gtk2/gtk/gtkselection.c

/* GTK - The GIMP Toolkit
 * Copyright (C) 1995-1997 Peter Mattis, Spencer Kimball and Josh MacDonald
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library. If not, see <http://www.gnu.org/licenses/>.
 */

/* This file implements most of the work of the ICCCM selection protocol.
 * The code was written after an intensive study of the equivalent part
 * of John Ousterhout’s Tk toolkit, and does many things in much the 
 * same way.
 *
 * The one thing in the ICCCM that isn’t fully supported here (or in Tk)
 * is side effects targets. For these to be handled properly, MULTIPLE
 * targets need to be done in the order specified. This cannot be
 * guaranteed with the way we do things, since if we are doing INCR
 * transfers, the order will depend on the timing of the requestor.
 *
 * By Owen Taylor <owt1@cornell.edu>	      8/16/97
 */

/* Terminology note: when not otherwise specified, the term "incr" below
 * refers to the _sending_ part of the INCR protocol. The receiving
 * portion is referred to just as “retrieval”. (Terminology borrowed
 * from Tk, because there is no good opposite to “retrieval” in English.
 * “send” can’t be made into a noun gracefully and we’re already using
 * “emission” for something else ....)
 */

/* The MOTIF entry widget seems to ask for the TARGETS target, then
   (regardless of the reply) ask for the TEXT target. It's slightly
   possible though that it somehow thinks we are responding negatively
   to the TARGETS request, though I don't really think so ... */

/*
 * Modified by the GTK+ Team and others 1997-2000.  See the AUTHORS
 * file for a list of people on the GTK+ Team.  See the ChangeLog
 * files for a list of changes.  These files are distributed with
 * GTK+ at ftp://ftp.gtk.org/pub/gtk/. 
 */

/**
 * SECTION:gtkselection
 * @Title: Selections
 * @Short_description: Functions for handling inter-process communication
 *     via selections
 * @See_also: #GtkWidget - Much of the operation of selections happens via
 *     signals for #GtkWidget. In particular, if you are using the functions
 *     in this section, you may need to pay attention to
 *     #GtkWidget::selection-get, #GtkWidget::selection-received and
 *     #GtkWidget::selection-clear-event signals
 *
 * The selection mechanism provides the basis for different types
 * of communication between processes. In particular, drag and drop and
 * #GtkClipboard work via selections. You will very seldom or
 * never need to use most of the functions in this section directly;
 * #GtkClipboard provides a nicer interface to the same functionality.
 *
 * Some of the datatypes defined this section are used in
 * the #GtkClipboard and drag-and-drop API’s as well. The
 * #GdkContentFormats object represents
 * lists of data types that are supported when sending or
 * receiving data. The #GtkSelectionData object is used to
 * store a chunk of data along with the data type and other
 * associated information.
 */

#include "config.h"

#include "gtkselection.h"
#include "gtkselectionprivate.h"

#include <stdarg.h>
#include <string.h>
#include "gdk.h"

#include "gtkmain.h"
#include "gtkdebug.h"
#include "gtkintl.h"
#include "gdk-pixbuf/gdk-pixbuf.h"

#include "gdk/gdkcontentformatsprivate.h"
#include "gdk/gdktextureprivate.h"

#ifdef GDK_WINDOWING_X11
#include "x11/gdkx.h"
#endif

#ifdef GDK_WINDOWING_WIN32
#include "win32/gdkwin32.h"
#endif

#ifdef GDK_WINDOWING_WAYLAND
#include <gdk/wayland/gdkwayland.h>
#endif

/****************
 * Target Lists *
 ****************/

/*
 * Target lists
 */


static GdkAtom utf8_atom;
static GdkAtom text_atom;
static GdkAtom ctext_atom;
static GdkAtom text_plain_atom;
static GdkAtom text_plain_utf8_atom;
static GdkAtom text_plain_locale_atom;
static GdkAtom text_uri_list_atom;

static void 
init_atoms (void)
{
  gchar *tmp;
  const gchar *charset;

  if (!utf8_atom)
    {
      utf8_atom = g_intern_static_string ("UTF8_STRING");
      text_atom = g_intern_static_string ("TEXT");
      ctext_atom = g_intern_static_string ("COMPOUND_TEXT");
      text_plain_atom = g_intern_static_string ("text/plain");
      text_plain_utf8_atom = g_intern_static_string ("text/plain;charset=utf-8");
      g_get_charset (&charset);
      tmp = g_strdup_printf ("text/plain;charset=%s", charset);
      text_plain_locale_atom = g_intern_string (tmp);
      g_free (tmp);

      text_uri_list_atom = g_intern_static_string ("text/uri-list");
    }
}

/**
 * gtk_content_formats_add_text_targets:
 * @list: a #GdkContentFormats
 * 
 * Appends the text targets supported by #GtkSelectionData to
 * the target list. All targets are added with the same @info.
 **/
GdkContentFormats *
gtk_content_formats_add_text_targets (GdkContentFormats *list)
{
  GdkContentFormatsBuilder *builder;

  g_return_val_if_fail (list != NULL, NULL);
  
  init_atoms ();

  builder = gdk_content_formats_builder_new ();
  gdk_content_formats_builder_add_formats (builder, list);
  gdk_content_formats_unref (list);

