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VB6 - Thumbnail view based on WIA 2.0

December 29, 2012, 7:43 am
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Background

As camera resolutions get higher and higher VB6's native image manipulation can get bogged down. This is especially true if you need to do some processing on he thumbnails such as dealing with odd sizes, portrait images, and so on. If you want to create a "viewer" based on one of the ListView controls and ImageList controls (v. 6 or v. 5) then you need to deal with mask-transparency and you might want an outline border.

While dropping down to API calls is fastest, the code can get complex making it harder to tailor even a known-working sample. One alternative is to make use of the WIA 2.0 Library available for XP SP1 and later and already installed as part of Vista or later.

With WIA you also have easy access to JPEG image files' embedded thumbnail image. These are created by many cameras now and can sometimes be optionally inserted using image editing software. When available, these prescaled thumbnails can be used as-is or as the basis for scaling to a specific desired thumbnail size. Even if you rescale it this may save time over scaling the entire full-size image.


Requirements

Since I'm using WIA 2.0 your computer must be running Windows XP SP1 or later. For XP you may have to download and install WIA 2.0 first. However:

Quote:
Purpose
The Windows Image Acquisition (WIA) Automation Layer is a full-featured image manipulation component that provides end-to-end image processing capabilities. The WIA Automation Layer makes it easy to acquire images from digital cameras, scanners, or Web cameras, and to rotate, scale, and annotate your image files. The WIA Automation Layer supersedes the WIA Scripting Model provided by Windows Image Acquisition (WIA) 1.0.

Developer audience
The WIA Automation Layer API is designed for use by Microsoft Visual Basic 6.0, Active Server Pages (ASP), and scripting programmers.

Run-time requirements
Applications that use the WIA Automation Layer API require Windows Vista or later. Earlier versions of Windows are not supported.
What does this mean?

It means now that Windows 8 is out, Windows XP is on "death watch" and Microsoft has begun removing download links for many XP add-ons.

You'll probably have to scrounge the "Windows® Image Acquisition Automation Library" download from some 3rd party if you failed to get it while it was hot (i.e. in the last 6 years or so).

The WIA 2.0 Automation Library documentation is found in the Windows SDK for Vista (or later) documentation (help) files.


Of course those developing on Vista (the last release officially supporting VB6 development anyway, and in my opinion the best) have no problem except for deployment.

But even then if you want to deploy your programs downlevel to XP SP1 through SP3 you'll want the WIAAutSDK.zip download. It contains a CHM document - but more importantly a redistributable wiaaut.dll that works on XP systems!


MakeThumbs.cls

This is a class wrapping several WIA objects that can be used to accept a photo/image file name and create a thumbnail StdPicture from it ready for adding to an ImageList control.

The class has several properties you set:

Set ThumbWidth & ThumbHeight to dimensions (in pixels) for the thumbnails. These dimensions include the 2px-wide border.

Set FrameColor to the desired frame color for the rectangular outline. This outline will be 1px wide with a 1px inner border of the MaskColor.

Set MaskColor to the transparency mask color to use for padding around the scaled thumbnail image from the source JPEG image.

Then you call the InitThumbs method to create the backdrop image containing the outline and the mask.

From there you can repeatedly call the FetchThumb method passing an image file name, getting back a StdPicture of the finished thumbnail image.

Use the result with any image control that has a Picture property or method argument and supports a mask color for transparency. The more obvious choices are probably ImageList controls used with a ListView or TreeView control.


JpegThumbs.vbp

This is a sample VB6 project using MakeThumbs. You browse to a folder containing images and then it loads and displays thumbnail images for all of the image file types it supports into an ImageList and ListView. Pretty simple, and the only gingerbread here is the ability to select among 3 thumbnail sizes.


Speed

I won't lie and call this a speed demon, though most of the time will probably be disk I/O. Requesting the same folder (or changing the thumbnail size after loading it once) may be twice or 3 times as quick due to disk caching.

A "first load" here seems to take about 1/8th of a second per image file for 3 to 4MB JPEGs. Doing the same steps using only VB6 native image processing techniques took me substantially longer, closer to 4 seconds per image. However I may have been using some poor techniques there too.

InitThumbs is slow by nature and I wish I had a better way to build the backdrop. But you only need to call it once when changing the dimension or color properties, not for every loaded image.


The Attachment

This contains the JpegThumbs project, including the MakeThumbs class module.
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VB6 - MSChart XY Scatter Demo

January 1, 2013, 6:40 am
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MSChart is a very complex control. Sometimes it can be frustrating to get just what you want out of it.

An example is a "scatter plot" of the sort shown here.

Code:
Option Explicit

'Just plop an instance of MSChart as MSChart1 onto a Form.

Private Sub Form_Load()
    Dim Series1 As Variant
    Dim Series2 As Variant
    Dim Series3 As Variant
    Dim Series As Integer
    Dim I As Integer
    Dim Row As Integer

    'Hold series data in Variant arrays here, as (X, Y) pairs
    'that follow each other:
    Series1 = Array(12, 20, 3, 10, 15, 20, 4, 50, 50, 27)
    Series2 = Array(1, 12, 23, 9, 48, 25, 16, 16, 30, 37)
    Series3 = Array(1, 43, 45, 45, 4, 25, 39, 5, 13, 6)
   
    With MSChart1
        .chartType = VtChChartType2dXY
        .RowCount = (UBound(Series1) + 1) \ 2
        .ColumnCount = 6 '2 columns per series, 3 series.
       
        'Set up each Series for small circles with no lines.
        For Series = 1 To 3
            With .Plot.SeriesCollection((Series - 1) * 2 + 1)
                .SeriesType = VtChSeriesType2dXY
                .ShowLine = False
                With .SeriesMarker
                    .Show = True
                    .Auto = False
                End With
                With .DataPoints(-1).Marker
                    .Style = VtMarkerStyleFilledCircle
                    .Size = ScaleX(7, vbPixels, vbTwips)
                    With .Pen.VtColor
                        Select Case Series
                            Case 1
                                .Set 192, 64, 64 'Red.
                            Case 2
                                .Set 64, 64, 192 'Blue.
                            Case 3
                                .Set 64, 192, 64 'Green.
                        End Select
                    End With
                End With
            End With
        Next
   
        For I = 0 To UBound(Series1) Step 2
            Row = I \ 2 + 1
            .DataGrid.SetData Row, 1, Series1(I), False
            .DataGrid.SetData Row, 2, Series1(I + 1), False
           
