gtk/docs/reference/gdk-pixbuf/tmpl/gdk-pixbuf-loader.sgml

<!-- ##### SECTION Title ##### -->
GdkPixbufLoader

<!-- ##### SECTION Short_Description ##### -->
Application-driven progressive image loading.

<!-- ##### SECTION Long_Description ##### -->
  <para>
    #GdkPixbufLoader provides a way for applications to drive the
    process of loading an image, by letting them send the image data
    directly to the loader instead of having the loader read the data
    from a file.  Applications can use this functionality instead of
    gdk_pixbuf_new_from_file() or gdk_pixbuf_animation_new_from_file() 
    when they need to parse image data in
    small chunks.  For example, it should be used when reading an
    image from a (potentially) slow network connection, or when
    loading an extremely large file.
  </para>

  <para>
    To use #GdkPixbufLoader to load an image, just create a new one,
    and call gdk_pixbuf_loader_write() to send the data to it.  When
    done, gdk_pixbuf_loader_close() should be called to end the stream
    and finalize everything.  The loader will emit three important
    signals throughout the process.  The first, "<link
    linkend="GdkPixbufLoader-size-prepared">size_prepared</link>",
    will be called as soon as the image has enough information to
    determine the size of the image to be used. If you want to scale
    the image while loading it, you can call gdk_pixbuf_loader_set_size()
    in response to this signal.
    </para>

    <para>The second signal, "<link
    linkend="GdkPixbufLoader-area-prepared">area_prepared</link>",
    will be called as soon as the pixbuf of the desired has been 
    allocated.  You can obtain it by calling gdk_pixbuf_loader_get_pixbuf(). 
    If you want to use it, simply ref it.  
    In addition, no actual information will be passed in yet, so the
    pixbuf can be safely filled with any temporary graphics (or an
    initial color) as needed.  You can also call
    gdk_pixbuf_loader_get_pixbuf() later and get the same pixbuf.
  </para>

  <para>
    The last signal, "<link
    linkend="GdkPixbufLoader-area-updated">area_updated</link>" gets
    called every time a region is updated.  This way you can update a
    partially completed image.  Note that you do not know anything
    about the completeness of an image from the area updated.  For
    example, in an interlaced image, you need to make several passes
    before the image is done loading.
  </para>

  <refsect2>
    <title>Loading an animation</title>

    <para>
      Loading an animation is almost as easy as loading an
      image.  Once the first "<link
      linkend="GdkPixbufLoader-area-prepared">area_prepared</link>" signal
      has been emitted, you can call gdk_pixbuf_loader_get_animation()
      to get the #GdkPixbufAnimation struct and gdk_pixbuf_animation_get_iter()
      to get an #GdkPixbufAnimationIter for displaying it. 
    </para>
  </refsect2>

<!-- ##### SECTION See_Also ##### -->
  <para>
    gdk_pixbuf_new_from_file(), gdk_pixbuf_animation_new_from_file()
  </para>

<!-- ##### STRUCT GdkPixbufLoader ##### -->
<para>
The <structname>GdkPixbufLoader</structname> struct contains only private
fields. 
</para>


<!-- ##### SIGNAL GdkPixbufLoader::area-prepared ##### -->
  <para>
    This signal is emitted when the pixbuf loader has allocated the pixbuf
    in the desired size.  After this signal is emitted, applications can 
    call gdk_pixbuf_loader_get_pixbuf() to fetch the partially-loaded pixbuf.
  </para>

@gdkpixbufloader: the object which received the signal.

<!-- ##### SIGNAL GdkPixbufLoader::area-updated ##### -->
  <para>
    This signal is emitted when a significant area of the image being
    loaded has been updated.  Normally it means that a complete
    scanline has been read in, but it could be a different area as
    well.  Applications can use this signal to know when to repaint
    areas of an image that is being loaded.
  </para>

@gdkpixbufloader: Loader which emitted the signal.
@arg1: 
@arg2: 
@arg3: 
@arg4: 
<!-- # Unused Parameters # -->
@x: X offset of upper-left corner of the updated area.
@y: Y offset of upper-left corner of the updated area.
@width: Width of updated area.
@height: Height of updated area.

<!-- ##### SIGNAL GdkPixbufLoader::closed ##### -->
  <para>
    This signal is emitted when gdk_pixbuf_loader_close() is called.
    It can be used by different parts of an application to receive
    notification when an image loader is closed by the code that
    drives it.
  </para>

@gdkpixbufloader: the object which received the signal.

<!--
Local variables:
mode: sgml
sgml-parent-document: ("../gdk-pixbuf.sgml" "book" "refsect2" "")
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<!-- ##### SIGNAL GdkPixbufLoader::size-prepared ##### -->
  <para>
    This signal is emitted when the pixbuf loader has been fed the
    initial amount of data that is required to figure out the size
    of the image that it will create.  Applications can call  
    gdk_pixbuf_loader_set_size() in response to this signal to set
    the desired size to which the image should be scaled.
  </para>

@gdkpixbufloader: the object which received the signal.
@arg1: 
@arg2: 
<!-- # Unused Parameters # -->
@width: the original width of the image
@height: the original height of the image

<!-- ##### FUNCTION gdk_pixbuf_loader_new ##### -->
<para>

</para>

@Returns: 


<!-- ##### FUNCTION gdk_pixbuf_loader_new_with_type ##### -->
<para>

</para>

@image_type: 
@error: 
@Returns: 


<!-- ##### FUNCTION gdk_pixbuf_loader_new_with_mime_type ##### -->
<para>

</para>

@mime_type: 
@error: 
@Returns: 


<!-- ##### FUNCTION gdk_pixbuf_loader_get_format ##### -->
<para>

</para>

@loader: 
@Returns: 


<!-- ##### FUNCTION gdk_pixbuf_loader_write ##### -->
<para>

</para>

@loader: 
@buf: 
@count: 
@error: 
@Returns: 


<!-- ##### FUNCTION gdk_pixbuf_loader_set_size ##### -->
<para>

</para>

@loader: 
@width: 
@height: 


<!-- ##### FUNCTION gdk_pixbuf_loader_get_pixbuf ##### -->
<para>

</para>

@loader: 
@Returns: 


<!-- ##### FUNCTION gdk_pixbuf_loader_get_animation ##### -->
<para>

</para>

@loader: 
@Returns: 


<!-- ##### FUNCTION gdk_pixbuf_loader_close ##### -->
<para>

</para>

@loader: 
@error: 
@Returns: