All Packages  Class Hierarchy  This Package  Previous  Next  Index

Class pmr.simplegraph.GIFEncoder

java.lang.Object
   |
   +----pmr.simplegraph.GIFEncoder

public class GIFEncoder

extends Object

  GIFEncoder is a class which takes an image and saves it to a stream
  using the GIF file format (Graphics Interchange
  Format). A GIFEncoder
  is constructed with either an AWT Image (which must be fully
  loaded) or a set of RGB arrays. The image can be written out with a
  call to Write.

 Three caveats:
 

   
GIFEncoder will convert the image to indexed color upon
    construction. This will take some time, depending on the size of
    the image. Also, actually writing the image out (Write) will take
    time.

   
The image cannot have more than 256 colors, since GIF is an 8
   bit format. For a 24 bit to 8 bit quantization algorithm, see
   Graphics Gems II III.2 by Xialoin Wu. Or check out his C source.

   
Since the image must be completely loaded into memory,
   GIFEncoder may have problems with large images. Attempting to
   encode an image which will not fit into memory will probably
   result in the following exception:

   java.awt.AWTException: Grabber returned false: 192

 

 GIFEncoder is based upon gifsave.c, which was written and released
 by:

 

                                  Sverre H. Huseby

                                   Bjoelsengt. 17

                                     N-0468 Oslo

                                       Norway

                                 Phone: +47 2 230539

                                 sverrehu@ifi.uio.no

 
 @version 0.90 21 Apr 1996
 @author Adam Doppelt



  


  
 
	GIFEncoder(byte[][], byte[][], byte[][])
  
 Construct a GIFEncoder.
  
 
	GIFEncoder(Image)
  
   Construct a GIFEncoder.


  


  
 
	Write(OutputStream)
  
   Writes the image out to a stream in the GIF file format.



  



GIFEncoder
  public GIFEncoder(Image image) throws AWTException


  
 Construct a GIFEncoder. The constructor will convert the image to
  an indexed color array. This may take some time.

  @param image The image to encode. The image must be
  completely loaded.
  @exception AWTException Will be thrown if the pixel grab fails. This
  can happen if Java runs out of memory. It may also indicate that the image
  contains more than 256 colors.


GIFEncoder
  public GIFEncoder(byte r[][],
                    byte g[][],
                    byte b[][]) throws AWTException


  
 Construct a GIFEncoder. The constructor will convert the image to
an indexed color array. This may take some time.


 Each array stores intensity values for the image. In other words,
r[x][y] refers to the red intensity of the pixel at column x, row
y.

  

    
 Parameters:
    
 r - An array containing the red intensity values.
    
 g - An array containing the green intensity values.
    
 b - An array containing the blue intensity values.
    
 Throws: AWTException
    
 Will be thrown if the image contains more than
256 colors.

  public void Write(OutputStream output) throws IOException

Writes the image out to a stream in the GIF file format. This will be a single GIF87a image, non-interlaced, with no background color. This may take some time.

@param output The stream to output to. This should probably be a buffered stream. @exception IOException Will be thrown if a write operation fails.

All Packages  Class Hierarchy  This Package  Previous  Next  Index