This is do-nothing print data");
            }
            catch (PosControlException e)
            {
                txtPrintResults.AppendText(
                            "PrintNormal threw a " +
                            "PosControlException! Description: " +
                            e.Message + "\r\n");

                return;
            }

            // When data is sent to an output device, POS for .NET
            // updates the OutputId property in the target object.
            // When an OutputCompleteEvent is sent to the app,
            // the OutputCompleteEventArgs will contain this id.
            Int32 id = posPrinter.OutputId;

            txtPrintResults.AppendText(
                        "PrintNormal has returned! OutputID = " +
                        id + "\r\n");
        }

        // Visual Studio-generated code.
        private void AsyncApp_Load(object sender, EventArgs e)
        {
        }

        #region Event Registration
        private void SetupEvents()
        {
            // All PosCommon objects support StatusUpdateEvent and
            // DirectIOEvent events, so simply register a handler
            // for those events.
            posCommon.StatusUpdateEvent +=
                        new StatusUpdateEventHandler(
                        co_OnStatusUpdateEvent);

            posCommon.DirectIOEvent +=
                        new DirectIOEventHandler(
                        co_OnDirectIOEvent);

            // In addition to the events common to all devices
            // (StatusUpdateEvent and DirectIOEvent), a device
            // type may also support DataEvent, ErrorEvent, or
            // OutputCompleteEvent events.
            //
            // In this example, the following code uses reflection
            // to determine which events are supported by this
            // object (posCommon).
            //
            // However, in the general case, an application will know
            // what type of device was returned when PosExplorer
            // CreateInstance() was called;therefore will not
            // need to use reflection, but can instead register
            // event handlers using the mechanism used for
            // StatusUpdateEvent and DirectIOEvent events above.
            EventInfo dataEvent =
                        posCommon.GetType().GetEvent(
                        "DataEvent");
            if (dataEvent != null)
            {
                dataEvent.AddEventHandler(posCommon,
                        new DataEventHandler(
                        co_OnDataEvent));

                txtPrintResults.AppendText("Registering Event: " +
                        "DataEvent\r\n");
            }

            EventInfo errorEvent =
                        posCommon.GetType().GetEvent(
                        "ErrorEvent");
            if (errorEvent != null)
            {
                errorEvent.AddEventHandler(posCommon,
                        new DeviceErrorEventHandler(
                        co_OnErrorEvent));

                txtPrintResults.AppendText("Registering Event: " +
                        "ErrorEvent\r\n");
            }

            EventInfo outputCompleteEvent =
                        posCommon.GetType().GetEvent(
                        "OutputCompleteEvent");
            if (outputCompleteEvent != null)
            {
                outputCompleteEvent.AddEventHandler(
                        posCommon, new OutputCompleteEventHandler(
                        co_OnOutputCompleteEvent));

                txtPrintResults.AppendText("Registering Event: " +
                        "OutputCompleteEvent\r\n");
            }
        }
        #endregion Event Registration

        #region Event Handlers
        private void co_OnDataEvent(
                        object obj,
                        DataEventArgs d)
        {
            txtPrintResults.AppendText(d.ToString() + "\r\n");
        }

        private void co_OnStatusUpdateEvent(
                        object source,
                        StatusUpdateEventArgs d)
        {
            txtPrintResults.AppendText(d.ToString() + "\r\n");
        }

        private void co_OnDirectIOEvent(
                        object source,
                        DirectIOEventArgs d)
        {
            txtPrintResults.AppendText(d.ToString() + "\r\n");
        }

        private void co_OnErrorEvent(
                        object source,
                        DeviceErrorEventArgs d)
        {
            string str = d.ToString();

            MessageBox.Show(d.ToString(),
                        "OnErrorEvent called",
                        MessageBoxButtons.OK,
                        MessageBoxIcon.Error);

            txtPrintResults.AppendText(d.ToString() + "\r\n");
        }

        private void co_OnOutputCompleteEvent(
                        object source,
                        OutputCompleteEventArgs d)
        {
            txtPrintResults.AppendText(d.ToString() + "\r\n");
        }
        #endregion Event Handlers
    }
}

