65.txt

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关于数据报表的打印设置




数据报表（DataReport）是VB6新增功能之一。用过它的朋友对这个设计器可以说是既爱且恨。尽管它功能强大，但却有个非常致命的缺点：无法在设计环境中改变纸张大小及走向。即使你在程序中使用Printer对象改变纸张大小及打印走向，也解决不了问题。对于非A4纸的报表或是横向打印的报表，连报表预览都不行。

问题的原因是：DR基于系统默认的打印设置创建自己的内部设备环境。而这个设备环境是没有向外界展现的。DR的内部设备环境与VB的Printer对象的内部设备环境是完全不同的，因此改变 打印机对象的属性对DR一点效果也没有。

解决这个问题的笨办法是，在预览或打印时改变系统默认打印机的设置。使用这个方法连自己都会觉得麻烦，更何况是你的用户。没办法，只能通过代码强行改变系统默认打印机的设置来解决。将下面的代码放入一个模块中：

Option Explicit


Public Enum PrinterOrientationConstants
        OrientPortrait = 1
        OrientLandscape = 2
End Enum
Private Type DEVMODE
        dmDeviceName As String * 32
        dmSpecVersion As Integer
        dmDriverVersion As Integer
        dmSize As Integer
        dmDriverExtra As Integer
        dmFields As Long
        dmOrientation As Integer
        dmPaperSize As Integer
        dmPaperLength As Integer
        dmPaperWidth As Integer
        dmScale As Integer
        dmCopies As Integer
        dmDefaultSource As Integer
        dmPrintQuality As Integer
        dmColor As Integer
        dmDuplex As Integer
        dmYResolution As Integer
        dmTTOption As Integer
        dmCollate As Integer
        dmFormName As String * 32
        dmUnusedPadding As Integer
        dmBitsPerPel As Integer
        dmPelsWidth As Long
        dmPelsHeight As Long
        dmDisplayFlags As Long
        dmDisplayFrequency As Long
End Type
Private Type PRINTER_DEFAULTS
        pDataType As String
        pDevMode As Long
        DesiredAccess As Long
End Type
Private Type PRINTER_INFO_2
        pServerName As Long
        pPrinterName As Long
        pShareName As Long
        pPortName As Long
        pDriverName As Long
        pComment As Long
        pLocation As Long
        pDevMode As Long
        pSepFile As Long
        pPrintProcessor As Long
        pDataType As Long
        pParameters As Long
        pSecurityDescriptor As Long
        Attributes As Long
        Priority As Long
        DefaultPriority As Long
        StartTime As Long
        UntilTime As Long
        Status As Long
        cJobs As Long
        AveragePPM As Long
End Type

Public Const DMPAPER_A5 = 11

Private Const DM_IN_BUFFER As Long = 8
Private Const DM_OUT_BUFFER As Long = 2
Private Const DM_ORIENTATION As Long = &H1
Private Const DM_PAPERSIZE = &H2&

Private Const PRINTER_ACCESS_ADMINISTER As Long = &H4
Private Const PRINTER_ACCESS_USE As Long = &H8
Private Const STANDARD_RIGHTS_REQUIRED As Long = &HF0000
Private Const PRINTER_ALL_ACCESS = (STANDARD_RIGHTS_REQUIRED _
    Or _
    PRINTER_ACCESS_ADMINISTER Or PRINTER_ACCESS_USE)

Private Declare Sub CopyMemory Lib "kernel32" Alias _
    "RtlMoveMemory" _
    (hpvDest As Any, hpvSource As Any, ByVal _
    cbCopy As Long)

Private Declare Function OpenPrinter Lib "winspool.drv" Alias _
        "OpenPrinterA" (ByVal pPrinterName As String, phPrinter As _
        Long, pDefault As Any) As Long

Private Declare Function ClosePrinter Lib "winspool.drv" _
        (ByVal hPrinter As Long) As Long

