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Como: Impressão no Windows Forms usando visualização de impressão

É muito comum na programação em Formulários do Windows oferecer visualização de impressão junto com os serviços de impressão.Uma maneira fácil de adicionar serviços de visualização da impressão ao seu aplicativo é usar um controle PrintPreviewDialog em combinação com a lógica de manipulação de eventos PrintPage para imprimir um arquivo.

Para visualizar um documento de texto com um controle PrintPreviewDialog

  1. Adicione PrintPreviewDialog, PrintDocument e duas Strings ao seu formulário.

    Private printPreviewDialog1 As New PrintPreviewDialog()
    Private WithEvents printDocument1 As New PrintDocument()
    
    ' Declare a string to hold the entire document contents.
    Private documentContents As String
    
    ' Declare a variable to hold the portion of the document that
    ' is not printed.
    Private stringToPrint As String
    
    private PrintPreviewDialog printPreviewDialog1 = new PrintPreviewDialog();
    private PrintDocument printDocument1 = new PrintDocument();
    
    // Declare a string to hold the entire document contents.
    private string documentContents;
    
    // Declare a variable to hold the portion of the document that
    // is not printed.
    private string stringToPrint;
    
  2. Defina a propriedade DocumentName para o documento que você deseja imprimir e abra e leia conteúdo do documento na string que você adicionou anteriormente.

    Private Sub ReadDocument() 
        Dim docName As String = "testPage.txt"
        Dim docPath As String = "c:\"
        printDocument1.DocumentName = docName
        Dim stream As New FileStream(docPath + docName, FileMode.Open)
        Try
            Dim reader As New StreamReader(stream)
            Try
                documentContents = reader.ReadToEnd()
            Finally
                reader.Dispose()
            End Try
        Finally
            stream.Dispose()
        End Try
        stringToPrint = documentContents
    
    End Sub
    
    private void ReadDocument()
    {
        string docName = "testPage.txt";
        string docPath = @"c:\";
        printDocument1.DocumentName = docName;
        using (FileStream stream = new FileStream(docPath + docName, FileMode.Open))
        using (StreamReader reader = new StreamReader(stream))
        {
            documentContents = reader.ReadToEnd();
        }
        stringToPrint = documentContents;
    }
    
  3. Assim como você faria para imprimir o documento, no manipulador de eventos PrintPage, use a propriedade Graphics da classe PrintPageEventArgs e o conteúdo do arquivo para calcular linhas por página e processar o conteúdo do documento.Depois que cada página é desenhada, verifique se ela é a última página e definia a propriedade HasMorePages do PrintPageEventArgs adequadamente.O evento PrintPage é gerado até que HasMorePages seja false.Quando o documento tiver terminado a renderização, reinicie a string para ser renderizada.Além disso, certifique-se de que o evento PrintPage está associado com seu método manipulador de eventos.

    Observação:

    Você talvez já tenha concluído as etapas 2 e 3 se você implementou a impressão em seu aplicativo .

    No código exemplo a seguir, o manipulador de eventos é usado para imprimir o arquivo "testPage.txt" na mesma fonte usada no fomulário.

    Sub printDocument1_PrintPage(ByVal sender As Object, _
        ByVal e As PrintPageEventArgs) Handles printDocument1.PrintPage
    
        Dim charactersOnPage As Integer = 0
        Dim linesPerPage As Integer = 0
    
        ' Sets the value of charactersOnPage to the number of characters 
        ' of stringToPrint that will fit within the bounds of the page.
        e.Graphics.MeasureString(stringToPrint, Me.Font, e.MarginBounds.Size, _
            StringFormat.GenericTypographic, charactersOnPage, linesPerPage)
    
        ' Draws the string within the bounds of the page.
        e.Graphics.DrawString(stringToPrint, Me.Font, Brushes.Black, _
            e.MarginBounds, StringFormat.GenericTypographic)
    
        ' Remove the portion of the string that has been printed.
        stringToPrint = stringToPrint.Substring(charactersOnPage)
    
        ' Check to see if more pages are to be printed.
        e.HasMorePages = stringToPrint.Length > 0
    
        ' If there are no more pages, reset the string to be printed.
        If Not e.HasMorePages Then
            stringToPrint = documentContents
        End If
    
    End Sub
    
    void printDocument1_PrintPage(object sender, PrintPageEventArgs e)
    {
        int charactersOnPage = 0;
        int linesPerPage = 0;
    
