"

 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:#Depth2Image

	instanceVariableNames:''

	classVariableNames:''

	poolDictionaries:''

	category:'Graphics-Images'

!

!Depth2Image 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 four-color (2 bit / pixel) images 

    (as used mainly on the NeXT).

    It mainly consists of methods already implemented in Image,

    reimplemented here for more performance.

    #blackIs0 / #whiteIs0 and #palette formats are supported here.

    [author:]

        Claus Gittinger

    [see also:]

        Depth1Image Depth4Image Depth8Image Depth16Image Depth24Image 

        ImageReader

"

! !

!Depth2Image class methodsFor:'queries'!

imageDepth

    "return the depth of images represented by instances of

     this class - here we return 2"

    ^ 2

    "Modified: 20.4.1996 / 23:40:12 / cg"

! !

    "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 }"

     shift     "{ Class: SmallInteger }"

     value     "{ Class: SmallInteger }" 

     p grey|

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

    "left pixel in high bits"

    byte := bytes at:(lineIndex + (x // 4)).

    shift := #(-6 -4 -2 0) at:((x \\ 4) + 1).

    value := (byte bitShift:shift) bitAnd:3.

    p := photometric.

    p == #whiteIs0 ifTrue:[

        value := 3 - value.

        p := #blackIs0

    ].

    p == #blackIs0 ifTrue:[

        (value == 0) ifTrue:[

            ^ Color black

        ].

        (value == 3) ifTrue:[

            ^ Color white

        ].

        (value == 1) ifTrue:[

            grey := 33

        ] ifFalse:[

            grey := 67

        ].

        ^ Color gray:grey

    ].

    photometric ~~ #palette ifTrue:[

        ^ self colorFromValue:value

    ].

    ^ colorMap at:(value+1).

    "Modified: 8.6.1996 / 10:52:38 / cg"

!

    "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 }"

     shift     "{ Class: SmallInteger }" |

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

    "left pixel is in high bits"

    index := lineIndex + (x // 4).

    byte := bytes at:index.

    shift := #(6 4 2 0) at:((x \\ 4) + 1).

    byte := (byte bitAnd:(3 bitShift:shift) bitInvert) bitOr:(aPixelValue bitShift:shift).

    bytes at:index put:byte

! !

!Depth2Image methodsFor:'dither helpers'!

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 2-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);

    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 & 3) == 0) {

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

                __srcIdx++;

            } else {

                __inByte = __inByte << 2;

            }

            __grey = (__inByte >> 6) & 3;

            __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

! !

!Depth2Image 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 }"

     color0 color1 color2 color3|

    photometric == #whiteIs0 ifTrue:[

        color0 := Color white.

        color1 := Color gray:67.

        color2 := Color gray:33.

        color3 := Color black

    ] ifFalse:[

        photometric == #blackIs0 ifTrue:[

            color0 := Color black.

            color1 := Color gray:33.

            color2 := Color gray:67.

            color3 := Color white

        ] ifFalse:[

            photometric == #palette ifTrue:[

                color0 := colorMap at:1.

                color1 := colorMap at:2.

                color2 := colorMap at:3.

                color3 := colorMap at:4.

            ] ifFalse:[

                color0 := self colorFromValue:0.

                color1 := self colorFromValue:1.

                color2 := self colorFromValue:2.

                color3 := self colorFromValue:3.

            ]

        ]

    ].

    "left pixel in high bits"

    x1 := xLow.

    x2 := xHigh.

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

    srcIndex := srcIndex + (x1 // 4).

    shift := #(-6 -4 -2 0) at:((x1 \\ 4) + 1).

    byte := bytes at:srcIndex.

    x1 to:x2 do:[:x |

        value := (byte bitShift:shift) bitAnd:3.

        (value == 0) ifTrue:[

            aBlock value:x value:color0

        ] ifFalse:[

            (value == 1) ifTrue:[

                aBlock value:x value:color1

            ] ifFalse:[

                (value == 2) ifTrue:[

                    aBlock value:x value:color2

                ] ifFalse:[

                    aBlock value:x value:color3

                ]

            ]

        ].

        shift == 0 ifTrue:[

            shift := -6.

            srcIndex := srcIndex + 1.

            x < x2 ifTrue:[

                byte := bytes at:srcIndex.

