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Name
GdkPixbufLoader -- Application-driven progressive image loading. Synopsis

#include <gdk-pixbuf/gdk-pixbuf.h>
#define     
gdkpixbufloader.html#GDK-PIXBUF-LOADER-CAPSGDK_PIXBUF_LOADER                (obj)
gdkpixbufloader.htmlGdkPixbufLoader * gdkpixbufloader.html#GDK-PIXBUF-LOADER-NEWgdk_pixbuf_loader_new       (void);
gboolean    
gdkpixbufloader.html#GDK-PIXBUF-LOADER-WRITEgdk_pixbuf_loader_write          ( gdkpixbufloader.htmlGdkPixbufLoader  *loader,
                                             const guchar *buf,
                                             size_t count);
GdkPixbuf*  
gdkpixbufloader.html#GDK-PIXBUF-LOADER-GET-PIXBUFgdk_pixbuf_loader_get_pixbuf     ( gdkpixbufloader.htmlGdkPixbufLoader  *loader);
GdkPixbufAnimation* 
gdkpixbufloader.html#GDK-PIXBUF-LOADER-GET-ANIMATIONgdk_pixbuf_loader_get_animation                                             (
gdkpixbufloader.htmlGdkPixbufLoader  *loader);
void        
gdkpixbufloader.html#GDK-PIXBUF-LOADER-CLOSEgdk_pixbuf_loader_close          ( gdkpixbufloader.htmlGdkPixbufLoader  *loader);

Object Hierarchy

  GtkObject
   +----GdkPixbufLoader
Signal Prototypes

" gdkpixbufloader.html#GDKPIXBUFLOADER-AREA-UPDATEDarea-updated "
            void        user_function      (
gdkpixbufloader.htmlGdkPixbufLoader  *gdkpixbufloader,
                                            gint arg1,
                                            gint arg2,
                                            gint arg3,
                                            gint arg4,
                                            gpointer user_data);
"
gdkpixbufloader.html#GDKPIXBUFLOADER-AREA-PREPAREDarea-prepared "
            void        user_function      (
gdkpixbufloader.htmlGdkPixbufLoader  *gdkpixbufloader,
                                            gpointer user_data);
"
gdkpixbufloader.html#GDKPIXBUFLOADER-FRAME-DONEframe-done "
            void        user_function      (
gdkpixbufloader.htmlGdkPixbufLoader  *gdkpixbufloader,
                                            gpointer arg1,
                                            gpointer user_data);
"
gdkpixbufloader.html#GDKPIXBUFLOADER-ANIMATION-DONEanimation-done "
            void        user_function      (
gdkpixbufloader.htmlGdkPixbufLoader  *gdkpixbufloader,
                                            gpointer user_data);
"
gdkpixbufloader.html#GDKPIXBUFLOADER-CLOSEDclosed "    void        user_function      ( gdkpixbufloader.htmlGdkPixbufLoader  *gdkpixbufloader,
                                            gpointer user_data);
Description
    gdkpixbufloader.htmlGdkPixbufLoader  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-file-loading.html#GDK-PIXBUF-NEW-FROM-FILEgdk_pixbuf_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.
  
    To use gdkpixbufloader.htmlGdkPixbufLoader  to load an image, just create a new one,
    and call 
gdkpixbufloader.html#GDK-PIXBUF-LOADER-WRITEgdk_pixbuf_loader_write () to send the data to it.  When
    done, 
gdkpixbufloader.html#GDK-PIXBUF-LOADER-CLOSEgdk_pixbuf_loader_close () should be called to end the stream
    and finalize everything.  The loader will emit two important
    signals throughout the process.  The first, "
gdkpixbufloader.html#GDKPIXBUFLOADER-AREA-PREPAREDarea_prepared ",
    will be called as soon as the image has enough information to
    determine the size of the image to be used.  It will pass a
    
GdkPixbuf in.  If you want to use it, you can 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 the
    
gdkpixbufloader.html#GDK-PIXBUF-LOADER-GET-PIXBUFgdk_pixbuf_loader_get_pixbuf () once this signal has been emitted
    and get the same pixbuf.
  
    The other signal, " gdkpixbufloader.html#GDKPIXBUFLOADER-AREA-UPDATEDarea_updated " 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.
  
Loading an animation
      Loading an animation is a little more complex then loading an
      image.  In addition to the above signals, there is also a "
gdkpixbufloader.html#GDKPIXBUFLOADER-FRAME-DONEframe_done " signal,
      as well as an "
gdkpixbufloader.html#GDKPIXBUFLOADER-ANIMATION-DONEanimation_done "
      signal.  The first lets the application know that it is dealing
      with an animation, instead of a static image.  It also passes a
      GdkPixbufFrame in the signal.  As before, if you want to keep
      the frame, you need to ref it.  Once the first "
gdkpixbufloader.html#GDKPIXBUFLOADER-FRAME-DONEframe_done " signal
      has been emitted, you can call 
gdkpixbufloader.html#GDK-PIXBUF-LOADER-GET-ANIMATIONgdk_pixbuf_loader_get_animation ()
      to get the GdkPixbufAnimation struct.  Each subsequent frame
      goes through a similar lifecycle.  For example "
gdkpixbufloader.html#GDKPIXBUFLOADER-AREA-PREPAREDarea_prepared " is
      re-emitted.  Then "
gdkpixbufloader.html#GDKPIXBUFLOADER-AREA-UPDATEDarea_updated " is
      emitted as many times as necessary.  Finally, "
gdkpixbufloader.html#GDKPIXBUFLOADER-ANIMATION-DONEanimation_done "
      is emitted as soon as all frames are done.
    
