'From Smalltalk/X, Version:3.2.1 on 17-oct-1997 at 9:13:03 pm'                  !

ImageReader subclass:#PBMReader

	instanceVariableNames:''

	classVariableNames:''

	poolDictionaries:''

	category:'Graphics-Images-Support'

!

!PBMReader class methodsFor:'documentation'!

documentation

"

    this class provides methods for loading and saving Portable BitMap-file 

    images (Jef Poskanzers portable bitmap package).

    Reading is supported for 1bit (pbm), greyscale (pgm) and 24bit (ppm) formats.

    (i.e. P1, P3, P4, P5 and P6 formats)

    Writing is (currently) only supported for the binary formats;

    i.e. 1-bit images as (pbm P4), 8-bit gray as (pgm P5) and 24-bit images as (pnm P6).

    Q: should we bring this one to perfection and base all others on

       pipe-readers to the various pbmplus converters ?

    [See also:]

        Image Form Icon

        BlitImageReader FaceReader GIFReader JPEGReader PCXReader 

        ST80FormReader SunRasterReader TargaReader TIFFReader WindowsIconReader 

        XBMReader XPMReader XWDReader 

"

! !

!PBMReader class methodsFor:'testing'!

canRepresent:anImage

    "return true, if anImage can be represented in my file format.

     Currently, only 1bit B&W, 8bit-grey and 24bit RGB images are supported."

    |depth photometric|

    anImage photometric == #rgb ifTrue:[

        ^ depth==24

    ].

    (depth := anImage depth) == 1 ifTrue:[^ true].

    depth == 8 ifTrue:[

        photometric := anImage photometric.

        ^ (photometric == #blackIs0) or:[photometric == #whiteIs0]

    ].

    ^ false

    "Modified: 17.10.1997 / 20:20:52 / cg"

! !

!PBMReader methodsFor:'reading from file'!

readDepth8PGMStream:aStream 

    "import portable gray map (PGM, P5 format); P5 is already read"

    |maxval|

    self skipPBMJunkOn:aStream.

    width := Integer readFrom:aStream.

    width > 0 ifFalse:[ 

        'PBMREADER: Invalid width' errorPrintNL.

        ^ nil

    ].

    self skipPBMJunkOn:aStream.

    height := Integer readFrom:aStream.

    height > 0 ifFalse:[ 

        'PBMREADER: Invalid height' errorPrintNL.

        ^ nil

    ].

    self skipPBMJunkOn:aStream.

    maxval := Integer readFrom:aStream.

    maxval >= 256 ifTrue:[

        'PBMREADER: Invalid format' errorPrintNL.

        ^ nil

    ].

    aStream nextLine "skipThrough: Character cr".

    "/ the rest is the binary image data ...

    aStream binary.

    data := ByteArray uninitializedNew:(width*height).

    aStream nextBytes:(data size) into:data.

    photometric := #blackIs0.

    samplesPerPixel := 1.

    bitsPerSample := #(8).

    "Modified: 14.10.1997 / 19:44:05 / cg"

! !

!PBMReader methodsFor:'writing to file'!

save:image onFile:aFileName

    "save image as PBM/PGM/PNM file on aFileName"

    |bitsPerPixel|

    outStream := FileStream newFileNamed:aFileName.

    outStream isNil ifTrue:[

        'PBMReader [error]: file create error' errorPrintNL. 

        ^ Image fileCreationErrorSignal 

            raiseWith:image

            errorString:('file creation error: ' , aFileName asString).

    ].

    image mask notNil ifTrue:[

        Image informationLostQuerySignal

            raiseWith:image

            errorString:('PBM format does not support an imageMask').

    ].

    width := image width.

    height := image height.

    photometric := image photometric.

    samplesPerPixel := image samplesPerPixel.

    bitsPerSample := image bitsPerSample.

    colorMap := image colorMap.

    data := image bits.

    bitsPerPixel := image bitsPerPixel.

    photometric == #rgb ifTrue:[

        ^ self writePNMFileOn:outStream

    ].

    samplesPerPixel == 1 ifTrue:[

        (bitsPerPixel == 1) ifTrue:[

            ^ self writePBMFileOn:outStream

        ].

        (bitsPerPixel == 8) ifTrue:[

            ^ self writePGMFileOn:outStream

        ].

    ].

    ^ Image cannotRepresentImageSignal 

        raiseWith:image

        errorString:('PBMReader cannot represent this image').

    "

     |img|

     img := Image fromFile:'bitmaps/SBrowser.xbm'.

     img inspect.

     PBMReader save:img onFile:'test.pbm'.

     img := Image fromFile:'test.pbm'.

     img inspect.

     |img mono|

     img := Image fromFile:'bitmaps/garfield.gif'.

     img inspect.

     mono := img asMonochromeFormOn:Display.

     img := mono asImage.

     img inspect.

     PBMReader save:img onFile:'test.pbm'.

     img := Image fromFile:'test.pbm'.

     img inspect.

    "

    "Modified: 14.10.1997 / 19:41:59 / cg"

!

writeCommonHeader:format on:aStream

    "common header for P4, P5 and P5 formats"

    aStream nextPutAll:format; cr.

    aStream nextPutAll:'#  Converted from Smalltalk Form on '.

    aStream nextPutAll:Date today printString.

    aStream nextPutAll:' at '; nextPutAll:Time now printString.

    aStream cr.

    aStream nextPutAll:width printString.

    aStream space.

    aStream nextPutAll:height printString.

    "Created: 14.10.1997 / 20:01:05 / cg"

!

writePBMFileOn:aStream

    "Saves the receivers image on the file fileName in Portable Bitmap format."

    self writeCommonHeader:'P4' on:aStream.

    aStream cr.

    aStream binary.

    photometric == #blackIs0 ifTrue:[

        aStream nextPutAll:data.

    ] ifFalse:[

        data invert.

        aStream nextPutAll:data.

        data invert.

    ].

    aStream close.

    "

     |i i2|

     i := Image fromFile:'bitmaps/SBrowser.xbm'.

     PBMReader save:i onFile:'foo.pbm'.

     i2 := Image fromFile:'foo.pbm'.

     i2 inspect.

    "

    "Modified: 14.10.1997 / 20:06:49 / cg"

!

writePGMFileOn:aStream

    "Saves the receivers image on the file fileName in Portable Greymap format."

    self writeCommonHeader:'P5' on:aStream.

    aStream space.

    aStream nextPutAll:255 printString.

    aStream cr.

    data size ~~ (width * height) ifTrue:[

        "/ self halt:'data size mismatch'.

    ].

    aStream binary.

    photometric == #blackIs0 ifTrue:[

        aStream nextPutAll:data.

    ] ifFalse:[

        data invert.

        aStream nextPutAll:data.

        data invert.

    ].

    aStream close.

    "

     |i gI i2|

     i := Image fromFile:'bitmaps/gifImages/garfield.gif'.

     gI := i asFloydSteinbergDitheredGrayImageDepth:8.

     PBMReader save:gI onFile:'foo.pgm'.

     i2 := Image fromFile:'foo.pgm'.

     i2 inspect.

    "

    "Modified: 14.10.1997 / 20:06:58 / cg"

!

writePNMFileOn:aStream

    "Saves the receivers image on the file fileName in Portable Anymap format."

    self writeCommonHeader:'P6' on:aStream.

    aStream space.

    aStream nextPutAll:255 printString.

    aStream cr.

    data size ~~ (width * height * 3) ifTrue:[

        "/ self halt:'data size mismatch'.

    ].

    aStream binary.

    aStream nextPutAll:data.

    aStream close.

    "

     |i i2|

     i := Image fromFile:'bitmaps/granite.tiff'.

     PBMReader save:i onFile:'foo.pnm'.

     i2 := Image fromFile:'foo.pnm'.

     i2 inspect.

    "

    "Modified: 14.10.1997 / 20:07:08 / cg"

! !