            .DataGrid.SetData Row, 3, Series2(I), False
            .DataGrid.SetData Row, 4, Series2(I + 1), False
           
            .DataGrid.SetData Row, 5, Series3(I), False
            .DataGrid.SetData Row, 6, Series3(I + 1), False
        Next
    End With
End Sub
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[VB6] Form-less CommonDialog (comdlg32.ocx)

January 1, 2013, 2:17 pm
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It is possible to show the common dialogs without using a Form to put the ActiveX control in. Here's how:

Code:

'In a BAS module
Option Explicit

Private Sub Main()
    Const cdlCCFullOpen = 2&, cdlCCHelpButton = 8&, cdlCFApply = &H200&, cdlCFBoth = 3&
    Const cdlCFEffects = &H100&, cdlCFHelpButton = 4&, cdlHelpContents = 3&
    Const cdlOFNAllowMultiselect = &H200&, cdlOFNExplorer = &H80000, cdlOFNHelpButton = &H10&
    Const cdlPDHelpButton = &H800&, cdlPDNoWarning = &H80&, cdlPDPrintSetup = &H40&

    On Error Resume Next

    With CreateObject("MSComDlg.CommonDialog")      'Late-bound
  'With New CommonDialog                          'Referenced comdlg32.ocx (not from Toolbox)
        .AboutBox

        .Flags = cdlCCFullOpen Or cdlCCHelpButton
        .ShowColor

        .Flags = cdlCFApply Or cdlCFBoth Or cdlCFEffects Or cdlCFHelpButton
        .ShowFont

        .HelpCommand = cdlHelpContents
        .HelpFile = Dir(Environ$("WINDIR") & "\Help\*.hlp")
        .ShowHelp

        .Flags = cdlOFNAllowMultiselect Or cdlOFNExplorer Or cdlOFNHelpButton
        .ShowOpen
        .ShowSave

        .Flags = cdlPDHelpButton Or cdlPDNoWarning
        .ShowPrinter
        .Flags = .Flags Or cdlPDPrintSetup
        .ShowPrinter
    End With
End Sub

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[VB6] Uncompressed AVI Writer

January 5, 2013, 10:23 am
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Here is a minimalistic cAviWriter class (less than 200 LOC w/ no dependencies) that can be used to create uncompressed AVIs for use in standard animation control.

Code:
Option Explicit

'=========================================================================
' API
'=========================================================================

'--- for AVIFileOpen
Private Const OF_WRITE                      As Long = &H1
Private Const OF_CREATE                    As Long = &H1000
'--- for CreateDIBSection
Private Const DIB_RGB_COLORS                As Long = 0

Private Declare Sub AVIFileInit Lib "avifil32.dll" ()
Private Declare Sub AVIFileExit Lib "avifil32.dll" ()
Private Declare Function AVIFileOpen Lib "avifil32.dll" Alias "AVIFileOpenA" (ppfile As Long, ByVal szFile As String, ByVal uMode As Long, ByVal lpHandler As Long) As Long
Private Declare Function AVIFileCreateStream Lib "avifil32.dll" (ByVal pfile As Long, ppavi As Long, psi As TAVISTREAMINFO) As Long
Private Declare Function AVIFileRelease Lib "avifil32.dll" (ByVal pfile As Long) As Long
Private Declare Function AVIStreamSetFormat Lib "avifil32.dll" (ByVal pavi As Long, ByVal lPos As Long, lpFormat As Any, ByVal cbFormat As Long) As Long
Private Declare Function AVIStreamWrite Lib "avifil32.dll" (ByVal pavi As Long, ByVal lStart As Long, ByVal lSamples As Long, ByVal lpBuffer As Long, ByVal cbBuffer As Long, ByVal dwFlags As Long, plSampWritten As Long, plBytesWritten As Long) As Long
Private Declare Function AVIStreamRelease Lib "avifil32.dll" (ByVal pavi As Long) As Long
Private Declare Sub CopyMemory Lib "kernel32" Alias "RtlMoveMemory" (Destination As Any, Source As Any, ByVal Length As Long)
Private Declare Function CreateCompatibleDC Lib "gdi32" (ByVal hDC As Long) As Long
Private Declare Function CreateDIBSection Lib "gdi32" (ByVal hDC As Long, lpBitsInfo As BITMAPINFOHEADER, ByVal wUsage As Long, lpBits As Long, ByVal handle As Long, ByVal dw As Long) As Long
Private Declare Function SelectObject Lib "gdi32" (ByVal hDC As Long, ByVal hObject As Long) As Long
Private Declare Function DeleteObject Lib "gdi32" (ByVal hObject As Long) As Long
Private Declare Function ApiBitBlt Lib "gdi32" Alias "BitBlt" (ByVal hdcDest As Long, ByVal X As Long, ByVal Y As Long, ByVal nWidth As Long, ByVal nHeight As Long, ByVal hdcSrc As Long, ByVal xSrc As Long, ByVal ySrc As Long, ByVal dwRop As Long) As Long
Private Declare Function DeleteDC Lib "gdi32" (ByVal hDC As Long) As Long

Private Type RECT
    Left                As Long
    Top                As Long
    Right              As Long
    Bottom              As Long
End Type

Private Type TAVISTREAMINFO
    fccType            As Long
    fccHandler          As Long
    dwFlags            As Long
    dwCaps              As Long
    wPriority          As Integer
    wLanguage          As Integer
    dwScale            As Long
    dwRate              As Long
    dwStart            As Long
    dwLength            As Long
    dwInitialFrames    As Long
    dwSuggestedBufferSize As Long
    dwQuality          As Long
    dwSampleSize        As Long
    rcFrame            As RECT
    dwEditCount        As Long
    dwFormatChangeCount As Long
    szName(0 To 63)    As Byte
End Type

Private Type BITMAPINFOHEADER
    biSize              As Long
    biWidth            As Long
    biHeight            As Long
    biPlanes            As Integer
    biBitCount          As Integer
    biCompression      As Long
    biSizeImage        As Long
    biXPelsPerMeter    As Long
    biYPelsPerMeter    As Long
    biClrUsed          As Long
    biClrImportant      As Long
End Type

'=========================================================================
' Constants and member variables
'=========================================================================

Private m_hAviFile              As Long
Private m_hAviStream            As Long
Private m_lSample              As Long
Private m_uBmpInfo              As BITMAPINFOHEADER
Private m_hDC                  As Long
Private m_hDib                  As Long
Private m_hPrevDib              As Long
Private m_lpBits                As Long

