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## com.trolltech.qt.gui
Class QImageWriter

    java.lang.Object
      com.trolltech.qt.internal.QSignalEmitterInternal
          com.trolltech.qt.QSignalEmitter
              com.trolltech.qt.QtJambiObject
                  com.trolltech.qt.gui.QImageWriter

All Implemented Interfaces:
  QtJambiInterface

    public class QImageWriter

extends QtJambiObject

The `QImageWriter` class provides a format independent interface for writing images to files or other devices. `QImageWriter` supports setting format specific options, such as the gamma level, compression level and quality, prior to storing the image. If you do not need such options, you can use `QImage::save()` or `QPixmap::save()` instead.

To store an image, you start by constructing a `QImageWriter` object. Pass either a file name or a device pointer, and the image format to `QImageWriter`'s constructor. You can then set several options, such as the gamma level (by calling `setGamma()`) and quality (by calling `setQuality()`). `canWrite()` returns true if `QImageWriter` can write the image (i.e., the image format is supported and the device is open for writing). Call `write()` to write the image to the device.

If any error occurs when writing the image, `write()` will return false. You can then call `error()` to find the type of error that occurred, or `errorString()` to get a human readable description of what went wrong.

Call `supportedImageFormats()` for a list of formats that `QImageWriter` can write. `QImageWriter` supports all built-in image formats, in addition to any image format plugins that support writing.

See also:
  `QImageReader`, `QImageIOHandler`, and `QImageIOPlugin`.

Nested Class Summary
`static class` | `QImageWriter.ImageWriterError` This enum describes errors that can occur when writing images with `QImageWriter`.

Nested classes/interfaces inherited from class com.trolltech.qt.QSignalEmitter
`QSignalEmitter.AbstractSignal, QSignalEmitter.Signal0, QSignalEmitter.Signal1, QSignalEmitter.Signal2, QSignalEmitter.Signal3, QSignalEmitter.Signal4, QSignalEmitter.Signal5, QSignalEmitter.Signal6, QSignalEmitter.Signal7, QSignalEmitter.Signal8, QSignalEmitter.Signal9`

Nested classes/interfaces inherited from class com.trolltech.qt.internal.QSignalEmitterInternal
`com.trolltech.qt.internal.QSignalEmitterInternal.AbstractSignalInternal`

Field Summary

Fields inherited from class com.trolltech.qt.internal.QSignalEmitterInternal
`currentSender`

Constructor Summary
`QImageWriter()` Constructs an empty `QImageWriter` object.
`QImageWriter(QIODevice device, QByteArray format)` Constructs a `QImageWriter` object using the device `device` and image format `format`.
`QImageWriter(java.lang.String fileName)` Constructs a `QImageWriter` objects that will write to a file with the name `fileName`, using the image format `format`.
`QImageWriter(java.lang.String fileName, QByteArray format)` Constructs a `QImageWriter` objects that will write to a file with the name `fileName`, using the image format `format`.

Method Summary
`boolean` | `canWrite()` Returns true if `QImageWriter` can write the image; i.e., the image format is supported and the assigned device is open for reading.
`int` | `compression()` Returns the compression of the image.
`QIODevice` | `device()` Returns the device currently assigned to `QImageWriter`, or 0 if no device has been assigned.
`QImageWriter.ImageWriterError` | `error()` Returns the type of error that last occurred.
`java.lang.String` | `errorString()` Returns a human readable description of the last error that occurred.
`java.lang.String` | `fileName()` If the currently assigned device is a `QFile`, or if `setFileName()` has been called, this function returns the name of the file `QImageWriter` writes to.
`QByteArray` | `format()` Returns the format `QImageWriter` uses for writing images.
`float` | `gamma()` Returns the gamma level of the image.
`int` | `quality()` Returns the quality level of the image.
`void` | `setCompression(int compression)` This is an image format specific function that set the compression of an image.
`void` | `setDevice(QIODevice device)` Sets `QImageWriter`'s device to `device`.
`void` | `setFileName(java.lang.String fileName)` Sets the file name of `QImageWriter` to `fileName`.
`void` | `setFormat(QByteArray format)` Sets the format `QImageWriter` will use when writing images, to `format`.
`void` | `setGamma(float gamma)` This is an image format specific function that sets the gamma level of the image to `gamma`.
`void` | `setQuality(int quality)` This is an image format specific function that sets the quality level of the image to `quality`.
`void` | `setText(java.lang.String key, java.lang.String text)` Sets the image text associated with the key `key` to `text`.
`static java.util.List` | `supportedImageFormats()` Returns the list of image formats supported by `QImageWriter`.
`boolean` | `supportsOption(QImageIOHandler.ImageOption option)` Returns true if the writer supports `option`; otherwise returns false.
`boolean` | `write(QImage image)` Writes the image `image` to the assigned device or file name.

