thumbnailextractor.c File Reference

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. More...

#include "platform.h"
#include "extractor.h"
#include <gdk-pixbuf/gdk-pixbuf.h>

Go to the source code of this file.

Defines
#define	THUMBSIZE   128
Functions
void	__attribute__ ((constructor))
static EXTRACTOR_KeywordList *	addKeyword (EXTRACTOR_KeywordType type, char *keyword, EXTRACTOR_KeywordList *next)
EXTRACTOR_Keywords *	libextractor_thumbnailgtk_extract (const char *filename, const unsigned char *data, size_t size, struct EXTRACTOR_Keywords *prev)
EXTRACTOR_Keywords *	libextractor_thumbnail_extract (const char *filename, const unsigned char *data, size_t size, struct EXTRACTOR_Keywords *prev, const char *options)
Variables
static char *	whitelist []

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Detailed Description

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.

Author:

Christian Grothoff

Definition in file thumbnailextractor.c.

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Define Documentation

#define THUMBSIZE   128

Definition at line 34 of file thumbnailextractor.c.

Referenced by libextractor_thumbnailgtk_extract().

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Function Documentation

void __attribute__

(

(constructor)

)

Definition at line 38 of file thumbnailextractor.c.

{
  g_type_init ();
}

static EXTRACTOR_KeywordList* addKeyword	(	EXTRACTOR_KeywordType	type,
		char *	keyword,
		EXTRACTOR_KeywordList *	next
	)			[static]

Definition at line 45 of file thumbnailextractor.c.

References EXTRACTOR_Keywords::keyword, EXTRACTOR_Keywords::keywordType, malloc, EXTRACTOR_Keywords::next, and NULL.

{
  EXTRACTOR_KeywordList *result;

  if (keyword == NULL)
    return next;
  result = malloc (sizeof (EXTRACTOR_KeywordList));
  result->next = next;
  result->keyword = keyword;
  result->keywordType = type;
  return result;
}

struct EXTRACTOR_Keywords* libextractor_thumbnail_extract	(	const char *	filename,
		const unsigned char *	data,
		size_t	size,
		struct EXTRACTOR_Keywords *	prev,
		const char *	options
	)

Definition at line 169 of file thumbnailextractor.c.

References libextractor_thumbnailgtk_extract().

{
  return libextractor_thumbnailgtk_extract (filename, data, size, prev);
}

struct EXTRACTOR_Keywords* libextractor_thumbnailgtk_extract	(	const char *	filename,
		const unsigned char *	data,
		size_t	size,
		struct EXTRACTOR_Keywords *	prev
	)

Definition at line 81 of file thumbnailextractor.c.

References addKeyword(), EXTRACTOR_binaryEncode(), EXTRACTOR_extractLast(), EXTRACTOR_MIMETYPE, EXTRACTOR_SIZE, EXTRACTOR_THUMBNAIL_DATA, free, height, malloc, NULL, THUMBSIZE, and width.

Referenced by libextractor_thumbnail_extract().

{
  GdkPixbufLoader *loader;
  GdkPixbuf *in;
  GdkPixbuf *out;
  size_t length;
  char *thumb;
  unsigned long width;
  unsigned long height;
  char *binary;
  const char *mime;
  int j;
  char *format;

  /* if the mime-type of the file is not whitelisted
     do not run the thumbnail extactor! */
  mime = EXTRACTOR_extractLast (EXTRACTOR_MIMETYPE, prev);
  if (mime == NULL)
    return prev;
  j = 0;
  while (whitelist[j] != NULL)
    {
      if (0 == strcmp (whitelist[j], mime))
        break;
      j++;
    }
  if (whitelist[j] == NULL)
    return prev;

  loader = gdk_pixbuf_loader_new ();
  gdk_pixbuf_loader_write (loader, data, size, NULL);
  in = gdk_pixbuf_loader_get_pixbuf (loader);
  gdk_pixbuf_loader_close (loader, NULL);
  if (in == NULL)
    {
      g_object_unref (loader);
      return prev;
    }
  g_object_ref (in);
  g_object_unref (loader);
  height = gdk_pixbuf_get_height (in);
  width = gdk_pixbuf_get_width (in);
  format = malloc (64);
  snprintf (format, 64, "%ux%u", (unsigned int) width, (unsigned int) height);
  prev = addKeyword (EXTRACTOR_SIZE, format, prev);
  if (height == 0)
    height = 1;
  if (width == 0)
    width = 1;
  if ((height <= THUMBSIZE) && (width <= THUMBSIZE))
    {
      g_object_unref (in);
      return prev;
    }
  if (height > THUMBSIZE)
    {
      width = width * THUMBSIZE / height;
      height = THUMBSIZE;
    }
  if (width > THUMBSIZE)
    {
      height = height * THUMBSIZE / width;
      width = THUMBSIZE;
    }
  out = gdk_pixbuf_scale_simple (in, width, height, GDK_INTERP_BILINEAR);
  g_object_unref (in);
  thumb = NULL;
  if (!gdk_pixbuf_save_to_buffer (out, &thumb, &length, "png", NULL, 
                                  "compression", 9, NULL))
    {
      g_object_unref (out);
      return prev;
    }
  g_object_unref (out);
  if (thumb == NULL)
    return prev;

  binary = EXTRACTOR_binaryEncode ((const unsigned char *) thumb, length);
  free (thumb);
  if (binary == NULL)
    return prev;
  return addKeyword (EXTRACTOR_THUMBNAIL_DATA, binary, prev);
}

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Variable Documentation

char* whitelist[] [static]

Initial value:

 {
  "image/jpeg",
  "image/gif",
  "image/miff",
  "image/mng",
  "image/png",
  "image/tiff",
  "image/x-bmp",
  "image/x-mng",
  "image/x-png",
  "image/x-xpm",
  "image/xcf",
  NULL,
}

Definition at line 65 of file thumbnailextractor.c.

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