'=========================================================================
' Methods
'=========================================================================

Public Function Init( _
            sFile As String, _
            ByVal lWidth As Long, _
            ByVal lHeight As Long, _
            Optional ByVal lRate As Long = 10) As Boolean
    Dim uStream        As TAVISTREAMINFO
   
    Terminate
    If AVIFileOpen(m_hAviFile, sFile, OF_CREATE Or OF_WRITE, 0) < 0 Then
        GoTo QH
    End If
    With uStream
        .fccType = pvToFourCC("vids")
        .fccHandler = 0 ' pvToFourCC("DIB ")
        .dwScale = 1
        .dwRate = lRate
        .rcFrame.Right = lWidth
        .rcFrame.Bottom = lHeight
    End With
    If AVIFileCreateStream(m_hAviFile, m_hAviStream, uStream) < 0 Then
        GoTo QH
    End If
    With m_uBmpInfo
        .biSize = Len(m_uBmpInfo)
        .biWidth = lWidth
        .biHeight = lHeight
        .biPlanes = 1
        .biBitCount = 24 ' 32
        .biSizeImage = ((lWidth * .biBitCount \ 8 + 3) And -4&) * lHeight
    End With
    If AVIStreamSetFormat(m_hAviStream, 0, m_uBmpInfo, Len(m_uBmpInfo)) < 0 Then
        GoTo QH
    End If
    m_hDC = CreateCompatibleDC(0)
    m_hDib = CreateDIBSection(m_hDC, m_uBmpInfo, DIB_RGB_COLORS, m_lpBits, 0, 0)
    m_hPrevDib = SelectObject(m_hDC, m_hDib)
    m_lSample = 0
    '--- success
    Init = True
    Exit Function
QH:
    Terminate
End Function

Public Function AddFrame( _
            oPic As StdPicture, _
            Optional ByVal lX As Long, _
            Optional ByVal lY As Long) As Boolean
    Dim hTempDC        As Long
    Dim hPrevBmp        As Long
   
    hTempDC = CreateCompatibleDC(m_hDC)
    hPrevBmp = SelectObject(hTempDC, oPic.handle)
    Call ApiBitBlt(m_hDC, 0, 0, m_uBmpInfo.biWidth, m_uBmpInfo.biHeight, hTempDC, lX, lY, vbSrcCopy)
    Call SelectObject(hTempDC, hPrevBmp)
    Call DeleteDC(hTempDC)
    If AVIStreamWrite(m_hAviStream, m_lSample, 1, m_lpBits, m_uBmpInfo.biSizeImage, 0, 0, 0) < 0 Then
        GoTo QH
    End If
    m_lSample = m_lSample + 1
    '--- success
    AddFrame = True
QH:
End Function

Private Sub Terminate()
    If m_hAviStream <> 0 Then
        Call AVIStreamRelease(m_hAviStream)
        m_hAviStream = 0
    End If
    If m_hAviFile <> 0 Then
        Call AVIFileRelease(m_hAviFile)
        m_hAviFile = 0
    End If
    If m_hDC <> 0 Then
        If m_hPrevDib <> 0 Then
            Call SelectObject(m_hDC, m_hPrevDib)
            m_hPrevDib = 0
        End If
        If m_hDib <> 0 Then
            Call DeleteObject(m_hDib)
            m_hDib = 0
            m_lpBits = 0
        End If
        Call DeleteDC(m_hDC)
        m_hDC = 0
    End If
End Sub

'= private ===============================================================

Private Function pvToFourCC(sText As String) As Long
    Call CopyMemory(pvToFourCC, ByVal StrPtr(StrConv(sText, vbFromUnicode)), 4)
End Function

'=========================================================================
' Base class events
'=========================================================================

Private Sub Class_Initialize()
    Call AVIFileInit
End Sub

Private Sub Class_Terminate()
    Terminate
    Call AVIFileExit
End Sub
The sample projects loads a transparent ajax-loader PNG strip and blends it with current vbButtonFace color (Form's back color). Then the frames are split from the bitmap strip and appended to a temporary AVI file. Then an animation control is placed on the form (all API) and the temp AVI file is loaded and played.

The nice thing about animation control is that it uses a separate thread to cycle the animation, so when long running tasks are executed on the UI thread the ajax-loader continues to spin. Enjoy!

cheers,
</wqw>
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VB6 - ImageListPicker Control

January 5, 2013, 10:32 am
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This is a simple GUI UserControl for "picking" from a list of pictures.

Your program loads some pictures into it, then the user can scroll the visible list horizontally and click on one to select it.


METHODS

Add - Add a StdPicture to the list.

Delete X - Delete picture X from the list. X from 1 to n.

ClearAll - Clears the list.


PROPERTIES

ListItems(X) - Retrieves item X as a StdPicture object.

ListIndex - Currently selected item, 0 = none selected.

ThumbNailHeight, ThumbnailWidth - Visible size in pixels for the scrolling thumbnails.

ThumbnailsMargin - Space between each thumbnail in pixels. Must be 3 or greater to allow room for the selection rectangle.


EVENTS

Click - Fired when user clicks on a thumbnail image.


No special requirements or dependencies. Uses intrinsic VB6 controls and image operations. Just add the .CTL and .CTX files to your Project folder then add the control using Project|Add|File...

Source provided in the attachment as part of a demo project, along with some sample pictures (which is why the attachment is so large).

You could enhance it to add "tag" values, "file names" and so on. It would be easy enough to create a "vertical" version of this control too.
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[VB6] DownloadURL2File Function (Unicode-aware) + IsInternetConnected Function

January 17, 2013, 2:26 pm
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Code:

