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; Modify Exif Date example by PB.  Feel free to use in any way. :)
; Works fine with photos taken with a Pentax Optio S digital camera.
; May work with photos by other cameras, but no guarantee is given!
;
; *** Any use of this procedure is entirely at your own risk! ***

Procedure ModifyExifDate(file$,ye,mo,da,ho,mi,se)
  If OpenFile(0,file$)=0
    ProcedureReturn 0 ; Couldn't open file, or it doesn't exist.
  Else
    a$=FormatDate("%yyyy:%mm:%dd %hh:%ii:%ss",Date(ye,mo,da,ho,mi,se)) ; Prepare new date to write.
    ; Next line writes new date into the 3 date offsets in the photo's Exif Data (228, 694 and 714).
    FileSeek(228) : WriteString(a$) : FileSeek(694) : WriteString(a$) : FileSeek(714) : WriteString(a$)
    CloseFile(0) : ProcedureReturn 1 ; Successful! :)
  EndIf
EndProcedure

Debug ModifyExifDate("C:\IMGP0695.JPG",2005,12,25,0,0,0) ; Modify date to Christmas Day for this example.

Code: Select all

UseJPEGImageDecoder()
#Exif_DateTime = 306
#Header = 12
Global date_time
Procedure.s GetExifDateTime(jpg$, writeIt, newDateTime$)
  OpenFile(0, jpg$)
  ; --> Byte 0 of EXIF begins after JPEG header
  FileSeek(#Header)
  ; --> Bytes 0-1 is word order 18761 ($4949) is Intel and 19789 ($4D4D) is Motorola
  wordOrder = ReadWord()
  If wordOrder = $4949
    ; --> Bytes 2-3 is TIFF format, it's always 42 ($2A). If not, give up.
    tifFormat = ReadWord()
    If tifFormat = $2A
      ; --> Bytes 4-7 is starting offset for IFD (Image File Directory)
      ifd1 = ReadLong()
      ; --> Move to start of IFD
      FileSeek(ifd1 + #Header)
      ; --> First 2 bytes of IFD is number of field entries
      nFields = ReadWord()
      ; --> Loop through all fields to find Date/Time stamp
      date_time = #False
      For i = 1 To nFields
        ; --> Bytes 0-1 contain the Tag for the field.
        currentTag = ReadWord()
        If currentTag = #Exif_DateTime
          ; --> Bytes 2-3 contain the field Type.
          ; --> We know this will be 2 (ASCII) For Date/Time
          fieldType = ReadWord()
          ; --> Bytes 4-7 contain the  Length of the field.
          fieldLength = ReadLong()
          currentloc = Loc()
          ; --> Bytes 8-11 contain a pointer to ASCII Date/Time
          fieldValue = ReadLong()
          ; --> Move to that pointer
          FileSeek(fieldValue + #Header)
          ; --> This is the start point of Dat/Time ASCII string
          If writeIt And newDateTime$
            WriteString(newDateTime$)
            date_time$ = newDateTime$
            MessageRequester("Info", "Date and Time have been changed.")
          Else
            date_time$ = ReadString()
          EndIf
          date_time = #True
          Break
        Else
          ; --> Move to next field. Each field is 12 bytes.
          ; --> currentTag (2 bytes) is current Loc() so we add 10
          FileSeek(Loc()+10)
        EndIf
      Next
      If date_time <> #True
        MessageRequester("Sorry", "Date Time field was not found.")
      EndIf
    Else
      MessageRequester("Error", "Invalid file format!")
    EndIf
  Else
    MessageRequester("Sorry", "Invalid file format!")
  EndIf
  CloseFile(0)
  ProcedureReturn date_time$
EndProcedure

If OpenWindow(0, 10, 10, 300, 200, #PB_Window_SystemMenu, "Exif Date/Time") And CreateGadgetList(WindowID())
  ButtonGadget(0, 10, 10, 280, 20, "Open JPG")
  TextGadget(1, 10, 40, 280, 60, "", #PB_Text_Center)
  TextGadget(2, 10, 80, 280, 20, "", #PB_Text_Center)
  ButtonGadget(3, 10, 110, 280, 20, "Change Date")
  DisableGadget(3, 1)
  DateGadget(4, 10, 140, 280, 20, "%yyyy:%mm:%dd  %hh:%ii")
  Repeat
    event = WaitWindowEvent()
    If event = #PB_EventGadget
      Select EventGadgetID()
        Case 0
          fileOpen$ = (OpenFileRequester("Select JPEG", "C:\Documents and Settings\Owner\My Documents\My Pictures\", "JPG files (JPG)|*.jpg;*.jpeg", 0))
          If fileOpen$
            dt$ = GetExifDateTime(fileOpen$, 0, "")
            If date_time
              SetGadgetText(1, fileOpen$)
              SetGadgetText(2, "Original Date/Time is " + dt$)
              DisableGadget(3, 0)
            EndIf
          EndIf
        Case 3
          ; --> DateGadget has no support for seconds so add your own below
          newDT$ = GetGadgetText(4) + ":00"
          dt$ = GetExifDateTime(fileOpen$, 1, newDT$)
      EndSelect
    EndIf
  Until event = #PB_Event_CloseWindow
EndIf
End

Code: Select all

UseJPEGImageDecoder() 
jpg$ = OpenFileRequester("Select JPEG", "C:\Documents and Settings\Owner\My Documents\My Pictures\", "JPG files (JPG)|*.jpg;*.jpeg", 0)
If jpg$
  OpenFile(0, jpg$) 
  FileSeek(188)
  dateInfo$ = "Modified: " + Chr(9)
  dateInfo$ + ReadString() + #CRLF$
  FileSeek(586)
  dateInfo$ + "Taken: " + Chr(9)
  dateInfo$ + ReadString() + #CRLF$
  FileSeek(606)
  dateInfo$ + "Digitized: " + Chr(9)
  dateInfo$ + ReadString()
  CloseFile(0) 
  MessageRequester("Exif Date Info", dateInfo$)
EndIf
End