  /* Keep in sync with gtk_selection_data_targets_include_text()
   */
  gdk_content_formats_builder_add_mime_type (builder, utf8_atom);  
  gdk_content_formats_builder_add_mime_type (builder, ctext_atom);  
  gdk_content_formats_builder_add_mime_type (builder, text_atom);  
  gdk_content_formats_builder_add_mime_type (builder, g_intern_static_string ("STRING"));  
  gdk_content_formats_builder_add_mime_type (builder, text_plain_utf8_atom);  
  if (!g_get_charset (NULL))
    gdk_content_formats_builder_add_mime_type (builder, text_plain_locale_atom);  
  gdk_content_formats_builder_add_mime_type (builder, text_plain_atom);  

  return gdk_content_formats_builder_free_to_formats (builder);
}

/**
 * gtk_content_formats_add_image_targets:
 * @list: a #GdkContentFormats
 * @writable: whether to add only targets for which GTK+ knows
 *   how to convert a pixbuf into the format
 * 
 * Appends the image targets supported by #GtkSelectionData to
 * the target list. All targets are added with the same @info.
 **/
GdkContentFormats *
gtk_content_formats_add_image_targets (GdkContentFormats *list,
		                       gboolean           writable)
{
  GdkContentFormatsBuilder *builder;
  GSList *formats, *f;
  gchar **mimes, **m;

  g_return_val_if_fail (list != NULL, NULL);

  builder = gdk_content_formats_builder_new ();
  gdk_content_formats_builder_add_formats (builder, list);
  gdk_content_formats_unref (list);

  formats = gdk_pixbuf_get_formats ();

  /* Make sure png comes first */
  for (f = formats; f; f = f->next)
    {
      GdkPixbufFormat *fmt = f->data;
      gchar *name; 
 
      name = gdk_pixbuf_format_get_name (fmt);
      if (strcmp (name, "png") == 0)
	{
	  formats = g_slist_delete_link (formats, f);
	  formats = g_slist_prepend (formats, fmt);

	  g_free (name);

	  break;
	}

      g_free (name);
    }  

  for (f = formats; f; f = f->next)
    {
      GdkPixbufFormat *fmt = f->data;

      if (writable && !gdk_pixbuf_format_is_writable (fmt))
	continue;
      
      mimes = gdk_pixbuf_format_get_mime_types (fmt);
      for (m = mimes; *m; m++)
	{
	  gdk_content_formats_builder_add_mime_type (builder, *m);  
	}
      g_strfreev (mimes);
    }

  g_slist_free (formats);

  return gdk_content_formats_builder_free_to_formats (builder);
}

/**
 * gtk_content_formats_add_uri_targets:
 * @list: a #GdkContentFormats
 * 
 * Appends the URI targets supported by #GtkSelectionData to
 * the target list. All targets are added with the same @info.
 **/
GdkContentFormats *
gtk_content_formats_add_uri_targets (GdkContentFormats *list)
{
  GdkContentFormatsBuilder *builder;

  g_return_val_if_fail (list != NULL, NULL);
  
  init_atoms ();

  builder = gdk_content_formats_builder_new ();
  gdk_content_formats_builder_add_formats (builder, list);
  gdk_content_formats_unref (list);

  gdk_content_formats_builder_add_mime_type (builder, text_uri_list_atom);  

  return gdk_content_formats_builder_free_to_formats (builder);
}

/**
 * gtk_selection_data_get_target:
 * @selection_data: a pointer to a #GtkSelectionData-struct.
 *
 * Retrieves the target of the selection.
 *
 * Returns: (transfer none): the target of the selection.
 **/
GdkAtom
gtk_selection_data_get_target (const GtkSelectionData *selection_data)
{
  g_return_val_if_fail (selection_data != NULL, 0);

  return selection_data->target;
}

/**
 * gtk_selection_data_get_data_type:
 * @selection_data: a pointer to a #GtkSelectionData-struct.
 *
 * Retrieves the data type of the selection.
 *
 * Returns: (transfer none): the data type of the selection.
 **/
GdkAtom
gtk_selection_data_get_data_type (const GtkSelectionData *selection_data)
{
  g_return_val_if_fail (selection_data != NULL, 0);

