[gthumb] [exiv2_tools] generate the thumbnail from the embedded data

[Paolo Bacchilega <paobac src gnome org>]

commit 75bc91f879bc78dd4afdfe5c836fb4a6abaf0a11
Author: Paolo Bacchilega <paobac src gnome org>
Date:   Fri Mar 26 16:30:24 2010 +0100

    [exiv2_tools] generate the thumbnail from the embedded data
    
    implemented a "generate-thumbnail" hook that read the thumbnail
    from the exif metadata to speed-up the thumbnail generation process
    for jpeg and tiff images with embedded thumbnails.

 extensions/exiv2_tools/exiv2-utils.cpp |   64 ++++++++++++++++++++++++++++++++
 extensions/exiv2_tools/exiv2-utils.h   |   35 +++++++++--------
 extensions/exiv2_tools/main.c          |    1 +
 3 files changed, 84 insertions(+), 16 deletions(-)
---
diff --git a/extensions/exiv2_tools/exiv2-utils.cpp b/extensions/exiv2_tools/exiv2-utils.cpp
index 74df98a..858d851 100644
--- a/extensions/exiv2_tools/exiv2-utils.cpp
+++ b/extensions/exiv2_tools/exiv2-utils.cpp
@@ -22,6 +22,8 @@
 
 #include <config.h>
 #include <glib.h>
+#define GDK_PIXBUF_ENABLE_BACKEND
+#include <gdk-pixbuf/gdk-pixbuf-io.h>
 #include <exiv2/basicio.hpp>
 #include <exiv2/error.hpp>
 #include <exiv2/image.hpp>
@@ -825,3 +827,65 @@ exiv2_write_metadata_to_buffer (void      **buffer,
 
 	return TRUE;
 }
+
+
+GdkPixbuf *
+exiv2_generate_thumbnail (const char *uri,
+			  const char *mime_type,
+			  int         size)
+{
+	GdkPixbuf *pixbuf = NULL;
+
+	if (! _g_content_type_is_a (mime_type, "image/jpeg")
+	    && ! _g_content_type_is_a (mime_type, "image/tiff"))
+	{
+		return NULL;
+	}
+
+	try {
+		char *path;
+
+		path = g_filename_from_uri (uri, NULL, NULL);
+		if (path != NULL) {
+			Exiv2::Image::AutoPtr image = Exiv2::ImageFactory::open (path);
+			image->readMetadata ();
+			Exiv2::ExifThumbC exifThumb (image->exifData ());
+			Exiv2::DataBuf thumb = exifThumb.copy ();
+
+			if (thumb.pData_ != NULL) {
+				GInputStream *stream = g_memory_input_stream_new_from_data (thumb.pData_, thumb.size_, NULL);
+				pixbuf = gdk_pixbuf_new_from_stream (stream, NULL, NULL);
+
+				Exiv2::ExifData &ed = image->exifData();
+				long w = ed["Exif.Photo.PixelXDimension"].toLong();
+				if (w > 0) {
+					char *s;
+
+					s = g_strdup_printf ("%ld", w);
+					gdk_pixbuf_set_option (pixbuf, "tEXt::Thumb::Image::Width", s);
+					g_object_set_data (G_OBJECT (pixbuf), "gnome-original-width", GINT_TO_POINTER ((int) w));
+
+					g_free (s);
+				}
+				long h = ed["Exif.Photo.PixelYDimension"].toLong();
+				if (h > 0) {
+					char *s;
+
+					s = g_strdup_printf ("%ld", w);
+					gdk_pixbuf_set_option (pixbuf, "tEXt::Thumb::Image::Height", s);
+					g_object_set_data (G_OBJECT (pixbuf), "gnome-original-height", GINT_TO_POINTER ((int) h));
+
+					g_free (s);
+				}
+
+				g_object_unref (stream);
+			}
+
+			g_free (path);
+		}
+	}
+	catch (Exiv2::AnyError& e) {
+	}
+
+	return pixbuf;
+}
diff --git a/extensions/exiv2_tools/exiv2-utils.h b/extensions/exiv2_tools/exiv2-utils.h
index 083e739..29771de 100644
--- a/extensions/exiv2_tools/exiv2-utils.h
+++ b/extensions/exiv2_tools/exiv2-utils.h
@@ -29,22 +29,25 @@
 
 G_BEGIN_DECLS
 
-gboolean  exiv2_read_metadata_from_file    (GFile           *file,
-					    GFileInfo       *info,
-					    GError         **error);
-gboolean  exiv2_read_metadata_from_buffer  (void            *buffer,
-					    gsize            buffer_size,
-					    GFileInfo       *info,
-					    GError         **error);
-gboolean  exiv2_read_sidecar               (GFile           *file,
-					    GFileInfo       *info);
-gboolean  exiv2_write_metadata  	   (SavePixbufData  *data);
-gboolean  exiv2_write_metadata_to_buffer   (void           **buffer,
-					    gsize           *buffer_size,
-					    GFileInfo       *info,
-					    GdkPixbuf       *pixbuf, /* optional */
-					    GError         **error);
-gboolean  exiv2_supports_writes            (const char      *mime_type);
+gboolean   exiv2_read_metadata_from_file    (GFile           *file,
+					     GFileInfo       *info,
+					     GError         **error);
+gboolean   exiv2_read_metadata_from_buffer  (void            *buffer,
+					     gsize            buffer_size,
+					     GFileInfo       *info,
+					     GError         **error);
+gboolean   exiv2_read_sidecar               (GFile           *file,
+					     GFileInfo       *info);
+gboolean   exiv2_supports_writes            (const char      *mime_type);
+gboolean   exiv2_write_metadata  	    (SavePixbufData  *data);
+gboolean   exiv2_write_metadata_to_buffer   (void           **buffer,
+					     gsize           *buffer_size,
+					     GFileInfo       *info,
+					     GdkPixbuf       *pixbuf, /* optional */
+					     GError         **error);
+GdkPixbuf *exiv2_generate_thumbnail         (const char      *uri,
+					     const char      *mime_type,
+					     int              size);
 
 G_END_DECLS
 
diff --git a/extensions/exiv2_tools/main.c b/extensions/exiv2_tools/main.c
index a9c55b9..00fd67a 100644
--- a/extensions/exiv2_tools/main.c
+++ b/extensions/exiv2_tools/main.c
@@ -230,6 +230,7 @@ gthumb_extension_activate (void)
 	gth_hook_add_callback ("save-pixbuf", 10, G_CALLBACK (exiv2_write_metadata), NULL);
 	if (gth_hook_present ("jpegtran-after"))
 		gth_hook_add_callback ("jpegtran-after", 10, G_CALLBACK (exiv2_jpeg_tran_cb), NULL);
+	gth_hook_add_callback ("generate-thumbnail", 10, G_CALLBACK (exiv2_generate_thumbnail), NULL);
 
 	for (i = 0; i < G_N_ELEMENTS (exiv2_sort_types); i++)
 		gth_main_register_sort_type (&exiv2_sort_types[i]);