Methods inherited from class com.trolltech.qt.QtJambiObject
`dispose, disposed, equals, finalize, reassignNativeResources, tr, tr, tr`

Methods inherited from class com.trolltech.qt.QSignalEmitter
`blockSignals, disconnect, disconnect, signalsBlocked, signalSender, thread`

Methods inherited from class com.trolltech.qt.internal.QSignalEmitterInternal
`__qt_signalInitialization`

Methods inherited from class java.lang.Object
`clone, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

Methods inherited from interface com.trolltech.qt.QtJambiInterface
`disableGarbageCollection, nativeId, nativePointer, reenableGarbageCollection, setJavaOwnership`

Constructor Detail

### QImageWriter

    public QImageWriter()

  Constructs an empty `QImageWriter` object. Before writing, you must call `setFormat()` to set an image format, then `setDevice()` or `setFileName()`.

### QImageWriter

    public QImageWriter(QIODevice device,
                        QByteArray format)

  Constructs a `QImageWriter` object using the device `device` and image format `format`.

### QImageWriter

    public QImageWriter(java.lang.String fileName)

  Constructs a `QImageWriter` objects that will write to a file with the name `fileName`, using the image format `format`. If `format` is not provided, `QImageWriter` will detect the image format by inspecting the extension of `fileName`.

### QImageWriter

    public QImageWriter(java.lang.String fileName,
                        QByteArray format)

  Constructs a `QImageWriter` objects that will write to a file with the name `fileName`, using the image format `format`. If `format` is not provided, `QImageWriter` will detect the image format by inspecting the extension of `fileName`.

Method Detail

### canWrite

    public final boolean canWrite()

  Returns true if `QImageWriter` can write the image; i.e., the image format is supported and the assigned device is open for reading.

See also:
  `write()`, `setDevice()`, and `setFormat()`.

### compression

    public final int compression()

  Returns the compression of the image.

See also:
  `setCompression()`.

### device

    public final QIODevice device()

  Returns the device currently assigned to `QImageWriter`, or 0 if no device has been assigned.

See also:
  `setDevice()`.

### error

    public final QImageWriter.ImageWriterError error()

  Returns the type of error that last occurred.

See also:
  `ImageWriterError` , and `errorString()`.

### errorString

    public final java.lang.String errorString()

  Returns a human readable description of the last error that occurred.

See also:
  `error()`.

### fileName

    public final java.lang.String fileName()

  If the currently assigned device is a `QFile`, or if `setFileName()` has been called, this function returns the name of the file `QImageWriter` writes to. Otherwise (i.e., if no device has been assigned or the device is not a `QFile`), an empty QString is returned.

See also:
  `setFileName()`, and `setDevice()`.

### format

    public final QByteArray format()

  Returns the format `QImageWriter` uses for writing images.

See also:
  `setFormat()`.

### gamma

    public final float gamma()

  Returns the gamma level of the image.

See also:
  `setGamma()`.

### quality

    public final int quality()

  Returns the quality level of the image.

See also:
  `setQuality()`.

### setCompression

    public final void setCompression(int compression)

  This is an image format specific function that set the compression of an image. For image formats that do not support setting the compression, this value is ignored.

  The value range of `compression` depends on the image format. For example, the "tiff" format supports two values, 0(no compression) and 1(LZW-compression).

See also:
  `compression()`.

### setDevice

    public final void setDevice(QIODevice device)

  Sets `QImageWriter`'s device to `device`. If a device has already been set, the old device is removed from `QImageWriter` and is otherwise left unchanged.

  If the device is not already open, `QImageWriter` will attempt to open the device in `QIODevice::WriteOnly` mode by calling open(). Note that this does not work for certain devices, such as `QProcess`, `QTcpSocket` and `QUdpSocket`, where more logic is required to open the device.

See also:
  `device()`, and `setFileName()`.

### setFileName

    public final void setFileName(java.lang.String fileName)

  Sets the file name of `QImageWriter` to `fileName`. Internally, `QImageWriter` will create a `QFile` and open it in `QIODevice::WriteOnly` mode, and use this file when writing images.

See also:
  `fileName()`, and `setDevice()`.

### setFormat

    public final void setFormat(QByteArray format)

  Sets the format `QImageWriter` will use when writing images, to `format`. `format` is a case insensitive text string. Example:

              QImageWriter writer = new QImageWriter();
              writer.setFormat(new QByteArray("png")); // same as writer.setFormat("PNG");

  You can call `supportedImageFormats()` for the full list of formats `QImageWriter` supports.

See also:
  `format()`.

### setGamma

    public final void setGamma(float gamma)

  This is an image format specific function that sets the gamma level of the image to `gamma`. For image formats that do not support setting the gamma level, this value is ignored.

  The value range of `gamma` depends on the image format. For example, the "png" format supports a gamma range from 0.0 to 1.0.

See also:
  `gamma()`, and `quality()`.

### setQuality

    public final void setQuality(int quality)

  This is an image format specific function that sets the quality level of the image to `quality`. For image formats that do not support setting the quality, this value is ignored.

  The value range of `quality` depends on the image format. For example, the "jpeg" format supports a quality range from 0 (low quality, high compression) to 100 (high quality, low compression).

See also:
  `quality()`.

### setText

    public final void setText(java.lang.String key,
                              java.lang.String text)

  Sets the image text associated with the key `key` to `text`. This is useful for storing copyright information or other information about the image. Example:

              QImage image = new QImage("some/image.jpeg");
              QImageWriter writer = new QImageWriter("images/outimage.png", new QByteArray("png"));
              writer.setText("Author", "John Smith");
              writer.write(image);

  If you want to store a single block of data (e.g., a comment), you can pass an empty key, or use a generic key like "Description".

  The key and text will be embedded into the image data after calling `write()`.

  Support for this option is implemented through `QImageIOHandler::Description` .

See also:
  `QImage::setText()`, and `QImageReader::text()`.

### supportsOption

    public final boolean supportsOption(QImageIOHandler.ImageOption option)

  Returns true if the writer supports `option`; otherwise returns false.

  Different image formats support different options. Call this function to determine whether a certain option is supported by the current format. For example, the PNG format allows you to embed text into the image's metadata (see text()).

              QImageWriter writer = new QImageWriter(fileName);
              if (writer.supportsOption(QImageIOHandler.ImageOption.Description))
                  writer.setText("Author", "John Smith");

  Options can be tested after the writer has been associated with a format.

See also:
  `QImageReader::supportsOption()`, and `setFormat()`.

### write

    public final boolean write(QImage image)

  Writes the image `image` to the assigned device or file name. Returns true on success; otherwise returns false. If the operation fails, you can call `error()` to find the type of error that occurred, or `errorString()` to get a human readable description of the error.

See also:
  `canWrite()`, `error()`, and `errorString()`.

### supportedImageFormats

    public static java.util.List supportedImageFormats()

  Returns the list of image formats supported by `QImageWriter`.

  By default, Qt can write the following formats:

  Format | Description
  --- | ---
  BMP | Windows Bitmap
  JPG | Joint Photographic Experts Group
  JPEG | Joint Photographic Experts Group
  PNG | Portable Network Graphics
  PPM | Portable Pixmap
  TIFF | Tagged Image File Format
  XBM | X11 Bitmap
  XPM | X11 Pixmap

  Reading and writing SVG files is supported through Qt's SVG Module.

See also:
  `setFormat()`, `QImageReader::supportedImageFormats()`, and `QImageIOPlugin`.

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