  return selection_data->type;
}

/**
 * gtk_selection_data_get_format:
 * @selection_data: a pointer to a #GtkSelectionData-struct.
 *
 * Retrieves the format of the selection.
 *
 * Returns: the format of the selection.
 **/
gint
gtk_selection_data_get_format (const GtkSelectionData *selection_data)
{
  g_return_val_if_fail (selection_data != NULL, 0);

  return selection_data->format;
}

/**
 * gtk_selection_data_get_data: (skip)
 * @selection_data: a pointer to a
 *   #GtkSelectionData-struct.
 *
 * Retrieves the raw data of the selection.
 *
 * Returns: (array) (element-type guint8): the raw data of the selection.
 **/
const guchar*
gtk_selection_data_get_data (const GtkSelectionData *selection_data)
{
  g_return_val_if_fail (selection_data != NULL, NULL);

  return selection_data->data;
}

/**
 * gtk_selection_data_get_length:
 * @selection_data: a pointer to a #GtkSelectionData-struct.
 *
 * Retrieves the length of the raw data of the selection.
 *
 * Returns: the length of the data of the selection.
 */
gint
gtk_selection_data_get_length (const GtkSelectionData *selection_data)
{
  g_return_val_if_fail (selection_data != NULL, -1);

  return selection_data->length;
}

/**
 * gtk_selection_data_get_data_with_length: (rename-to gtk_selection_data_get_data)
 * @selection_data: a pointer to a #GtkSelectionData-struct.
 * @length: (out): return location for length of the data segment
 *
 * Retrieves the raw data of the selection along with its length.
 *
 * Returns: (array length=length): the raw data of the selection
 */
const guchar*
gtk_selection_data_get_data_with_length (const GtkSelectionData *selection_data,
                                         gint                   *length)
{
  g_return_val_if_fail (selection_data != NULL, NULL);

  *length = selection_data->length;

  return selection_data->data;
}

/**
 * gtk_selection_data_get_display:
 * @selection_data: a pointer to a #GtkSelectionData-struct.
 *
 * Retrieves the display of the selection.
 *
 * Returns: (transfer none): the display of the selection.
 **/
GdkDisplay *
gtk_selection_data_get_display (const GtkSelectionData *selection_data)
{
  g_return_val_if_fail (selection_data != NULL, NULL);

  return selection_data->display;
}

/**
 * gtk_selection_data_set:
 * @selection_data: a pointer to a #GtkSelectionData-struct.
 * @type: the type of selection data
 * @format: format (number of bits in a unit)
 * @data: (array length=length): pointer to the data (will be copied)
 * @length: length of the data
 * 
 * Stores new data into a #GtkSelectionData object. Should
 * only be called from a selection handler callback.
 * Zero-terminates the stored data.
 **/
void 
gtk_selection_data_set (GtkSelectionData *selection_data,
			GdkAtom		  type,
			gint		  format,
			const guchar	 *data,
			gint		  length)
{
  g_return_if_fail (selection_data != NULL);

  g_free (selection_data->data);
  
  selection_data->type = type;
  selection_data->format = format;
  
  if (data)
    {
      selection_data->data = g_new (guchar, length+1);
      memcpy (selection_data->data, data, length);
      selection_data->data[length] = 0;
    }
  else
    {
      g_return_if_fail (length <= 0);
      
      if (length < 0)
	selection_data->data = NULL;
      else
	selection_data->data = (guchar *) g_strdup ("");
    }
  
  selection_data->length = length;
}

static gboolean
selection_set_string (GtkSelectionData *selection_data,
		      const gchar      *str,
		      gint              len)
{
  gchar *tmp = g_strndup (str, len);
  gchar *latin1 = gdk_utf8_to_string_target (tmp);
  g_free (tmp);
  
  if (latin1)
    {
      gtk_selection_data_set (selection_data,
			      g_intern_static_string ("STRING"),
			      8, (guchar *) latin1, strlen (latin1));
      g_free (latin1);
      
      return TRUE;
    }
  else
    return FALSE;
}

static gboolean
selection_set_compound_text (GtkSelectionData *selection_data,
			     const gchar      *str,
			     gint              len)
{
  gboolean result = FALSE;

#ifdef GDK_WINDOWING_X11
  gchar *tmp;
  guchar *text;
  GdkAtom encoding;
  gint format;
  gint new_length;

  if (GDK_IS_X11_DISPLAY (selection_data->display))
    {
      tmp = g_strndup (str, len);
      if (gdk_x11_display_utf8_to_compound_text (selection_data->display, tmp,
                                                 &encoding, &format, &text, &new_length))
        {
          gtk_selection_data_set (selection_data, encoding, format, text, new_length);
          gdk_x11_free_compound_text (text);

          result = TRUE;
        }
      g_free (tmp);
    }
#endif

  return result;
}

/* Normalize \r and \n into \r\n
 */
static gchar *
normalize_to_crlf (const gchar *str, 
		   gint         len)
{
  GString *result = g_string_sized_new (len);
  const gchar *p = str;
  const gchar *end = str + len;

