gdk-pixbuf-loader.c 16.3 KB
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/* GdkPixbuf library - Progressive loader object
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 *
 * Copyright (C) 1999 The Free Software Foundation
 *
 * Authors: Mark Crichton <crichton@gimp.org>
 *          Miguel de Icaza <miguel@gnu.org>
 *          Federico Mena-Quintero <federico@gimp.org>
 *          Jonathan Blandford <jrb@redhat.com>
 *
 * This library is free software; you can redistribute it and/or
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 * modify it under the terms of the GNU Lesser General Public
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 * 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
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 * Lesser General Public License for more details.
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 *
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 * You should have received a copy of the GNU Lesser General Public
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 * License along with this library; if not, write to the
 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA 02111-1307, USA.
 */

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#include <string.h>

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#include "gdk-pixbuf-private.h"
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#include "gdk-pixbuf-loader.h"
#include "gdk-pixbuf-io.h"
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#include "gdk-pixbuf-marshal.h"
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enum {
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  AREA_UPDATED,
  AREA_PREPARED,
  CLOSED,
  LAST_SIGNAL
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};
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static void gdk_pixbuf_loader_class_init    (GdkPixbufLoaderClass   *klass);
static void gdk_pixbuf_loader_init          (GdkPixbufLoader        *loader);
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static void gdk_pixbuf_loader_finalize      (GObject                *loader);
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static gpointer parent_class = NULL;
static guint    pixbuf_loader_signals[LAST_SIGNAL] = { 0 };
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/* Internal data */
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#define LOADER_HEADER_SIZE 128

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typedef struct
{
  GdkPixbufAnimation *animation;
  gboolean closed;
  guchar header_buf[LOADER_HEADER_SIZE];
  gint header_buf_offset;
  GdkPixbufModule *image_module;
  gpointer context;
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} GdkPixbufLoaderPrivate;
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/**
 * gdk_pixbuf_loader_get_type:
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 * @void:
 *
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 * Registers the #GdkPixubfLoader class if necessary, and returns the type ID
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 * associated to it.
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 *
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 * Return value: The type ID of the #GdkPixbufLoader class.
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 **/
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GType
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gdk_pixbuf_loader_get_type (void)
{
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  static GType loader_type = 0;
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  if (!loader_type)
    {
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      static const GTypeInfo loader_info = {
        sizeof (GdkPixbufLoaderClass),
        (GBaseInitFunc) NULL,
        (GBaseFinalizeFunc) NULL,
        (GClassInitFunc) gdk_pixbuf_loader_class_init,
        NULL,           /* class_finalize */
        NULL,           /* class_data */
        sizeof (GdkPixbufLoader),
        0,              /* n_preallocs */
        (GInstanceInitFunc) gdk_pixbuf_loader_init
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      };
      
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      loader_type = g_type_register_static (G_TYPE_OBJECT,
                                            "GdkPixbufLoader",
                                            &loader_info,
                                            0);
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    }
  
  return loader_type;
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}

static void
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gdk_pixbuf_loader_class_init (GdkPixbufLoaderClass *class)
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{
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  GObjectClass *object_class;
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  object_class = (GObjectClass *) class;
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  parent_class = g_type_class_peek_parent (class);
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  object_class->finalize = gdk_pixbuf_loader_finalize;
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  pixbuf_loader_signals[AREA_PREPARED] =
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    g_signal_new ("area_prepared",
                  G_TYPE_FROM_CLASS (object_class),
                  G_SIGNAL_RUN_LAST,
                  G_STRUCT_OFFSET (GdkPixbufLoaderClass, area_prepared),
                  NULL, NULL,
                  gdk_pixbuf_marshal_VOID__VOID,
                  G_TYPE_NONE, 0);
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  pixbuf_loader_signals[AREA_UPDATED] =
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    g_signal_new ("area_updated",
                  G_TYPE_FROM_CLASS (object_class),
                  G_SIGNAL_RUN_LAST,
                  G_STRUCT_OFFSET (GdkPixbufLoaderClass, area_updated),
                  NULL, NULL,
                  gdk_pixbuf_marshal_VOID__INT_INT_INT_INT,
                  G_TYPE_NONE, 4,
                  G_TYPE_INT,
                  G_TYPE_INT,
                  G_TYPE_INT,
                  G_TYPE_INT);
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  pixbuf_loader_signals[CLOSED] =
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    g_signal_new ("closed",
                  G_TYPE_FROM_CLASS (object_class),
                  G_SIGNAL_RUN_LAST,
                  G_STRUCT_OFFSET (GdkPixbufLoaderClass, closed),
                  NULL, NULL,
                  gdk_pixbuf_marshal_VOID__VOID,
                  G_TYPE_NONE, 0);
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}

