Document the Microsoft XP tags as being in UTF-16LE

diff --git a/libexif/exif-tag.c b/libexif/exif-tag.c
index 61a3e96..d649032 100644 (file)
--- a/libexif/exif-tag.c
+++ b/libexif/exif-tag.c
@@ -615,15 +615,30 @@ static const struct {
         N_("A tag used to record fractions of seconds for the "
            "<DateTimeDigitized> tag."),
         { ESL_NNNN, ESL_NNNN, ESL_OOOO, ESL_NNNN, ESL_NNNN } },
-       {EXIF_TAG_XP_TITLE, "XPTitle", N_("XP Title"), "",
+       /* Not in EXIF 2.2 (Microsoft extension) */
+       {EXIF_TAG_XP_TITLE, "XPTitle", N_("XP Title"),
+        N_("A character string giving the title of the image, encoded in "
+           "UTF-16LE."),
         { ESL_OOOO, ESL_NNNN, ESL_NNNN, ESL_NNNN, ESL_NNNN } },
-       {EXIF_TAG_XP_COMMENT, "XPComment", N_("XP Comment"), "",
+       /* Not in EXIF 2.2 (Microsoft extension) */
+       {EXIF_TAG_XP_COMMENT, "XPComment", N_("XP Comment"), 
+        N_("A character string containing a comment about the image, encoded "
+           "in UTF-16LE."),
         { ESL_OOOO, ESL_NNNN, ESL_NNNN, ESL_NNNN, ESL_NNNN } },
-       {EXIF_TAG_XP_AUTHOR, "XPAuthor", N_("XP Author"), "",
+       /* Not in EXIF 2.2 (Microsoft extension) */
+       {EXIF_TAG_XP_AUTHOR, "XPAuthor", N_("XP Author"), 
+        N_("A character string containing the name of the image creator, "
+           "encoded in UTF-16LE."),
         { ESL_OOOO, ESL_NNNN, ESL_NNNN, ESL_NNNN, ESL_NNNN } },
-       {EXIF_TAG_XP_KEYWORDS, "XPKeywords", N_("XP Keywords"), "",
+       /* Not in EXIF 2.2 (Microsoft extension) */
+       {EXIF_TAG_XP_KEYWORDS, "XPKeywords", N_("XP Keywords"), 
+        N_("A character string containing key words describing the image, "
+           "encoded in UTF-16LE."),
         { ESL_OOOO, ESL_NNNN, ESL_NNNN, ESL_NNNN, ESL_NNNN } },
-       {EXIF_TAG_XP_SUBJECT, "XPSubject", N_("XP Subject"), "",
+       /* Not in EXIF 2.2 (Microsoft extension) */
+       {EXIF_TAG_XP_SUBJECT, "XPSubject", N_("XP Subject"), 
+        N_("A character string giving the image subject, encoded in "
+           "UTF-16LE."),
         { ESL_OOOO, ESL_NNNN, ESL_NNNN, ESL_NNNN, ESL_NNNN } },
        {EXIF_TAG_FLASH_PIX_VERSION, "FlashPixVersion", "FlashPixVersion",
         N_("The FlashPix format version supported by a FPXR file."),
@@ -833,6 +848,7 @@ static const struct {
        /* Not in EXIF 2.2 */
        {EXIF_TAG_GAMMA, "Gamma", N_("Gamma"),
         N_("Indicates the value of coefficient gamma.")},
+       /* Not in EXIF 2.2 */
        {EXIF_TAG_PRINT_IMAGE_MATCHING, "PrintImageMatching", N_("PRINT Image Matching"),
         N_("Related to Epson's PRINT Image Matching technology")},
 #endif
@@ -1033,6 +1049,7 @@ get_support_level_any_type (ExifTag tag, ExifIfd ifd)
                         * data types and isn't marked not recorded.
                         */
                        const ExifSupportLevel supp = ExifTagTable[i].esl[ifd][0];
+                       /* If level is not recorded, keep searching for another */
                        if (supp != EXIF_SUPPORT_LEVEL_NOT_RECORDED) {
                                unsigned int dt;
                                for (dt = 0; dt < EXIF_DATA_TYPE_COUNT; ++dt) {

diff --git a/libexif/exif-utils.c b/libexif/exif-utils.c
index a6e7696..b63290b 100644 (file)
--- a/libexif/exif-utils.c
+++ b/libexif/exif-utils.c
@@ -213,10 +213,12 @@ exif_set_srational (unsigned char *buf, ExifByteOrder order,
        exif_set_slong (buf + 4, order, value.denominator);
 }
 
+/*! This function converts rather UCS-2LE than UTF-16 to UTF-8.
+ * It should really be replaced by iconv().
+ */
 void
 exif_convert_utf16_to_utf8 (char *out, const unsigned short *in, int maxlen)
 {
-       /* This function converts rather UCS2 than UTF16 to UTF8 */
        if (maxlen <= 0) {
                return;
        }

diff --git a/libexif/exif.h b/libexif/exif.h
index c4b98ce..e577183 100644 (file)
--- a/libexif/exif.h
+++ b/libexif/exif.h
@@ -17,6 +17,17 @@
  * libexif installation. If you are using libtool to build your
  * package, you can also integrate make use of libexif-uninstalled.pc.
  *
+ * An application using libexif would typically first create an #ExifLoader to
+ * load EXIF data into memory. From there, it would extract that data as
+ * an #ExifData to start manipulating it. Each IFD is represented by its own
+ * #ExifContent within that #ExifData, which contains all the tag data in
+ * #ExifEntry form.  If the MakerNote data is required, an #ExifMnoteData
+ * can be extracted from the #ExifData and manipulated with the MakerNote
+ * functions.
+ *
+ * libexif is written in C using an object-based style that defines
+ * sets of functions that operate on each data structure.
+ *
  * \section data_structures Primary Data Structures
  *
  * #ExifLoader
@@ -43,7 +54,11 @@
  * Strings of 8 bit characters ("char*"). When libexif is compiled with
  * NLS, character set and encoding are as set in the current locale,
  * except for strings that come directly from the data in EXIF
- * tags which are generally returned in raw form.
+ * tags which are generally returned in raw form.  Most EXIF strings are
+ * defined to be plain 7-bit ASCII so this raw form should be acceptable in
+ * any UNIX locale, but some software ignores the specification and
+ * writes 8-bit characters.  It is up to the application to detect this
+ * and deal with it intelligently.
  *
  * \section memory_management Memory Management Patterns
  *