Change EXIF metadata handling into a registered function

This allows much greater flexibility from templates regarding
EXIF metadata handling, no more hardcoded symbols. It's possible
to display essentially any attribute known to Exiv2. Please see
http://exiv2.org/metadata.html

This brings two new functions that can be called from templates:
 * get_exif_value (exiv2_attribute)
 * get_exif_value_fixed (exiv2_attribute)

Both functions take a string argument of metadata attribute name
from Exiv2 namespace. The difference is that get_exif_value_fixed()
does some extra formatting for several basic attributes
(e.g. datetime format).

1 files changed, 28 insertions, 30 deletions

diff --git a/src/jpeg-utils.h b/src/jpeg-utils.h
index a682fd1..05a6a49 100644
--- a/src/jpeg-utils.h
+++ b/src/jpeg-utils.h
@@ -26,43 +26,41 @@ G_BEGIN_DECLS
 
 #define SQUARED_SIMPLE_SHAVE_AMOUNT 5  /* percent */
 
-
-/*  TODO: we want to have numerical values here at some point in the future  */
-typedef struct {
-  gchar *datetime;
-  gchar *camera_model;
-  gchar *iso;
-  gchar *focal_length;
-  gchar *focal_length_35mm;
-  gchar *aperture;
-  gchar *exposure;
-  gchar *flash;
-
-  gchar *exif_software;
-  gchar *exif_imgdesc;
-  gchar *exif_artist;
-  gchar *exif_copyright;
-  gchar *exif_usercomment;
-
-  gchar *iptc_objectname;
-  gchar *iptc_copyright;
-  gchar *iptc_credit;
-  gchar *iptc_caption;
-  gchar *iptc_author;
-
-  gchar *jpeg_comment;
-} TExifData;
+/*  EXIF data known keys  */
+#define EXIF_APERTURE           "Exif.Photo.FNumber"
+#define EXIF_CAMERA_MODEL       "Exif.Image.Model"
+#define EXIF_DATETIME           "Exif.Photo.DateTimeOriginal"
+#define EXIF_EXPOSURE           "Exif.Photo.ExposureTime"
+#define EXIF_FLASH              "Exif.Photo.Flash"
+#define EXIF_FOCAL_LENGTH       "Exif.Photo.FocalLength"
+#define EXIF_ISO                "Exif.Photo.ISOSpeedRatings"
+#define EXIF_IMAGE_DESCRIPTION  "Exif.Image.ImageDescription"
+#define EXIF_ARTIST             "Exif.Image.Artist"
+#define EXIF_COPYRIGHT          "Exif.Image.Copyright"
+#define EXIF_COMMENT            "Exif.Photo.UserComment"
+#define IPTC_COPYRIGHT          "Iptc.Application2.Copyright"
+#define IPTC_CAPTION            "Iptc.Application2.Caption"
+#define IPTC_AUTHOR             "Iptc.Application2.Byline"
+#define JPEG_COMMENT            "Jpeg.Comment"
+
+
+typedef struct ExifData ExifData;
 
 
 /*
- *   get_exif: retrieve EXIF info from a JPEG image
+ *   EXIF and IPTC info retrieval, keeps the source file open until freed
  */
-TExifData * get_exif (const gchar *filename);
+ExifData * read_exif (const gchar *filename);
+void exif_data_free (ExifData *data);
 
 /*
- *   free_exif_struct: free allocated structure
+ *   Retrieves the value of the specified key or NULL if the key does not exist.
+ *   The key argument belongs to Exiv2 namespace - see http://exiv2.org/tags.html
+ *
+ *   The get_exif_data_fixed() function does some pretty printing for selected keys.
  */
-void free_exif_data (TExifData *data);
+gchar * get_exif_data (ExifData *exif, const gchar *key);
+gchar * get_exif_data_fixed (ExifData *exif, const gchar *key);
 
 
 /*