Private Declare Function DocumentProperties Lib "winspool.drv" _
        Alias "DocumentPropertiesA" (ByVal hWnd As Long, ByVal hPrinter _
    As Long, _
        ByVal pDeviceName As String, pDevModeOutput As _
    Any, _
    pDevModeInput As Any, _
        ByVal fMode As Long) As Long

Private Declare Function GetPrinter Lib "winspool.drv" _
        Alias "GetPrinterA" (ByVal hPrinter As Long, ByVal Level As Long, _
        pPrinter As Any, ByVal cbBuf As Long, pcbNeeded As Long) As _
    Long

Private Declare Function SetPrinter Lib "winspool.drv" _
        Alias "SetPrinterA" (ByVal hPrinter As Long, ByVal Level As Long, _
        pPrinter As Any, ByVal Command As Long) As Long

Function SetDefaultPrinterOrientation(ByVal eOrientation As _
    PrinterOrientationConstants) As Boolean

        Dim bDevMode() As Byte
        Dim bPrinterInfo2() As Byte
        Dim hPrinter As Long
        Dim lResult As Long
        Dim nSize As Long
        Dim sPrnName As String
        Dim dm As DEVMODE
        Dim pd As PRINTER_DEFAULTS
        Dim pi2 As PRINTER_INFO_2

        ' 获取默认打印机的设备名称
        sPrnName = Printer.DeviceName
        ' 由于要调用SetPrinter，所以
        ' 如果是在NT下就要求PRINTER_ALL_ACCESS
        pd.DesiredAccess = PRINTER_ALL_ACCESS

        ' 获取打印机句柄
        If OpenPrinter(sPrnName, hPrinter, pd) Then
                ' 获取PRINTER_INFO_2结构要求的字节数

               Call GetPrinter(hPrinter, 2&, 0&, 0&, nSize)
                ReDim bPrinterInfo2(1 To nSize) As Byte
                lResult = GetPrinter(hPrinter, 2, bPrinterInfo2(1), nSize,nSize)
                Call CopyMemory(pi2, bPrinterInfo2(1), Len(pi2))
                nSize = DocumentProperties(0&, hPrinter, sPrnName, 0&, 0&, 0)
                      ReDim bDevMode(1 To nSize)
                If pi2.pDevMode Then
                        Call CopyMemory(bDevMode(1), ByVal pi2.pDevMode, Len(dm))
                Else
                        Call DocumentProperties(0&, hPrinter, sPrnName, bDevMode(1),0&, DM_OUT_BUFFER)
                End If

                Call CopyMemory(dm, bDevMode(1), Len(dm))
                With dm
                        ' 设置新的走向
                        .dmOrientation = eOrientation
                        .dmFields = DM_ORIENTATION
                        '.dmPaperSize = DMPAPER_A5 将纸张大小设为A5，请自行更改所需大小
                        '.dmFields = DM_PAPERSIZE  必须，否则无法设置纸张大小
                End With
                Call CopyMemory(bDevMode(1), dm, Len(dm))

                Call DocumentProperties(0&, hPrinter, sPrnName, _
                        bDevMode(1), bDevMode(1), DM_IN_BUFFER Or _
                        DM_OUT_BUFFER)

                pi2.pDevMode = VarPtr(bDevMode(1))

                lResult = SetPrinter(hPrinter, 2, pi2, 0&)

                Call ClosePrinter(hPrinter)
                SetDefaultPrinterOrientation = True
        Else
                SetDefaultPrinterOrientation = False
        End If

End Function
在打印或预览之前直接调用SetDefaultPrinterOrientation 打印走向常数。注意：红色注释部分用于改变纸张的大小。

这个解决方案仍有两个问题： 

1。对有些型号的打印机不起作用，例如佳能的BJC-265SP 
2。即使是在预浏DR时，也必须改变打印机的设置。这时如果有其它使用打印机默认设 置的程序(如Notepad)要进行打印作业，就可能造成混乱。


尽管如此，这个方法是目前唯一好用的方法。