Android Question Problem viewing image attachment POP3

bryon · Sep 18, 2015

Good morning,
I'm using the Net library and also Erel's Mailparser module:

https://www.b4x.com/android/forum/threads/using-pop3-to-communicate-with-android-devices.11310/

No other changes have been done to the example except adding my login credentials.

All is well with downloading messages and images as attachments, however, when I attempt to view the image, it appears corrupted. I can see the file listing with a file manager app but it displays as a broken icon.

Can someone please try this and let me know if images are downloaded and displayed correctly on your device?

Any other ideas or comments would be appreciated.

Thanks,
Bryon

bryon · Sep 18, 2015

..and then I found the following from this thread:
https://www.b4x.com/android/forum/threads/saving-a-picture.10200/#content

B4X:

 'send the intent that asks the media scanner to scan the file
    Dim i As Intent
    i.Initialize("android.intent.action.MEDIA_SCANNER_SCAN_FILE", _
        "file://" & File.Combine(File.DirdefaultExternal & "/momblog/images/",filename))
    Dim p As Phone
    p.SendBroadcastIntent(i)

But it didn't help. I did notice though, that the icon wen't from "broken" to a completely black icon.

Suggestions to try?

rboeck · Sep 19, 2015

Did you see message #95 on https://www.b4x.com/android/forum/t...communicate-with-android-devices.11310/page-5
I think this is as small correction of the mailparsing routines.

bryon · Sep 21, 2015

Thanks rboeck, that didn't help though. My files are downloading, B4A just can't seem to access them..

Erel · Sep 21, 2015

Compare the image file data to the original file data (with a hex editor).

bryon · Sep 21, 2015

Thanks Erel, for responding.

Okay, so there is a difference between the downloaded file and the original.

I tried two images I had on my hard drive:
- "IdeaDrivedrawing.JPG"
- "Birds_flying.bmp"

First screenshot ("POP3_downloads[1].png") shows how the files show up on my device after POP3 download. These files would not display and when I tried initializing a bitmap, I encountered: "java.lang.RuntimeException: Error loading bitmap."

B4X:

Dim TestBitmap as bitmap
TestBitmap.Initialize(File.DirDefaultExternal & "/momblog/images/", MailParser.filename)

The original "IdeaDrivedrawing.JPG" had two additional bytes: FF and D9 at the end of the file that the POP3 downloaded file did not have.
The original "Birds_flying.bmp" had three additional bytes: 00, 00 and 00 at the end.

I loaded the POP3 versions into my hex editor and added the missing bytes, then copied them back to my phone where they then worked as expected. they also show up as images in my file manager too. (See next screenshot ("Files_fixed[1].png")

Somewhere they are losing some bytes.

I included the POP3 example with the mailparser module where I added media scanning code immediately after it saves the attachment in the Sub HandlePart().

Also, added the following line as per rboeck's suggestion previously in this thread:

B4X:

If nextPart = -1 Then nextPart = Mail.Length + 4

in Sub ParseMultipartBody().

Could you please have a look at the mailparser (or maybe even DecodeBase64) to see if there is something amiss?

My hardware is rooted Galaxy S5 connected to dev computer via USB cable. Will try same experiment at home with WiFi bridge.

Thank you.

-bryon

bryon · Sep 22, 2015

For completeness, I just tried with wifi bridge and with all the variations of debuggers and release compiles.

Same thing is happening. It's losing the last several bytes of the file.

Erel · Sep 22, 2015

Try to send a very small image.
Assuming that the image will not arrive completely then check the value of Body (in HandlePart sub). See whether it includes all the data.

If you are unable to fix it then save the raw message arrived and upload it.

bryon · Sep 22, 2015

Thanks Erel,

I found this:

B4X:

            If nextPart-4 > index Then
                HandlePart(headers.ToString, Mail.SubString2(index, nextPart-4), Msg)
            End If

and removed the if/then check and the -4 which left me with this:

B4X:

HandlePart(headers.ToString, Mail.SubString2(index, nextPart), Msg)

Which gives me the whole file. I don't know why the removal of 4 bytes is necessary. After you've found the boundary with

B4X:

nextPart = Mail.IndexOf2("--" & boundary, index)

isn't the complete file all you have left?

Can you explain why that check was in there please?

Thank you!

Erel · Sep 24, 2015

Does it work with this code?

B4X:

Sub ParseMultipartBody (Mail As String, Msg As Message)
   'find first boundary
   index = Mail.IndexOf2("--" & boundary, index)
   ReadNextLine(Mail)
   Dim headers As StringBuilder
   headers.Initialize
   Do While index < Mail.Length
     Dim line As String
     line = ReadNextLine(Mail)
     If line.Length > 0 Then
       headers.Append(line).Append(" ")
     Else If index < Mail.Length Then
       Dim nextPart As Int
       nextPart = Mail.IndexOf2("--" & boundary, index)
       If nextPart = -1 Then nextPart = Mail.Length + 4
       If nextPart-4 > index Then
         HandlePart(headers.ToString, Mail.SubString2(index, nextPart-4), Msg)
       End If
       index = nextPart
       ReadNextLine(Mail)
       headers.Initialize
     End If
   Loop
End Sub

bryon · Sep 25, 2015

With this code it is still cutting off two bytes at the end of the file.

Android Question Problem viewing image attachment POP3

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