// ASYNCAPP.DESIGNER.CS
namespace AsyncOutputApp
{
    partial class AsyncApp
    {
        /// <summary>
        /// Required designer variable.
        /// </summary>
        private System.ComponentModel.IContainer components = null;

        /// <summary>
        /// Clean up any resources being used.
        /// </summary>
        /// <param name="disposing">true if managed resources should be disposed; otherwise, false.</param>
        protected override void Dispose(bool disposing)
        {
            if (disposing && (components != null))
            {
                components.Dispose();
            }
            base.Dispose(disposing);
        }

        #region Windows Form Designer generated code

        /// <summary>
        /// Required method for Designer support - do not modify
        /// the contents of this method with the code editor.
        /// </summary>
        private void InitializeComponent()
        {
            this.txtPrintResults = new System.Windows.Forms.TextBox();
            this.btnPrintSync = new System.Windows.Forms.Button();
            this.btnPrintAsync = new System.Windows.Forms.Button();
            this.SuspendLayout();
            //
            // txtPrintResults
            //
            this.txtPrintResults.BackColor = System.Drawing.SystemColors.Window;
            this.txtPrintResults.Location = new System.Drawing.Point(12, 119);
            this.txtPrintResults.Multiline = true;
            this.txtPrintResults.Name = "txtPrintResults";
            this.txtPrintResults.ReadOnly = true;
            this.txtPrintResults.ScrollBars = System.Windows.Forms.ScrollBars.Vertical;
            this.txtPrintResults.Size = new System.Drawing.Size(650, 200);
            this.txtPrintResults.TabIndex = 3;
            //
            // btnPrintSync
            //
            this.btnPrintSync.Location = new System.Drawing.Point(12, 12);
            this.btnPrintSync.Name = "btnPrintSync";
            this.btnPrintSync.Size = new System.Drawing.Size(132, 39);
            this.btnPrintSync.TabIndex = 1;
            this.btnPrintSync.Text = "Print Synchronous";
            this.btnPrintSync.UseVisualStyleBackColor = true;
            this.btnPrintSync.Click += new System.EventHandler(this.btnPrintSync_Click);
            //
            // btnPrintAsync
            //
            this.btnPrintAsync.Location = new System.Drawing.Point(12, 57);
            this.btnPrintAsync.Name = "btnPrintAsync";
            this.btnPrintAsync.Size = new System.Drawing.Size(132, 39);
            this.btnPrintAsync.TabIndex = 2;
            this.btnPrintAsync.Text = "Print Asynchronously";
            this.btnPrintAsync.UseVisualStyleBackColor = true;
            this.btnPrintAsync.Click += new System.EventHandler(this.btnPrintAsync_Click);
            //
            // AsyncApp
            //
            this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 13F);
            this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
            this.ClientSize = new System.Drawing.Size(685, 331);
            this.Controls.Add(this.btnPrintAsync);
            this.Controls.Add(this.btnPrintSync);
            this.Controls.Add(this.txtPrintResults);
            this.Name = "AsyncApp";
            this.Text = "Form1";
            this.Load += new System.EventHandler(this.AsyncApp_Load);
            this.ResumeLayout(false);
            this.PerformLayout();

        }

        #endregion

        private System.Windows.Forms.TextBox txtPrintResults;
        private System.Windows.Forms.Button btnPrintSync;
        private System.Windows.Forms.Button btnPrintAsync;
    }
}

O programa deve exibir o seguinte texto se você primeiro pressionar o botão Imprimir síncrono e, em seguida, o botão Imprimir assíncrono.

Dispositivo de abertura: AsyncOutputPrinter, digite: PosPrinterRegistering Event: ErrorEventRegistering Event: OutputCompleteEventPrinting ocorrerá de forma síncrona. Chamando PrintNormal para começar a imprimir... PrintNormal voltou! OutputID = 0A impressão ocorrerá de forma assíncrona. Chamando PrintNormal para começar a imprimir... PrintNormal voltou! OutputID = 1Microsoft.PointOfService.OutputCompleteEventArgs, TimeStamp: 11:35:39 AM, EventId: 1, OutputId: 1.

Consulte Também

Tarefas

• Exemplo de saída assíncrona

Conceitos

• Gestão de Eventos

Outros Recursos

• Desenvolvendo um objeto de serviço personalizado