| Copyright | Will Thompson and Iñaki García Etxebarria |
|---|---|
| License | LGPL-2.1 |
| Maintainer | Iñaki García Etxebarria |
| Safe Haskell | Safe-Inferred |
| Language | Haskell2010 |
GI.GdkPixbuf.Objects.PixbufLoader
Description
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 pixbufLoaderWrite to send the data
to it. When done, pixbufLoaderClose should be
called to end the stream and finalize everything.
The loader will emit three important signals throughout the process:
- PixbufLoader::sizePrepared 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
pixbufLoaderSetSizein response to this signal. - PixbufLoader::areaPrepared will be emitted as
soon as the pixbuf of the desired has been allocated. You can obtain
the
GdkPixbufinstance by callingpixbufLoaderGetPixbuf. If you want to use it, simply acquire a reference to it. You can also callgdk_pixbuf_loader_get_pixbuf()later to get the same pixbuf. - PixbufLoader::areaUpdated 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 PixbufLoader::areaPrepared signal has been
emitted, you can call pixbufLoaderGetAnimation to
get the PixbufAnimation instance, and then call
and pixbufAnimationGetIter to get a
PixbufAnimationIter to retrieve the pixbuf for the
desired time stamp.
Synopsis
- newtype PixbufLoader = PixbufLoader (ManagedPtr PixbufLoader)
- class (GObject o, IsDescendantOf PixbufLoader o) => IsPixbufLoader o
- toPixbufLoader :: (MonadIO m, IsPixbufLoader o) => o -> m PixbufLoader
- pixbufLoaderClose :: (HasCallStack, MonadIO m, IsPixbufLoader a) => a -> m ()
- pixbufLoaderGetAnimation :: (HasCallStack, MonadIO m, IsPixbufLoader a) => a -> m (Maybe PixbufAnimation)
- pixbufLoaderGetFormat :: (HasCallStack, MonadIO m, IsPixbufLoader a) => a -> m (Maybe PixbufFormat)
- pixbufLoaderGetPixbuf :: (HasCallStack, MonadIO m, IsPixbufLoader a) => a -> m (Maybe Pixbuf)
- pixbufLoaderNew :: (HasCallStack, MonadIO m) => m PixbufLoader
- pixbufLoaderNewWithMimeType :: (HasCallStack, MonadIO m) => Text -> m PixbufLoader
- pixbufLoaderNewWithType :: (HasCallStack, MonadIO m) => Text -> m PixbufLoader
- pixbufLoaderSetSize :: (HasCallStack, MonadIO m, IsPixbufLoader a) => a -> Int32 -> Int32 -> m ()
- pixbufLoaderWrite :: (HasCallStack, MonadIO m, IsPixbufLoader a) => a -> ByteString -> m ()
- pixbufLoaderWriteBytes :: (HasCallStack, MonadIO m, IsPixbufLoader a) => a -> Bytes -> m ()
- type PixbufLoaderAreaPreparedCallback = IO ()
- afterPixbufLoaderAreaPrepared :: (IsPixbufLoader a, MonadIO m) => a -> ((?self :: a) => PixbufLoaderAreaPreparedCallback) -> m SignalHandlerId
- onPixbufLoaderAreaPrepared :: (IsPixbufLoader a, MonadIO m) => a -> ((?self :: a) => PixbufLoaderAreaPreparedCallback) -> m SignalHandlerId
- type PixbufLoaderAreaUpdatedCallback = Int32 -> Int32 -> Int32 -> Int32 -> IO ()
- afterPixbufLoaderAreaUpdated :: (IsPixbufLoader a, MonadIO m) => a -> ((?self :: a) => PixbufLoaderAreaUpdatedCallback) -> m SignalHandlerId
- onPixbufLoaderAreaUpdated :: (IsPixbufLoader a, MonadIO m) => a -> ((?self :: a) => PixbufLoaderAreaUpdatedCallback) -> m SignalHandlerId
- type PixbufLoaderClosedCallback = IO ()
- afterPixbufLoaderClosed :: (IsPixbufLoader a, MonadIO m) => a -> ((?self :: a) => PixbufLoaderClosedCallback) -> m SignalHandlerId
- onPixbufLoaderClosed :: (IsPixbufLoader a, MonadIO m) => a -> ((?self :: a) => PixbufLoaderClosedCallback) -> m SignalHandlerId
- type PixbufLoaderSizePreparedCallback = Int32 -> Int32 -> IO ()
- afterPixbufLoaderSizePrepared :: (IsPixbufLoader a, MonadIO m) => a -> ((?self :: a) => PixbufLoaderSizePreparedCallback) -> m SignalHandlerId
- onPixbufLoaderSizePrepared :: (IsPixbufLoader a, MonadIO m) => a -> ((?self :: a) => PixbufLoaderSizePreparedCallback) -> m SignalHandlerId
Exported types
newtype PixbufLoader Source #
Memory-managed wrapper type.
