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| 作者：本站收集 日期：2005-8-4 11:14:38 |
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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。 |
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责任编辑： 原点 |
投稿作者： 本站收集 |
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信息来源： 网络 |
录入时间： 2005-8-4 11:14:38 |
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