            ]

        ] ifFalse:[

            shift := shift + 2.

        ]

    ].

    "Created: 7.6.1996 / 19:12:31 / cg"

    "Modified: 10.6.1996 / 10:32:47 / 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 x coordinate and 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 }"

     shift    "{ Class: SmallInteger }"

     value    "{ Class: SmallInteger }"

     x1       "{ Class: SmallInteger }"

     x2       "{ Class: SmallInteger }"|

    "left pixel in high bits"

    x1 := xLow.

    x2 := xHigh.

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

    srcIndex := srcIndex + (x1 // 4).

    shift := #(-6 -4 -2 0) at:((x1 \\ 4) + 1).

    byte := bytes at:srcIndex.

    x1 to:x2 do:[:x |

        value := (byte bitShift:shift) bitAnd:3.

        aBlock value:x value:value.

        shift == 0 ifTrue:[

            shift := -6.

            srcIndex := srcIndex + 1.

            x < x2 ifTrue:[

                byte := bytes at:srcIndex.

            ]

        ] ifFalse:[

            shift := shift + 2.

        ]

    ].

    "Created: 7.6.1996 / 19:09:42 / cg"

    "Modified: 8.6.1996 / 13:36:28 / cg"

! !

!Depth2Image methodsFor:'magnification'!

magnifyRowFrom:srcBytes offset:srcStart

	  into:dstBytes offset:dstStart factor:mX

    "magnify a single pixel row - can only magnify by integer factors"

%{

    unsigned char *srcP, *dstP;

    int _mag;

    REGISTER int i;

    REGISTER unsigned char _byte;

    int _pixels;

    REGISTER int outcnt, bits, bit, mask, incnt;

    int shift;

    OBJ w = _INST(width);

    /* helper for two-plane magnification by 2 */

    static unsigned char mag2[16] = {0x00, 0x05, 0x0a, 0x0f, 0x50, 0x55, 0x5a, 0x5f, 

				     0xa0, 0xa5, 0xaa, 0xaf, 0xf0, 0xf5, 0xfa, 0xff};

    if (__bothSmallInteger(srcStart, dstStart)

     && __bothSmallInteger(w, mX)

     && __isByteArray(srcBytes) && __isByteArray(dstBytes)) {

	_mag = _intVal(mX);

	srcP = _ByteArrayInstPtr(srcBytes)->ba_element - 1 + _intVal(srcStart);

	dstP = _ByteArrayInstPtr(dstBytes)->ba_element - 1 + _intVal(dstStart);

	_pixels = _intVal(w);

	 switch (_mag) {

	     case 1:

		break;

	     case 2:

		 /* tuned for this common case */

		 while (_pixels > 0) {

		     _byte = *srcP++;

		     *dstP++ = mag2[ _byte >> 4 ];

		     if (_pixels > 2) {

			 *dstP++ = mag2[ _byte & 0x0F ];

		     }

		     _pixels -= 4;

		 }

		 break;

	     default:

		 bits = 0, incnt = 0, outcnt = 0;

		 shift = 6;

		 _byte = *srcP++;

		 while (_pixels--) {

		     bit = (_byte >> shift) & 3;

		     incnt++;

		     if (incnt == 4) {

			 incnt = 0;

			 shift = 6;

			 _byte = *srcP++;

		     } else {

			 shift -= 2;

		     }

		     for (i=_mag; i>0; i--) {

			 bits = (bits << 2) | bit;

			 outcnt++;

			 if (outcnt == 4) {

			     *dstP++ = bits;

			     bits = 0;

			     outcnt = 0;

			 }

		     }

		 }

		 break;

	}

	RETURN (self);

    }

%}

.

    self primitiveFailed

! !

!Depth2Image methodsFor:'queries'!

bitsPerPixel

    "return the number of bits per pixel"

    ^ 2

!

bitsPerRow

    "return the number of bits in one scanline of the image"