Microsoft KB Archive/113957

= VB3 How to View Photos from the NWIND.MDB Database in VB =

Article ID: 113957

Article Last Modified on 1/8/2003

-

APPLIES TO


 * Microsoft Visual Basic 3.0 Professional Edition

-



This article was previously published under Q113957



SUMMARY
This article shows by example how to view the photos in the Microsoft Access versions 1.x and 2.0 NWIND.MDB database.

NOTE: To run the code in this article, you will need to have both Microsoft Access version 1.x or 2.0 and the Microsoft Jet 2.0/Visual Basic 3.0 Compatibility Layer .DLL files.



Step-by-Step Example to View the Photos
 Start a new project in Visual Basic. Form1 is created by default. Add two Labels, two Text box controls, two Picture box controls and two Data controls to Form1.  Using the following table as a guide, set the properties of the controls you added in step 2.   Control     Property               New Value Label1     Caption                Access 1.x   Label2      Caption                Access 2.0 Data1      DatabaseName           C:\ACCESS\NWIND.MDB Data1      RecordSource           Employees Data2      DatabaseName           C:\ACCESS2\SAMPAPPS\NWIND.MDB Data2      RecordSource           Employees   Place the following code in the (general) (declarations) section of MODULE1.BAS: Option Explicit

Global Const LENGTH_FOR_SIZE = 4 Global Const OBJECT_SIGNATURE = &H1C15 Global Const OBJECT_HEADER_SIZE = 20 Global Const CHECKSUM_SIGNATURE = &HFE05AD00 Global Const CHECKSUM_STRING_SIZE = 4

' PT : Window sizing information for object '     Used in OBJECTHEADER type Type PT     Width As Integer Height As Integer End Type

' OBJECTHEADER : Contains relevant information about object '  Type OBJECTHEADER Signature As Integer        'Type signature (0x1c15) HeaderSize As Integer       'Size of header (sizeof(struct 'OBJECTHEADER) + cchName +                                  'cchClass) ObjectType As Long          'OLE Object type code (OT_STATIC,                                   'OT_LINKED, OT_EMBEDDED) NameLen As Integer          'Count of characters in object 'name (CchSz(szName) + 1) ClassLen As Integer         'Count of characters in class 'name (CchSz(szClass) + 1) NameOffset As Integer       'Offset of object name in                                   'structure (sizeof(OBJECTHEADER)) ClassOffset As Integer      'Offset of class name in                                   'structure (ibName + cchName) ObjectSize As PT            'Original size of object (see                                   'code below for value) OleInfo As String * 256 End Type

Type OLEHEADER OleVersion As Long Format As Long OleInfo As String * 512 End Type

' Enter each of the following Declare statements as one, single line: Declare Function GetTempFileName Lib "Kernel" (ByVal cDriveLetter As     Integer, ByVal  lpPrefixString As String, ByVal wUnique As Integer,      ByVal lpTempFileName As String) As Integer Declare Sub hmemcpy Lib "Kernel" (dest As Any, source As Any,     ByVal bytes As Long)

Function CopyOleBitmapToFile (OleField As Field) As String

Const BUFFER_SIZE = 8192

Dim tempFileName As String Dim Handle As Integer Dim Buffer As String

Dim BytesNeeded As Long

Dim Buffers As Long Dim Remainder As Long

Dim ObjHeader As OBJECTHEADER Dim sOleHeader As String

Dim ObjectOffset As Long Dim BitmapOffset As Long Dim BitmapHeaderOffset As Integer

Dim r As Integer Dim i As Long

tempFileName = "" If OleField.FieldSize > OBJECT_HEADER_SIZE Then

' Get the Microsoft Access OLE header: sOleHeader = OleField.GetChunk(0, OBJECT_HEADER_SIZE) hmemcpy ObjHeader, ByVal sOleHeader, OBJECT_HEADER_SIZE

' Calculate the offset where the OLE object starts: ObjectOffset = ObjHeader.HeaderSize + 1

' Get enough bytes after the OLE header to get the bitmap header: Buffer = OleField.GetChunk(ObjectOffset, 512)

' Make sure the class of the object is a Paint Brush object: If Mid(Buffer, 12, 6) = "PBrush" Then

BitmapHeaderOffset = InStr(Buffer, "BM")

If BitmapHeaderOffset > 0 Then

' Calculate the beginning of the bitmap: BitmapOffset = ObjectOffset + BitmapHeaderOffset - 1

' Calculate the size of the bitmap: ' Enter the following two lines as one, single line: BytesNeeded = OleField.FieldSize - OBJECT_HEADER_SIZE - BitmapHeaderOffset - CHECKSUM_STRING_SIZE + 1

' Calculate the number of buffers needed to copy ' the OLE object based on the bitmap size: Buffers = BytesNeeded \ BUFFER_SIZE Remainder = BytesNeeded Mod BUFFER_SIZE

' Get a unique, temp filename: tempFileName = Space(255) r = GetTempFileName(0, "", -1, tempFileName)

' Copy the bitmap to the temporary file chunk by chunk: Handle = FreeFile Open tempFileName For Binary As #Handle

For i = 0 To Buffers - 1 ' Enter the following two lines as one, single lin: Buffer = OleField.GetChunk(BitmapOffset + i *                    BUFFER_SIZE, BUFFER_SIZE) Put #Handle,, Buffer Next

' Copy the remaining chunk of the bitmap to the file: ' Enter the following two lines as one, single line: Buffer = OleField.GetChunk(BitmapOffset + Buffers *                 BUFFER_SIZE, Remainder) Put #Handle,, Buffer Close #Handle End If        End If      End If      CopyOleBitmapToFile = Trim(tempFileName) End Function

Sub DisplayOleBitmap (ctlPict As Control, OleField As Field)

Const DT_LONGBINARY = 11

Dim r As Integer Dim Handle As Integer Dim OleFileName As String

If OleField.Type = DT_LONGBINARY Then

OleFileName = CopyOleBitmapToFile(OleField)

If OleFileName <> "" Then

' Display the bitmap: ctlPict.Picture = LoadPicture(OleFileName)

' Delete the temporary file: Kill OleFileName End If     End If   End Sub   Add the following to the Data1 Reposition event: Sub Data1_Reposition Screen.MousePointer = 11 ' Make sure this is the current record: If Not (Data1.Recordset.EOF And Data1.Recordset.BOF) Then ' Change Photo to the name of the OLE field ' for the record set you are using: DisplayOleBitmap Picture1, Data1.Recordset("Photo") End If     Screen.MousePointer = 0 End Sub   Add the following to the Data2 Reposition event: Sub Data2_Reposition Screen.MousePointer = 11 ' Make sure this is the current record: If Not (Data2.Recordset.EOF And Data2.Recordset.BOF) Then ' Change Photo to the name of the OLE field ' for the record set you are using: DisplayOleBitmap Picture2, Data2.Recordset("Photo") End If     Screen.MousePointer = 0 End Sub </li> From the Run menu, choose Start (ALT, R, S), or press the F5 key to run the program. Click the Data1 control; then click the Data2 control.</li></ol>

<div class="references_section">