"

 COPYRIGHT (c) 1994 by Claus Gittinger

	      All Rights Reserved

 This software is furnished under a license and may be used

 only in accordance with the terms of that license and with the

 inclusion of the above copyright notice.   This software may not

 be provided or otherwise made available to, or used by, any

 other person.  No title to or ownership of the software is

 hereby transferred.

"

'From Smalltalk/X, Version:2.10.3 on 22-sep-1994 at 7:31:01 pm'!

ImageReader subclass:#PCXReader

	 instanceVariableNames:''

	 classVariableNames:''

	 poolDictionaries:''

	 category:'Graphics-Support'

!

PCXReader comment:'

COPYRIGHT (c) 1994 by Claus Gittinger

	      All Rights Reserved

'!

!PCXReader class methodsFor:'testing'!

isValidPCXHeader:aHeader

    "return true, if aHeader looks like a PCX image header"

    "check id"

    ((aHeader at:1) ~~ 16r0A) ifTrue:[

	^ false

    ].

    "check version"

    (#(0 2 3 5) includes:(aHeader at:2)) ifFalse:[

	^ false

    ].

    ^ true

!

isValidImageFile:aFilename

    "return true, if aFilename contains a PCX image"

    inStream := self streamReadingFile:aFilename.

    inStream isNil ifTrue:[^ false].

    inStream binary.

    header := ByteArray uninitializedNew:128.

    inStream close.

	^ false

    ].

    ^ true

! !

!PCXReader class methodsFor:'initialization'!

initialize

    "tell Image-class, that a new fileReader is present"

    Image fileFormats at:'.pcx'  put:self.

! !

!PCXReader methodsFor:'reading from file'!

fromStreamWithHeader:header 

    | inDepth version compression nPlanes xmin ymin xmax ymax

      paletteType rawMap rMap gMap bMap 

      endIndex "{Class: SmallInteger }"

      srcIndex "{Class: SmallInteger }"

      dstIndex "{Class: SmallInteger }"

      rowIndex "{Class: SmallInteger }"

      h        "{Class: SmallInteger }"

      byte     "{Class: SmallInteger }"

      nByte    "{Class: SmallInteger }"

    version := header at:2.

"/    'version=' print. version printNL.

    compression := header at:3.

"/    'compression=' print. compression printNL.

    (#(0 1) includes:compression) ifFalse:[

	self error:'PCXREADER: unknown compression'.

	^ nil

    ].

    inDepth := header at:4.

"/    'depth=' print. inDepth printNL.

    nPlanes := header at:66.

"/    'planes=' print. nPlanes printNL.

    bytesPerRow := header wordAt:67.

"/    'bytesPerRow=' print. bytesPerRow printNL.

    paletteType := header at:69.

    "

     although it would be easy to implement ...

     I have no test pictures for other formats.

     So its not (yet) implemented

    "

    ((inDepth ~~ 8) or:[nPlanes ~~ 1]) ifTrue:[

	'PCXReader: can only handle 1-plane 256 color images' errorPrintNL.

	^ nil

    ].

    xmin := header wordAt:5.

    ymin := header wordAt:7.

    xmax := header wordAt:9.

    ymax := header wordAt:11.

    width := (xmax - xmin + 1).

    height := (ymax - ymin + 1).

"/    'width=' print. width printNL.

"/    'height=' print. width printNL.

    (version == 2) ifTrue:[

	"read the 16-entry colormap"

	rawMap := ByteArray uninitializedNew:(16*3).

	rawMap replaceFrom:1 to:(16*3) with:header startingAt:17.

	rMap := Array new:16.

	gMap := Array new:16.

	bMap := Array new:16.

	srcIndex := 1.

	1 to:16 do:[:i |

	    rMap at:i put:(rawMap at:srcIndex).

	    srcIndex := srcIndex + 1.

	    gMap at:i put:(rawMap at:srcIndex).

	    srcIndex := srcIndex + 1.

	    bMap at:i put:(rawMap at:srcIndex).

	    srcIndex := srcIndex + 1.

	].

    ].

	rowIndex := 1.

	h := height.

	1 to:h do:[:row |

	    dstIndex := rowIndex.

	    endIndex := dstIndex + bytesPerRow.

		    dataBytes at:dstIndex put:byte.

		    dstIndex := dstIndex + 1.

		] ifFalse:[

		    nByte := byte bitAnd:2r00111111.

		    value notNil ifTrue:[

			idx2 := endIndex min:(dstIndex + nByte - 1).

			dataBytes from:dstIndex to:idx2 put:value.

			dstIndex := dstIndex + nByte.

		    ]

		].

	    ].

	    rowIndex := rowIndex + bytesPerRow

	]

    ] ifFalse:[

	"

	 actually untested ...

	"

    ].

    (version == 5) ifTrue:[

	"read the 256-entry colormap"

	].

	rawMap := ByteArray uninitializedNew:(256*3).

	rMap := Array new:256.

	gMap := Array new:256.

	bMap := Array new:256.

	srcIndex := 1.

	1 to:256 do:[:i |

	    rMap at:i put:(rawMap at:srcIndex).

	    srcIndex := srcIndex + 1.

	    gMap at:i put:(rawMap at:srcIndex).

	    srcIndex := srcIndex + 1.

	    bMap at:i put:(rawMap at:srcIndex).

	    srcIndex := srcIndex + 1.

	].

    ].

    photometric := #palette.

    samplesPerPixel := 1.

    bitsPerSample := #(8).

    colorMap := Array with:rMap with:gMap with:bMap.

    "

     |i f|

    "

!

fromFile:aFilename 

    | fileSize header img |

    inStream := self class streamReadingFile:aFilename.

    inStream isNil ifTrue:[^ nil].

    inStream binary.

    fileSize := inStream size.

    fileSize < 128 ifTrue:[

	inStream close.

	self error:'PCXREADER: short file'.

	^ nil

    ].

    header := ByteArray uninitializedNew:128.

    inStream nextBytes:128 into:header.

    (self class isValidPCXHeader:header) ifFalse:[

	inStream close.

	self error:'PCXREADER: wrong header'.

	^ nil

    ].

    img := self fromStreamWithHeader:header.

    inStream close.

    ^ img

! !

PCXReader initialize!