Loading an animation

Loading an animation is almost as easy as loading an image. Once the first "area_prepared" 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.

GdkPixbufLoader

typedef struct _GdkPixbufLoader GdkPixbufLoader;

The GdkPixbufLoader struct contains only private fields.

gdk_pixbuf_loader_new ()

GdkPixbufLoader*    gdk_pixbuf_loader_new               (void);

Creates a new pixbuf loader object.

gdk_pixbuf_loader_new_with_type ()

GdkPixbufLoader*    gdk_pixbuf_loader_new_with_type     (const char *image_type,
                                                         GError **error);

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.

The list of supported image formats depends on what image loaders are installed, but typically "png", "jpeg", "gif", "tiff" and "xpm" are among the supported formats. To obtain the full list of supported image formats, call gdk_pixbuf_format_get_name() on each of the GdkPixbufFormat structs returned by gdk_pixbuf_get_formats().

gdk_pixbuf_loader_new_with_mime_type ()

GdkPixbufLoader*    gdk_pixbuf_loader_new_with_mime_type
                                                        (const char *mime_type,
                                                         GError **error);

Creates a new pixbuf loader object that always attempts to parse image data as if it were an image of mime type mime_type, instead of identifying the type automatically. Useful if you want an error if the image isn't the expected mime type, for loading image formats that can't be reliably identified by looking at the data, or if the user manually forces a specific mime type.

The list of supported mime types depends on what image loaders are installed, but typically "image/png", "image/jpeg", "image/gif", "image/tiff" and "image/x-xpixmap" are among the supported mime types. To obtain the full list of supported mime types, call gdk_pixbuf_format_get_mime_types() on each of the GdkPixbufFormat structs returned by gdk_pixbuf_get_formats().

Since 2.4

gdk_pixbuf_loader_get_format ()

GdkPixbufFormat*    gdk_pixbuf_loader_get_format        (GdkPixbufLoader *loader);

Obtains the available information about the format of the currently loading image file.

Since 2.2

gdk_pixbuf_loader_write ()

gboolean            gdk_pixbuf_loader_write             (GdkPixbufLoader *loader,
                                                         const guchar *buf,
                                                         gsize count,
                                                         GError **error);

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. If FALSE is returned, error will be set to an error from the GDK_PIXBUF_ERROR or G_FILE_ERROR domains.

gdk_pixbuf_loader_set_size ()

void                gdk_pixbuf_loader_set_size          (GdkPixbufLoader *loader,
                                                         int width,
                                                         int height);

Causes the image to be scaled while it is loaded. The desired image size can be determined relative to the original size of the image by calling gdk_pixbuf_loader_set_size() from a signal handler for the ::size_prepared signal.

Attempts to set the desired image size are ignored after the emission of the ::size_prepared signal.

Since 2.2

gdk_pixbuf_loader_get_pixbuf ()

GdkPixbuf*          gdk_pixbuf_loader_get_pixbuf        (GdkPixbufLoader *loader);

Queries the GdkPixbuf that a pixbuf loader is currently creating. In general it only makes sense to call this function after 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 gdk_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 g_object_ref() should be sufficient to continue using it. Additionally, if the loader is an animation, it will return the "static image" of the animation (see gdk_pixbuf_animation_get_static_image()).

gdk_pixbuf_loader_get_animation ()

GdkPixbufAnimation* gdk_pixbuf_loader_get_animation     (GdkPixbufLoader *loader);

Queries the GdkPixbufAnimation that a pixbuf loader is currently creating. In general it only makes sense to call this function after the "area_prepared" signal has been emitted by the loader. If the loader doesn't have enough bytes yet (hasn't emitted the "area_prepared" signal) this function will return NULL.

gdk_pixbuf_loader_close ()

gboolean            gdk_pixbuf_loader_close             (GdkPixbufLoader *loader,
                                                         GError **error);

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 corrupt, an error will be returned. If FALSE is returned, error 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.

The "area-prepared" signal

void                user_function                      (GdkPixbufLoader *loader,
                                                        gpointer         user_data)      : Run Last

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.

The "area-updated" signal

void                user_function                      (GdkPixbufLoader *loader,
                                                        gint             x,
                                                        gint             y,
                                                        gint             width,
                                                        gint             height,
                                                        gpointer         user_data)      : Run Last

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.

The "closed" signal

void                user_function                      (GdkPixbufLoader *loader,
                                                        gpointer         user_data)      : Run Last

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.

The "size-prepared" signal

void                user_function                      (GdkPixbufLoader *loader,
                                                        gint             width,
                                                        gint             height,
                                                        gpointer         user_data)      : Run Last

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.