GdkPixbuf.PixbufLoader¶

Subclasses:: None

Methods¶

Inherited:: GObject.Object (37)
Structs:: GObject.ObjectClass (5)

class	`new` ()
class	`new_with_mime_type` (mime_type)
class	`new_with_type` (image_type)
	`close` ()
	`get_animation` ()
	`get_format` ()
	`get_pixbuf` ()
	`set_size` (width, height)
	`write` (buf)
	`write_bytes` (buffer)

Virtual Methods¶

Inherited:: GObject.Object (7)

	`do_area_prepared` ()
	`do_area_updated` (x, y, width, height)
	`do_closed` ()
	`do_size_prepared` (width, height)

Properties¶

None

Signals¶

Inherited:: GObject.Object (1)

Name	Short Description
`area-prepared`	This signal is emitted when the pixbuf loader has allocated the pixbuf in the desired size.
`area-updated`	This signal is emitted when a significant area of the image being loaded has been updated.
`closed`	This signal is emitted when `GdkPixbuf.PixbufLoader.close`() is called.
`size-prepared`	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.

Fields¶

Inherited:: GObject.Object (1)

Name	Type	Access	Description
parent_instance	`GObject.Object`	r
priv	`object`	r

Class Details¶

class GdkPixbuf.PixbufLoader(**kwargs)¶

Bases:: GObject.Object
Abstract:: No
Structure:: GdkPixbuf.PixbufLoaderClass

Incremental image loader.

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.

To use GdkPixbufLoader to load an image, create a new instance, and call [method`GdkPixbuf`.PixbufLoader.write] to send the data to it. When done, [method`GdkPixbuf`.PixbufLoader.close] should be called to end the stream and finalize everything.

The loader will emit three important signals throughout the process:

[signal`GdkPixbuf`.PixbufLoader::size-prepared] will be emitted 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 [method`GdkPixbuf`.PixbufLoader.set_size] in response to this signal.
[signal`GdkPixbuf`.PixbufLoader::area-prepared] will be emitted as soon as the pixbuf of the desired has been allocated. You can obtain the GdkPixbuf instance by calling [method`GdkPixbuf`.PixbufLoader.get_pixbuf]. If you want to use it, simply acquire a reference to it. You can also call gdk_pixbuf_loader_get_pixbuf() later to get the same pixbuf.
[signal`GdkPixbuf`.PixbufLoader::area-updated] will be emitted 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 updated area. For example, in an interlaced image you will need to make several passes before the image is done loading.

Loading an animation

Loading an animation is almost as easy as loading an image. Once the first [signal`GdkPixbuf`.PixbufLoader::area-prepared] signal has been emitted, you can call [method`GdkPixbuf`.PixbufLoader.get_animation] to get the [class`GdkPixbuf`.PixbufAnimation] instance, and then call and [method`GdkPixbuf`.PixbufAnimation.get_iter] to get a [class`GdkPixbuf`.PixbufAnimationIter] to retrieve the pixbuf for the desired time stamp.

classmethod new()¶

Returns:: A newly-created pixbuf loader.
Return type:: GdkPixbuf.PixbufLoader

Creates a new pixbuf loader object.

classmethod new_with_mime_type(mime_type)¶

Parameters:: mime_type (str) – the mime type to be loaded
Raises:: GLib.Error
Returns:: A newly-created pixbuf loader.
Return type:: GdkPixbuf.PixbufLoader

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.

This function is 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 GdkPixbuf.PixbufFormat.get_mime_types() on each of the GdkPixbuf.PixbufFormat structs returned by GdkPixbuf.Pixbuf.get_formats().

New in version 2.4.

classmethod new_with_type(image_type)¶

Parameters:: image_type (str) – name of the image format to be loaded with the image
Raises:: GLib.Error
Returns:: A newly-created pixbuf loader.
Return type:: GdkPixbuf.PixbufLoader

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.

This function is 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 GdkPixbuf.PixbufFormat.get_name() on each of the GdkPixbuf.PixbufFormat structs returned by GdkPixbuf.Pixbuf.get_formats().

close()¶

Raises:: GLib.Error
Returns:: TRUE if all image data written so far was successfully passed out via the update_area signal
Return type:: bool

Informs a pixbuf loader that no further writes with GdkPixbuf.PixbufLoader.write() will occur, so that it can free its internal loading structures.