Private Declare Function CloseHandle Lib "kernel32.dll" (ByVal hObject As Long) As Long
Private Declare Function CreateFileW Lib "kernel32.dll" (ByVal lpFileName As Long, ByVal dwDesiredAccess As Long, ByVal dwShareMode As Long, ByVal lpSecurityAttributes As Long, ByVal dwCreationDisposition As Long, Optional ByVal dwFlagsAndAttributes As Long, Optional ByVal hTemplateFile As Long) As Long
Private Declare Function InternetCloseHandle Lib "wininet.dll" (ByVal hInternet As Long) As Long
Private Declare Function InternetOpenW Lib "wininet.dll" (ByVal lpszAgent As Long, ByVal dwAccessType As Long, ByVal lpszProxyName As Long, ByVal lpszProxyBypass As Long, ByVal dwFlags As Long) As Long
Private Declare Function InternetOpenUrlW Lib "wininet.dll" (ByVal hInternet As Long, ByVal lpszUrl As Long, ByVal lpszHeaders As Long, ByVal dwHeadersLength As Long, ByVal dwFlags As Long, ByVal dwContext As Long) As Long
Private Declare Function InternetReadFile Lib "wininet.dll" (ByVal hFile As Long, ByVal lpBuffer As Long, ByVal dwNumberOfBytesToRead As Long, ByRef lpdwNumberOfBytesRead As Long) As Long
Private Declare Function SysReAllocStringLen Lib "oleaut32.dll" (ByVal pBSTR As Long, Optional ByVal pszStrPtr As Long, Optional ByVal Length As Long) As Long
Private Declare Function WriteFile Lib "kernel32.dll" (ByVal hFile As Long, ByVal lpBuffer As Long, ByVal nNumberOfBytesToWrite As Long, Optional ByRef lpNumberOfBytesWritten As Long, Optional ByVal lpOverlapped As Long) As Long

'Downloads the file specified by the sURL argument to the local file pointed
'by the sFileName parameter. The optional Chunk parameter determines the number
'of bytes to be downloaded at a time. Bigger chunks download faster while smaller
'ones enables the GUI to be more responsive. Returns the total number of bytes
'successfully written to disk. Maximum download size of 2047.99 MB only.

Public Function DownloadURL2File(ByRef sURL As String, ByRef sFileName As String, Optional ByVal Chunk As Long = 1024&) As Long
    Const INTERNET_OPEN_TYPE_DIRECT = 1&, INTERNET_FLAG_DONT_CACHE = &H4000000, INTERNET_FLAG_RELOAD = &H80000000
    Const GENERIC_WRITE = &H40000000, FILE_SHARE_NONE = 0&, CREATE_ALWAYS = 2&
    Const INVALID_HANDLE_VALUE = -1&, ERROR_INSUFFICIENT_BUFFER = &H7A&
    Dim hInternet As Long, hURL As Long, hFile As Long, nBytesRead As Long, nBytesWritten As Long
    Dim bSuccess As Boolean, sBuffer_Ptr As Long, sBuffer_Size As Long, sBuffer As String

    If LenB(sURL) = 0& Or LenB(sFileName) = 0& Or Chunk < 2& Then Exit Function

    hInternet = InternetOpenW(StrPtr(App.Title), INTERNET_OPEN_TYPE_DIRECT, 0&, 0&, 0&)
    If hInternet Then
        hURL = InternetOpenUrlW(hInternet, StrPtr(sURL), 0&, 0&, INTERNET_FLAG_DONT_CACHE Or INTERNET_FLAG_RELOAD, 0&)
        If hURL Then
            hFile = CreateFileW(StrPtr(sFileName), GENERIC_WRITE, FILE_SHARE_NONE, 0&, CREATE_ALWAYS) 'Overwrite existing
            If hFile <> INVALID_HANDLE_VALUE Then
                Do: SysReAllocStringLen VarPtr(sBuffer), , (sBuffer_Size + Chunk) * 0.5!
                    sBuffer_Size = LenB(sBuffer):  sBuffer_Ptr = StrPtr(sBuffer)
                    Do While InternetReadFile(hURL, sBuffer_Ptr, sBuffer_Size, nBytesRead)
                        If nBytesRead Then
                            bSuccess = (WriteFile(hFile, sBuffer_Ptr, nBytesRead, nBytesWritten) <> 0&) _
                                        And (nBytesWritten = nBytesRead): Debug.Assert bSuccess
                            DoEvents
                            If bSuccess Then DownloadURL2File = DownloadURL2File + nBytesWritten
                        Else
                            Exit Do
                        End If
                    Loop
                Loop While Err.LastDllError = ERROR_INSUFFICIENT_BUFFER
                hFile = CloseHandle(hFile):                              Debug.Assert hFile
            End If
            hURL = InternetCloseHandle(hURL):                            Debug.Assert hURL
        End If
        hInternet = InternetCloseHandle(hInternet):                      Debug.Assert hInternet
    End If
End Function
Code:

Private Declare Function InternetCheckConnectionW Lib "wininet.dll" (Optional ByVal lpszUrl As Long, Optional ByVal dwFlags As Long, Optional ByVal dwReserved As Long) As Long

'Allows an application to check if a connection to the Internet can be established.
Public Function IsInternetConnected(Optional ByRef sURL As String = "http://www.google.com/") As Boolean
    Const FLAG_ICC_FORCE_CONNECTION = &H1&

    IsInternetConnected = InternetCheckConnectionW(StrPtr(sURL), FLAG_ICC_FORCE_CONNECTION)
End Function
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JACZip Archiver

January 19, 2013, 2:40 pm
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JACZip is a straight forward ZIP Archive/Unarchive program using the
built in facilities within Windows. The Microsoft implementation of
the ZIP function into the Windows Explorer is to say the least
cumbersome, and with WinZip you never really know what it has done.
If the old Command Line PKZIP supported long file names, I would
probably still be using it.

The program has been tested on Vista and Win7. XP SP2 also supports
zipped files, but JACZip has not been tested on that platform. It
requires "Microsoft Shell Controls And Automation", "Microsoft
Scripting Runtime", as well as the "Microsoft Common Dialog Control",
and the "Microsoft Flexgrid Control".

A more detailed explanation is contained in the readme file.

J.A. Coutts
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DataGrid Multiple Row Selection

January 27, 2013, 10:53 am
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The Data Bound DataGrid Control provides the ability to select
multiple rows using the CTRL key and mouse, but it lacks the
ability to use the SHIFT key in conjunction with the mouse.
The routines below add that ability by utilizing the MouseUp event.
Code:
Option Explicit

Dim PrevBmk          As Long
Dim CurrentBmk      As Long

Private Sub DataGrid1_Click()
        If DataGrid1.SelBookmarks.Count > 0 Then
                'If there is a bookmark present, make it the previous bookmark
                CurrentBmk = DataGrid1.SelBookmarks(DataGrid1.SelBookmarks.Count - 1)
        End If
End Sub

