Fixed IFD to update internal offsets on copy()

src/ifd.cpp

@@ -20,14 +20,14 @@
  */
 /*
   File:      ifd.cpp
-  Version:   $Name:  $ $Revision: 1.2 $
+  Version:   $Name:  $ $Revision: 1.3 $
   Author(s): Andreas Huggel (ahu) <ahuggel@gmx.net>
   History:   26-Jan-04, ahu: created
              11-Feb-04, ahu: isolated as a component
  */
 // *****************************************************************************
 #include "rcsid.hpp"
-EXIV2_RCSID("@(#) $Name:  $ $Revision: 1.2 $ $RCSfile: ifd.cpp,v $")
+EXIV2_RCSID("@(#) $Name:  $ $Revision: 1.3 $ $RCSfile: ifd.cpp,v $")
 
 // *****************************************************************************
 // included header files
@@ -271,9 +271,9 @@ namespace Exif {
         return rc;
     } // Ifd::readSubIfd
 
-    long Ifd::copy(char* buf, ByteOrder byteOrder, long offset) const
+    long Ifd::copy(char* buf, ByteOrder byteOrder, long offset)
     {
-        if (offset == 0) offset = offset_;
+        if (offset != 0) offset_ = offset;
 
         // Add the number of entries to the data buffer
         us2Data(buf, entries_.size(), byteOrder);
@@ -281,16 +281,17 @@ namespace Exif {
 
         // Add all directory entries to the data buffer
         long dataSize = 0;
-        const const_iterator b = entries_.begin();
-        const const_iterator e = entries_.end();
-        const_iterator i = b;
+        const iterator b = entries_.begin();
+        const iterator e = entries_.end();
+        iterator i = b;
         for (; i != e; ++i) {
             us2Data(buf+o, i->tag(), byteOrder);
             us2Data(buf+o+2, i->type(), byteOrder);
             ul2Data(buf+o+4, i->count(), byteOrder);
             if (i->size() > 4) {
-                // Calculate offset, data immediately follows the IFD
-                ul2Data(buf+o+8, offset + size() + dataSize, byteOrder);
+                // Set the offset of the entry, data immediately follows the IFD
+                i->setOffset(size() + dataSize);
+                ul2Data(buf+o+8, offset_ + i->offset(), byteOrder);
                 dataSize += i->size();
             }
             else {

src/ifd.hpp

@@ -21,7 +21,7 @@
 /*!
   @file    ifd.hpp
   @brief   Encoding and decoding of IFD (Image File Directory) data
-  @version $Name:  $ $Revision: 1.4 $
+  @version $Name:  $ $Revision: 1.5 $
   @author  Andreas Huggel (ahu)
            <a href="mailto:ahuggel@gmx.net">ahuggel@gmx.net</a>
   @date    09-Jan-04, ahu: created
@@ -137,7 +137,7 @@ namespace Exif {
                  bytes unless it is 0.
          */
         long size() const { return size_; }
-        //! Return the offset from the start of the IFD
+        //! Return the offset from the start of the IFD to the data of the entry
         uint32 offset() const { return offset_; }
         /*!
           @brief Return a pointer to the data area. Do not attempt to write
@@ -288,8 +288,8 @@ namespace Exif {
             Ifd& dest, const char* buf, ByteOrder byteOrder, uint16 tag
         ) const;
         /*!
-          @brief Copy the IFD to a data array, return the number of bytes
-                 written. 
+          @brief Copy the IFD to a data array, update the offsets of the IFD and
+                 all its entries, return the number of bytes written.
 
                  First the number of IFD entries is written (2 bytes), followed
                  by all directory entries: tag (2), type (2), number of data
@@ -312,12 +312,12 @@ namespace Exif {
                  original position, i.e., the offset of the IFD will be used.
           @return Returns the number of characters written.
          */
-        long copy(char* buf, ByteOrder byteOrder, long offset =0) const;
+        long copy(char* buf, ByteOrder byteOrder, long offset =0);
         //! @name Accessors
         //@{
         //! Ifd id of the IFD
         IfdId ifdId() const { return ifdId_; }
-        //! Offset of the IFD from SOI
+        //! Offset of the IFD from the start of the TIFF header
         long offset() const { return offset_; }
         //! Get the offset to the next IFD from the start of the TIFF header
         long next() const { return next_; }