1 files changed, 236 insertions, 0 deletions

diff --git a/src/plugins/thumbnailgtk_extractor.c b/src/plugins/thumbnailgtk_extractor.c
new file mode 100644
index 0000000..63ac359
--- /dev/null
+++ b/src/plugins/thumbnailgtk_extractor.c
@@ -0,0 +1,236 @@
+/*
+     This file is part of libextractor.
+     (C) 2005, 2009, 2012 Vidyut Samanta and Christian Grothoff
+
+     libextractor is free software; you can redistribute it and/or modify
+     it under the terms of the GNU General Public License as published
+     by the Free Software Foundation; either version 3, or (at your
+     option) any later version.
+
+     libextractor is distributed in the hope that it will be useful, but
+     WITHOUT ANY WARRANTY; without even the implied warranty of
+     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+     General Public License for more details.
+
+     You should have received a copy of the GNU General Public License
+     along with libextractor; see the file COPYING.  If not, write to the
+     Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+     Boston, MA 02111-1307, USA.
+ */
+/**
+ * @file plugins/thumbnailgtk_extractor.c
+ * @author Christian Grothoff
+ * @brief this extractor produces a binary (!) encoded
+ * thumbnail of images (using gdk pixbuf).  The bottom
+ * of the file includes a decoder method that can be used
+ * to reproduce the 128x128 PNG thumbnails.  We use
+ * libmagic to test if the input data is actually an
+ * image before trying to give it to gtk.
+ */
+#include "platform.h"
+#include "extractor.h"
+#include <magic.h>
+#include <glib.h>
+#include <gdk-pixbuf/gdk-pixbuf.h>
+
+/**
+ * Target size for the thumbnails (width and height).
+ */
+#define THUMBSIZE 128
+
+/**
+ * Maximum image size supported (to avoid unreasonable
+ * allocations)
+ */
+#define MAX_IMAGE_SIZE (32 * 1024 * 1024)
+
+
+/**
+ * Global handle to MAGIC data.
+ */
+static magic_t magic;
+
+
+/**
+ * Main method for the thumbnailer plugin.
+ *
+ * @param ec extraction context
+ */
+void
+EXTRACTOR_thumbnailgtk_extract_method (struct EXTRACTOR_ExtractContext *ec)
+{
+  GdkPixbufLoader *loader;
+  GdkPixbuf *in;
+  GdkPixbuf *out;
+  size_t length;
+  char *thumb;
+  unsigned long width;
+  unsigned long height;
+  char format[64];
+  void *data;
+  uint64_t size;
+  size_t off;
+  ssize_t iret;
+  void *buf;
+  const char *mime;
+
+  iret = ec->read (ec->cls,
+                   &data,
+                   16 * 1024);
+  if (-1 == iret)
+    return;
+  if (NULL == (mime = magic_buffer (magic, data, iret)))
+    return;
+  if (0 != strncmp (mime,
+                    "image/",
+                    strlen ("image/")))
+    return; /* not an image */
+
+  /* read entire image into memory */
+  size = ec->get_size (ec->cls);
+  if (UINT64_MAX == size)
+    size = MAX_IMAGE_SIZE; /* unknown size, cap at max */
+  if (size > MAX_IMAGE_SIZE)
+    return; /* FAR too big to be an image */
+  if (NULL == (buf = malloc (size)))
+    return; /* too big to fit into memory on this system */
+
+  /* start with data already read */
+  memcpy (buf, data, iret);
+  off = iret;
+  while (off < size)
+    {
+      iret = ec->read (ec->cls, &data, size - off);
+      if (iret <= 0)
+        {
+          /* io error */
+          free (buf);
+          return;
+        }
+      memcpy (buf + off, data, iret);
+      off += iret;
+    }
+
+  loader = gdk_pixbuf_loader_new ();
+  gdk_pixbuf_loader_write (loader, 
+                           buf, 
+                           size, NULL);
+  free (buf);
+  in = gdk_pixbuf_loader_get_pixbuf (loader);
+  gdk_pixbuf_loader_close (loader, NULL);
+  if (NULL == in)
+    {
+      g_object_unref (loader);
+      return;
+    }
+  g_object_ref (in);
+  g_object_unref (loader);
+  height = gdk_pixbuf_get_height (in);
+  width = gdk_pixbuf_get_width (in);
+  snprintf (format, 
+            sizeof (format),
+            "%ux%u",
+            (unsigned int) width, 
+            (unsigned int) height);
+  if (0 != ec->proc (ec->cls,
+                     "thumbnailgtk",
+                     EXTRACTOR_METATYPE_IMAGE_DIMENSIONS,
+                     EXTRACTOR_METAFORMAT_UTF8,
+                     "text/plain",
+                     format,
+                     strlen (format) + 1))
+    {
+      g_object_unref (in);
+      return;
+    }
+  if ((height <= THUMBSIZE) && (width <= THUMBSIZE))
+    {
+      g_object_unref (in);
+      return;
+    }
+  if (height > THUMBSIZE)
+    {
+      width = width * THUMBSIZE / height;
+      height = THUMBSIZE;
+    }
+  if (width > THUMBSIZE)
+    {
+      height = height * THUMBSIZE / width;
+      width = THUMBSIZE;
+    }
+  if ( (0 == height) || (0 == width) )
+    {
+      g_object_unref (in);
+      return;
+    }
+  out = gdk_pixbuf_scale_simple (in, width, height,
+                                 GDK_INTERP_BILINEAR);
+  g_object_unref (in);
+  thumb = NULL;
+  length = 0;
+  if (NULL == out)
+    return;
+  if (! gdk_pixbuf_save_to_buffer (out, &thumb, 
+                                   &length, 
+                                   "png", NULL, 
+                                   "compression", "9", 
+                                   NULL))
+    {
+      g_object_unref (out);
+      return;
+    }
+  g_object_unref (out);
+  if (NULL == thumb)
+    return;
+  ec->proc (ec->cls,
+            "thumbnailgtk",
+            EXTRACTOR_METATYPE_THUMBNAIL,
+            EXTRACTOR_METAFORMAT_BINARY,
+            "image/png",
+            thumb, length);  
+  free (thumb);
+}
+
+
+/**
+ * This plugin sometimes is installed under the alias 'thumbnail'.
+ * So we need to provide a second entry method.
+ *
+ * @param ec extraction context
+ */
+void
+EXTRACTOR_thumbnail_extract_method (struct EXTRACTOR_ExtractContext *ec)
+{
+  EXTRACTOR_thumbnailgtk_extract_method (ec);
+}
+
+
+/**
+ * Initialize glib and load magic file.
+ */
+void __attribute__ ((constructor)) 
+ole_gobject_init ()
+{
+  g_type_init ();
+  magic = magic_open (MAGIC_MIME_TYPE);
+  if (0 != magic_load (magic, NULL))
+    {
+      /* FIXME: how to deal with errors? */
+    }
+}
+
+
+/**
+ * Destructor for the library, cleans up.
+ */
+void __attribute__ ((destructor)) 
+mime_ltdl_fini () 
+{
+  if (NULL != magic)
+    {
+      magic_close (magic);
+      magic = NULL;
+    }
+}
+
+/* end of thumbnailgtk_extractor.c */