Enumerate EXIF in VB6 - Is it possible?

I have been searching for a long time for a dependable way to extract EXIF
from a JPG using Visual Basic 6. I have tired all the online VB6 API offerings
(i.e. ExifReader.cls, clsImageInfo.cls, clsJPEGparser.cls) and each one of
them always encounters occasionally a JPG it can't process (API code abends,
while other applications such as IrfanView have no problem displaying the EXIF
data for the JPG). My problem is I don't know win32 API well enough nor the
EXIF model so I can't debug the VB6 CLS examples that occasionally fail.

This issue caused me to try FreeImage from VB6, however after a couple of days
I finally give up searching online for any examples calling FreeImage from VB6
for metadata. Today I thought I would make one last attempt and scanned the
VB.Net examples. I found a ~30 line example (Sample 10) from the package that
was promising but confusing since I have never coded in .NET. I did manage to
figure out that Sample 10 from the group depends literally on thousands of
lines of class library code in order to iterate the EXIF data via FreeImage. I
found this from .NET class libraries ImageMetadata.cs, MetadaaModel.cs and
MetadataTag.cs.

So it seems that extracting EXIF is an even greater task than I expected. With
no examples to get at Metadata by calling FreeImage from VB6 it sounds like
the only solution may be to go back to one of the VB6 CLS files and try to
debug the API with documentation on EXIF for the rare oddity where the API
fails.

Am I wrong or am I wrong? (Thanks!)

Finally! I struck upon something popular that makes sense, the PHP example. I
was able to learn enough from the PHP code to make something that works in
VB6. Here is a starter for anyone else who can't seem to get off the ground
with the 1 line VB6 example ;-) :

Note: Add or replace this code in the FileImage package:

FreeImage3151Win32\FreeImage\Wrapper\VB6\test

Replace existing code in SimpleTest.frm with this to test metadata:

Option Explicit
' NOTE :
' To run this test program, you will have to copy the FreeImage.dll file in this directory.
' Change also the "test.tif" file name with a path to any tif file on your hard disk
'
Private Sub btnTest_Click()
  Dim tstText As String
  Dim dib As Long
  Dim bOK As Long
  Dim i As Long
  Dim tstTag() As FREE_IMAGE_TAG

  dib = FreeImage_Load(FIF_JPEG, "IMG_5061.JPG", 0) 'in our source dir for testing

  tstText = "FIMD_EXIF_EXIF"
  Erase tstTag
  bOK = FreeImage_GetAllMetadataTags(FIMD_EXIF_EXIF, dib, tstTag())
  If bOK > 0 Then
    For i = 1 To UBound(tstTag) - 1
        tstText = tstText & vbCrLf & tstTag(i).Description & ":    " & tstTag(i).Key & " = " & tstTag(i).StringValue
    Next
    MsgBox tstText
  Else
    MsgBox "Nothing returned for FIMD_EXIF_EXIF"
  End If

   tstText = "FIMD_EXIF_MAIN"
   Erase tstTag
  bOK = FreeImage_GetAllMetadataTags(FIMD_EXIF_MAIN, dib, tstTag())
  If bOK > 0 Then
    For i = 1 To UBound(tstTag) - 1
        tstText = tstText & vbCrLf & tstTag(i).Description & ":    " & tstTag(i).Key & " = " & tstTag(i).StringValue
    Next
    MsgBox tstText
  Else
    MsgBox "Nothing returned for FIMD_EXIF_MAIN"
  End If

  tstText = "FIMD_EXIF_INTEROP"
  Erase tstTag
  bOK = FreeImage_GetAllMetadataTags(FIMD_EXIF_INTEROP, dib, tstTag())
  If bOK > 0 Then
    For i = 1 To UBound(tstTag) - 1
        tstText = tstText & vbCrLf & tstTag(i).Description & ":    " & tstTag(i).Key & " = " & tstTag(i).StringValue
    Next
    MsgBox tstText
  Else
    MsgBox "Nothing returned for FIMD_EXIF_INTEROP"
  End If

  ' Unload the dib

FreeImage_Unload (dib)

End Sub

At least this will get me started. Good luck to everyone else searching for a
similar solution and please share your own discoveries .... Don

Notice above, the last two lines jumped out of my shaded code block:

.......... (see above)

' Unload the dib
  FreeImage_Unload (dib)

End Sub

And the hits just keep on comin'!