        // Sets the value of charactersOnPage to the number of characters 
        // of stringToPrint that will fit within the bounds of the page.
        e.Graphics.MeasureString(stringToPrint, this.Font,
            e.MarginBounds.Size, StringFormat.GenericTypographic,
            out charactersOnPage, out linesPerPage);
    
        // Draws the string within the bounds of the page.
        e.Graphics.DrawString(stringToPrint, this.Font, Brushes.Black,
        e.MarginBounds, StringFormat.GenericTypographic);
    
        // Remove the portion of the string that has been printed.
        stringToPrint = stringToPrint.Substring(charactersOnPage);
    
        // Check to see if more pages are to be printed.
        e.HasMorePages = (stringToPrint.Length > 0);
    
        // If there are no more pages, reset the string to be printed.
        if (!e.HasMorePages)
            stringToPrint = documentContents;
    }
    
  4. Defina a propriedade Document do controle PrintPreviewDialog como o componente PrintDocument no fomulário.

    printPreviewDialog1.Document = printDocument1
    
    printPreviewDialog1.Document = printDocument1;
    
  5. Chame o método ShowDialog no controle PrintPreviewDialog.Você normalmente chamaria ShowDialog a partir do método manipulador de eventos Click de um botão.Chamar ShowDialog gera o evento PrintPage e processa a saída para o controle PrintPreviewDialog.Quando o usuário clica no ícone de impressão na caixa de diálogo, o evento PrintPage é gerado novamente, enviando a saída para a impressora ao invés da caixa de diálogo de visualização.É por isso que a string é reiniciada no final do processo de renderização na etapa 3.

    O exemplo de código a seguir mostra o método manipulador de eventos Click para um botão no formulário.Este método manipulador de eventos chama os métodos para ler o documento e exibir a caixa de diálogo Visualizar Impressão.

    Private Sub printPreviewButton_Click(ByVal sender As Object, _
        ByVal e As EventArgs) Handles printPreviewButton.Click
    
        ReadDocument()
        printPreviewDialog1.Document = printDocument1
        printPreviewDialog1.ShowDialog()
    End Sub
    
            private void printPreviewButton_Click(object sender, EventArgs e)
            {
                ReadDocument();
                printPreviewDialog1.Document = printDocument1;
            printPreviewDialog1.ShowDialog();
    
            }
    

Exemplo

Imports System
Imports System.Drawing
Imports System.IO
Imports System.Drawing.Printing
Imports System.Windows.Forms



Class Form1
    Inherits Form

    Private WithEvents printPreviewButton As Button

    Private printPreviewDialog1 As New PrintPreviewDialog()
    Private WithEvents printDocument1 As New PrintDocument()

    ' Declare a string to hold the entire document contents.
    Private documentContents As String

    ' Declare a variable to hold the portion of the document that
    ' is not printed.
    Private stringToPrint As String

    Public Sub New() 
        Me.printPreviewButton = New System.Windows.Forms.Button()
        Me.printPreviewButton.Location = New System.Drawing.Point(12, 12)
        Me.printPreviewButton.Size = New System.Drawing.Size(125, 23)
        Me.printPreviewButton.Text = "Print Preview"
        Me.ClientSize = New System.Drawing.Size(292, 266)
        Me.Controls.Add(Me.printPreviewButton)

    End Sub

    Private Sub ReadDocument() 
        Dim docName As String = "testPage.txt"
        Dim docPath As String = "c:\"
        printDocument1.DocumentName = docName
        Dim stream As New FileStream(docPath + docName, FileMode.Open)
        Try
            Dim reader As New StreamReader(stream)
            Try
                documentContents = reader.ReadToEnd()
            Finally
                reader.Dispose()
            End Try
        Finally
            stream.Dispose()
        End Try
        stringToPrint = documentContents

    End Sub

    Sub printDocument1_PrintPage(ByVal sender As Object, _
        ByVal e As PrintPageEventArgs) Handles printDocument1.PrintPage

        Dim charactersOnPage As Integer = 0
        Dim linesPerPage As Integer = 0

        ' Sets the value of charactersOnPage to the number of characters 
        ' of stringToPrint that will fit within the bounds of the page.
        e.Graphics.MeasureString(stringToPrint, Me.Font, e.MarginBounds.Size, _
            StringFormat.GenericTypographic, charactersOnPage, linesPerPage)

        ' Draws the string within the bounds of the page.
        e.Graphics.DrawString(stringToPrint, Me.Font, Brushes.Black, _
            e.MarginBounds, StringFormat.GenericTypographic)

        ' Remove the portion of the string that has been printed.
        stringToPrint = stringToPrint.Substring(charactersOnPage)

        ' Check to see if more pages are to be printed.
        e.HasMorePages = stringToPrint.Length > 0

        ' If there are no more pages, reset the string to be printed.
        If Not e.HasMorePages Then
            stringToPrint = documentContents
        End If

    End Sub

    Private Sub printPreviewButton_Click(ByVal sender As Object, _
        ByVal e As EventArgs) Handles printPreviewButton.Click

        ReadDocument()
        printPreviewDialog1.Document = printDocument1
        printPreviewDialog1.ShowDialog()
    End Sub

    <STAThread()>  _
    Shared Sub Main() 
        Application.EnableVisualStyles()
        Application.SetCompatibleTextRenderingDefault(False)
        Application.Run(New Form1())

    End Sub
End Class 
using System;
using System.Drawing;
using System.IO;
using System.Drawing.Printing;
using System.Windows.Forms;

namespace PrintPreviewApp
{
    public partial class Form1 : Form
    {
        private Button printPreviewButton;

        private PrintPreviewDialog printPreviewDialog1 = new PrintPreviewDialog();
        private PrintDocument printDocument1 = new PrintDocument();

        // Declare a string to hold the entire document contents.
        private string documentContents;

        // Declare a variable to hold the portion of the document that
        // is not printed.
        private string stringToPrint;

        public Form1()
        {
            this.printPreviewButton = new System.Windows.Forms.Button();
            this.printPreviewButton.Location = new System.Drawing.Point(12, 12);
            this.printPreviewButton.Size = new System.Drawing.Size(125, 23);
            this.printPreviewButton.Text = "Print Preview";
            this.printPreviewButton.Click += new System.EventHandler(this.printPreviewButton_Click);
            this.ClientSize = new System.Drawing.Size(292, 266);
            this.Controls.Add(this.printPreviewButton);
            printDocument1.PrintPage +=
                new PrintPageEventHandler(printDocument1_PrintPage);
        }
        private void ReadDocument()
        {
            string docName = "testPage.txt";
            string docPath = @"c:\";
            printDocument1.DocumentName = docName;
            using (FileStream stream = new FileStream(docPath + docName, FileMode.Open))
            using (StreamReader reader = new StreamReader(stream))
            {
                documentContents = reader.ReadToEnd();
            }
            stringToPrint = documentContents;
        }

        void printDocument1_PrintPage(object sender, PrintPageEventArgs e)
        {
            int charactersOnPage = 0;
            int linesPerPage = 0;

            // Sets the value of charactersOnPage to the number of characters 
            // of stringToPrint that will fit within the bounds of the page.
            e.Graphics.MeasureString(stringToPrint, this.Font,
                e.MarginBounds.Size, StringFormat.GenericTypographic,
                out charactersOnPage, out linesPerPage);

            // Draws the string within the bounds of the page.
            e.Graphics.DrawString(stringToPrint, this.Font, Brushes.Black,
            e.MarginBounds, StringFormat.GenericTypographic);

            // Remove the portion of the string that has been printed.
            stringToPrint = stringToPrint.Substring(charactersOnPage);

            // Check to see if more pages are to be printed.
            e.HasMorePages = (stringToPrint.Length > 0);

            // If there are no more pages, reset the string to be printed.
            if (!e.HasMorePages)
                stringToPrint = documentContents;
        }
        private void printPreviewButton_Click(object sender, EventArgs e)
        {
            ReadDocument();
            printPreviewDialog1.Document = printDocument1;
        printPreviewDialog1.ShowDialog();

        }

        [STAThread]
        static void Main()
        {
            Application.EnableVisualStyles();
            Application.SetCompatibleTextRenderingDefault(false);
            Application.Run(new Form1());
        }
    }
}

Compilando o código

Este exemplo requer:

Consulte também

Tarefas

Como: Imprimir um arquivo de texto multi-páginas no Windows Forms

Conceitos

Impressão Mais Segura em Formulários do Windows

Outros recursos

Suporte a Impressão em Formulários do Windows