static void
gdk_pixbuf_loader_init (GdkPixbufLoader *loader)
{
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  GdkPixbufLoaderPrivate *priv;
  
  priv = g_new0 (GdkPixbufLoaderPrivate, 1);
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  loader->priv = priv;
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}

static void
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gdk_pixbuf_loader_finalize (GObject *object)
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{
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  GdkPixbufLoader *loader;
  GdkPixbufLoaderPrivate *priv = NULL;
  
  loader = GDK_PIXBUF_LOADER (object);
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  priv = loader->priv;
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  if (!priv->closed)
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    g_warning ("GdkPixbufLoader finalized without calling gdk_pixbuf_loader_close() - this is not allowed. You must explicitly end the data stream to the loader before dropping the last reference.");
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  if (priv->animation)
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    g_object_unref (priv->animation);
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  g_free (priv);
  
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  G_OBJECT_CLASS (parent_class)->finalize (object);
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}

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static void
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gdk_pixbuf_loader_prepare (GdkPixbuf          *pixbuf,
                           GdkPixbufAnimation *anim,
			   gpointer            loader)
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{
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  GdkPixbufLoaderPrivate *priv = NULL;
  
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  priv = GDK_PIXBUF_LOADER (loader)->priv;
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  if (anim)
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    g_object_ref (anim);
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  else
    anim = gdk_pixbuf_non_anim_new (pixbuf);
  
  priv->animation = anim;
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  g_signal_emit (loader, pixbuf_loader_signals[AREA_PREPARED], 0);
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}

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static void
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gdk_pixbuf_loader_update (GdkPixbuf *pixbuf,
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			  gint       x,
			  gint       y,
			  gint       width,
			  gint       height,
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			  gpointer   loader)
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{
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  GdkPixbufLoaderPrivate *priv = NULL;
  
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  priv = GDK_PIXBUF_LOADER (loader)->priv;
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  g_signal_emit (loader,
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                 pixbuf_loader_signals[AREA_UPDATED],
                 0,
                 x, y,
                 /* sanity check in here.  Defend against an errant loader */
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                 MIN (width, gdk_pixbuf_animation_get_width (priv->animation)),
                 MIN (height, gdk_pixbuf_animation_get_height (priv->animation)));
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}

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static gint
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gdk_pixbuf_loader_load_module (GdkPixbufLoader *loader,
                               const char      *image_type,
                               GError         **error)
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{
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  GdkPixbufLoaderPrivate *priv = loader->priv;
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  if (image_type)
    {
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      priv->image_module = _gdk_pixbuf_get_named_module (image_type,
                                                         error);
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    }
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  else
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    {
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      priv->image_module = _gdk_pixbuf_get_module (priv->header_buf,
                                                   priv->header_buf_offset,
                                                   NULL,
                                                   error);
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    }
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  if (priv->image_module == NULL)
    return 0;
  
  if (priv->image_module->module == NULL)
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    if (!_gdk_pixbuf_load_module (priv->image_module, error))
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      return 0;
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  if (priv->image_module->module == NULL)
    return 0;
  
  if ((priv->image_module->begin_load == NULL) ||
      (priv->image_module->stop_load == NULL) ||
      (priv->image_module->load_increment == NULL))
    {
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      g_set_error (error,
                   GDK_PIXBUF_ERROR,
                   GDK_PIXBUF_ERROR_UNSUPPORTED_OPERATION,
                   _("Incremental loading of image type '%s' is not supported"),
                   image_type);

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      return 0;
    }
  
  priv->context = priv->image_module->begin_load (gdk_pixbuf_loader_prepare,
						  gdk_pixbuf_loader_update,
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						  loader,
                                                  error);
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  if (priv->context == NULL)
    {
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      /* Defense against broken loaders; DO NOT take this as a GError
       * example
       */
      if (error && *error == NULL)
        {
          g_warning ("Bug! loader '%s' didn't set an error on failure",
                     priv->image_module->module_name);
          g_set_error (error,
                       GDK_PIXBUF_ERROR,
                       GDK_PIXBUF_ERROR_FAILED,
                       _("Internal error: Image loader module '%s'"
                         " failed to begin loading an image, but didn't"
                         " give a reason for the failure"),
                       priv->image_module->module_name);

