相逢情便深，恨不相逢早:
背景：
开始做中谷项目时我还不知道怎么用DLL。后来看别人用才试着去学习使用。虽然现在已经会用了，但DLL的强大之处我了解的还远远不够。下面先简单说下DLL。
DLL是神马？
Windows操作系统是非常依赖于动态链接库（DLL）中的函数和数据的，实际上操作系统中几乎所有的内容都由DLL以一种或另外一种形式代表着，例如显示的字体和图标存储在GDI DLL中、显示windows桌面和处理用户的输入所需要的代码被存储在一个User DLL中、Windows编程所需要的大量API函数也呗包含在Kernel DLL中。
使用DLL优点多多：
最主要的一点是多个应用程序、甚至不同语言编写的应用程序可以共享一个DLL文件，实现资源“共享”，这样就大大缩小了应用程序的执行代码，有效利用内存；另一个优点是DLL文件作为一个单独的程序模块，封装性、独立性好，在软件需要升级的时候，开发人员只需要修改相应的DLl文件就可以了，而且，当DLL中的函数改变后，只要不是参数的改变，程序代码并不需要重新编译，这在编程时大大提高了软件开发和维护的效率。
纸上得来终觉浅：
打印：
很多窗体都需要打印功能，为了调用方便，我把打印写成一个类封装成DLL，然后在程序里添加引用。Print类代码也附到这里，不是重点。
Imports System.Drawing
Imports System.Drawing.Printing
Imports System.Windows.Forms
Public Class Class1
Private PrintFont As New Font("宋体", 10)
Private PrintLines As Integer = 50
Private PrintRecordNumber As Integer = 45
Private DataGridSource As DataGridView
Private ev As PrintPageEventArgs
Private PrintDataGrid As PrintDocument
Private PrintPriview As PrintPreviewDialog
Private PageSetup As PageSetupDialog
Private PrintScale As Double = 1
Private DataGridColumn As DataColumn
Private DataGridRow As DataRow
Private DataGridTable As DataTable
Private Cols As Integer
Private Rows As Integer = 1
Private ColsCount As Integer
Private PrintingLineNumber As Integer = 0
Private PageRecordNumber As Integer
Dim X_unit As Integer
Dim Y_unit As Integer
Dim _strPrint As String
Private PrintingPageNumber As Integer = 0
Private PageNumber As Integer
Private PrintRecordLeave As Integer
Private PrintRecordComplete As Integer = 0
‘‘‘ <summary>
‘‘‘ 设置打印字体
‘‘‘ </summary>
‘‘‘ <value></value>
‘‘‘ <remarks></remarks>
Public WriteOnly Property setPrintFont() As System.Drawing.Font
Set(ByVal Value As System.Drawing.Font)
PrintFont = Value
End Set
End Property
Public WriteOnly Property setPrintRecordNumber() As Integer
Set(ByVal Value As Integer)
PrintRecordNumber = Value
End Set
End Property
‘‘‘ <summary>
‘‘‘ 设置表头
‘‘‘ </summary>
‘‘‘ <value></value>
‘‘‘ <returns></returns>
‘‘‘ <remarks></remarks>
Public Property setstrPrint() As String
Set(ByVal value As String)
_strPrint = value
End Set
Get
Return _strPrint
End Get
End Property
Sub New(ByVal TableSource As DataGridView)
DataGridSource = TableSource
DataGridTable = New DataTable
DataGridTable = DataGridSource.DataSource()
ColsCount = DataGridTable.Columns.Count
End Sub
Public Sub Print()
Try
PrintDataGrid = New System.Drawing.Printing.PrintDocument
AddHandler PrintDataGrid.PrintPage, AddressOf Me.PrintDataGrid_PrintPage
‘*
PageSetup = New PageSetupDialog
PageSetup.PageSettings = PrintDataGrid.DefaultPageSettings
If PageSetup.ShowDialog() = DialogResult.Cancel Then
Exit Sub
End If
‘*
If PrintDataGrid.DefaultPageSettings.Landscape = False Then
PrintLines = PrintDataGrid.DefaultPageSettings.PaperSize.Height / (PrintFont.Height + 5)
Else
PrintLines = PrintDataGrid.DefaultPageSettings.PaperSize.Width / (PrintFont.Height + 5)
End If
‘*
If PrintDataGrid.DefaultPageSettings.PaperSize.PaperName.ToString = "custom" Then
End If
‘*
PrintPriview = New PrintPreviewDialog
PrintPriview.Document = PrintDataGrid
PrintPriview.ShowDialog()
Catch ex As Exception
MessageBox.Show("错误:" & ex.ToString)
End Try
End Sub
Private Sub PrintDataGrid_PrintPage(ByVal sender As Object, ByVal ev As System.Drawing.Printing.PrintPageEventArgs)
Dim strPrint As String = Nothing
Dim DrawBrush As New SolidBrush(System.Drawing.Color.Blue)
Dim X As Integer
Dim Y As Integer
Dim DrawPoint As New PointF(X, Y)
‘Dim row_count As Integer
PrintRecordLeave = DataGridTable.Rows.Count - PrintRecordComplete
‘*
PageNumber = PrintRecordLeave / PrintRecordNumber
PrintingPageNumber = 0
‘*
If PrintDataGrid.DefaultPageSettings.Landscape = True Then
