GdkPixbufLoader {RGtk2} | R Documentation

## GdkPixbufLoader

### Description

Application-driven progressive image loading.

### Methods and Functions

`gdkPixbufLoaderNew()`
`gdkPixbufLoaderNewWithType(image.type, .errwarn = TRUE)`
`gdkPixbufLoaderNewWithMimeType(mime.type, .errwarn = TRUE)`
`gdkPixbufLoaderGetFormat(object)`
`gdkPixbufLoaderWrite(object, buf, .errwarn = TRUE)`
`gdkPixbufLoaderSetSize(object, width, height)`
`gdkPixbufLoaderGetPixbuf(object)`
`gdkPixbufLoaderGetAnimation(object)`
`gdkPixbufLoaderClose(object, .errwarn = TRUE)`
`gdkPixbufLoader(image.type, mime.type, .errwarn = TRUE)`

### Hierarchy

    GObject
       +----GdkPixbufLoader

### Detailed Description

`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 `gdkPixbufNewFromFile` or `gdkPixbufAnimationNewFromFile` 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, just create a new one, and call `gdkPixbufLoaderWrite` to send the data to it. When done, `gdkPixbufLoaderClose` should be called to end the stream and finalize everything. The loader will emit three important signals throughout the process. The first, "size_prepared", 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 `gdkPixbufLoaderSetSize` in response to this signal. The second signal, "area_prepared", will be called as soon as the pixbuf of the desired has been allocated. You can obtain it by calling `gdkPixbufLoaderGetPixbuf`. 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 `gdkPixbufLoaderGetPixbuf` later and get the same pixbuf.

The last signal, "area_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 almost as easy as loading an image. Once the first "area_prepared" signal has been emitted, you can call `gdkPixbufLoaderGetAnimation` to get the `GdkPixbufAnimation` struct and `gdkPixbufAnimationGetIter` to get an `GdkPixbufAnimationIter` for displaying it.

### Structures

`GdkPixbufLoader`

  The `GdkPixbufLoader` struct contains only private fields.

### Convenient Construction

`gdkPixbufLoader` is the result of collapsing the constructors of `GdkPixbufLoader` (`gdkPixbufLoaderNew`, `gdkPixbufLoaderNewWithType`, `gdkPixbufLoaderNewWithMimeType`) and accepts a subset of its arguments matching the required arguments of one of its delegate constructors.

### Signals

`area-prepared(loader, user.data)`

  This signal is emitted when the pixbuf loader has allocated the pixbuf in the desired size. After this signal is emitted, applications can call `gdkPixbufLoaderGetPixbuf` to fetch the partially-loaded pixbuf.

  `loader`

    the object which received the signal.

  `user.data`

    user data set when the signal handler was connected.

`area-updated(loader, x, y, width, height, 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.

  `loader`

    the object which received the signal.

  `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.

  `user.data`

    user data set when the signal handler was connected.

`closed(loader, user.data)`

  This signal is emitted when `gdkPixbufLoaderClose` 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.

  `loader`

    the object which received the signal.

  `user.data`

    user data set when the signal handler was connected.

`size-prepared(loader, width, height, 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 of the image that it will create. Applications can call `gdkPixbufLoaderSetSize` in response to this signal to set the desired size to which the image should be scaled.

  `loader`

    the object which received the signal.

  `width`

    the original width of the image

  `height`

    the original height of the image

  `user.data`

    user data set when the signal handler was connected.

### Author(s)

Derived by RGtkGen from GTK+ documentation

### References

https://developer.gnome.org/gdk-pixbuf/stable/GdkPixbufLoader.html

[Package RGtk2 version 2.20.36.3 Index]