"

 COPYRIGHT (c) 1993 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.

"

Image subclass:#Depth4Image

	instanceVariableNames:''

	classVariableNames:''

	poolDictionaries:''

	category:'Graphics-Images'

!

!Depth4Image class methodsFor:'documentation'!

copyright

"

 COPYRIGHT (c) 1993 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.

"

!

documentation

"

    this class represents 16-color (4 bit / pixel) images.

    Most images coming from the windows world are represented as Depth4Images.

    It mainly consists of methods already implemented in Image,

    reimplemented here for more performance.

    [author:]

        Claus Gittinger

    [see also:]

        Depth1Image Depth2Image Depth8Image Depth16Image Depth24Image

        ImageReader

"

! !

!Depth4Image class methodsFor:'queries'!

imageDepth

    "return the depth of images represented by instances of

     this class - here we return 4"

    ^ 4

    "Modified: 20.4.1996 / 23:40:18 / cg"

! !

!Depth4Image methodsFor:'accessing - pixels'!

colorAtX:x y:y

    "retrieve a pixel at x/y; return a color.

     Pixels start at x=0 , y=0 for upper left pixel, end at

     x = width-1, y=height-1 for lower right pixel"

    |lineIndex "{ Class: SmallInteger }"

     byte      "{ Class: SmallInteger }"

     value     "{ Class: SmallInteger }" |

    lineIndex := (self bytesPerRow * y) + 1.

    "left pixel in high bits"

    byte := bytes at:(lineIndex + (x // 2)).

    x even ifTrue:[

        value := (byte bitShift:-4) bitAnd:16rF.

    ] ifFalse:[

        value := byte bitAnd:16rF.

    ].

    photometric == #whiteIs0 ifTrue:[

        ^ Color gray:100 - (100 / 15 * value)

    ].

    photometric == #blackIs0 ifTrue:[

        ^ Color gray:(100 / 15 * value)

    ].

    photometric ~~ #palette ifTrue:[

        ^ self colorFromValue:value

    ].

    ^ colorMap at:(value + 1)

    "Modified: 8.6.1996 / 10:52:43 / cg"

    "Created: 24.4.1997 / 17:33:51 / cg"

!

pixelAtX:x y:y

    "retrieve a pixel at x/y; return a pixelValue.

     Pixels start at x=0 , y=0 for upper left pixel, end at

     x = width-1, y=height-1 for lower right pixel"

    |lineIndex "{ Class: SmallInteger }"

     byte      "{ Class: SmallInteger }" |

    lineIndex := (self bytesPerRow * y) + 1.

    "left pixel in high bits"

    byte := bytes at:(lineIndex + (x // 2)).

    x even ifTrue:[

        ^ (byte bitShift:-4) bitAnd:16rF.

    ].

    ^ byte bitAnd:16rF.

    "Created: 24.4.1997 / 16:06:43 / cg"

!

pixelAtX:x y:y put:aPixelValue

    "set the pixel at x/y to aPixelValue.

     Pixels start at x=0 , y=0 for upper left pixel, end at

     x = width-1, y=height-1 for lower right pixel"

    |lineIndex "{ Class: SmallInteger }"

     index     "{ Class: SmallInteger }"

     byte      "{ Class: SmallInteger }" |

    lineIndex := (self bytesPerRow * y) + 1.

    "left pixel is in high bits"

    index := lineIndex + (x // 2).

    byte := bytes at:index.

    x even ifTrue:[

        byte := (byte bitAnd:16rF) bitOr:(aPixelValue bitShift:4)

    ] ifFalse:[

        byte := (byte bitAnd:16rF0) bitOr:aPixelValue

    ].

    bytes at:index put:byte

    "Created: 24.4.1997 / 17:06:39 / cg"

! !

!Depth4Image methodsFor:'dither helpers'!

orderedDitheredGrayBitsWithDitherMatrix:ditherMatrix ditherWidth:dW depth:depth

    "return the bitmap for a dithered depth-bitmap from the image;

     with a constant ditherMatrix, this can be used for thresholding.

     Redefined to make use of knowing that pixels are 4-bit values."

    |dH nDither   

     greyLevels greyMap1 greyMap2

     bytesPerRow  "{Class: SmallInteger }"

     bytesPerOutRow  "{Class: SmallInteger }"

     pixelsPerByte   "{Class: SmallInteger }"

     outBits

     w               "{Class: SmallInteger }"

     h               "{Class: SmallInteger }" |

    nDither := ditherMatrix size.

    dH := nDither / dW.

    w := width.

    h := height.

    greyLevels := 1 bitShift:depth.

    pixelsPerByte := 8 / depth.

    bytesPerRow := self bytesPerRow.

    bytesPerOutRow := (w * depth + 7) // 8.

    outBits := ByteArray uninitializedNew:(bytesPerOutRow * h).

