使用打印预览打印

2025-05-07

除了打印服务之外，Windows 窗体编程中也经常提供打印预览。向应用程序添加打印预览的一种简单方法是将 PrintPreviewDialog 控件与 PrintPage 用于打印文件的事件处理逻辑结合使用。

使用 PrintPreviewDialog 控件预览文本文档

在 Visual Studio 中，使用 “解决方案资源管理器” 窗格，然后双击要打印的窗体。这将打开视觉设计器。
在 “工具箱 ”窗格中，双击 PrintDocument 组件和 PrintPreviewDialog 组件，将其添加到窗体。
将 Button 添加到窗体，或使用窗体上已有的按钮。
在窗体的可视化设计器中，选择该按钮。在属性窗格中，选择事件筛选器按钮，然后双击 Click 事件以生成事件处理程序。

Click 事件代码应可见。在事件处理程序的作用域外，将两个私有字符串变量添加到名为 documentContents 的类中： stringToPrint。

// 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="";

' 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

返回 Click 事件处理程序代码，将 DocumentName 属性设置为要打印的文档，然后将文档的内容打开并读取到之前添加的字符串。

string docName = "testPage.txt";
string docPath = @"C:\";
string fullPath = System.IO.Path.Combine(docPath, docName);
printDocument1.DocumentName = docName;
stringToPrint = System.IO.File.ReadAllText(fullPath);

Dim docName As String = "testPage.txt"
Dim docPath As String = "C:\Users\v-rsatao\Desktop\"
Dim fullPath As String = System.IO.Path.Combine(docPath, docName)

PrintDocument1.DocumentName = docName
stringToPrint = System.IO.File.ReadAllText(fullPath)

在PrintPage事件处理程序中，就像在打印文档时一样，使用PrintPageEventArgs类的Graphics属性和文件内容来计算每页的行数并呈现文档的内容。绘制每个页面后，检查它是否是最后一页，并相应地设置 HasMorePages 属性 PrintPageEventArgs 。引发 PrintPage 事件，直到 HasMorePages 为 false。文档完成呈现后，重置要呈现的字符串。此外，请确保事件 PrintPage 与其事件处理方法相关联。

注释

如果在应用程序中实现了打印，步骤 5 和 6 可能已经完成。

在下面的代码示例中，事件处理程序用于以窗体上所用的同一字体打印“testPage.txt”文件。

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 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

将表单中的 PrintPreviewDialog 控件的 Document 属性设定为 PrintDocument 组件。

printPreviewDialog1.Document = printDocument1;

PrintPreviewDialog1.Document = PrintDocument1

在 PrintPreviewDialog 控件上调用 ShowDialog 方法。请注意以下突出显示的代码，通常您会在按钮的事件处理方法中调用ShowDialog。调用 ShowDialog 将 PrintPage 引发事件并将输出呈现给 PrintPreviewDialog 控件。当用户选择对话框上的打印图标时， PrintPage 将再次引发该事件，将输出发送到打印机而不是预览对话框。因此，字符串在步骤 4 的渲染过程结束时被重置。

下面的代码示例显示了 Click 窗体上按钮的事件处理方法。事件处理方法调用方法来读取文档并显示打印预览对话框。

private void Button1_Click(object sender, EventArgs e)
{
    string docName = "testPage.txt";
    string docPath = @"C:\";
    string fullPath = System.IO.Path.Combine(docPath, docName);
    printDocument1.DocumentName = docName;
    stringToPrint = System.IO.File.ReadAllText(fullPath);

    printPreviewDialog1.Document = printDocument1;

    printPreviewDialog1.ShowDialog();
}

Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click

    Dim docName As String = "testPage.txt"
    Dim docPath As String = "C:\Users\v-rsatao\Desktop\"
    Dim fullPath As String = System.IO.Path.Combine(docPath, docName)

    PrintDocument1.DocumentName = docName
    stringToPrint = System.IO.File.ReadAllText(fullPath)

    PrintPreviewDialog1.Document = PrintDocument1

    PrintPreviewDialog1.ShowDialog()

End Sub

通过

使用打印预览打印

使用 PrintPreviewDialog 控件预览文本文档

另请参阅

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