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, 145 insertions, 175 deletions

diff --git a/src/jpeg-utils.cpp b/src/jpeg-utils.cpp
index 34d3997..031ecc0 100644
--- a/src/jpeg-utils.cpp
+++ b/src/jpeg-utils.cpp
@@ -30,204 +30,174 @@
 #include "gallery-utils.h"
 
 
+struct ExifData {
+  Exiv2::Image::AutoPtr image;
+};
+
 
 /*
- *   get_exif: retrieve EXIF informations 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)
 {
-  TExifData *data;
+  ExifData *data;
 
-  data = (TExifData*) g_malloc0 (sizeof (TExifData));
+  data = (ExifData*) g_malloc0 (sizeof (ExifData));
 
-  try
-  {
-     Exiv2::Image::AutoPtr image = Exiv2::ImageFactory::open (filename);
-     g_assert (image.get() != 0);
-     image->readMetadata();
-
-     Exiv2::ExifData &exifData = image->exifData();
-     if (! exifData.empty())  {
-       /*  EXIF::Aperture  */
-       try {
-         float val = exifData["Exif.Photo.FNumber"].toFloat();
-         if (val >= 0)
-           data->aperture = g_strdup_printf ("f/%.1f", val);
-       } catch (...) { }
-
-       /*  EXIF::Camera model  */
-       try {
-         data->camera_model = g_strdup (exifData["Exif.Image.Model"].toString().c_str());
-       } catch (...) { }
-
-       /*  EXIF::DateTime  */
-       try {
-         const char *val = NULL;
-         try {
-           val = exifData["Exif.Photo.DateTimeOriginal"].toString().c_str();
-         } catch (...) { }
-         if (! val || strlen (val) == 0)
-           try {
-             val = exifData["Exif.Image.DateTime"].toString().c_str();
-           } catch (...) { }
-
-         if (val && strlen (val) > 0) {
-           struct tm tt;
-           char conv[1024];
-
-           memset (&conv, 0, sizeof (conv));
-           memset (&tt, 0, sizeof (struct tm));
-
-           if (sscanf (val, "%d:%d:%d %d:%d:%d", &tt.tm_year, &tt.tm_mon, &tt.tm_mday, &tt.tm_hour, &tt.tm_min, &tt.tm_sec) == 6)
-             {
-               tt.tm_year -= 1900;
-               tt.tm_mon--;
-               mktime (&tt);
-               if (strftime (&conv[0], sizeof (conv), "%c", &tt))
-                   data->datetime = g_strdup (&conv[0]);
-             }
-         }
-       } catch (...) { }
-
-       /*  EXIF::Shutter speed  */
-       try {
-         float val = exifData["Exif.Photo.ExposureTime"].toFloat();
-         if (val > 0) {
-           if (val < 0.5)
-             data->exposure = g_strdup_printf ("1/%.0f s", 1/val);
-           else
-             data->exposure = g_strdup_printf ("%.1f s", val);
-         }
-       } catch (...) { }
-
-       /*  EXIF::Flash  */
-       try {
-         long int val = exifData["Exif.Photo.Flash"].toLong();
-         if (val > 0 && (val & 1) == 1)
-           data->flash = g_strdup ("Flash fired");
-         else
-           data->flash = g_strdup ("--");
-       } catch (...) { }