Private Sub DataGrid1_MouseUp(Button As Integer, Shift As Integer, x As Single, y As Single)
        Dim M%, N%
        If Shift > 0 And DataGrid1.SelBookmarks.Count = 0 Then
                'Prompt user to utilize row selection column
                MsgBox "You must use the far left column to select multiple records!"
        ElseIf Shift = vbShiftMask Then
                PrevBmk = CurrentBmk 'Save previous bookmark
                CurrentBmk = DataGrid1.SelBookmarks(DataGrid1.SelBookmarks.Count - 1)
                Debug.Print PrevBmk, CurrentBmk
                If PrevBmk = 0 Then Exit Sub 'no previous bookmark
                N% = CurrentBmk - PrevBmk 'Number of bookmarks to be made (+/-)
                Select Case N% 'Set step direction for/next routine
                        Case Is < 0
                                M% = 1 'Step forward
                        Case Is = 0
                                Exit Sub 'Only 1 selected
                        Case Is > 0
                                M% = -1 'Step reverse
                End Select
                For N% = N% To -M% Step M%
                        DataGrid1.SelBookmarks.Add DataGrid1.GetBookmark(-N%)
                        Debug.Print DataGrid1.SelBookmarks(DataGrid1.SelBookmarks.Count - 1)
                Next N%
        End If
End Sub
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Search

[VB6] Dereferencing Pointers sans CopyMemory

January 28, 2013, 11:14 am
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Here are several functions which retrieves the value or data located at the memory address specified by the given pointer. These functions perform the inverse operation of VarPtr, StrPtr and ObjPtr. Rather than using the ubiquitous CopyMemory, alternative APIs are presented instead.

The API declarations:

Code:

Private Declare Function ObjSetAddRef Lib "msvbvm60.dll" Alias "__vbaObjSetAddref" (ByRef ObjDest As Object, ByVal Ptr2Obj As Long) As Long
Private Declare Function SysReAllocString Lib "oleaut32.dll" (ByVal pBSTR As Long, Optional ByVal pszStrPtr As Long) As Long
Private Declare Sub CopyBytes Lib "msvbvm60.dll" Alias "__vbaCopyBytes" (ByVal ByteLen As Long, ByVal Destination As Long, ByVal Source As Long)
Private Declare Sub GetMem1 Lib "msvbvm60.dll" (ByVal Ptr As Long, ByRef RetVal As Byte)
Private Declare Sub GetMem2 Lib "msvbvm60.dll" (ByVal Ptr As Long, ByRef RetVal As Integer)
Private Declare Sub GetMem4 Lib "msvbvm60.dll" (ByVal Ptr As Long, ByRef RetVal As Long)
Private Declare Sub GetMem8 Lib "msvbvm60.dll" (ByVal Ptr As Long, ByRef RetVal As Currency)
The pointer dereferencing functions:

Code:

'Retrieves the Byte value from the specified memory address
Public Function GetBytFromPtr(ByVal Ptr As Long) As Byte
    GetMem1 Ptr, GetBytFromPtr
End Function

'Retrieves the Integer value from the specified memory address
Public Function GetIntFromPtr(ByVal Ptr As Long) As Integer
    GetMem2 Ptr, GetIntFromPtr
End Function

'Retrieves the Long value from the specified memory address
Public Function GetLngFromPtr(ByVal Ptr As Long) As Long
    GetMem4 Ptr, GetLngFromPtr
End Function

'Retrieves the Currency value from the specified memory address
Public Function GetCurFromPtr(ByVal Ptr As Long) As Currency
    GetMem8 Ptr, GetCurFromPtr
End Function

'Returns a copy of a null-terminated Unicode string (LPWSTR/LPCWSTR)
Public Function GetStrFromPtr(ByVal Ptr As Long) As String
    SysReAllocString VarPtr(GetStrFromPtr), Ptr
End Function

'Returns an object from the given pointer
Public Function GetObjFromPtr(ByVal Ptr As Long) As Object
    ObjSetAddRef GetObjFromPtr, Ptr
End Function

'Returns a copy of a UDT given a pointer (replace As UDT with any desired Type)
Public Function GetUDTFromPtr(ByVal Ptr As Long) As UDT
    CopyBytes LenB(GetUDTFromPtr), VarPtr(GetUDTFromPtr), Ptr
End Function

Sample usage:

Code:

Private Type UDT        'Len  LenB
                        '---------
    Byt As Byte        '  1    4  <-- padded to fill 32 bits
    Bln As Boolean      '  2    2
    Int As Integer      '  2    2
    Lng As Long        '  4    4
    Obj As Object      '  4    4
    Sng As Single      '  4    4
    Str As String      '  4    4
    Cur As Currency    '  8    8
    Dtm As Date        '  8    8
    Dbl As Double      '  8    8
    Vnt As Variant      ' 16    16
    FLS As String * 40  ' 40    80  <-- Unicode in memory; ANSI when written to disk
                        '---------
End Type                '101  144
Code:

Public Sub DerefPtrs()    'Call from Debug window
    Dim U As UDT

    Debug.Print
    Debug.Print "GetBytFromPtr = " & GetBytFromPtr(VarPtr(CByte(&HAD)))
    Debug.Print "GetIntFromPtr = " & GetIntFromPtr(VarPtr(&HEAD))
    Debug.Print "GetLngFromPtr = " & GetLngFromPtr(VarPtr(&HADC0FFEE))
    Debug.Print "GetCurFromPtr = " & GetCurFromPtr(VarPtr(1234567890.1234@))
    Debug.Print "GetStrFromPtr = """ & GetStrFromPtr(StrPtr(App.Title)) & """"
    Debug.Print "GetObjFromPtr = """ & GetObjFromPtr(ObjPtr(App)).Path & """"
    Debug.Print

    With U
        .Byt = &HFF
        .Bln = True
        .Int = &H7FFF
        .Lng = &H7FFFFFFF
        Set .Obj = Forms
        .Sng = 3.402823E+38!
        .Str = "The Quick Brown Fox Jumps Over The Lazy Dog"
        .Cur = 922337203685477.5807@
        .Dtm = Now
        .Dbl = 4.94065645841247E-324
        .Vnt = CDec(7.92281625142643E+27)
        .FLS = "Jackdaws Love My Big Sphinx Of Quartz..."
    End With

    With GetUDTFromPtr(VarPtr(U))
        Debug.Print "Byt = " & .Byt
        Debug.Print "Bln = " & .Bln
        Debug.Print "Int = " & .Int
        Debug.Print "Lng = " & .Lng
        Debug.Print "Obj = """ & TypeName(.Obj) & """"
        Debug.Print "Sng = " & .Sng
        Debug.Print "Str = """ & .Str & """"
        Debug.Print "Cur = " & .Cur
        Debug.Print "Dtm = " & .Dtm
        Debug.Print "Dbl = " & .Dbl
        Debug.Print "Vnt = " & .Vnt
        Debug.Print "FLS = """ & .FLS & """"
    End With
End Sub





References:

SysReAllocString function at MSDN

Hidden Gems for Free by Michel Rutten

[Benchmark] CopyMemory vs. __vbaCopyBytes by Henrik Ilgen

Using The Native Functions in VBs Runtime DLL by Voodoo Attack!!
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VB6 - DirectShow WebCam Minimal Code

January 29, 2013, 10:56 pm
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There are a number of possible APIs in Windows for previewing and capturing from webcams. One of the most popular for its broad support on Windows versions and its relative ease of use when requirements are simple is the AviCap/Video for Windows API.