Constructors
| PixbufLoader (ManagedPtr PixbufLoader) |
Instances
| Eq PixbufLoader Source # | |
Defined in GI.GdkPixbuf.Objects.PixbufLoader | |
| GObject PixbufLoader Source # | |
Defined in GI.GdkPixbuf.Objects.PixbufLoader | |
| ManagedPtrNewtype PixbufLoader Source # | |
Defined in GI.GdkPixbuf.Objects.PixbufLoader Methods toManagedPtr :: PixbufLoader -> ManagedPtr PixbufLoader | |
| TypedObject PixbufLoader Source # | |
Defined in GI.GdkPixbuf.Objects.PixbufLoader | |
| HasParentTypes PixbufLoader Source # | |
Defined in GI.GdkPixbuf.Objects.PixbufLoader | |
| IsGValue (Maybe PixbufLoader) Source # | Convert |
Defined in GI.GdkPixbuf.Objects.PixbufLoader Methods gvalueGType_ :: IO GType gvalueSet_ :: Ptr GValue -> Maybe PixbufLoader -> IO () gvalueGet_ :: Ptr GValue -> IO (Maybe PixbufLoader) | |
| type ParentTypes PixbufLoader Source # | |
Defined in GI.GdkPixbuf.Objects.PixbufLoader type ParentTypes PixbufLoader = '[Object] | |
class (GObject o, IsDescendantOf PixbufLoader o) => IsPixbufLoader o Source #
Type class for types which can be safely cast to PixbufLoader, for instance with toPixbufLoader.
Instances
| (GObject o, IsDescendantOf PixbufLoader o) => IsPixbufLoader o Source # | |
Defined in GI.GdkPixbuf.Objects.PixbufLoader | |
toPixbufLoader :: (MonadIO m, IsPixbufLoader o) => o -> m PixbufLoader Source #
Cast to PixbufLoader, for types for which this is known to be safe. For general casts, use castTo.
Methods
Click to display all available methods, including inherited ones
Methods
bindProperty, bindPropertyFull, close, forceFloating, freezeNotify, getv, isFloating, notify, notifyByPspec, ref, refSink, runDispose, stealData, stealQdata, thawNotify, unref, watchClosure, write, writeBytes.
Getters
getAnimation, getData, getFormat, getPixbuf, getProperty, getQdata.
Setters
close
Arguments
| :: (HasCallStack, MonadIO m, IsPixbufLoader a) | |
| => a |
|
| -> m () | (Can throw |
Informs a pixbuf loader that no further writes with
pixbufLoaderWrite 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.
getAnimation
pixbufLoaderGetAnimation Source #
Arguments
| :: (HasCallStack, MonadIO m, IsPixbufLoader a) | |
| => a |
|
| -> m (Maybe PixbufAnimation) | Returns: The animation that the loader is currently loading |
Queries the PixbufAnimation that a pixbuf loader is currently creating.
In general it only makes sense to call this function after the PixbufLoader::areaPrepared 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.
getFormat
pixbufLoaderGetFormat Source #
Arguments
| :: (HasCallStack, MonadIO m, IsPixbufLoader a) | |
| => a |
|
| -> m (Maybe PixbufFormat) | Returns: A |
Obtains the available information about the format of the currently loading image file.
Since: 2.2
getPixbuf
pixbufLoaderGetPixbuf Source #
Arguments
| :: (HasCallStack, MonadIO m, IsPixbufLoader a) | |
| => a |
|
| -> m (Maybe Pixbuf) | Returns: The pixbuf that the loader is creating |
Queries the Pixbuf that a pixbuf loader is currently creating.
In general it only makes sense to call this function after the PixbufLoader::areaPrepared 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 pixbufLoaderWrite,
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 pixbufAnimationGetStaticImage).
new
Arguments
| :: (HasCallStack, MonadIO m) | |
| => m PixbufLoader | Returns: A newly-created pixbuf loader. |
Creates a new pixbuf loader object.
newWithMimeType
pixbufLoaderNewWithMimeType Source #
Arguments
| :: (HasCallStack, MonadIO m) | |
| => Text |
|
| -> m PixbufLoader | Returns: A newly-created pixbuf loader. (Can throw |
Creates a new pixbuf loader object that always attempts to parse
image data as if it were an image of MIME type mimeType, 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
pixbufFormatGetMimeTypes on each of the PixbufFormat
structs returned by pixbufGetFormats.
Since: 2.4
newWithType
pixbufLoaderNewWithType Source #
Arguments
| :: (HasCallStack, MonadIO m) | |
| => Text |
|
| -> m PixbufLoader | Returns: A newly-created pixbuf loader. (Can throw |
Creates a new pixbuf loader object that always attempts to parse
image data as if it were an image of type imageType, 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 pixbufFormatGetName on each
of the PixbufFormat structs returned by pixbufGetFormats.
setSize
Arguments
| :: (HasCallStack, MonadIO m, IsPixbufLoader a) | |
| => a |
|
| -> Int32 |
|
| -> Int32 |
|
| -> m () |
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 pixbufLoaderSetSize from a
signal handler for the sizePrepared signal.
