Package org.eclipse.swt.graphics

Class ImageLoader

java.lang.Object
org.eclipse.swt.graphics.ImageLoader
public class ImageLoader extends Object
Instances of this class are used to load images from, and save images to, a file or stream.

Currently supported image formats are:

  • BMP (Windows or OS/2 Bitmap)
  • ICO (Windows Icon)
  • JPEG
  • GIF
  • PNG
  • TIFF
ImageLoaders can be used to:
  • load/save single images in all formats
  • load/save multiple images (GIF/ICO/TIFF)
  • load/save animated GIF images
  • load interlaced GIF/PNG images
  • load progressive JPEG images

NOTE: ImageLoader is implemented in Java on some platforms, which has certain performance implications. Performance and memory sensitive applications may benefit from using one of the constructors provided by Image, as these are implemented natively.

See Also:

  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    int
    backgroundPixel
    the background pixel for the logical screen (this corresponds to the GIF89a Background Color Index value).
    int
    compression
    This is the compression used when saving jpeg and png files.
    ImageData[]
    data
    the array of ImageData objects in this ImageLoader.
    int
    logicalScreenHeight
    the height of the logical screen on which the images reside, in pixels (this corresponds to the GIF89a Logical Screen Height value)
    int
    logicalScreenWidth
    the width of the logical screen on which the images reside, in pixels (this corresponds to the GIF89a Logical Screen Width value)
    int
    repeatCount
    the number of times to repeat the display of a sequence of animated images (this corresponds to the commonly-used GIF application extension for "NETSCAPE 2.0 01").

  • Constructor Summary

    Constructors
    Constructor
    Description
    ImageLoader()
    Construct a new empty ImageLoader.

  • Method Summary

    Modifier and Type
    Method
    Description
    void
    addImageLoaderListener(ImageLoaderListener listener)
    Adds the listener to the collection of listeners who will be notified when image data is either partially or completely loaded.
    boolean
    hasListeners()
    Returns true if the receiver has image loader listeners, and false otherwise.
    ImageData[]
    load(InputStream stream)
    Loads an array of ImageData objects from the specified input stream.
    ImageData[]
    load(String filename)
    Loads an array of ImageData objects from the file with the specified name.
    void
    notifyListeners(ImageLoaderEvent event)
    Notifies all image loader listeners that an image loader event has occurred.
    void
    removeImageLoaderListener(ImageLoaderListener listener)
    Removes the listener from the collection of listeners who will be notified when image data is either partially or completely loaded.
    void
    save(OutputStream stream, int format)
    Saves the image data in this ImageLoader to the specified stream.
    void
    save(String filename, int format)
    Saves the image data in this ImageLoader to a file with the specified name.

    Methods inherited from class java.lang.Object

    clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

  • Field Details

    • data

      public ImageData[] data
      the array of ImageData objects in this ImageLoader. This array is read in when the load method is called, and it is written out when the save method is called

    • logicalScreenWidth

      public int logicalScreenWidth
      the width of the logical screen on which the images reside, in pixels (this corresponds to the GIF89a Logical Screen Width value)

    • logicalScreenHeight

      public int logicalScreenHeight
      the height of the logical screen on which the images reside, in pixels (this corresponds to the GIF89a Logical Screen Height value)

    • backgroundPixel

      public int backgroundPixel
      the background pixel for the logical screen (this corresponds to the GIF89a Background Color Index value). The default is -1 which means 'unspecified background'

    • repeatCount

      public int repeatCount
      the number of times to repeat the display of a sequence of animated images (this corresponds to the commonly-used GIF application extension for "NETSCAPE 2.0 01"). The default is 1. A value of 0 means 'display repeatedly'

    • compression

      public int compression
      This is the compression used when saving jpeg and png files.

      When saving jpeg files, the value is from 1 to 100, where 1 is very high compression but low quality, and 100 is no compression and high quality; default is 75.

      When saving png files, the value is from 0 to 3, but they do not impact the quality because PNG is lossless compression. 0 is uncompressed, 1 is low compression and fast, 2 is default compression, and 3 is high compression but slow.

      Since:
      3.8

  • Constructor Details

    • ImageLoader

      public ImageLoader()
      Construct a new empty ImageLoader.

