Android Question Add thumbnail with WriteToStream method

Discussion in 'Android Questions' started by Ivan Aldaz, May 17, 2017.

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  1. Ivan Aldaz

    Ivan Aldaz Member Licensed User

    Hi all.

    I´m trying to add a thumbnail to a picture modified in a canvas. The original picture has a thumbnail 'inside', but the one generated with 'OutPutStream' and the 'WriteToStream' method doesn't have it.

    Executing the code attached below you can see the result in the 'Logs' window. You'll need the 'JpegUtils' library.

    Is there any way to add or append a thumbnail to a .jpg file generated this way? I know 'LoadBitmapSample', but it creates a new file, and that's not what I'm looking for. I want the thumbnail in the same file as the picture, like in the original picture.

    Sub Activity_Create(FirstTime As Boolean)

    Dim exif As ExifData
    Dim canvas1 As Canvas
    Dim bitmap1, bitmap2 As Bitmap
    Dim brect As Rect
    Dim iv As ImageView
    File.Copy(File.DirAssets, "Sample.jpg"File.DirRootExternal,"Sample.jpg")

    File.DirRootExternal, "sample.jpg")
    0,0,bitmap1.Width, bitmap1.Height)

    'Add picture to canvas
        canvas1.DrawBitmap(bitmap1, Null, brect)
    'Add a circle to canvas
        canvas1.DrawCircle(100dip100dip40dipColors.Red, False10dip)
    'Show modified picture
        iv.Gravity = 


    'Save picture 
        Dim Out As OutputStream
        Out = 
    File.OpenOutput(File.DirRootExternal, "SampleWithCircle.jpg"False)

    'This code does'n work to add a thumb
        Dim thumb As Bitmap = LoadBitmapSample(File.DirRootExternal, "SampleWithCircle.jpg"100dip100dip)
    '    Dim Out2 As OutputStream
    '    Out2 = File.OpenOutput(File.DirRootExternal, "SampleWithCircle.jpg", True)
    '    thumb.WriteToStream(Out2,100,"JPEG")
    '    Out2.Close

    'Test if "Sample.jpg" has thumbnail
        exif.Initialize(File.DirRootExternal, "Sample.jpg")
    Log("Sample has thumbnail: " & exif.hasThumbnail)              

    'Test if "SampleWithCircle.jpg" has thumbnail
        exif.Initialize(File.DirRootExternal, "SampleWithCircle.jpg")
    Log("SampleWithCircle has thumbnail: " & exif.hasThumbnail)  
    End Sub
    Thanks in advance.

    Attached Files:

  2. eps

    eps Well-Known Member Licensed User

  3. Ivan Aldaz

    Ivan Aldaz Member Licensed User

    Thank you for your promt answer, eps

    Maybe I have to convert the bitmap to a string, but the only way I see that the thumbnail could be added is by "exif.setAttribute (tag As java.lang.String, value As java.lang.String) As void". Post #2 in that thread shows all the exif tags, but don't find the one that could match.
  4. eps

    eps Well-Known Member Licensed User

    I don't know - you'll have to investigate...

    Maybe extract the exif you have in the original image which 'works' and then work backwards?

    There are :

    ThumbnailImageLength - null
    ThumbnailImageWidth - null
  5. Ivan Aldaz

    Ivan Aldaz Member Licensed User

    But then I'd have the thumbnail of the unmodified picture. There must be a method in Java that writes the exif thumbnail, so I could use with r.Runmethod(...), but I don't find it...
  6. eps

    eps Well-Known Member Licensed User

    that's just the size of the thumbnail..

    You also need to look at (from the link above)

    • ThumbnailRange As long[] [read only]
    • ThumbnailBytes As byte[] [read only]
    • GpsDateTime As long [read only]
    • ThumbnailBitmap As [read only]
    • Thumbnail As byte[] [read only]
    • DateTime As long [read only]
  7. Ivan Aldaz

    Ivan Aldaz Member Licensed User

    Thank you again for your time, eps

    I've seen that properties in the link above, but all of them are [read only], and all I get is information about the thumbnail that is already embedded in the picture.
  8. DonManfred

    DonManfred Expert Licensed User

    Can you upload such a Picture with embedded thumbnail?
    I tried the pic above and the ExifInterface does not return any information about the/a thumbnail.
  9. Ivan Aldaz

    Ivan Aldaz Member Licensed User

    Hi, DonManfred.

    I've tried with the uploaded image, and think the thumbnail is there. It can be shown by adding the next code after exif.Initialize (the first two lines are not new):

    exif.Initialize(File.DirRootExternal, "Sample.jpg"'This lines are not new
        Log("Sample has thumbnail: " & exif.hasThumbnail)
    Dim ivThumb As ImageView
        ivThumb.Bitmap= exif.DecodeThumbnail(exif.Thumbnail)
        ivThumb.Gravity = 

    But don't see any value the properties either.

    Log("Thumb Length: " & exif.getAttribute("ThumbnailImageLength")) 
    Log("Thumb Width: " & exif.getAttribute("ThumbnailImageWidth"))
  10. Ivan Aldaz

    Ivan Aldaz Member Licensed User

    I've tried this (code taken from an answer by Erel in another thread), using this (

    Dim exif As JavaObject
    ""Array(File.Combine(File.DirRootExternal, "SampleWithCircle.jpg")))

    Private Sub ExifConst(tag As StringAs String
    Dim jo As JavaObject
    Return jo.InitializeStatic("").GetField(tag)
    End Sub

    But doesn'twork too. I get this error message:

    "java.lang.RuntimeException: Field: TAG_ORF_THUMBNAIL_IMAGE not found in:"
  11. Erel

    Erel Administrator Staff Member Licensed User

    Can you post a link to that thread?

    TAG_ORF_THUMBNAIL_IMAGE is only available in Android O.
  12. Ivan Aldaz

    Ivan Aldaz Member Licensed User

    Hi. The post I took the code from is

    Just changed

    ExifConst("TAG_ARTIST"), "John Due")

    ExifConst("TAG_ORF_THUMBNAIL"), thumb)
    thumb = loadBitmapSample(File.DirRootExternal,"SampleWithCircle.jpg"50dip50dip)
    but didn't know that "TAG_ORF_THUMBNAIL_IMAGE is only available in Android O.". I saw this label in exifInterface.html and tried.
  13. Erel

    Erel Administrator Staff Member Licensed User

    I was surprised as you wrote "code taken from an answer by Erel in another thread".
  14. Ivan Aldaz

    Ivan Aldaz Member Licensed User

    I understand, of course you won't post a non-working code. That's why I wrote 'using this' ... 'and this'. The second 'this' was used to take the constant and change it on your code.

    My apologies.
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