如何在Form1中触发Form2的PrintPage事件？

我当前处于Form1窗体中，希望触发Form2内的PrintPage事件。

Form2中目标事件处理代码：

Public Sub PrintDocument1_PrintPage_1(sender As Object, e As Printing.PrintPageEventArgs) Handles PrintDocument1.PrintPage
    Dim dm As New Bitmap(Me.Panel1.Width, Me.Panel1.Height)
    Panel1.DrawToBitmap(dm, New Rectangle(0, 0, Me.Panel1.Width, Me.Panel1.Height))
    e.Graphics.DrawImage(dm, 0, 0)

    Dim aPS As New PageSetupDialog
    aPS.Document = PrintDocument1
End Sub

我希望在Form1的printall方法指定位置触发该事件，printall方法代码：

Public Sub printall()
    If txtempname.Items.Count = 0 Then
        MessageBox.Show("There is no Record to Print")
    Else
        For i = 0 To txtempname.Items.Count - 1
            txtempname.SelectedIndex = i
            getEmployeeInfo()
            getattendance()
            getDeductions()
            getExtraDeductions()
            getLoans()
            calculate()
            printallnote()
            PrintPayslip.payslip()

            ' 需要在这里触发PrintPage事件

            PrintPayslip.print()
            PrintPayslip.Close()
        Next
    End If
End Sub

方法1：通过调用PrintDocument的Print()触发事件 #

如果PrintPayslip是Form2的实例，可直接调用其内部PrintDocument1的Print()方法触发PrintPage事件。若不想弹出默认打印对话框，可设置PrintController为StandardPrintController：

Public Sub printall()
    If txtempname.Items.Count = 0 Then
        MessageBox.Show("There is no Record to Print")
    Else
        For i = 0 To txtempname.Items.Count - 1
            txtempname.SelectedIndex = i
            getEmployeeInfo()
            getattendance()
            getDeductions()
            getExtraDeductions()
            getLoans()
            calculate()
            printallnote()
            PrintPayslip.payslip()

            ' 触发PrintPage事件
            PrintPayslip.PrintDocument1.PrintController = New Printing.StandardPrintController()
            PrintPayslip.PrintDocument1.Print()

            PrintPayslip.print()
            PrintPayslip.Close()
        Next
    End If
End Sub

方法2：将打印逻辑封装为独立公共方法（更推荐） #

直接触发事件处理方法并非最佳实践，建议把打印逻辑抽成公共方法，让事件处理方法和Form1都可调用：

1. 在Form2中添加公共方法：

Public Sub PrintPanelContent(e As Printing.PrintPageEventArgs)
    Dim dm As New Bitmap(Me.Panel1.Width, Me.Panel1.Height)
    Panel1.DrawToBitmap(dm, New Rectangle(0, 0, Me.Panel1.Width, Me.Panel1.Height))
    e.Graphics.DrawImage(dm, 0, 0)

    Dim aPS As New PageSetupDialog
    aPS.Document = PrintDocument1
End Sub

2. 修改Form2的PrintPage事件处理方法，调用该公共方法：

Public Sub PrintDocument1_PrintPage_1(sender As Object, e As Printing.PrintPageEventArgs) Handles PrintDocument1.PrintPage
    PrintPanelContent(e)
End Sub

3. 在Form1中手动调用该方法（需构建正确的PrintPageEventArgs实例）：

' 在printall方法的指定位置
Dim args As New Printing.PrintPageEventArgs(
    PrintPayslip.PrintDocument1.DefaultPageSettings,
    New Printing.Margins(10,10,10,10),
    New RectangleF(0,0, PrintPayslip.PrintDocument1.DefaultPageSettings.PrintableArea.Width, PrintPayslip.PrintDocument1.DefaultPageSettings.PrintableArea.Height),
    New Rectangle(0,0, PrintPayslip.Panel1.Width, PrintPayslip.Panel1.Height)
)
PrintPayslip.PrintPanelContent(args)

此方法更符合面向对象设计，避免直接依赖事件处理方法，代码可维护性更强。

内容的提问来源于stack exchange，提问作者Karl