-
-       /*  EXIF::Focal length  */
-       try {
-         float val = exifData["Exif.Photo.FocalLength"].toFloat();
-         if (val >= 0)
-           data->focal_length = g_strdup_printf ("%.0f mm", val);
-       } catch (...) { }
-
-       /*  EXIF::ISO  */
-       try {
-         long int val = exifData["Exif.Photo.ISOSpeedRatings"].toLong();
-         if (val > 0)
-           data->iso = g_strdup_printf ("%ld", val);
-       } catch (...) { }
-
-       /*  EXIF::Software  */
-       try {
-         data->exif_software = g_strdup (exifData["Exif.Image.Software"].toString().c_str());
-       } catch (...) { }
-
-       /*  EXIF::Image description  */
-       try {
-         data->exif_imgdesc = g_strdup (exifData["Exif.Image.ImageDescription"].toString().c_str());
-       } catch (...) { }
-
-       /*  EXIF::Artist  */
-       try {
-         data->exif_artist = g_strdup (exifData["Exif.Image.Artist"].toString().c_str());
-       } catch (...) { }
-
-       /*  EXIF::Copyright  */
-       try {
-         data->exif_copyright = g_strdup (exifData["Exif.Image.Copyright"].toString().c_str());
-       } catch (...) { }
-
-       /*  EXIF::User comment  */
-       try {
-         data->exif_usercomment = g_strdup (exifData["Exif.Photo.UserComment"].toString().c_str());
-       } catch (...) { }
-     }
-
-     Exiv2::IptcData &iptcData = image->iptcData();
-     if (! iptcData.empty()) {
-       /*  IPTC::Object name  */
-       try {
-         data->iptc_objectname = g_strdup (iptcData["Iptc.Application2.ObjectName"].toString().c_str());
-       } catch (...) { }
-
-       /*  IPTC::Copyright  */
-       try {
-         data->iptc_copyright = g_strdup (iptcData["Iptc.Application2.Copyright"].toString().c_str());
-       } catch (...) { }
-
-       /*  IPTC::Credit  */
-       try {
-         data->iptc_credit = g_strdup (iptcData["Iptc.Application2.Credit"].toString().c_str());
-       } catch (...) { }
-
-       /*  IPTC::Caption  */
-       try {
-         data->iptc_caption = g_strdup (iptcData["Iptc.Application2.Caption"].toString().c_str());
-       } catch (...) { }
-
-       /*  IPTC::Author  */
-       try {
-         data->iptc_author = g_strdup (iptcData["Iptc.Application2.Byline"].toString().c_str());
-       } catch (...) { }
-     }
-
-     /*  JPEG::Comment  */
-     try {
-       data->jpeg_comment = g_strdup (image->comment().c_str());
-     } catch (...) { }
+  try {
+    data->image = Exiv2::ImageFactory::open (filename);
+    g_assert (data->image.get() != 0);
+    data->image->readMetadata();
   }
   catch (Exiv2::AnyError& e)
   {
-    log_error ("get_exif: Caught Exiv2 exception: '%s'\n", e.what());
-    free_exif_data (data);
+    log_error ("read_exif: Caught Exiv2 exception: '%s'\n", e.what());
+    exif_data_free (data);
     return NULL;
   }
 
