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# QImageIOHandler Class Reference
[com.trolltech.qt.gui module]

The `QImageIOHandler` class defines the common image I/O interface for all image formats in Qt. More...

## Detailed Description

The `QImageIOHandler` class defines the common image I/O interface for all image formats in Qt.

Qt uses `QImageIOHandler` for reading and writing images through `QImageReader` and `QImageWriter`. You can also derive from this class to write your own image format handler using Qt's plugin mechanism.

Call `setDevice` to assign a device to the handler, and `setFormat` to assign a format to it. One `QImageIOHandler` may support more than one image format. `canRead` returns true if an image can be read from the device, and `read` and `write` return true if reading or writing an image was completed successfully.

`QImageIOHandler` also has support for animations formats, through the functions `loopCount`, `imageCount`, `nextImageDelay` and `currentImageNumber`.

In order to determine what options an image handler supports, Qt will call `supportsOption` and `setOption`. Make sure to reimplement these functions if you can provide support for any of the options in the `ImageOption` enum.

To write your own image handler, you must at least reimplement `canRead` and `read`. Then create a QImageIOPlugin that can create the handler. Finally, install your plugin, and `QImageReader` and `QImageWriter` will then automatically load the plugin, and start using it.

See also `QImageIOPlugin`, `QImageReader`, and `QImageWriter`.