        }
      
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      return 0;
    }
  
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  if (priv->header_buf_offset
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      && priv->image_module->load_increment (priv->context, priv->header_buf, priv->header_buf_offset, error))
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    return priv->header_buf_offset;
  
  return 0;
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}

static int
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gdk_pixbuf_loader_eat_header_write (GdkPixbufLoader *loader,
				    const guchar    *buf,
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				    gsize            count,
                                    GError         **error)
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{
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  gint n_bytes;
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  GdkPixbufLoaderPrivate *priv = loader->priv;
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  n_bytes = MIN(LOADER_HEADER_SIZE - priv->header_buf_offset, count);
  memcpy (priv->header_buf + priv->header_buf_offset, buf, n_bytes);
  
  priv->header_buf_offset += n_bytes;
  
  if (priv->header_buf_offset >= LOADER_HEADER_SIZE)
    {
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      if (gdk_pixbuf_loader_load_module (loader, NULL, error) == 0)
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	return 0;
    }
  
  return n_bytes;
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}

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/**
 * gdk_pixbuf_loader_write:
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 * @loader: A pixbuf loader.
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 * @buf: Pointer to image data.
 * @count: Length of the @buf buffer in bytes.
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 * @error: return location for errors
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 *
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 * This will cause a pixbuf loader to parse the next @count bytes of
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 * an image.  It will return %TRUE if the data was loaded successfully,
 * and %FALSE if an error occurred.  In the latter case, the loader
 * will be closed, and will not accept further writes. If %FALSE is
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 * returned, @error will be set to an error from the #GDK_PIXBUF_ERROR
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 * or #G_FILE_ERROR domains.
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 *
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 * Return value: %TRUE if the write was successful, or %FALSE if the loader
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 * cannot parse the buffer.
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 **/
gboolean
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gdk_pixbuf_loader_write (GdkPixbufLoader *loader,
			 const guchar    *buf,
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			 gsize            count,
                         GError         **error)
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{
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  GdkPixbufLoaderPrivate *priv;
  
  g_return_val_if_fail (loader != NULL, FALSE);
  g_return_val_if_fail (GDK_IS_PIXBUF_LOADER (loader), FALSE);
  
  g_return_val_if_fail (buf != NULL, FALSE);
  g_return_val_if_fail (count >= 0, FALSE);
  
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  priv = loader->priv;
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  /* we expect it's not to be closed */
  g_return_val_if_fail (priv->closed == FALSE, FALSE);
  
  if (priv->image_module == NULL)
    {
      gint eaten;
      
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      eaten = gdk_pixbuf_loader_eat_header_write (loader, buf, count, error);
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      if (eaten <= 0)
	return FALSE;
      
      count -= eaten;
      buf += eaten;
    }
  
  if (count > 0 && priv->image_module->load_increment)
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    {
      gboolean retval;
      retval = priv->image_module->load_increment (priv->context, buf, count,
                                                   error);
      if (!retval && error && *error == NULL)
        {
          /* Fix up busted image loader */
          g_warning ("Bug! loader '%s' didn't set an error on failure",
                     priv->image_module->module_name);
          g_set_error (error,
                       GDK_PIXBUF_ERROR,
                       GDK_PIXBUF_ERROR_FAILED,
                       _("Internal error: Image loader module '%s'"
                         " failed to begin loading an image, but didn't"
                         " give a reason for the failure"),
                       priv->image_module->module_name);
        }

      return retval;
    }
      
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  return TRUE;
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}

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/**
 * gdk_pixbuf_loader_new:
 *
 * Creates a new pixbuf loader object.
 *
 * Return value: A newly-created pixbuf loader.
 **/
GdkPixbufLoader *
gdk_pixbuf_loader_new (void)
{
  return g_object_new (GDK_TYPE_PIXBUF_LOADER, NULL);
}

/**
 * gdk_pixbuf_loader_new_with_type:
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 * @image_type: name of the image format to be loaded with the image
 * @error: return location for an allocated #GError, or %NULL to ignore errors
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 *
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 * Creates a new pixbuf loader object that always attempts to parse
 * image data as if it were an image of type @image_type, instead of
 * identifying the type automatically. Useful if you want an error if
 * the image isn't the expected type, for loading image formats
 * that can't be reliably identified by looking at the data, or if
 * the user manually forces a specific type.
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 *
 * Return value: A newly-created pixbuf loader.
 **/
GdkPixbufLoader *
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gdk_pixbuf_loader_new_with_type (const char *image_type,
                                 GError    **error)
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{
  GdkPixbufLoader *retval;
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  GError *tmp;
  
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  retval = g_object_new (GDK_TYPE_PIXBUF_LOADER, NULL);

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  tmp = NULL;
  gdk_pixbuf_loader_load_module(retval, image_type, &tmp);
  if (tmp != NULL)
    {
      g_propagate_error (error, tmp);
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      g_object_unref (retval);
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      return NULL;
    }
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  return retval;
}

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/**
 * gdk_pixbuf_loader_get_pixbuf:
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 * @loader: A pixbuf loader.
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 *
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 * Queries the #GdkPixbuf that a pixbuf loader is currently creating.
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 * In general it only makes sense to call this function after the
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 * "area_prepared" signal has been emitted by the loader; this means
 * that enough data has been read to know the size of the image that
 * will be allocated.  If the loader has not received enough data via
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 * gdk_pixbuf_loader_write(), then this function returns %NULL.  The
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 * returned pixbuf will be the same in all future calls to the loader,
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 * so simply calling g_object_ref() should be sufficient to continue
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 * using it.  Additionally, if the loader is an animation, it will
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 * return the "static image" of the animation
 * (see gdk_pixbuf_animation_get_static_image()).
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 * 
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 * Return value: The #GdkPixbuf that the loader is creating, or %NULL if not
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 * enough data has been read to determine how to create the image buffer.
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 **/
GdkPixbuf *
gdk_pixbuf_loader_get_pixbuf (GdkPixbufLoader *loader)
{
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  GdkPixbufLoaderPrivate *priv;
  
  g_return_val_if_fail (loader != NULL, NULL);
  g_return_val_if_fail (GDK_IS_PIXBUF_LOADER (loader), NULL);
  
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  priv = loader->priv;
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  if (priv->animation)
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    return gdk_pixbuf_animation_get_static_image (priv->animation);
  else
    return NULL;
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}

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/**
 * gdk_pixbuf_loader_get_animation:
 * @loader: A pixbuf loader
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 *
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 * Queries the #GdkPixbufAnimation that a pixbuf loader is currently creating.
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 * In general it only makes sense to call this function afer the "area_prepared"
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 * signal has been emitted by the loader. If the loader doesn't have enough
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 * bytes yet (hasn't emitted the "area_prepared" signal) this function will 
 * return %NULL.
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 *
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 * Return value: The #GdkPixbufAnimation that the loader is loading, or %NULL if
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 not enough data has been read to determine the information.
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**/
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GdkPixbufAnimation *
gdk_pixbuf_loader_get_animation (GdkPixbufLoader *loader)
{
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  GdkPixbufLoaderPrivate *priv;
  
  g_return_val_if_fail (loader != NULL, NULL);
  g_return_val_if_fail (GDK_IS_PIXBUF_LOADER (loader), NULL);
  
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  priv = loader->priv;
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  return priv->animation;
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}

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/**
 * gdk_pixbuf_loader_close:
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 * @loader: A pixbuf loader.
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 * @error: return location for a #GError, or %NULL to ignore errors
 *
 * Informs a pixbuf loader that no further writes with
 * gdk_pixbuf_loader_write() will occur, so that it can free its
 * internal loading structures. Also, tries to parse any data that
 * hasn't yet been parsed; if the remaining data is partial or
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 * corrupt, an error will be returned.  If %FALSE is returned, @error
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 * will be set to an error from the #GDK_PIXBUF_ERROR or #G_FILE_ERROR
 * domains. If you're just cancelling a load rather than expecting it
 * to be finished, passing %NULL for @error to ignore it is
 * reasonable.
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 *
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 * Returns: %TRUE if all image data written so far was successfully
            passed out via the update_area signal
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 **/
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gboolean
gdk_pixbuf_loader_close (GdkPixbufLoader *loader,
                         GError         **error)
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{
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  GdkPixbufLoaderPrivate *priv;
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  gboolean retval = TRUE;
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  g_return_val_if_fail (loader != NULL, TRUE);
  g_return_val_if_fail (GDK_IS_PIXBUF_LOADER (loader), TRUE);
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  priv = loader->priv;
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  /* we expect it's not closed */
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  g_return_val_if_fail (priv->closed == FALSE, TRUE);
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  /* We have less the 128 bytes in the image.  Flush it, and keep going. */
  if (priv->image_module == NULL)
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    {
      GError *tmp = NULL;
      gdk_pixbuf_loader_load_module (loader, NULL, &tmp);
      if (tmp != NULL)
	{
	  g_propagate_error (error, tmp);
	  retval = FALSE;
	}
    }  
  if (retval && priv->image_module && priv->image_module->stop_load && priv->context)
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    retval = priv->image_module->stop_load (priv->context, error);
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  priv->closed = TRUE;
  
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  g_signal_emit (loader, pixbuf_loader_signals[CLOSED], 0);
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  return retval;
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}
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