  while (p < end)
    {
      if (*p == '\n')
	g_string_append_c (result, '\r');

      if (*p == '\r')
	{
	  g_string_append_c (result, *p);
	  p++;
	  if (p == end || *p != '\n')
	    g_string_append_c (result, '\n');
	  if (p == end)
	    break;
	}

      g_string_append_c (result, *p);
      p++;
    }

  return g_string_free (result, FALSE);  
}

/* Normalize \r and \r\n into \n
 */
static gchar *
normalize_to_lf (gchar *str, 
		 gint   len)
{
  GString *result = g_string_sized_new (len);
  const gchar *p = str;

  while (1)
    {
      if (*p == '\r')
	{
	  p++;
	  if (*p != '\n')
	    g_string_append_c (result, '\n');
	}

      if (*p == '\0')
	break;

      g_string_append_c (result, *p);
      p++;
    }

  return g_string_free (result, FALSE);  
}

static gboolean
selection_set_text_plain (GtkSelectionData *selection_data,
			  const gchar      *str,
			  gint              len)
{
  const gchar *charset = NULL;
  gchar *result;
  GError *error = NULL;

  result = normalize_to_crlf (str, len);
  if (selection_data->target == text_plain_atom)
    charset = "ASCII";
  else if (selection_data->target == text_plain_locale_atom)
    g_get_charset (&charset);

  if (charset)
    {
      gchar *tmp = result;
      result = g_convert_with_fallback (tmp, -1, 
					charset, "UTF-8", 
					NULL, NULL, NULL, &error);
      g_free (tmp);
    }

  if (!result)
    {
      g_warning ("Error converting from %s to %s: %s",
		 "UTF-8", charset, error->message);
      g_error_free (error);
      
      return FALSE;
    }
  
  gtk_selection_data_set (selection_data,
			  selection_data->target, 
			  8, (guchar *) result, strlen (result));
  g_free (result);
  
  return TRUE;
}

static guchar *
selection_get_text_plain (const GtkSelectionData *selection_data)
{
  const gchar *charset = NULL;
  gchar *str, *result;
  gsize len;
  GError *error = NULL;

  str = g_strdup ((const gchar *) selection_data->data);
  len = selection_data->length;
  
  if (selection_data->type == text_plain_atom)
    charset = "ISO-8859-1";
  else if (selection_data->type == text_plain_locale_atom)
    g_get_charset (&charset);

  if (charset)
    {
      gchar *tmp = str;
      str = g_convert_with_fallback (tmp, len, 
				     "UTF-8", charset,
				     NULL, NULL, &len, &error);
      g_free (tmp);

      if (!str)
	{
	  g_warning ("Error converting from %s to %s: %s",
		     charset, "UTF-8", error->message);
	  g_error_free (error);

	  return NULL;
	}
    }
  else if (!g_utf8_validate (str, -1, NULL))
    {
      g_warning ("Error converting from %s to %s: %s",
		 "text/plain;charset=utf-8", "UTF-8", "invalid UTF-8");
      g_free (str);

      return NULL;
    }

  result = normalize_to_lf (str, len);
  g_free (str);

  return (guchar *) result;
}

/**
 * gtk_selection_data_set_text:
 * @selection_data: a #GtkSelectionData
 * @str: a UTF-8 string
 * @len: the length of @str, or -1 if @str is nul-terminated.
 * 
 * Sets the contents of the selection from a UTF-8 encoded string.
 * The string is converted to the form determined by
 * @selection_data->target.
 * 
 * Returns: %TRUE if the selection was successfully set,
 *   otherwise %FALSE.
 **/
gboolean
gtk_selection_data_set_text (GtkSelectionData     *selection_data,
			     const gchar          *str,
			     gint                  len)
{
  g_return_val_if_fail (selection_data != NULL, FALSE);

  if (len < 0)
    len = strlen (str);
  
  init_atoms ();

  if (selection_data->target == utf8_atom)
    {
      gtk_selection_data_set (selection_data,
			      utf8_atom,
			      8, (guchar *)str, len);
      return TRUE;
    }
  else if (selection_data->target == g_intern_static_string ("STRING"))
    {
      return selection_set_string (selection_data, str, len);
    }
  else if (selection_data->target == ctext_atom ||
	   selection_data->target == text_atom)
    {
      if (selection_set_compound_text (selection_data, str, len))
	return TRUE;
      else if (selection_data->target == text_atom)
	return selection_set_string (selection_data, str, len);
    }
  else if (selection_data->target == text_plain_atom ||
	   selection_data->target == text_plain_utf8_atom ||
	   selection_data->target == text_plain_locale_atom)
    {
      return selection_set_text_plain (selection_data, str, len);
    }