X_unit = PrintDataGrid.DefaultPageSettings.PaperSize.Height / (DataGridTable.Columns.Count + 2)
Y_unit = PrintDataGrid.DefaultPageSettings.PaperSize.Width / PrintLines
Else
X_unit = PrintDataGrid.DefaultPageSettings.PaperSize.Width / (DataGridTable.Columns.Count + 2)
Y_unit = PrintDataGrid.DefaultPageSettings.PaperSize.Height / PrintLines
End If
‘*
If DataGridTable.Rows.Count - PrintingPageNumber * PrintRecordNumber >= PrintRecordNumber Then
PageRecordNumber = PrintRecordNumber
Else
PageRecordNumber = (DataGridTable.Rows.Count - PrintingPageNumber * PrintRecordNumber) Mod PrintRecordNumber
End If
While PrintingPageNumber <= PageNumber
‘*
‘strPrint = DataGridSource.CaptionText
DrawPoint = New PointF(X_unit, Y_unit)
ev.Graphics.DrawString(strPrint, PrintFont, DrawBrush, DrawPoint)
‘*
Dim ColumnText(DataGridTable.Columns.Count) As String
Dim Cols As Integer
‘Dim Table As Integer
For Cols = 0 To DataGridTable.Columns.Count - 1
ColumnText(Cols) = DataGridTable.Columns(Cols).ToString
‘*
DrawPoint = New PointF(X_unit * (Cols + 1), Y_unit * 2)
ev.Graphics.DrawString(ColumnText(Cols), PrintFont, DrawBrush, DrawPoint)
Next
DrawPoint = New PointF(X_unit, Y_unit * 2)
Call DrawLine(DrawPoint, ev)
‘*
Dim printingline As Integer = 0
‘*
Dim strNonce As String = ""
Dim strUpData As String = ""
While printingline < PageRecordNumber
DataGridRow = DataGridTable.Rows(PrintRecordComplete)
‘*
For Cols = 0 To DataGridTable.Columns.Count - 1
DrawPoint.X = X_unit * (Cols + 1)
DrawPoint.Y = Y_unit * (printingline + 1 + 2)
If Cols = 0 Then
If strUpData <> "" And strNonce <> "" Then
If strUpData <> DataGridRow(ColumnText(0)) Then
ev.HasMorePages = True
Exit Sub
End If
End If
End If
ev.Graphics.DrawString(Convert.ToString(DataGridRow(ColumnText(Cols))), PrintFont, DrawBrush, DrawPoint)
strUpData = DataGridRow(ColumnText(0))
Next
DrawPoint.X = X_unit * 1
DrawPoint.Y = Y_unit * (printingline + 1 + 2)
Call DrawLine(DrawPoint, ev)
printingline += 1
PrintRecordComplete += 1
‘*
If PrintRecordComplete >= DataGridTable.Rows.Count Then
ev.HasMorePages = False
Exit Sub
End If
End While
PrintingPageNumber += 1
If PrintingPageNumber > PageNumber Then
ev.HasMorePages = False
Else
ev.HasMorePages = True
Exit While
End If
End While
End Sub
Private Sub DrawLine(ByVal point As PointF, ByVal ev As System.Drawing.Printing.PrintPageEventArgs)
Dim blackPen As New Pen(System.Drawing.Color.Black, 1)
ev.Graphics.DrawLine(blackPen, point.X, point.Y + PrintFont.Height, point.X * (ColsCount + 1), point.Y + PrintFont.Height)
End Sub
End Class
在事件中调用时代码如下：
Private Sub btnPrint_Click(sender As Object, e As EventArgs) Handles btnPrint.Click
If dgvWindWorkLog.DataSource Is Nothing Then
MsgBox("没有可打印的内容，请重新操作！", vbOKOnly, "系统提示")
Exit Sub
End If
‘加载dll文件，利用反射
Dim assembly As Assembly = assembly.LoadFrom(Application.StartupPath & "\\Print.dll")
Dim Print As New Print.Class1(Me.dgvWindWorkLog) ‘实例化打印类
Print.setstrPrint = "工作记录卡" ‘设置打印标题
Print.Print()
End Sub
几报加载浑错：
以上操作均没有错，如果在同一个Demo中测试，一切正常，打印效果老好了。然后将dll文件拷贝到中谷项目目录下，在事件中调用，提示错误。
测试了好多次都觉得不应该有错，我觉得哪里都一样就是到了项目中就运行不起来。还有下面这个问题，这两个问题我整整解决了一天。唉，只怪咱水平有限、经验有限啊！
报表：
不知道这叫不叫无独有偶，竟然同一天遇到两个一样的问题。
这也是做好的一个报表.grf，添加到程序中，结果每次运行到
Report = NewgrproLib.GridppReport
Report.LoadFromFile(Application.StartupPath& "\\报表.grf")时就提示上面的错误。
拨开云雾见青天：
我测试Demo的目标框架是.NET Framework 4.5，而中谷项目是.NETFramework 3.5。
于是……
宝剑锋从磨砺出：
No.1 经历了一次下次就知道如何解决和预防此类问题，自己做测试一定要细心。
其实报表中最大的问题，是我开发用的Grid++Report5.6，,给同组人的是5.0，（因为我很久前在机房合作开发时装了Grid++，安装文件找不到了，就跟当时给我传文件的那个同学又要了一份，结果两次的文件并不是同一版本）。这下热闹了，我们各种调试、各种注册、各种。。。终于决定删除重做。
No.2 合作开发一定要统一版本，不管是开发环境（包括比如VS版本、framework）、SVN客户端、调试工具以及开发过程中用到的控件等。因为稍不注意就可能是推翻重来，那可是血的代价啊！