But a downside of VfW is that the driver model Windows uses to support video capture devices changed after the end of 16-bit Windows (Win3.1, etc.). This means several things, but most commonly frustrating is that instead of mapping multiple webcams as device 1, 2, ... 9 they work through a compatibility layer thats maps one of them as device 1.

This can make selecting the webcam to use difficult to impractical. And using more than one webcam at a time doesn't seem possible.

The usual answer has been: "Use DirectShow instead of VfW."


DirectShow vs. VB6

One problem with using DirectShow is that Microsoft seemed to have lost enthusiasm after providing only a partial implementation. The parts of DirectShow (also called ActiveMovie) we did get a VB6-friendly API for are implemented in the Quartz.dll which should be part of Windows in any recent version (and perhaps even back to most "late" Windows 95 versions like 95B or OSR2.x).

You can still do a lot of things using just what we have, but the finer points of using DirectShow in VB6 require a 3rd party DLL to wrap a few more DirectShow C++ interfaces.


This "Minimal Approach" to VB6, DirectShow, and WebCams

What I have done here is to try to stretch things as far as I could manage.

Here is what you can do:
  • Choose among your webcams and display a live preview image.
  • "Snap" and display a still image from the webcam feed.

Here is what you can't do:
  • Get a "friendly" list of just the usable webcams.
  • Control the capture resolution/dimensions or other capture settings or even raise the built-in dialogs to let the user do so.


The Demo

What I wanted to accomplish was to see how far I could get with the two tasks we can perform without using any 3rd party libraries.


Form1

This is the main UI Form, which uses Form2 as a dialog when requested via its menu ("Add new camera...").

There is a lot more code there than I'd like that does nothing except manage the menu. As you add cameras they are added to the menu. There is also code there to load and save "settings" which include the index of the selected camera and list of added cameras by name.

Basically a lot of UI-management code which I hope doesn't obscure the DirectShow-related logic itself.

The other ugly hunk of code in there is the BuildGraph() function, which is a small interpreter of a sort that processes a "filter script" and a "connection script" to add the necessary filters and connect them to create a webcam preview graph for DirectShow.


Form2

Since I can't find any way to find just the list of usuable webcams, the user has to pick them out from among the full list of available "filters" (as they are called)! Not practical at all for a real application, but it works for a test/demo program.

That's what Form2 in the demo Project is for, a dialog from which to pick new cameras.

Note that your camera might appear there once, twice, or even three or more times depending on how many "filters" of different kinds it supports. Just pick any of them, the demo program will just use the name and sort it out later.


Module1

This contains some GDI and OLE API calls to convert the captured frame from a "packed DIB" into a StdPicture object that can be used with PaintPicture, etc. This raw StdPicture is created using a "memory DC" so there are some limits on how you can use it, i.e. simply assigning it to a PictureBox.Picture has some issues.

But in this demo we need to scale it anyway since we can't control the actual capture dimensions.

You could rework this passing in the hDC of a Form, PictureBox etc. I suppose.


Running the DSMini1 Project

The attached ZIP archive contains the entire Project.

All you should need to do is unzip the archive, then open the Project in VB6. If you have a webcam connected, you can just go ahead and run it within the IDE.

From there you will have to "Add" your webcam by browsing the filter list.

After a valid add, the live preview starts immediately at the left.

Clicking on the Snap button should take a snapshot and display it in the PictureBox at the right.

If you have another webcam connectd you shuld be able to add that one too. Once you have two or more added you can choose among them via Form1's menu.

Settings are persisted in Settings.txt, so a subsequent run should save you the trouble of picking cameras again.


Remarks

I don't know what webcams this will work with, but I know it works with two very different ones I've tried so far.
Attached Images
   
Attached Files
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Simple "Mass on Spring" Simulation

February 1, 2013, 12:40 pm
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This code simulates oscillation of mass on a spring and graphs that motion. To use this code, just start a new project, place a picture box on the form, paste the code into the form's Load event, and run the program.

Code:
'set up the display------------------------------
Form1.ScaleMode = 3
With Picture1
.Appearance = 0
.BorderStyle = 0
.AutoRedraw = True
.Width = 257
.Height = 257
.ScaleMode = 0
.ScaleWidth = .Width
.ScaleHeight = -.Height
.ScaleLeft = 0
.ScaleTop = .Height \ 2
End With

'run the simulation------------------------------
Dim f As Double 'net force acting on mass
Dim a As Double 'acceleration
Dim v As Double 'velocity
Dim p As Double 'position
Dim k As Double 'spring constant
Dim d As Double 'damping factor
Dim m As Double 'mass
Dim i As Double 'time increment
Dim t As Double 'time

p = 100
k = 0.1
d = 0.15
m = 2
i = 0.01

For t = 0 To 257 Step i
f = (-p * k) + (-v * d)
a = f / m
v = v + a * i
p = p + v * i
Picture1.PSet (t, p)
Next t
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VB6 Real Unicode Display in RichTextBox without installing RICHTX32.OCX

February 1, 2013, 2:25 pm
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Hi Guys!

I combined two nice features for a part of my project and I decided to share it with you. Well, I had three chalanges when I was doing this:

1. Use a RichTextBox for unicode display;
2. Use real unicode characters like superscript numbers (not fake offsets)
3. Not to use a setup which is nearly a must if you are using RichTextBox control to copy and register RICHTX32.OCX file. (because my project was only 380KB which looks stupid for a setup.)

Infact, I did a very small part of the job. This is a nice combination of two different modules written by some other hardworking people.

After a long research dilettante suggested me this project to display real unicode contents RTB Superscript.zip‎. It is written only "Superscript" but it does a quite well job with unicodes, too... However, only compatible RichText Box object...