  • Method Details

    • load

      public ImageData[] load(InputStream stream)
      Loads an array of ImageData objects from the specified input stream. Throws an error if either an error occurs while loading the images, or if the images are not of a supported type. Returns the loaded image data array.
      Parameters:
      stream - the input stream to load the images from
      Returns:
      an array of ImageData objects loaded from the specified input stream
      Throws:
      IllegalArgumentException -
      • ERROR_NULL_ARGUMENT - if the stream is null
      SWTException -
      • ERROR_IO - if an IO error occurs while reading from the stream
      • ERROR_INVALID_IMAGE - if the image stream contains invalid data
      • ERROR_UNSUPPORTED_FORMAT - if the image stream contains an unrecognized format

    • load

      public ImageData[] load(String filename)
      Loads an array of ImageData objects from the file with the specified name. Throws an error if either an error occurs while loading the images, or if the images are not of a supported type. Returns the loaded image data array.
      Parameters:
      filename - the name of the file to load the images from
      Returns:
      an array of ImageData objects loaded from the specified file
      Throws:
      IllegalArgumentException -
      • ERROR_NULL_ARGUMENT - if the file name is null
      SWTException -
      • ERROR_IO - if an IO error occurs while reading from the file
      • ERROR_INVALID_IMAGE - if the image file contains invalid data
      • ERROR_UNSUPPORTED_FORMAT - if the image file contains an unrecognized format

    • save

      public void save(OutputStream stream, int format)
      Saves the image data in this ImageLoader to the specified stream. The format parameter can have one of the following values:
      IMAGE_BMP
      Windows BMP file format, no compression
      IMAGE_BMP_RLE
      Windows BMP file format, RLE compression if appropriate
      IMAGE_GIF
      GIF file format
      IMAGE_ICO
      Windows ICO file format
      IMAGE_JPEG
      JPEG file format
      IMAGE_PNG
      PNG file format
      Parameters:
      stream - the output stream to write the images to
      format - the format to write the images in
      Throws:
      IllegalArgumentException -
      • ERROR_NULL_ARGUMENT - if the stream is null
      SWTException -
      • ERROR_IO - if an IO error occurs while writing to the stream
      • ERROR_INVALID_IMAGE - if the image data contains invalid data
      • ERROR_UNSUPPORTED_FORMAT - if the image data cannot be saved to the requested format

    • save

      public void save(String filename, int format)
      Saves the image data in this ImageLoader to a file with the specified name. The format parameter can have one of the following values:
      IMAGE_BMP
      Windows BMP file format, no compression
      IMAGE_BMP_RLE
      Windows BMP file format, RLE compression if appropriate
      IMAGE_GIF
      GIF file format
      IMAGE_ICO
      Windows ICO file format
      IMAGE_JPEG
      JPEG file format
      IMAGE_PNG
      PNG file format
      Parameters:
      filename - the name of the file to write the images to
      format - the format to write the images in
      Throws:
      IllegalArgumentException -
      • ERROR_NULL_ARGUMENT - if the file name is null
      SWTException -
      • ERROR_IO - if an IO error occurs while writing to the file
      • ERROR_INVALID_IMAGE - if the image data contains invalid data
      • ERROR_UNSUPPORTED_FORMAT - if the image data cannot be saved to the requested format

    • addImageLoaderListener

      public void addImageLoaderListener(ImageLoaderListener listener)
      Adds the listener to the collection of listeners who will be notified when image data is either partially or completely loaded.

      An ImageLoaderListener should be added before invoking one of the receiver's load methods. The listener's imageDataLoaded method is called when image data has been partially loaded, as is supported by interlaced GIF/PNG or progressive JPEG images.

      Parameters:
      listener - the listener which should be notified
      Throws:
      IllegalArgumentException -
      • ERROR_NULL_ARGUMENT - if the listener is null
      See Also:

    • removeImageLoaderListener

      public void removeImageLoaderListener(ImageLoaderListener listener)
      Removes the listener from the collection of listeners who will be notified when image data is either partially or completely loaded.
      Parameters:
      listener - the listener which should no longer be notified
      Throws:
      IllegalArgumentException -
      • ERROR_NULL_ARGUMENT - if the listener is null
      See Also:

    • hasListeners

      public boolean hasListeners()
      Returns true if the receiver has image loader listeners, and false otherwise.
      Returns:
      true if there are ImageLoaderListeners, and false otherwise
      See Also:

    • notifyListeners

      public void notifyListeners(ImageLoaderEvent event)
      Notifies all image loader listeners that an image loader event has occurred. Pass the specified event object to each listener.
      Parameters:
      event - the ImageLoaderEvent to send to each ImageLoaderListener