  return FALSE;
}

/**
 * gtk_selection_data_get_text:
 * @selection_data: a #GtkSelectionData
 * 
 * Gets the contents of the selection data as a UTF-8 string.
 * 
 * Returns: (type utf8) (nullable) (transfer full): if the selection data contained a
 *   recognized text type and it could be converted to UTF-8, a newly
 *   allocated string containing the converted text, otherwise %NULL.
 *   If the result is non-%NULL it must be freed with g_free().
 **/
guchar *
gtk_selection_data_get_text (const GtkSelectionData *selection_data)
{
  guchar *result = NULL;

  g_return_val_if_fail (selection_data != NULL, NULL);

  init_atoms ();
  
  if (selection_data->length >= 0 &&
      (selection_data->type == g_intern_static_string ("STRING") ||
       selection_data->type == ctext_atom ||
       selection_data->type == utf8_atom))
    {
      gchar **list;
      gint i;
      gint count = gdk_text_property_to_utf8_list_for_display (selection_data->display,
      							       selection_data->type,
						   	       selection_data->format, 
						               selection_data->data,
						               selection_data->length,
						               &list);
      if (count > 0)
	result = (guchar *) list[0];

      for (i = 1; i < count; i++)
	g_free (list[i]);
      g_free (list);
    }
  else if (selection_data->length >= 0 &&
	   (selection_data->type == text_plain_atom ||
	    selection_data->type == text_plain_utf8_atom ||
	    selection_data->type == text_plain_locale_atom))
    {
      result = selection_get_text_plain (selection_data);
    }

  return result;
}

/**
 * gtk_selection_data_set_pixbuf:
 * @selection_data: a #GtkSelectionData
 * @pixbuf: a #GdkPixbuf
 * 
 * Sets the contents of the selection from a #GdkPixbuf
 * The pixbuf is converted to the form determined by
 * @selection_data->target.
 * 
 * Returns: %TRUE if the selection was successfully set,
 *   otherwise %FALSE.
 **/
gboolean
gtk_selection_data_set_pixbuf (GtkSelectionData *selection_data,
			       GdkPixbuf        *pixbuf)
{
  GSList *formats, *f;
  gchar **mimes, **m;
  GdkAtom atom;
  gboolean result;
  gchar *str, *type;
  gsize len;

  g_return_val_if_fail (selection_data != NULL, FALSE);
  g_return_val_if_fail (GDK_IS_PIXBUF (pixbuf), FALSE);

  formats = gdk_pixbuf_get_formats ();

  for (f = formats; f; f = f->next)
    {
      GdkPixbufFormat *fmt = f->data;

      mimes = gdk_pixbuf_format_get_mime_types (fmt);
      for (m = mimes; *m; m++)
	{
	  atom = g_intern_string (*m);
	  if (selection_data->target == atom)
	    {
	      str = NULL;
	      type = gdk_pixbuf_format_get_name (fmt);
	      result = gdk_pixbuf_save_to_buffer (pixbuf, &str, &len,
						  type, NULL,
                                                  ((strcmp (type, "png") == 0) ?
                                                   "compression" : NULL), "2",
                                                  NULL);
	      if (result)
		gtk_selection_data_set (selection_data,
					atom, 8, (guchar *)str, len);
	      g_free (type);
	      g_free (str);
	      g_strfreev (mimes);
	      g_slist_free (formats);

	      return result;
	    }
	}

      g_strfreev (mimes);
    }

  g_slist_free (formats);
 
  return FALSE;
}

/**
 * gtk_selection_data_set_surface:
 * @selection_data: a #GtkSelectionData
 * @surface: a cairo image surface
 * 
 * Sets the contents of the selection from a cairo image surface.
 * The surface is converted to the form determined by
 * @selection_data->target.
 * 
 * Returns: %TRUE if the selection was successfully set,
 *   otherwise %FALSE.
 **/
gboolean
gtk_selection_data_set_surface (GtkSelectionData *selection_data,
			        cairo_surface_t  *surface)
{
  GdkPixbuf *pixbuf;
  gboolean retval;

  pixbuf = gdk_pixbuf_get_from_surface (surface,
                                        0, 0,
                                        cairo_image_surface_get_width (surface),
                                        cairo_image_surface_get_height (surface));
  retval = gtk_selection_data_set_pixbuf (selection_data, pixbuf);
  g_object_unref (pixbuf);

  return retval;
}

/**
 * gtk_selection_data_get_surface:
 * @selection_data: a #GtkSelectionData
 * 
 * Gets the contents of the selection data as a cairo surface.
 * 
 * Returns: (nullable) (transfer full): if the selection data
 *   contained a recognized image type and it could be converted to a
 *   cairo surface, a newly allocated surface is returned, otherwise
 *   %NULL.  If the result is non-%NULL it must be freed with
 *   g_object_unref().
 **/
cairo_surface_t *
gtk_selection_data_get_surface (GtkSelectionData *selection_data)
{
  GdkPixbuf *pixbuf;
  cairo_surface_t *surface;

