vb.net 中的打印预览为空

Question

这是我的代码：

Imports System.Drawing
Imports System.Drawing.Printing
Imports System.Data
Imports System.Data.OleDb
Public Class Form3
Dim dgv As New DataGridView()
Dim print As New PrintDocument()
Dim preview As New PrintPreviewDialog()
Private Sub Form3_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
    Dim con As New OleDbConnection("Provider=Microsoft.Jet.Oledb.4.0;Data Source=C:UsersuserDocumentsInventoryInventoryLoginInventoryLoginSupplies.mdb")
    Try
        con.Open()
        Dim sql As String
        sql = "SELECT * From [product info]"
        Dim adapter As New OleDbDataAdapter(sql, con)
        Dim dt As New DataTable("product info")
        adapter.Fill(dt)
        preview.PrintPreviewControl.Zoom = 1
        preview.Document = print
        preview.Show()
        AddHandler print.PrintPage, AddressOf print_PrintPage
    Catch Ex As Exception
        MessageBox.Show(Ex.Message)
    End Try
End Sub
Protected Sub print_PrintPage(ByVal sender As Object, ByVal e As PrintPageEventArgs)
    Dim ColumnCount As Integer = dgv.ColumnCount
    Dim RowCount As Integer = dgv.RowCount
    Dim CellTopPos As Integer = print.PrinterSettings.DefaultPageSettings.Margins.Top
    For Row = 0 To RowCount - 2
        Dim CellLeftPos As Integer = print.PrinterSettings.DefaultPageSettings.Margins.Left
        For Cell = 0 To ColumnCount - 1
            Dim CellValue As String = dgv.Rows(Row).Cells(Cell).Value.ToString()
            Dim CellWidth = dgv.Rows(Row).Cells(Cell).Size.Width + 10
            Dim CellHeight = dgv.Rows(Row).Cells(Cell).Size.Height
            Dim Brush As New SolidBrush(Color.Black)
            e.Graphics.DrawString(CellValue, New Font("tahoma", 10), Brush, CellLeftPos, CellTopPos)
            e.Graphics.DrawRectangle(Pens.Black, CellLeftPos, CellTopPos, CellWidth, CellHeight)
            CellLeftPos += CellWidth
        Next
        CellTopPos += dgv.Rows(Row).Cells(0).Size.Height
    Next
End Sub
End Class

我正在尝试预览和打印数据网格视图中的项目 vb.net用户需要单击"打印预览"按钮才能在打印文档之前查看文档，但是当我单击该按钮时，它只显示一个空白页面。如何使数据网格视图中的记录显示在预览页面中？

Answer 1

我删除了Dim dgv As New DataGridView，并替换为当前DataGridView的名称。