Obtener el ID de un tamaño de papel

Como obtener el ID numerico de un formulario de impresión.

Clase EnumPrinterFormsClass de Sergey Berezniker (originalmente publicada en Universalthread
http://www.universalthread.com/wconnect/wc.dll?2,84,13,5 FAQ ID: 22445).

NOTA: Necesita VFP8 o superior

************************************************************
* Funcion: PrintFormID
* Obtiene el ID de un formulario de impresión
* Parametros:
*     tcImpresora  - Nombre de la Impresora, "" tomar los forms del PC
*     tcFormulario - Nombre del formulario personalizado previamente creado
*     tlsilencioso - En modo silencioso
* Ejemplos:
*   lnret = PrintFormID("", "100x80")
*   lnret = PrintFormID("HP Laser", "100x80",.T.)
* Retorno
*      >0 - correcto, devuelve el ID del formulario
*      -1 - Error, no se pudo obtener la lista de formularios de impresion
*      -2 - Error, formulario no encontrado
* Notas
* Creación           : 14/02/2006 Pablo Roca
* Ultima Modificacion: 14/02/2006 Pablo Roca
************************************************************
FUNCTION PrintFormID(tcImpresora, tcFormulario, tlsilencioso)
  LOCAL loPrintForm, lnret, i
  LOCAL loForm, lnForm, lcLabel
  LOCAL lalineas(1), lcst, llret
  lcst = ""
  lnForm = 0
  loPrintForm = NEWOBJECT("EnumForms", "EnumPrinterFormsClass.fxp")
  * obtenemos la lista de formularios
  IF NOT loPrintForm.GetFormList(tcImpresora)
    * no se puede obtener la lista de formularios
    lnret = -1
    IF !tlsilencioso
      MESSAGEBOX("No se pudo obtener la lista de formularios de impresión.",16,"ATENCION")
    ENDIF
  ELSE
    * recorremos la lista de formularios buscando nuestro formulario
    FOR i=1 TO loPrintForm.oFormList.Count
      loForm = loPrintForm.oFormList.Item(i)
      IF loForm.FormName = tcFormulario
        lnForm = loForm.FormID
        EXIT
      ENDIF
    ENDFOR
    IF lnForm <> 0
      lnret = lnForm
    ELSE
      * formulario no encontrado
      lnret = -2
      IF !tlsilencioso
        MESSAGEBOX("Formulario ("+tcFormulario+") no encontrado.",16,"ATENCION")
      ENDIF
    ENDIF
  ENDIF

  loPrintForm = NULL
  RETURN lnret
ENDFUNC

Ahora la clase EnumPrinterForms:

*--------------------------------------------
* EnumPrinterFormsClass.prg
DEFINE CLASS EnumForms AS Custom
  HIDDEN hHeap, nInch2mm, nCm2mm, nCoefficient
  * Specified a Printer name for which the list of supported forms is retrieved
  *   If empty, retrieved the list of formds defined on local PC
  cPrinterName = ""
  * The form attributes are stored in in thousandths of millimeters
  * It can be coverted by class to inches ("English") or centimeters ("Metric")
  cUnit = "Internal"
  * Specified how to round result of conversion
  nRound = 0
  * Conversion Coefficients
  nInch2mm = 25.4
  nCm2mm = 10
  nCoefficient = 0
  * Error code and Error message returned by Win API
  nApiErrorCode = 0
  cApiErrorMessage = ""
  * Error message returned by class itself (none-API error)
  cErrorMessage = ""
  hHeap = 0
  * Collection of Print Forms retrieved
  oFormList = Null
  PROCEDURE Init(tcUnit, tnRound)
    IF PCOUNT() >= 1 AND INLIST(tcUnit, "English", "Metric")
      This.cUnit = PROPER(tcUnit)
    ENDIF
    IF PCOUNT() = 2
      This.nRound = tnRound
    ENDIF
    This.oFormList = CREATEOBJECT("Collection")
    * Load DLLs
    This.LoadApiDlls()
    * Allocate a heap
    This.hHeap = HeapCreate(0, 4096*10, 0)
    * Calculate conversion coefficient
    DO CASE
      CASE PROPER(This.cUnit) = "English"
        This.nCoefficient = This.nInch2mm * 1000
      CASE PROPER(This.cUnit) = "Metric"
        This.nCoefficient = This.nCm2mm * 1000
      OTHERWISE
        This.cUnit = "Internal"
        This.nCoefficient = 1
    ENDCASE
  ENDPROC

  PROCEDURE Destroy
    IF This.hHeap <> 0
      HeapDestroy(This.hHeap)
    ENDIF
  ENDPROC

  PROCEDURE GetFormList(tcPrinterName)
    LOCAL lhPrinter, llSuccess, lnNeeded, lnNumberOfForms, lnBuffer, i
    IF PCOUNT() > 0
      This.cPrinterName = tcPrinterName
    ENDIF
    This.ClearErrors()
    * Open a printer
    lhPrinter = 0
    lcPrinterName = This.cPrinterName
    IF EMPTY(lcPrinterName)
      lnResult = OpenPrinter(0, @lhPrinter, 0)
    ELSE
      lnResult = OpenPrinter(@lcPrinterName, @lhPrinter, 0)
    ENDIF
    IF  lnResult = 0
      This.cErrorMessage = "Unable to get printer handle for '" ;
        + This.cPrinterName + "'."
      This.nApiErrorCode = GetLastError()
      This.cApiErrorMessage = This.ApiErrorText(This.nApiErrorCode)
      RETURN .F.
    ENDIF
    lnNeeded = 0
    lnNumberOfForms = 0
    * Get the size of the buffer required to fit all forms in lnNeeded
    IF EnumForms(lhPrinter, 1,  0, 0, ;
        @lnNeeded,    @lnNumberOfForms  ) = 0
      IF GetLastError() <> 122   && The buffer too small error
        This.cErrorMessage = "Unable to Enumerate Forms."
        This.nApiErrorCode = GetLastError()
        This.cApiErrorMessage = This.ApiErrorText(This.nApiErrorCode)
        RETURN .F.
      ENDIF
    ENDIF
    * Get the list of forms
    lnBuffer = HeapAlloc(This.hHeap, 0, lnNeeded)
    llSuccess = .T.
    IF EnumForms(lhPrinter, 1, lnBuffer, @lnNeeded, ;
        @lnNeeded,    @lnNumberOfForms  ) = 0
      This.cErrorMessage = "Unable to Enumerate Forms."
      This.nApiErrorCode = GetLastError()
      This.cApiErrorMessage = This.ApiErrorText(This.nApiErrorCode)
      llSuccess = .F.
    ENDIF
    IF llSuccess
      * Put list of the forms into collection with Form number (i) as a key
      * A collection here can be replaced with an array or a cursor.
      FOR i=1 TO lnNumberOfForms
        loOneForm = This.OneFormObj()
        WITH loOneForm
          lnPointer = lnBuffer + (i-1) * 32
          .FormID    = i
          .FormFlags = This.Long2NumFromBuffer(lnPointer)
          .FormName = This.StrZFromBuffer(lnPointer+4)
          .Width    = ROUND(This.Long2NumFromBuffer(lnPointer+8)  / ;
            This.nCoefficient, This.nRound)
          .Height   = ROUND(This.Long2NumFromBuffer(lnPointer+12) / ;
            This.nCoefficient, This.nRound)
          .Left = ROUND(This.Long2NumFromBuffer(lnPointer+16) / ;
            This.nCoefficient, This.nRound)
          .Top = ROUND(This.Long2NumFromBuffer(lnPointer+20) / ;
            This.nCoefficient, This.nRound)
          .Right = ROUND(This.Long2NumFromBuffer(lnPointer+24) / ;
            This.nCoefficient, This.nRound)
          .Bottom = ROUND(This.Long2NumFromBuffer(lnPointer+28) / ;
            This.nCoefficient, This.nRound)
        ENDWITH
        This.oFormList.Add(loOneForm, TRANSFORM(i))
      ENDFOR
    ENDIF
    =HeapFree(This.hHeap, 0, lnBuffer )
    =ClosePrinter(lhPrinter)
    RETURN llSuccess
    * Create an object with forms attributes

  PROCEDURE OneFormObj
    LOCAL loOneForm
    loOneForm = NEWOBJECT("Empty")
    ADDPROPERTY(loOneForm, "FormFlags", 0)
    ADDPROPERTY(loOneForm, "FormId", 0)
    ADDPROPERTY(loOneForm, "FormName", "")
    ADDPROPERTY(loOneForm, "Width", 0)
    ADDPROPERTY(loOneForm, "Height", 0)
    ADDPROPERTY(loOneForm, "Left", 0)
    ADDPROPERTY(loOneForm, "Top", 0)
    ADDPROPERTY(loOneForm, "Right", 0)
    ADDPROPERTY(loOneForm, "Bottom", 0)
    RETURN loOneForm
  ENDPROC

  PROCEDURE ClearErrors
    This.cErrorMessage = ""
    This.nApiErrorCode = 0
    This.cApiErrorMessage = ""
  ENDPROC

  * Retrieve zero-terminated string from a buffer into VFP variable
  PROCEDURE StrZFromBuffer(tnPointer)
    LOCAL lcStr, lnStrPointer
    lcStr = SPACE(256)
    lnStrPointer = 0
    = RtlCopy(@lnStrPointer, tnPointer, 4)
    lstrcpy(@lcStr, lnStrPointer)
    RETURN LEFT(lcStr, AT(CHR(0),lcStr)-1)
  ENDPROC

  * Convert Long integer into VFP numeric variable
  PROCEDURE Long2NumFromBuffer(tnPointer)
    LOCAL lnNum
    lnNum = 0
    = RtlCopy(@lnNum, tnPointer, 4)
    RETURN lnNum
  ENDPROC

  * Converts VFP number to the Long integer
  FUNCTION Num2LOng(tnNum)
    DECLARE RtlMoveMemory IN WIN32API AS RtlCopyLong ;
      STRING @Dest, Long @Source, Long Length
    LOCAL lcString
    lcString = SPACE(4)
    =RtlCopyLong(@lcString, BITOR(tnNum,0), 4)
    RETURN lcString
  ENDFUNC

  * Convert Long integer into VFP numeric variable
  FUNCTION Long2Num(tcLong)
    DECLARE RtlMoveMemory IN WIN32API AS RtlCopyNum ;
      Long @Dest, String @Source, Long Length
    LOCAL lnNum
    lnNum = 0
    =RtlCopyNum(@lnNum, tcLong, 4)
    RETURN lnNum
  ENDFUNC

  HIDDEN PROCEDURE ApiErrorText
    LPARAMETERS tnErrorCode
    Local lcErrBuffer
    lcErrBuffer = REPL(CHR(0),1024)
    =FormatMessage(0x1000 ,.NULL., tnErrorCode, 0, @lcErrBuffer, 1024,0)
    RETURN LEFT(lcErrBuffer, AT(CHR(0),lcErrBuffer)- 1 )
  ENDPROC

  HIDDEN PROCEDURE LoadApiDlls
    DECLARE INTEGER OpenPrinter IN winspool.drv;
      STRING  @pPrinterName,;
      INTEGER @phPrinter,;
      INTEGER pDefault
    DECLARE INTEGER ClosePrinter IN winspool.drv;
      INTEGER hPrinter
    DECLARE LONG EnumForms IN winspool.drv AS EnumForms ;
      LONG hPrinter, LONG Level, LONG pForm, ;
      LONG cbBuf, LONG @pcbNeeded, ;
      LONG @ pcReturned
    DECLARE INTEGER HeapCreate IN Win32API;
      INTEGER dwOptions, INTEGER dwInitialSize,;
      INTEGER dwMaxSize
    DECLARE INTEGER HeapAlloc IN Win32API;
      INTEGER hHeap, INTEGER dwFlags, INTEGER dwBytes
    DECLARE lstrcpy IN Win32API;
      STRING @lpstring1, INTEGER lpstring2
    DECLARE INTEGER HeapFree IN Win32API;
      INTEGER hHeap, INTEGER dwFlags, INTEGER lpMem
    DECLARE HeapDestroy IN Win32API;
      INTEGER hHeap
    DECLARE RtlMoveMemory IN WIN32API AS RtlCopy ;
      Long @Dest, Long Source, Long Length
    DECLARE lstrcpy IN Win32API;
      STRING @lpstring1, INTEGER lpstring2
    DECLARE INTEGER GetLastError IN kernel32
    Declare Integer FormatMessage In kernel32.dll ;
      Integer dwFlags, String @lpSource, ;
      Integer dwMessageId, Integer dwLanguageId, ;
      String @lpBuffer, Integer nSize, Integer Arguments
  ENDPROC

ENDDEFINE

Pablo Roca