  pixbuf = gtk_selection_data_get_pixbuf (selection_data);
  surface = gdk_cairo_surface_create_from_pixbuf (pixbuf, 1, NULL);
  g_object_unref (pixbuf);

  return surface;
}

/**
 * gtk_selection_data_get_pixbuf:
 * @selection_data: a #GtkSelectionData
 * 
 * Gets the contents of the selection data as a #GdkPixbuf.
 * 
 * Returns: (nullable) (transfer full): if the selection data
 *   contained a recognized image type and it could be converted to a
 *   #GdkPixbuf, a newly allocated pixbuf is returned, otherwise
 *   %NULL.  If the result is non-%NULL it must be freed with
 *   g_object_unref().
 **/
GdkPixbuf *
gtk_selection_data_get_pixbuf (const GtkSelectionData *selection_data)
{
  GdkPixbufLoader *loader;
  GdkPixbuf *result = NULL;

  g_return_val_if_fail (selection_data != NULL, NULL);

  if (selection_data->length > 0)
    {
      loader = gdk_pixbuf_loader_new ();
      
      gdk_pixbuf_loader_write (loader, 
			       selection_data->data,
			       selection_data->length,
			       NULL);
      gdk_pixbuf_loader_close (loader, NULL);
      result = gdk_pixbuf_loader_get_pixbuf (loader);
      
      if (result)
	g_object_ref (result);
      
      g_object_unref (loader);
    }

  return result;
}

/**
 * gtk_selection_data_set_texture:
 * @selection_data: a #GtkSelectionData
 * @texture: a #GdkTexture
 * 
 * Sets the contents of the selection from a #GdkTexture.
 * The surface is converted to the form determined by
 * @selection_data->target.
 * 
 * Returns: %TRUE if the selection was successfully set,
 *   otherwise %FALSE.
 **/
gboolean
gtk_selection_data_set_texture (GtkSelectionData *selection_data,
                                GdkTexture       *texture)
{
  cairo_surface_t *surface;
  gboolean retval;

  g_return_val_if_fail (selection_data != NULL, FALSE);
  g_return_val_if_fail (GDK_IS_TEXTURE (texture), FALSE);

  surface = gdk_texture_download_surface (texture);
  retval = gtk_selection_data_set_surface (selection_data, surface);
  cairo_surface_destroy (surface);

  return retval;
}

/**
 * gtk_selection_data_get_texture:
 * @selection_data: a #GtkSelectionData
 * 
 * Gets the contents of the selection data as a #GdkPixbuf.
 * 
 * Returns: (nullable) (transfer full): if the selection data
 *   contained a recognized image type and it could be converted to a
 *   #GdkTexture, a newly allocated texture is returned, otherwise
 *   %NULL.  If the result is non-%NULL it must be freed with
 *   g_object_unref().
 **/
GdkTexture *
gtk_selection_data_get_texture (const GtkSelectionData *selection_data)
{
  GdkTexture *texture;
  GdkPixbuf *pixbuf;

  g_return_val_if_fail (selection_data != NULL, NULL);

  pixbuf = gtk_selection_data_get_pixbuf (selection_data);
  if (pixbuf == NULL)
    return NULL;

  texture = gdk_texture_new_for_pixbuf (pixbuf);
  g_object_unref (pixbuf);

  return texture;
}

/**
 * gtk_selection_data_set_uris:
 * @selection_data: a #GtkSelectionData
 * @uris: (array zero-terminated=1): a %NULL-terminated array of
 *     strings holding URIs
 * 
 * Sets the contents of the selection from a list of URIs.
 * The string is converted to the form determined by
 * @selection_data->target.
 * 
 * Returns: %TRUE if the selection was successfully set,
 *   otherwise %FALSE.
 **/
gboolean
gtk_selection_data_set_uris (GtkSelectionData  *selection_data,
			     gchar            **uris)
{
  g_return_val_if_fail (selection_data != NULL, FALSE);
  g_return_val_if_fail (uris != NULL, FALSE);

  init_atoms ();

  if (selection_data->target == text_uri_list_atom)
    {
      GString *list;
      gint i;
      gchar *result;
      gsize length;
      
      list = g_string_new (NULL);
      for (i = 0; uris[i]; i++)
	{
	  g_string_append (list, uris[i]);
	  g_string_append (list, "\r\n");
	}

      result = g_convert (list->str, list->len,
			  "ASCII", "UTF-8", 
			  NULL, &length, NULL);
      g_string_free (list, TRUE);
      
      if (result)
	{
	  gtk_selection_data_set (selection_data,
				  text_uri_list_atom,
				  8, (guchar *)result, length);
	  
	  g_free (result);