Details
GDK_PIXBUF_LOADER()
#define GDK_PIXBUF_LOADER(obj)		   (GTK_CHECK_CAST ((obj), GDK_TYPE_PIXBUF_LOADER, GdkPixbufLoader))     Casts a GtkObject to a gdkpixbufloader.htmlGdkPixbufLoader .
  
obj : A GTK+ object.

gdk_pixbuf_loader_new ()
gdkpixbufloader.htmlGdkPixbufLoader * gdk_pixbuf_loader_new      (void); Creates a new pixbuf loader object.
Returns :  A newly-created pixbuf loader. 
gdk_pixbuf_loader_write ()
gboolean    gdk_pixbuf_loader_write         ( gdkpixbufloader.htmlGdkPixbufLoader  *loader,
                                             const guchar *buf,
                                             size_t count);
This will cause a pixbuf loader to parse the next count bytes of 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.
loader :  A pixbuf loader. buf :  Pointer to image data. count :  Length of the buf buffer in bytes. Returns :  TRUE if the write was successful, or FALSE if the loader
cannot parse the buffer.
gdk_pixbuf_loader_get_pixbuf ()
GdkPixbuf*  gdk_pixbuf_loader_get_pixbuf    ( gdkpixbufloader.htmlGdkPixbufLoader  *loader); Queries the GdkPixbuf that a pixbuf loader is currently creating.  In general
it only makes sense to call this function afer the "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 
gdkpixbufloader.html#GDK-PIXBUF-LOADER-WRITEgdk_pixbuf_loader_write (), then this function returns NULL.
The returned pixbuf will be the same in all future calls to the loader, so
simply calling 
gdk-pixbuf-refcounting.html#GDK-PIXBUF-REFgdk_pixbuf_ref () should be sufficient to continue using it.  Additionally,
if the loader is an animation, it will return the first frame of the animation.
loader :  A pixbuf loader. Returns :  The GdkPixbuf that the loader is creating, or NULL if not
enough data has been read to determine how to create the image buffer.
gdk_pixbuf_loader_get_animation ()
GdkPixbufAnimation* gdk_pixbuf_loader_get_animation
                                            (
gdkpixbufloader.htmlGdkPixbufLoader  *loader); Queries the GdkPixbufAnimation that a pixbuf loader is currently creating.
In general it only makes sense to call this function afer the "area_prepared"
signal has been emitted by the loader.  If the image is not an animation,
then it will return 
NULL.
loader :  A pixbuf loader Returns :  The GdkPixbufAnimation that the loader is loading, or NULL if
not enough data has been read to determine the information.
gdk_pixbuf_loader_close ()
void        gdk_pixbuf_loader_close         ( gdkpixbufloader.htmlGdkPixbufLoader  *loader); Informs a pixbuf loader that no further writes with gdk_pixbuf_load_write()
will occur, so that it can free its internal loading structures.
loader :  A pixbuf loader. 
Signals
The "area-updated" signal
void        user_function                  ( gdkpixbufloader.htmlGdkPixbufLoader  *gdkpixbufloader,
                                            gint arg1,
                                            gint arg2,
                                            gint arg3,
                                            gint arg4,
                                            gpointer user_data);
    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.
  
gdkpixbufloader : the object which received the signal. arg1 :  arg2 :  arg3 :  arg4 :  user_data : user data set when the signal handler was connected. 
The "area-prepared" signal
void        user_function                  ( gdkpixbufloader.htmlGdkPixbufLoader  *gdkpixbufloader,
                                            gpointer user_data);
    This signal is emitted when the pixbuf loader has been fed the
    initial amount of data that is required to figure out the size and
    format of the image that it will create.  After this signal is
    emitted, applications can call 
gdkpixbufloader.html#GDK-PIXBUF-LOADER-GET-PIXBUFgdk_pixbuf_loader_get_pixbuf () to
    fetch the partially-loaded pixbuf.
  
gdkpixbufloader : the object which received the signal. user_data : user data set when the signal handler was connected. 
The "frame-done" signal
void        user_function                  ( gdkpixbufloader.htmlGdkPixbufLoader  *gdkpixbufloader,
                                            gpointer arg1,
                                            gpointer user_data);
    This signal is emitted when a frame is done loading.  It will be
    emitted for each frame in an animation data stream.
  
gdkpixbufloader : the object which received the signal. arg1 :  user_data : user data set when the signal handler was connected. 
The "animation-done" signal
void        user_function                  ( gdkpixbufloader.htmlGdkPixbufLoader  *gdkpixbufloader,
                                            gpointer user_data);
    This signal is emitted when an animation is done loading.
  
gdkpixbufloader : the object which received the signal. user_data : user data set when the signal handler was connected. 
The "closed" signal
void        user_function                  ( gdkpixbufloader.htmlGdkPixbufLoader  *gdkpixbufloader,
                                            gpointer user_data);
    This signal is emitted when gdkpixbufloader.html#GDK-PIXBUF-LOADER-CLOSEgdk_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.
  
gdkpixbufloader : the object which received the signal. user_data : user data set when the signal handler was connected. 
See Also
    gdk-pixbuf-file-loading.html#GDK-PIXBUF-NEW-FROM-FILEgdk_pixbuf_new_from_file ()
  
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