    (outBits isNil or:[bytes isNil]) ifTrue:[

        ^ nil

    ].

    greyMap1 := self greyMapForRange:(greyLevels-1).                    "/ the pixels

    greyMap1 := (greyMap1 collect:[:b | b isNil ifTrue:[

                                            0

                                        ] ifFalse:[

                                            b truncated

                                        ]

                                  ]) asByteArray.      

    greyMap2 := self greyMapForRange:(greyLevels-1).

    greyMap2 := (greyMap2 collect:[:el | 

                                        el isNil ifTrue:[

                                            0

                                        ] ifFalse:[

                                            ((el - el truncated)  "/ the error (0..1)

                                            * nDither) rounded

                                        ]]) asByteArray.

%{

    int __dW = __intVal(dW);

    int __dH = __intVal(dH);

    int __byte;

    int __dT, __dO;

    int __depth = __intVal(depth);

    int __dstIdx = 0;

    int __srcIdx = 0;

    int __bitCnt;

    int __inByte;

    int __grey, __pixel;

    int __w = __intVal(w);

    int __h = __intVal(h);

    int __x;

    int __y;

    int __oX, __oY, __dY;

    int __nextDst;

    int __nextSrc;

    int __bytesPerRow = __intVal(bytesPerRow);

    int __bytesPerOutRow = __intVal(bytesPerOutRow);

    unsigned char *__outBits = __ByteArrayInstPtr(outBits)->ba_element;

    unsigned char *__ditherMatrix = __ByteArrayInstPtr(ditherMatrix)->ba_element;

    unsigned char *__bytes = __ByteArrayInstPtr(__INST(bytes))->ba_element;

    unsigned char *__greyMap1 = __ByteArrayInstPtr(greyMap1)->ba_element;

    unsigned char *__greyMap2 = __ByteArrayInstPtr(greyMap2)->ba_element;

    __oY = __dY = 0;

    for (__y=0; __y<__h; __y++) {

        __nextDst = __dstIdx + __bytesPerOutRow;

        __nextSrc = __srcIdx + __bytesPerRow;

        __byte = 0;

        __bitCnt = 8;

        __oX = 0;

        for (__x=0; __x<__w; __x++) {

            if (__x & 1) {

                /* odd */

                __grey = __inByte & 0xF;

                __srcIdx++;

            } else {

                __inByte = __bytes[__srcIdx];        

                __grey = (__inByte >> 4) & 0xF;

            }

            __pixel = __greyMap1[__grey];            /* 0..(greyLevels-1) */

            __dO    = __greyMap2[__grey];            /* 0.. nDither-1) */

            __dT = __ditherMatrix[__dY + __oX];

            if (__dO > __dT)                         /* dither says: next pixel */

                __pixel++;

            __oX++;

            if (__oX == __dW) __oX = 0;

            __byte = (__byte << __depth) | __pixel;

            __bitCnt = __bitCnt - __depth;

            if (__bitCnt == 0) {

                __outBits[__dstIdx] = __byte;

                __dstIdx++;

                __byte = 0;

                __bitCnt = 8;

            }

        }

        if (__bitCnt != 8) {

            __byte = __byte << __bitCnt;

            __outBits[__dstIdx] = __byte;

        }

        __oY++; __dY += __dW;

        if (__oY == __dH) {

            __oY = 0;

            __dY = 0;

        }

        __srcIdx = __nextSrc;

        __dstIdx = __nextDst;

    }

%}.

    ^ outBits

!

orderedDitheredMonochromeBitsWithDitherMatrix:ditherMatrix ditherWidth:dW

    "return the dithered monochrome bits for the receiver image;

     with a constant ditherMatrix, this can be used for thresholding.

     Redefined to make use of knowing that pixels are 4-bit values."

    |f dH nDither   

     greyMap monoBits

     bytesPerMonoRow "{Class: SmallInteger }"

     bytesPerRow     "{Class: SmallInteger }"

     w               "{Class: SmallInteger }"

     h               "{Class: SmallInteger }"|

    nDither := ditherMatrix size.

    dH := nDither / dW.

    w := width.

    h := height.

    bytesPerRow := self bytesPerRow.

    bytesPerMonoRow := w + 7 // 8.

    monoBits := ByteArray uninitializedNew:(bytesPerMonoRow * h).

    (monoBits isNil or:[bytes isNil]) ifTrue:[

        ^ nil

    ].

    greyMap := self greyByteMapForRange:nDither.

%{

    int __dW = __intVal(dW);

    int __dH = __intVal(dH);

    int __byte;

    int __dT;

    int __dstIdx = 0;

    int __srcIdx = 0;

    int __bitCnt;

    int __inByte;

    int __grey;

    int __w = __intVal(w);

    int __h = __intVal(h);

    int __x;

    int __y;

    int __oX, __oY, __dY;

    int __nextDst;

    int __nextSrc;

    int __bytesPerRow = __intVal(bytesPerRow);

    int __bytesPerMonoRow = __intVal(bytesPerMonoRow);

    unsigned char *__monoBits = __ByteArrayInstPtr(monoBits)->ba_element;

    unsigned char *__ditherMatrix = __ByteArrayInstPtr(ditherMatrix)->ba_element;

    unsigned char *__bytes = __ByteArrayInstPtr(__INST(bytes))->ba_element;

    unsigned char *__greyMap = __ByteArrayInstPtr(greyMap)->ba_element;

    __oY = __dY = 0;

    for (__y=0; __y<__h; __y++) {

        __nextDst = __dstIdx + __bytesPerMonoRow;

        __nextSrc = __srcIdx + __bytesPerRow;

        __byte = 0;

        __bitCnt = 8;

        __oX = 0;

        for (__x=0; __x<__w; __x++) {

            if (__x & 1) {

                /* odd */

                __grey = __inByte & 0xF;

                __srcIdx++;

            } else {

                __inByte = __bytes[__srcIdx];   /* 0..255 */

                __grey = (__inByte >> 4) & 0xF;

            }

            __grey = __greyMap[__grey];

            __dT = __ditherMatrix[__dY + __oX];

            __oX++;

            if (__oX == __dW) __oX = 0;

            __byte = __byte << 1;

            if (__grey > __dT) {

                __byte = __byte | 1;       /* white */

            }

            __bitCnt--;

            if (__bitCnt == 0) {

                __monoBits[__dstIdx] = __byte;

                __dstIdx++;

                __byte = 0;

                __bitCnt = 8;

            }

        }

        if (__bitCnt != 8) {

            __byte = __byte << __bitCnt;

            __monoBits[__dstIdx] = __byte;

        }

        __oY++; __dY += __dW;

        if (__oY == __dH) {

            __oY = 0;

            __dY = 0;

        }

        __srcIdx = __nextSrc;

        __dstIdx = __nextDst;

    }

%}.

    ^ monoBits

! !

!Depth4Image methodsFor:'enumerating'!

colorsAtY:y from:xLow to:xHigh do:aBlock

    "perform aBlock for each pixel from x1 to x2 in row y.

     The block is passed the color at each pixel.

     This method allows slighly faster processing of an

     image than using atX:y:, since some processing can be

     avoided when going from pixel to pixel. However, for

     real image processing, specialized methods should be written."

    |srcIndex "{ Class: SmallInteger }"

     byte     "{ Class: SmallInteger }"

     shift    "{ Class: SmallInteger }"

     value    "{ Class: SmallInteger }"

     x1       "{ Class: SmallInteger }"

     x2       "{ Class: SmallInteger }"

     colorArray p |

    (p := photometric) == #palette ifTrue:[

        colorArray := colorMap.

    ] ifFalse:[

        colorArray := Array new:16.

        (p == #whiteIs0 or:[p == #blackIs0]) ifTrue:[

            0 to:15 do:[:i |

                colorArray at:(i+1) put:(Color gray:100 - (100 / 15 * i))

            ].

            p == #blackIs0 ifTrue:[

                colorArray reverse

            ]

        ] ifFalse:[

            0 to:15 do:[:i |

                colorArray at:(i+1) put:(self colorFromValue:i).

            ].

        ]

    ].

    x1 := xLow.

    x2 := xHigh.

    srcIndex := (self bytesPerRow * y) + 1.

    srcIndex := srcIndex + (x1 // 2).

    x1 even ifTrue:[

        shift := -4

    ] ifFalse:[

        shift := 0

    ].

    x1 to:x2 do:[:x |

        shift == 0 ifTrue:[

            byte := bytes at:srcIndex.

            value := byte bitAnd:16rF.

            shift := -4.

            srcIndex := srcIndex + 1.

        ] ifFalse:[

            byte := bytes at:srcIndex.

            value := (byte bitShift:-4) bitAnd:16rF.

            shift := 0

        ].

        aBlock value:x value:(colorArray at:(value + 1)).

    ]

    "Created: 7.6.1996 / 19:12:33 / cg"

    "Modified: 10.6.1996 / 10:29:39 / cg"

!

valuesAtY:y from:xLow to:xHigh do:aBlock

    "perform aBlock for each pixelValue from x1 to x2 in row y.

     The block is passed the pixelValue at each pixel.

     This method allows slighly faster processing of an

     image than using valueAtX:y:, since some processing can be

     avoided when going from pixel to pixel. However, for

     real image processing, specialized methods should be written."

    |srcIndex   "{ Class: SmallInteger }"

     byte       "{ Class: SmallInteger }"