This function 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.

Remember that this function does not release a reference on the loader, so you will need to explicitly release any reference you hold.

get_animation()¶

Returns:: The animation that the loader is currently loading
Return type:: GdkPixbuf.PixbufAnimation or None

Queries the GdkPixbuf.PixbufAnimation that a pixbuf loader is currently creating.

In general it only makes sense to call this function after the [signal`GdkPixbuf`.PixbufLoader::area-prepared] signal has been emitted by the loader.

If the loader doesn’t have enough bytes yet, and hasn’t emitted the area-prepared signal, this function will return NULL.

get_format()¶

Returns:: A GdkPixbuf.PixbufFormat
Return type:: GdkPixbuf.PixbufFormat or None

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

New in version 2.2.

get_pixbuf()¶

Returns:: The pixbuf that the loader is creating
Return type:: GdkPixbuf.Pixbuf or None

Queries the GdkPixbuf.Pixbuf that a pixbuf loader is currently creating.

In general it only makes sense to call this function after the [signal`GdkPixbuf`.PixbufLoader::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 GdkPixbuf.PixbufLoader.write(), then this function returns NULL.

The returned pixbuf will be the same in all future calls to the loader, so if you want to keep using it, you should acquire a reference to it.

Additionally, if the loader is an animation, it will return the “static image” of the animation (see GdkPixbuf.PixbufAnimation.get_static_image()).

set_size(width, height)¶

Parameters:

width (int) – The desired width of the image being loaded.
height (int) – The desired height of the image being loaded.

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 GdkPixbuf.PixbufLoader.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.

New in version 2.2.

write(buf)¶

Parameters:: buf (bytes) – Pointer to image data.
Raises:: GLib.Error
Returns:: TRUE if the write was successful, or FALSE if the loader cannot parse the buffer
Return type:: bool

Parses the next count bytes in the given image buffer.

write_bytes(buffer)¶

Parameters:: buffer (GLib.Bytes) – The image data as a GBytes buffer.
Raises:: GLib.Error
Returns:: TRUE if the write was successful, or FALSE if the loader cannot parse the buffer
Return type:: bool

Parses the next contents of the given image buffer.

New in version 2.30.

do_area_prepared() virtual¶

do_area_updated(x, y, width, height) virtual¶

Parameters:

x (int) –
y (int) –
width (int) –
height (int) –

do_closed() virtual¶

do_size_prepared(width, height) virtual¶

Parameters:

width (int) –
height (int) –

Signal Details¶

GdkPixbuf.PixbufLoader.signals.area_prepared(pixbuf_loader)¶

Signal Name:: area-prepared
Flags:: RUN_LAST
Parameters:: pixbuf_loader (GdkPixbuf.PixbufLoader) – The object which received the signal

This signal is emitted when the pixbuf loader has allocated the pixbuf in the desired size.

After this signal is emitted, applications can call GdkPixbuf.PixbufLoader.get_pixbuf() to fetch the partially-loaded pixbuf.

GdkPixbuf.PixbufLoader.signals.area_updated(pixbuf_loader, x, y, width, height)¶

Signal Name:

area-updated

Flags:

RUN_LAST

Parameters:

pixbuf_loader (GdkPixbuf.PixbufLoader) – The object which received the signal
x (int) – X offset of upper-left corner of the updated area.
y (int) – Y offset of upper-left corner of the updated area.
width (int) – Width of updated area.
height (int) – Height of updated area.

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.

GdkPixbuf.PixbufLoader.signals.closed(pixbuf_loader)¶

Signal Name:: closed
Flags:: RUN_LAST
Parameters:: pixbuf_loader (GdkPixbuf.PixbufLoader) – The object which received the signal

This signal is emitted when GdkPixbuf.PixbufLoader.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.

GdkPixbuf.PixbufLoader.signals.size_prepared(pixbuf_loader, width, height)¶

Signal Name:

size-prepared

Flags:

RUN_LAST

Parameters:

pixbuf_loader (GdkPixbuf.PixbufLoader) – The object which received the signal
width (int) – the original width of the image
height (int) – the original height of the image

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 GdkPixbuf.PixbufLoader.set_size() in response to this signal to set the desired size to which the image should be scaled.