At first I was very happy with this but then I realized that it causes error in computers which has no RICHTX32.OCX file in System 32 folder.
I sworn my not to use setup for a 380KB project.

Then in another thread ,again dilettante, suggested me a code (Naked RichEdit.zip‎) which draws it's own RichTextBox which is only depending on "riched20.dll", nearly found in any PC.

Then I made some tweaks, modifications and combined them, droped some notes into code to help for some basic features.

And TA-TAA:

Attachment 95963 !!!

I hope someone will find it useful, too...


PS: If anybody knows how to change the font in the code, please do let me know :D
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VB6 Real Unicode Display in Rich Edit without installing RICHTX32.OCX

February 1, 2013, 2:25 pm
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Hi Guys!

I combined two nice features for a part of my project and I decided to share it with you. Well, I had three challanges when I was doing this:

1. Use a RichTextBox for unicode display;
2. Use real unicode characters like superscript numbers (not fake offsets)
3. Not to use a setup which is nearly a must if you are using RichTextBox control to copy and register RICHTX32.OCX file. (because my project was only 380KB which looks stupid for a setup.)

Infact, I did a very small part of the job. This is a nice combination of two different modules written by some other hardworking people.

After a long research dilettante suggested me this project to display real unicode contents RTB Superscript.zip‎. It is written only "Superscript" but it does a quite well job with unicodes, too... However, only compatible RichText Box object...

At first I was very happy with this but then I realized that it causes error in computers which has no RICHTX32.OCX file in System 32 folder.
I sworn my not to use setup for a 380KB project.

Then in another thread ,again dilettante, suggested me a code (Naked RichEdit.zip‎) which draws it's own RichTextBox which is only depending on "riched20.dll", nearly found in any PC.

Then I made some tweaks, modifications and combined them, droped some notes into code to help for some basic features.

And TA-TAA:

Attachment 95963 !!!

I hope someone will find it useful, too...


PS: If anybody knows how to change the font in the code, please do let me know :D
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check if internet is connected or not

February 10, 2013, 4:51 pm
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add this in module


Code:
Option Explicit
Public Declare Function RasEnumConnections Lib "RasApi32.dll" Alias "RasEnumConnectionsA" (lpRasCon As Any, lpcb As Long, lpcConnections As Long) As Long
Public Declare Function RasGetConnectStatus Lib "RasApi32.dll" Alias "RasGetConnectStatusA" (ByVal hRasCon As Long, lpStatus As Any) As Long
Public Const RAS95_MaxEntryName = 256
Public Const RAS95_MaxDeviceType = 16
Public Const RAS95_MaxDeviceName = 32

Public Type RASCONN95
      dwSize As Long
      hRasCon As Long
      szEntryName(RAS95_MaxEntryName) As Byte
      szDeviceType(RAS95_MaxDeviceType) As Byte
      szDeviceName(RAS95_MaxDeviceName) As Byte
End Type

Public Type RASCONNSTATUS95
      dwSize As Long
      RasConnState As Long
      dwError As Long
      szDeviceType(RAS95_MaxDeviceType) As Byte
      szDeviceName(RAS95_MaxDeviceName) As Byte
End Type

Public Function IsConnected() As Boolean
Dim TRasCon(255) As RASCONN95
Dim lg As Long
Dim lpcon As Long
Dim RetVal As Long
Dim Tstatus As RASCONNSTATUS95

TRasCon(0).dwSize = 412
lg = 256 * TRasCon(0).dwSize
RetVal = RasEnumConnections(TRasCon(0), lg, lpcon)

If RetVal <> 0 Then
    MsgBox "Error " & Err & " Has Occured!", vbOKOnly + vbCritical, "Error!"
    Exit Function
End If
     
Tstatus.dwSize = 160
RetVal = RasGetConnectStatus(TRasCon(0).hRasCon, Tstatus)

If Tstatus.RasConnState = &H2000 Then
    IsConnected = True
Else
    IsConnected = False
End If
End Function



Code:
Private Sub Command2_Click()
Text1.Text = IsConnected

End Sub
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Form Window Setup With Pixel Perfect Accuracy

February 11, 2013, 11:35 pm
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One of the biggest issues with setting up your form for doing graphical programming is to get it right perfectly. You searched on Google how to do it; you messed around with the Widths and Heights; setting the Scalemode to vbPixels; messed around with Screen.TwipsPerPixel X and Y; and....still no luck. It ends up never being the values you put in to begin with, not to mention the borders of the form as well as the top of your window throws off the values a notch. Luckily I created a function that does just that. This simple sub routine will allow you to set the window anywhere you want on screen and allows you to set the size of your form window with pixel perfect accuracy by just the interior of your form window. This assumes that you are using either a borderstyle of sizable, fixed single, or none. After running this small sample program, you will see that the scalewidth and scaleheights are exact as the values you wanted. And if you take a snapshot of it pressing your PrintScreen key, paste it in a paint program, and get the width and heights of within your window, you will see it'll be exactly the number of pixels you wanted. Enjoy as code like this is not easy to come by. It should be universal. If not, you can adjust the offsets. I tested it on a bunch of resolutions and its all the same so far.

[EDIT] Fixed the code shown below. Now it should be ok.

vb Code:
  1. Option Explicit
  2.  
  3. Private Sub Window_Setup(Window As Form, Optional ByVal X As Long = -1, Optional ByVal Y As Long = -1, Optional ByVal Width As Long = -1, Optional ByVal Height As Long = -1, Optional Caption As String = " ", Optional Auto_Redraw As Boolean = False, Optional ByVal Back_Color As Long = -1)
  4.     'Use -1 for default values and "" for default strings.
  5.     With Window
  6.         If Caption <> " " Then .Caption = Caption 'Else use current setting. Note: Some people may want "" as the caption.
  7.         .AutoRedraw = Auto_Redraw
  8.         .ScaleMode = vbPixels
  9.         If X <> -1 Then .Left = X * Screen.TwipsPerPixelX 'Else use current setting.
  10.         If Y <> -1 Then .Top = Y * Screen.TwipsPerPixelY 'Else use current setting.
  11.         If .BorderStyle = vbSizable Then
  12.             If Width <> -1 Then .Width = (Width * Screen.TwipsPerPixelX) + (16 * Screen.TwipsPerPixelX) 'Else use current setting.
  13.             If Height <> -1 Then .Height = (Height * Screen.TwipsPerPixelY) + (38 * Screen.TwipsPerPixelY) 'Else use current setting.
  14.         ElseIf .BorderStyle = vbFixedSingle Then
  15.             If Width <> -1 Then .Width = (Width * Screen.TwipsPerPixelX) + (6 * Screen.TwipsPerPixelX) 'Else use current setting.
  16.             If Height <> -1 Then .Height = (Height * Screen.TwipsPerPixelY) + (28 * Screen.TwipsPerPixelY) 'Else use current setting.
  17.         ElseIf .BorderStyle = 0 Then
  18.             If Width <> -1 Then .Width = (Width * Screen.TwipsPerPixelX) 'Else use current setting.
  19.             If Height <> -1 Then .Height = (Height * Screen.TwipsPerPixelY) 'Else use current setting.
  20.         End If
  21.         If Back_Color <> -1 Then .BackColor = Back_Color 'Else use current setting.
  22.         .Show
  23.         .SetFocus
  24.     End With
  25. End Sub
  26.  
  27. Private Sub Form_Load()
  28.     Window_Setup frmMain, 0, 0, 255, 255
  29.     Print frmMain.ScaleWidth & ", " & frmMain.ScaleHeight
  30. End Sub
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Getting data from an URL provided