   return data;
 }
 
-/*
- *   free_exif_struct: free allocated structure
- */
 void
-free_exif_data (TExifData *data)
+exif_data_free (ExifData *data)
 {
   if (data) {
-    g_free (data->aperture);
-    g_free (data->camera_model);
-    g_free (data->datetime);
-    g_free (data->exposure);
-    g_free (data->flash);
-    g_free (data->focal_length);
-    g_free (data->focal_length_35mm);
-    g_free (data->iso);
-
-    g_free (data->exif_software);
-    g_free (data->exif_imgdesc);
-    g_free (data->exif_artist);
-    g_free (data->exif_copyright);
-    g_free (data->exif_usercomment);
-
-    g_free (data->iptc_objectname);
-    g_free (data->iptc_copyright);
-    g_free (data->iptc_credit);
-    g_free (data->iptc_caption);
-    g_free (data->iptc_author);
-
-    g_free (data->jpeg_comment);
-
+    /* FIXME: free data->image */
     g_free (data);
   }
 }
 
 
+/*
+ *   Retrieves 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
+ */
+gchar *
+get_exif_data (ExifData *exif, const gchar *key)
+{
+  try {
+    if (g_strcmp0 (key, JPEG_COMMENT) == 0) {
+      return g_strdup (exif->image->comment().c_str());
+    }
+
+    if (g_str_has_prefix (key, "Exif.")) {
+      Exiv2::ExifData &exifData = exif->image->exifData();
+      if (! exifData.empty()) {
+        return g_strdup (exifData[key].toString().c_str());
+      }
+    }
+
+    if (g_str_has_prefix (key, "Iptc.")) {
+      Exiv2::IptcData &iptcData = exif->image->iptcData();
+      if (! iptcData.empty()) {
+        return g_strdup (iptcData[key].toString().c_str());
+      }
+    }
+
+    return NULL;
+  }
+  catch (...) {
+    return NULL;
+  }
+}
+
+gchar *
+get_exif_data_fixed (ExifData *exif, const gchar *key)
+{
+  try
+  {
+    if (g_str_has_prefix (key, EXIF_APERTURE)) {
+      Exiv2::ExifData &exifData = exif->image->exifData();
+      if (! exifData.empty()) {
+        float val = exifData["Exif.Photo.FNumber"].toFloat();
+        if (val >= 0)
+          return g_strdup_printf ("f/%.1f", val);
+      }
+    }
+
+    if (g_str_has_prefix (key, EXIF_DATETIME)) {
+      Exiv2::ExifData &exifData = exif->image->exifData();
+      if (! exifData.empty()) {
+        const char *val = NULL;
+        try {
+          val = exifData["Exif.Photo.DateTimeOriginal"].toString().c_str();
+        } catch (...) { }
+        if (! val || strlen (val) == 0)
+          try {
+            val = exifData["Exif.Image.DateTime"].toString().c_str();
+          } catch (...) { }
+
+        if (val && strlen (val) > 0) {
+          struct tm tt;
+          char conv[1024];
+
+          memset (&conv, 0, sizeof (conv));
+          memset (&tt, 0, sizeof (struct tm));
+
+          if (sscanf (val, "%d:%d:%d %d:%d:%d", &tt.tm_year, &tt.tm_mon, &tt.tm_mday, &tt.tm_hour, &tt.tm_min, &tt.tm_sec) == 6)
+            {
+              tt.tm_year -= 1900;
+              tt.tm_mon--;
+              mktime (&tt);
+              if (strftime (&conv[0], sizeof (conv), "%c", &tt))
+                  return g_strdup (&conv[0]);
+            }
+        }
+      }
+    }
+
+    if (g_str_has_prefix (key, EXIF_EXPOSURE)) {
+      Exiv2::ExifData &exifData = exif->image->exifData();
+      if (! exifData.empty()) {
+        float val = exifData["Exif.Photo.ExposureTime"].toFloat();
+        if (val > 0) {
+          if (val < 0.5)
+            return g_strdup_printf ("1/%.0f s", 1/val);
+          else
+            return g_strdup_printf ("%.1f s", val);
+        }
+      }
+    }
+
+    if (g_str_has_prefix (key, EXIF_FLASH)) {
+      Exiv2::ExifData &exifData = exif->image->exifData();
+      if (! exifData.empty()) {
+        long int val = exifData["Exif.Photo.Flash"].toLong();
+        if (val > 0 && (val & 1) == 1)
+          return g_strdup ("Flash fired");
+        else
+          return g_strdup ("--");
+      }
+    }
+
+    if (g_str_has_prefix (key, EXIF_FOCAL_LENGTH)) {
+      Exiv2::ExifData &exifData = exif->image->exifData();
+      if (! exifData.empty()) {
+        float val = exifData["Exif.Photo.FocalLength"].toFloat();
+        if (val >= 0)
+          return g_strdup_printf ("%.0f mm", val);
+      }
+    }
+
+    if (g_str_has_prefix (key, EXIF_ISO)) {
+      Exiv2::ExifData &exifData = exif->image->exifData();
+      if (! exifData.empty()) {
+        long int val = exifData["Exif.Photo.ISOSpeedRatings"].toLong();
+        if (val > 0)
+          return g_strdup_printf ("%ld", val);
+      }
+    }
+  }
+  catch (...) {
+    return NULL;
+  }
+
+  return get_exif_data (exif, key);
+}
+
+
 static void
 autorotate_image (MagickWand *magick_wand)
 {