Copyright (c) Kazuki Yasumatsu, 1995. All rights reserved.

Used with permission. Modified for use in Squeak.

	private
	checkCodeSize setParameters: updatePixelPosition

	private-bits access
	flushBits nextBits nextBitsPut:

	private-decoding
	readBitData readBody readCode readColorTable: readHeader readWord skipBitData

	private-encoding
	flushCode readPixelFrom: writeBitData: writeCode: writeCodeAndCheckCodeSize: writeHeader writeWord:

	private-packing
	fillBuffer flushBuffer nextByte nextBytePut: peekByte

	accessing	top
	nextImage Read in the next GIF image from the stream. Read it all into memory first for speed.
	nextPutImage: Encoding anImage on stream.
	setStream: Feed it in from an existing source
	understandsImageFormat Test to see if the image stream format is understood by this decoder. This should be implemented in each subclass of ImageReadWriter so that a proper decoder can be selected without ImageReadWriter having to know about all possible image file types.

	private	top
	checkCodeSize
	setParameters:
	updatePixelPosition

	private-bits access	top
	flushBits
	nextBits
	nextBitsPut:

	private-decoding	top
	readBitData using modified Lempel-Ziv Welch algorithm.
	readBody Read the GIF blocks. Modified to return a form.
	readCode
	readColorTable:
	readHeader
	readWord
	skipBitData

	private-encoding	top
	flushCode
	readPixelFrom: Since bits is a Bitmap with 32 bit values, watch out for the padding at the end of each row. But, GIF format already wants padding to 32 bit boundary! OK as is. tk 9/14/97
	writeBitData: using modified Lempel-Ziv Welch algorithm.
	writeCode:
	writeCodeAndCheckCodeSize:
	writeHeader
	writeWord:

	private-packing	top
	fillBuffer
	flushBuffer
	nextByte
	nextBytePut:
	peekByte

	class initialization	top
	initialize GIFReadWriter initialize