February 14, 2013, 7:01 am
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My task is to develop code in VB Classic, to open and URL (provided) and grab the information on the page and pass to application.

a) Open the URL site
b) Get the data on the page of the URL
c) Pass the data back to the appication

Appreciate your help
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VB6 - BasicBuffer, Binary Stream Class

February 14, 2013, 11:50 am
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Description

A simple stream-style buffer class.

This is a kind of binary stream, similar to an ADO Steam object in Type = adBinary mode or an OLE IStream object. It accepts and returns Byte arrays, Integers, and Longs but not text String values.

It can be useful whenever you want a data structure that supports something similar to concatenating Byte arrays when you need to accumulate data arriving in bits and pieces and extract chunks for use. Things like Winsock control and MSComm control binary communication come to mind.

The properties and methods are similar to those of an ADO Stream.

This class has a lot of things in it to handle common needs. Remove anything you don't need in your programs.

I have done a lot of testing, but bug reports and fixes would be welcome.


Properties

ChunkSize As Long [R/W]
EOS As Boolean [RO]
HaveAtLeast(Length As Long) As Boolean [RO]
IsOpen As Boolean [RO]
Position As Long [R/W]
Size As Long [RO]


Methods

CloseBuf()
CurrentBytes() As Byte()
DeleteBytes(Optional ByVal Length As Long = -1)
ExtractBytes(Optional ByVal Length As Long = -1) As Byte()
ExtractInteger() As Integer
ExtractLong() As Long
OpenBuf()
ReadBytes(Optional ByVal Length As Long = -1) As Byte()
ReadInteger() As Integer
ReadLong() As Long
ScanForBytes(ByRef Target() As Byte) As Long
SetEOS()
ShrinkBuf()
WriteBytes(ByRef Bytes() As Byte)
WriteInteger(ByVal Value As Integer)
WriteLong(ByVal Value As Long)


Attachment

The attached archive contains BasicBuffer.cls as well as a testing Project.

It uses character data for easy reading/debugging here (converting to/from Unicode as needed) though BasicBuffers are normally for binary data.

This looks weird but tries to provide a test for correctness of as many operations as possible.


Requirements

No special requirements. You just need VB6. It may also work in Office VBA and VB5 (not tested).

See comments in the code for more help in understanding its use.
Attached Files
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How disable cookie warning, when call method .Write of Object("HTMLFile")?

February 15, 2013, 7:52 am
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How disable cookie warning, when call method .Write of Object("HTMLFile")?
Code:
Code:
Set objDocument = CreateObject("HTMLFile")
Set oHttp = CreateObject("MSXML2.ServerXmlHttp.6.0")
   
sTemp = colUrls(i)
       
oHttp.Open "GET", sTemp, False
oHttp.setRequestHeader "Content-Type", "text/xml"
oHttp.sEnd
       
objDocument.Write oHttp.responsetext    '<--- warning shows in this place
look at the screen:
Attachment 96491
Attached Images
 
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Email Client Program

February 18, 2013, 11:02 am
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JACMail is an Email Client Program designed to allow fast and efficient recovery of email
from a POP3 server, and the sending of email through an SMTP server. It is primarily oriented
towards text based messaging with attachments, and does not directly support highly formatted
HTML based email or embedded objects. It receives and stores both "text/plain" and "text/html"
messages, and Web based emails can be sent to the default browser for viewing. It also
supports Plain Authentication based SMTP and multiple mailboxes. The mailboxes are stored in
an Access database utilising ODBC.

The code uses IP Version independent system calls, so it will only work on Windows systems
that actively support both IPv4 and IPv6. That more or less restricts it to Windows Vista or
later. It utilises the following standard components and references: RICHED32.DLL, RICHTX32.OCX,
COMDLG32.OCX, MSSTDFMT.DLL, MSBIND.DLL, MSADODC.OCX, MSDATGRD.OCX, which the user
must have available in order to compile the program. WS2_32.DLL is required to run the program.

J.A. Coutts
Attached Images
 
Attached Files
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Pure VB6 TreeView Control

February 19, 2013, 10:58 am
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....or ListView if you set the 'Indentation' Property to zero.... ;-)


Why I created this:
I am developing a treeview control BUT this isn't it!

At this stage, I am just creating the classes that will provide the 'engine' for my final work. However, in the course of doing so, I knocked up a very basic VB6 User Control and a hosting form in order to test them. I do not intend to use this Control myself (I'll be writing a new one that draws the nodes and provides for 'proper' hit-tests etc) so may not develop it further unless I need to add functionality to the classes that I need to test. Therefore there may or may not be updates to this post. However, somebody might find it useful to learn from in its current state...

I'd also appreciate peer code review as I'm a self-taught coder and may be doing some things less efficiently than I could be (or making other glaring mistakes)!

FEATURES:
  • full keyboard support
  • Drag-And-Drop between nodes
  • User-definable node caption colours
  • User-definable Background colour or picture

WATCH OUT FOR:
  • Barely any error handlers added as yet (cos I want to expose all errors during testing)
  • Not extensively commented (since I'm re-writing, re-designing as I go along)

Please do not report errors/crashes with the demo form - it is just a demo. I am however interested in errors raised by the classes and, to a lesser extent, the User Control. I'll repeat; it's really the classes that I am submitting - the rest is just a way of demonstrating/testing them...

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