	  return TRUE;
	}
    }

  return FALSE;
}

/**
 * gtk_selection_data_get_uris:
 * @selection_data: a #GtkSelectionData
 * 
 * Gets the contents of the selection data as array of URIs.
 *
 * Returns:  (array zero-terminated=1) (element-type utf8) (transfer full): if
 *   the selection data contains a list of
 *   URIs, a newly allocated %NULL-terminated string array
 *   containing the URIs, otherwise %NULL. If the result is
 *   non-%NULL it must be freed with g_strfreev().
 **/
gchar **
gtk_selection_data_get_uris (const GtkSelectionData *selection_data)
{
  gchar **result = NULL;

  g_return_val_if_fail (selection_data != NULL, NULL);

  init_atoms ();
  
  if (selection_data->length >= 0 &&
      selection_data->type == text_uri_list_atom)
    {
      gchar **list;
      gint count = gdk_text_property_to_utf8_list_for_display (selection_data->display,
      							       utf8_atom,
						   	       selection_data->format, 
						               selection_data->data,
						               selection_data->length,
						               &list);
      if (count > 0)
	result = g_uri_list_extract_uris (list[0]);
      
      g_strfreev (list);
    }

  return result;
}


/**
 * gtk_selection_data_get_targets:
 * @selection_data: a #GtkSelectionData object
 * @targets: (out) (array length=n_atoms) (transfer container):
 *           location to store an array of targets. The result stored
 *           here must be freed with g_free().
 * @n_atoms: location to store number of items in @targets.
 * 
 * Gets the contents of @selection_data as an array of targets.
 * This can be used to interpret the results of getting
 * the standard TARGETS target that is always supplied for
 * any selection.
 * 
 * Returns: %TRUE if @selection_data contains a valid
 *    array of targets, otherwise %FALSE.
 **/
gboolean
gtk_selection_data_get_targets (const GtkSelectionData  *selection_data,
				GdkAtom                **targets,
				gint                    *n_atoms)
{
  g_return_val_if_fail (selection_data != NULL, FALSE);

  if (selection_data->length >= 0 &&
      selection_data->format == 32 &&
      selection_data->type == g_intern_static_string ("ATOM"))
    {
      if (targets)
	*targets = g_memdup (selection_data->data, selection_data->length);
      if (n_atoms)
	*n_atoms = selection_data->length / sizeof (GdkAtom);

      return TRUE;
    }
  else
    {
      if (targets)
	*targets = NULL;
      if (n_atoms)
	*n_atoms = -1;

      return FALSE;
    }
}

/**
 * gtk_targets_include_text:
 * @targets: (array length=n_targets): an array of #GdkAtoms
 * @n_targets: the length of @targets
 * 
 * Determines if any of the targets in @targets can be used to
 * provide text.
 * 
 * Returns: %TRUE if @targets include a suitable target for text,
 *   otherwise %FALSE.
 **/
gboolean 
gtk_targets_include_text (GdkAtom *targets,
                          gint     n_targets)
{
  gint i;
  gboolean result = FALSE;

  g_return_val_if_fail (targets != NULL || n_targets == 0, FALSE);

  /* Keep in sync with gdk_content_formats_add_text_targets()
   */
 
  init_atoms ();
 
  for (i = 0; i < n_targets; i++)
    {
      if (targets[i] == utf8_atom ||
	  targets[i] == text_atom ||
	  targets[i] == g_intern_static_string ("STRING") ||
	  targets[i] == ctext_atom ||
	  targets[i] == text_plain_atom ||
	  targets[i] == text_plain_utf8_atom ||
	  targets[i] == text_plain_locale_atom)
	{
	  result = TRUE;
	  break;
	}
    }
  
  return result;
}

/**
 * gtk_selection_data_targets_include_text:
 * @selection_data: a #GtkSelectionData object
 * 
 * Given a #GtkSelectionData object holding a list of targets,
 * determines if any of the targets in @targets can be used to
 * provide text.
 * 
 * Returns: %TRUE if @selection_data holds a list of targets,
 *   and a suitable target for text is included, otherwise %FALSE.
 **/
gboolean
gtk_selection_data_targets_include_text (const GtkSelectionData *selection_data)
{
  GdkAtom *targets;
  gint n_targets;
  gboolean result = FALSE;

  g_return_val_if_fail (selection_data != NULL, FALSE);

  init_atoms ();

  if (gtk_selection_data_get_targets (selection_data, &targets, &n_targets))
    {
      result = gtk_targets_include_text (targets, n_targets);
      g_free (targets);
    }

  return result;
}

/**
 * gtk_targets_include_image:
 * @targets: (array length=n_targets): an array of #GdkAtoms
 * @n_targets: the length of @targets
 * @writable: whether to accept only targets for which GTK+ knows
 *   how to convert a pixbuf into the format
 * 
 * Determines if any of the targets in @targets can be used to
 * provide a #GdkPixbuf.
 * 
 * Returns: %TRUE if @targets include a suitable target for images,
 *   otherwise %FALSE.
 **/
gboolean 
gtk_targets_include_image (GdkAtom *targets,
			   gint     n_targets,
			   gboolean writable)
{
  GdkContentFormats *list;
  gint i;
  gboolean result = FALSE;

