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Thread: [RESOLVED] Save an image file in Alternate Data Stream

  1. #1

    Thread Starter
    Hyperactive Member
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    Resolved [RESOLVED] Save an image file in Alternate Data Stream

    I am using the ADS for normal strings very successfully, but I cannot work out how to save/retrieve an image file.

    Say I had Cover.jpg and I wanted to attach it to CD1Track01.mp3 as an ADS - CD1Track01.mp3:Cover.jpg.

    How do I write and then read the ADS so that I end up with Cover.jpg (or .png/.gif/.bmp) again for showing.

    VB6 SP6.

    Many thanks.

    PS. In case you are wondering why I don't use the Tag metadata. Well I do; my favourite is AudioGenie but this stopped developing in 2010 and knows nothing of Aiff, Opus etc and cannot read/write images to half of its supported formats. The other TagsLib.dll from un4seen.com reads/writes everything, with pictures, but gives me occasional crashes. I'm just fed up with it all!

  2. #2
    PowerPoster
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    Feb 2006
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    19,343

    Re: Save an image file in Alternate Data Stream

    Seems simple enough. This demo adds a canned "album art" image to SomeFile.txt though an .MP3 file wouldn't be any different:

    Code:
    Option Explicit
    
    Private Const FILE_NAME As String = "SomeFile.txt"
    
    Private Declare Function DeleteFile Lib "kernel32" Alias "DeleteFileA" ( _
        ByVal FileName As String) As Long
    
    Private ArtBytes() As Byte
    
    Private Sub DisplayArt()
        Dim StdPicture As StdPicture
    
        With New WIA.Vector
            .BinaryData = ArtBytes
            Set StdPicture = .Picture
        End With
        With Picture1
            .AutoRedraw = True
            With StdPicture
                .Render Picture1.hDC, _
                        0, _
                        0, _
                        ScaleX(Picture1.ScaleWidth, Picture1.ScaleMode, vbPixels), _
                        ScaleY(Picture1.ScaleHeight, Picture1.ScaleMode, vbPixels), _
                        0, _
                        .Height, _
                        .Width, _
                        -.Height, _
                        ByVal 0&
            End With
            .Picture = .Image
            .AutoRedraw = False
        End With
    End Sub
    
    Private Sub cmdAdd_Click()
        Dim F As Integer
    
        cmdAdd.Enabled = False
        F = FreeFile(0)
        Open "Resources\CWB.gif" For Binary Access Read As #F
        ReDim ArtBytes(LOF(F) - 1)
        Get #F, , ArtBytes
        Close #F
        F = FreeFile(0)
        Open FILE_NAME & ":Art" For Binary Access Write As #F
        Put #F, , ArtBytes
        Close #F
        DisplayArt
        cmdRemove.Enabled = True
    End Sub
    
    Private Sub cmdRemove_Click()
        cmdRemove.Enabled = False
        'Note that VB6 "Kill" will not accept an alternate data stream name:
        DeleteFile FILE_NAME & ":Art"
        Picture1.Picture = Nothing
        cmdAdd.Enabled = True
    End Sub
    
    Private Sub Form_Load()
        Dim F As Integer
    
        On Error Resume Next
        GetAttr FILE_NAME
        If Err Then Exit Sub
        Err.Clear
        GetAttr FILE_NAME & ":Art"
        If Err Then
            cmdAdd.Enabled = True
        Else
            On Error GoTo 0
            F = FreeFile(0)
            Open FILE_NAME & ":Art" For Binary Access Read As #F
            ReDim ArtBytes(LOF(F) - 1)
            Get #F, , ArtBytes
            Close #F
            DisplayArt
            cmdRemove.Enabled = True
        End If
    End Sub
    Name:  sshot.png
Views: 47
Size:  4.6 KB

    What am I missing?
    Attached Files Attached Files

  3. #3

    Thread Starter
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    Re: Save an image file in Alternate Data Stream

    As always - many thanks dil. I haven't been using the wia due to quality issues. I have been using a routine (which I think came from you) using GDI+. This works extremely well but needs a filename, unless you knowe a different method.

    Code:
    Private Sub DrawThumbnail(ByVal sFileName As String)
        Dim Graphics As Long, img As Long
        Dim W As Single, H As Single, wNew As Single, hNew As Single, Ratio As Double
        Dim wMax As Long, hMax As Long
        
        GdiStartup
        GdipLoadImageFromFile StrPtr(sFileName), img                'Load the image into memory
        
        Pic1.Cls
            
        If img > 0 Then
            GdipGetImageDimension img, W, H
                    
            If W > 0 And H > 0 Then
                Dimensions = "Picture size: " & W & " x " & H
                PicFileName = sFileName
                wMax = Pic1.ScaleWidth: hMax = Pic1.ScaleHeight
                Ratio = Min(wMax / W, hMax / H)                     'Resize keeping Ratio
                wNew = W * Ratio: hNew = H * Ratio
                GdipCreateFromHDC Pic1.hDC, Graphics                'Initialize the graphics class - required for all drawing
                GdipSetInterpolationMode Graphics, 7                'QualityModeHigh = 2 : InterpolationModeHighQualityBicubic = 7
                GdipSetSmoothingMode Graphics, SmoothingModeAntiAlias '<-- is ignored in ClipPath  :/
                GdipDrawImageRectI Graphics, img, (wMax - wNew) / 2, (hMax - hNew) / 2, wNew, hNew
            Else
                Dimensions = "Image Corrupt"
            End If
        Else
            Dimensions = "No Image found!"
        End If
            
        GdipDisposeImage img                                        'Delete the image
        GdipDeleteGraphics Graphics                                 'Delete the graphics
        GdiShutdown
        fraPic.Caption = Dimensions
        cmdCopyArt.Enabled = InStrB(Dimensions, "Picture size:")
    End Sub

  4. #4
    PowerPoster
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    Re: Save an image file in Alternate Data Stream

    Well why not use GdipLoadImageFromStream()?

    You can extract what you need from Stream.cls to create a stream on memory or a resource, see the CreateMemStream() and CreateResStream() methods. Or you could just use the class as is.

    Here is a Project I had handy with that class in it, though the Project itself does not address your situation.
    Attached Files Attached Files

  5. #5

    Thread Starter
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    Re: Save an image file in Alternate Data Stream

    Oh just what was needed thank you. Sorry need to spread my self around before rep!!

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