Attempts to set the desired image size are ignored after the emission of the sizePrepared signal.
Since: 2.2
write
Arguments
| :: (HasCallStack, MonadIO m, IsPixbufLoader a) | |
| => a |
|
| -> ByteString |
|
| -> m () | (Can throw |
Parses the next count bytes in the given image buffer.
writeBytes
pixbufLoaderWriteBytes Source #
Arguments
| :: (HasCallStack, MonadIO m, IsPixbufLoader a) | |
| => a |
|
| -> Bytes |
|
| -> m () | (Can throw |
Parses the next contents of the given image buffer.
Since: 2.30
Signals
areaPrepared
type PixbufLoaderAreaPreparedCallback = IO () Source #
This signal is emitted when the pixbuf loader has allocated the pixbuf in the desired size.
After this signal is emitted, applications can call
pixbufLoaderGetPixbuf to fetch the partially-loaded
pixbuf.
afterPixbufLoaderAreaPrepared :: (IsPixbufLoader a, MonadIO m) => a -> ((?self :: a) => PixbufLoaderAreaPreparedCallback) -> m SignalHandlerId Source #
Connect a signal handler for the areaPrepared signal, to be run after the default handler. When overloading is enabled, this is equivalent to
after pixbufLoader #areaPrepared callback
By default the object invoking the signal is not passed to the callback.
If you need to access it, you can use the implit ?self parameter.
Note that this requires activating the ImplicitParams GHC extension.
onPixbufLoaderAreaPrepared :: (IsPixbufLoader a, MonadIO m) => a -> ((?self :: a) => PixbufLoaderAreaPreparedCallback) -> m SignalHandlerId Source #
Connect a signal handler for the areaPrepared signal, to be run before the default handler. When overloading is enabled, this is equivalent to
on pixbufLoader #areaPrepared callback
areaUpdated
type PixbufLoaderAreaUpdatedCallback Source #
Arguments
| = Int32 |
|
| -> Int32 |
|
| -> Int32 |
|
| -> Int32 |
|
| -> IO () |
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.
afterPixbufLoaderAreaUpdated :: (IsPixbufLoader a, MonadIO m) => a -> ((?self :: a) => PixbufLoaderAreaUpdatedCallback) -> m SignalHandlerId Source #
Connect a signal handler for the areaUpdated signal, to be run after the default handler. When overloading is enabled, this is equivalent to
after pixbufLoader #areaUpdated callback
By default the object invoking the signal is not passed to the callback.
If you need to access it, you can use the implit ?self parameter.
Note that this requires activating the ImplicitParams GHC extension.
onPixbufLoaderAreaUpdated :: (IsPixbufLoader a, MonadIO m) => a -> ((?self :: a) => PixbufLoaderAreaUpdatedCallback) -> m SignalHandlerId Source #
Connect a signal handler for the areaUpdated signal, to be run before the default handler. When overloading is enabled, this is equivalent to
on pixbufLoader #areaUpdated callback
closed
type PixbufLoaderClosedCallback = IO () Source #
This signal is emitted when pixbufLoaderClose 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.
afterPixbufLoaderClosed :: (IsPixbufLoader a, MonadIO m) => a -> ((?self :: a) => PixbufLoaderClosedCallback) -> m SignalHandlerId Source #
Connect a signal handler for the closed signal, to be run after the default handler. When overloading is enabled, this is equivalent to
after pixbufLoader #closed callback
By default the object invoking the signal is not passed to the callback.
If you need to access it, you can use the implit ?self parameter.
Note that this requires activating the ImplicitParams GHC extension.
onPixbufLoaderClosed :: (IsPixbufLoader a, MonadIO m) => a -> ((?self :: a) => PixbufLoaderClosedCallback) -> m SignalHandlerId Source #
Connect a signal handler for the closed signal, to be run before the default handler. When overloading is enabled, this is equivalent to
on pixbufLoader #closed callback
sizePrepared
type PixbufLoaderSizePreparedCallback Source #
Arguments
| = Int32 |
|
| -> Int32 |
|
| -> IO () |
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 pixbufLoaderSetSize in response
to this signal to set the desired size to which the image
should be scaled.
afterPixbufLoaderSizePrepared :: (IsPixbufLoader a, MonadIO m) => a -> ((?self :: a) => PixbufLoaderSizePreparedCallback) -> m SignalHandlerId Source #
Connect a signal handler for the sizePrepared signal, to be run after the default handler. When overloading is enabled, this is equivalent to
after pixbufLoader #sizePrepared callback
By default the object invoking the signal is not passed to the callback.
If you need to access it, you can use the implit ?self parameter.
Note that this requires activating the ImplicitParams GHC extension.
onPixbufLoaderSizePrepared :: (IsPixbufLoader a, MonadIO m) => a -> ((?self :: a) => PixbufLoaderSizePreparedCallback) -> m SignalHandlerId Source #
Connect a signal handler for the sizePrepared signal, to be run before the default handler. When overloading is enabled, this is equivalent to
on pixbufLoader #sizePrepared callback