Here is a way to find the DateTimeOriginal value of a JPG with a little
"minimalism" of my own :-)

Private Sub CreateDate(myJPG as string)
  Dim keySearch As String
  Dim dib As Long
  Dim bDone As Boolean
  Dim tstTag As FREE_IMAGE_TAG

  dib = FreeImage_Load(FIF_JPEG, myJPG, 0) 'in our source dir for testing

  keySearch = "DateTimeOriginal"

  bDone = FreeImage_GetMetadataEx(FIMD_EXIF_EXIF, dib, keySearch, tstTag)
  If bDone Then
        MsgBox tstTag.Key & " = " & tstTag.StringValue
  Else
    MsgBox "Not found"
  End If

  ' Unload the dib
  FreeImage_Unload (dib)
End Sub

Hi,

I gave you a complete example including a lot more information about metadata
extraction with FreeImage from VB6 yesterday. Maybe you should monitor the
forums you are posting to...

https://sourceforge.net/projects/freeimage/forums/forum/36110/topic/4752688

Carsten

"Maybe you should monitor the forums you are posting to..."

Hello Carsten:

I checked the "Monitor" button but I got no emails stating anything was
updated. I am not sure how this one works but I certainly didn't mean to
offend you or anyone else. I do admit that I just registered for this forum
and have never used SourceForge fora prior to these last couple of posts. My
only experience is that in other fora I can subscribe to threads and here I
assumed that " |_| Monitor This " check box meant that I would be put on a
mailing list when it was updated. If that is not the way it works, my advanced
apologies. You are correct that I depend on notification automation for
updates and if I don't get an email, then I assume no one updated and don't go
back and check it often otherwise.

Apparently this forum does not update either, as I found your post by accident
just now as I was about to add more information that I have gathered.

Casten gave a great example in his referenced link above so please refer to
that for the correct way to go about this. Thank you so much. See his link for
further information. As a final post, I do want to close this out with some
further info on the code above, junky as it is. Note that the EXIF data
overfills a msgbox call so you won't see all the EXIF data it extracts, so I
have entered a typical test run output below.

For reference, here is the data I got from the respective calls from a Canon
SD850:

FIMD_EXIF_EXIF:
ApertureValue = F2.8
ColorSpace = sRGB
ComponentsConfiguration = YCbCr
CompressedBitsPerPixel = 5 bits/pixel
CustomRendered = Normal process
DateTimeDigitized = 2010:07:01 15:20:00
DateTimeOriginal = 2010:07:01 15:20:00
DigitalZoomRatio = 3264/3264
ExifVersion = 0220
ExposureBiasValue = 0
ExposureMode = Auto exposure
ExposureTime = 1/60 sec
FNumber = F2.8
FileSrc = Digital Still Camera (DSC)
Flash = Flash did not fire, auto mode
FlashPixVersion = 0100
FocalLength = 5.8 mm
FocalPlaneResolutionUnit = inches
FocalPlaneXResolution = 43520/3
FocalPlaneYResolution = 2448000/169
ISOSpeedRatings = 125
MaxApertureValue = F2.8
MeteringMode = Multi-segment
PixelXDimension = 900
PixelYDimension = 675
SceneCaptureType = Standard
SensingMethod = One-chip color area sensor
ShutterSpeedValue = 1/32 sec
SubjectDistance = 0.560 meters
UserComment =

FIMD_EXIF_INTEROP:
InteroperabilityIndex = R98
InteroperabilityVersion = 0100
RelatedImageLength = 2448

FIMD_EXIF_MAIN:
BitsPerSample = 8 8 8
DateTime = 2011:10:10 21:09:46
ImageLength = 2448
ImageWidth = 3264
Make = Canon
Model = Canon PowerShot SD850 IS
Orientation = top, left side
PhotometricInterpretation = 2
ResolutionUnit = inches
SamplesPerPixel = 3
Software = Adobe Photoshop CS5 Windows
XResolution = 180
YCbCrPositioning = Center of pixel array