  g_return_val_if_fail (targets != NULL || n_targets == 0, FALSE);

  list = gdk_content_formats_new (NULL, 0);
  list = gtk_content_formats_add_image_targets (list, writable);
  for (i = 0; i < n_targets && !result; i++)
    {
      if (gdk_content_formats_contain_mime_type (list, targets[i]))
        {
          result = TRUE;
          break;
	}
    }
  gdk_content_formats_unref (list);

  return result;
}
				    
/**
 * gtk_selection_data_targets_include_image:
 * @selection_data: a #GtkSelectionData object
 * @writable: whether to accept only targets for which GTK+ knows
 *   how to convert a pixbuf into the format
 * 
 * Given a #GtkSelectionData object holding a list of targets,
 * determines if any of the targets in @targets can be used to
 * provide a #GdkPixbuf.
 * 
 * Returns: %TRUE if @selection_data holds a list of targets,
 *   and a suitable target for images is included, otherwise %FALSE.
 **/
gboolean 
gtk_selection_data_targets_include_image (const GtkSelectionData *selection_data,
					  gboolean                writable)
{
  GdkAtom *targets;
  gint n_targets;
  gboolean result = FALSE;

  g_return_val_if_fail (selection_data != NULL, FALSE);

  init_atoms ();

  if (gtk_selection_data_get_targets (selection_data, &targets, &n_targets))
    {
      result = gtk_targets_include_image (targets, n_targets, writable);
      g_free (targets);
    }

  return result;
}

/**
 * gtk_targets_include_uri:
 * @targets: (array length=n_targets): an array of #GdkAtoms
 * @n_targets: the length of @targets
 * 
 * Determines if any of the targets in @targets can be used to
 * provide an uri list.
 * 
 * Returns: %TRUE if @targets include a suitable target for uri lists,
 *   otherwise %FALSE.
 **/
gboolean 
gtk_targets_include_uri (GdkAtom *targets,
			 gint     n_targets)
{
  gint i;
  gboolean result = FALSE;

  g_return_val_if_fail (targets != NULL || n_targets == 0, FALSE);

  /* Keep in sync with gdk_content_formats_add_uri_targets()
   */

  init_atoms ();

  for (i = 0; i < n_targets; i++)
    {
      if (targets[i] == text_uri_list_atom)
	{
	  result = TRUE;
	  break;
	}
    }
  
  return result;
}

/**
 * gtk_selection_data_targets_include_uri:
 * @selection_data: a #GtkSelectionData object
 * 
 * Given a #GtkSelectionData object holding a list of targets,
 * determines if any of the targets in @targets can be used to
 * provide a list or URIs.
 * 
 * Returns: %TRUE if @selection_data holds a list of targets,
 *   and a suitable target for URI lists is included, otherwise %FALSE.
 **/
gboolean
gtk_selection_data_targets_include_uri (const GtkSelectionData *selection_data)
{
  GdkAtom *targets;
  gint n_targets;
  gboolean result = FALSE;

  g_return_val_if_fail (selection_data != NULL, FALSE);

  init_atoms ();

  if (gtk_selection_data_get_targets (selection_data, &targets, &n_targets))
    {
      result = gtk_targets_include_uri (targets, n_targets);
      g_free (targets);
    }

  return result;
}

/**
 * gtk_selection_data_copy:
 * @data: a pointer to a #GtkSelectionData-struct.
 * 
 * Makes a copy of a #GtkSelectionData-struct and its data.
 * 
 * Returns: a pointer to a copy of @data.
 **/
GtkSelectionData*
gtk_selection_data_copy (const GtkSelectionData *data)
{
  GtkSelectionData *new_data;
  
  g_return_val_if_fail (data != NULL, NULL);
  
  new_data = g_slice_new (GtkSelectionData);
  *new_data = *data;

  if (data->data)
    {
      new_data->data = g_malloc (data->length + 1);
      memcpy (new_data->data, data->data, data->length + 1);
    }
  
  return new_data;
}

/**
 * gtk_selection_data_free:
 * @data: a pointer to a #GtkSelectionData-struct.
 * 
 * Frees a #GtkSelectionData-struct returned from
 * gtk_selection_data_copy().
 **/
void
gtk_selection_data_free (GtkSelectionData *data)
{
  g_return_if_fail (data != NULL);
  
  g_free (data->data);
  
  g_slice_free (GtkSelectionData, data);
}

G_DEFINE_BOXED_TYPE (GtkSelectionData, gtk_selection_data,
                     gtk_selection_data_copy,
                     gtk_selection_data_free)