ImageReader.st
author claus
Sat, 18 Mar 1995 06:13:39 +0100
changeset 118 25e775072a89
parent 105 6a4a21c17e5d
child 120 1421e5ec5622
permissions -rw-r--r--
*** empty log message ***

"
 COPYRIGHT (c) 1991 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:2.10.4 on 18-feb-1995 at 2:18:34 am'!

Object subclass:#ImageReader
	 instanceVariableNames:'width height data byteOrder inStream outStream photometric
		samplesPerPixel bitsPerSample colorMap'
	 classVariableNames:'ReverseBits'
	 poolDictionaries:''
	 category:'Graphics-Images support'
!

ImageReader comment:'
COPYRIGHT (c) 1991 by Claus Gittinger
	      All Rights Reserved

$Header: /cvs/stx/stx/libview/ImageReader.st,v 1.16 1995-03-18 05:11:27 claus Exp $
'!

!ImageReader primitiveFunctions!
%{

/*
 * ccitt decompression
 */
static short *whiteCountTable;
static char  *whiteShiftTable;
static short *blackCountTable;
static char  *blackShiftTable;

struct ccitt_def {
    unsigned short bits;
    short nBits;
};

static struct ccitt_def 
whiteDef[] = {
    { 0x3500, 8 }, /* 0 */
    { 0x1c00, 6 },
    { 0x7000, 4 },
    { 0x8000, 4 },
    { 0xb000, 4 },
    { 0xc000, 4 },
    { 0xe000, 4 },
    { 0xf000, 4 },
    { 0x9800, 5 },
    { 0xA000, 5 },
    { 0x3800, 5 }, /* 10 */
    { 0x4000, 5 },
    { 0x2000, 6 },
    { 0x0c00, 6 },
    { 0xd000, 6 },
    { 0xd400, 6 },
    { 0xa800, 6 },
    { 0xac00, 6 },
    { 0x4e00, 7 },
    { 0x1800, 7 },
    { 0x1000, 7 }, /* 20 */
    { 0x2e00, 7 },
    { 0x0600, 7 },
    { 0x0800, 7 },
    { 0x5000, 7 },
    { 0x5600, 7 },
    { 0x2600, 7 },
    { 0x4800, 7 },
    { 0x3000, 7 },
    { 0x0200, 8 },
    { 0x0300, 8 }, /* 30 */ 
    { 0x1a00, 8 }, 
    { 0x1b00, 8 }, 
    { 0x1200, 8 }, 
    { 0x1300, 8 }, 
    { 0x1400, 8 }, 
    { 0x1500, 8 }, 
    { 0x1600, 8 }, 
    { 0x1700, 8 }, 
    { 0x2800, 8 }, 
    { 0x2900, 8 }, /* 40 */
    { 0x2a00, 8 }, 
    { 0x2b00, 8 }, 
    { 0x2c00, 8 }, 
    { 0x2d00, 8 }, 
    { 0x0400, 8 }, 
    { 0x0500, 8 }, 
    { 0x0a00, 8 }, 
    { 0x0b00, 8 }, 
    { 0x5200, 8 }, 
    { 0x5300, 8 }, /* 50 */
    { 0x5400, 8 }, 
    { 0x5500, 8 }, 
    { 0x2400, 8 }, 
    { 0x2500, 8 }, 
    { 0x5800, 8 }, 
    { 0x5900, 8 }, 
    { 0x5a00, 8 }, 
    { 0x5b00, 8 }, 
    { 0x4a00, 8 }, 
    { 0x4b00, 8 }, /* 60 */
    { 0x3200, 8 }, 
    { 0x3300, 8 }, 
    { 0x3400, 8 }, 
/* ---------------- */
    { 0xd800, 5 }, /* 64 */
    { 0x9000, 5 }, /* 128 */
    { 0x5c00, 6 }, /* 192 */
    { 0x6e00, 7 }, /* 256 */
    { 0x3600, 8 }, /* 320 */
    { 0x3700, 8 },
    { 0x6400, 8 },
    { 0x6500, 8 },
    { 0x6800, 8 },
    { 0x6700, 8 }, /* 640 */
    { 0x6600, 9 }, /* 704 */
    { 0x6680, 9 },
    { 0x6900, 9 },
    { 0x6980, 9 },
    { 0x6a00, 9 },
    { 0x6a80, 9 },
    { 0x6b00, 9 },
    { 0x6b80, 9 },
    { 0x6c00, 9 },
    { 0x6c80, 9 },
    { 0x6d00, 9 },
    { 0x6d80, 9 },
    { 0x4c00, 9 },
    { 0x4c80, 9 },
    { 0x4d00, 9 }, /* 1600 */
    { 0x6000, 6 }, /* 1664 */
    { 0x4d80, 9 }, /* 1728 */
/* -------------------------------- */
    { 0x0100, 11 }, /* 1792 */
    { 0x0180, 11 },
    { 0x01a0, 11 }, /* 1920 */
    { 0x0120, 12 }, /* 1984 */
    { 0x0130, 12 },
    { 0x0140, 12 },
    { 0x0150, 12 },
    { 0x0160, 12 },
    { 0x0170, 12 },
    { 0x01c0, 12 },
    { 0x01d0, 12 },
    { 0x01e0, 12 },
    { 0x01f0, 12 }, /* 2560 */
/* -------------------------------- */
    { 0x0010, 12 }, /* EOL */
};

static struct ccitt_def 
blackDef[] = {
    { 0x0dc0, 10 }, /* 0 */
    { 0x4000, 3 },
    { 0xc000, 2 },
    { 0x8000, 2 },
    { 0x6000, 3 },
    { 0x3000, 4 },
    { 0x2000, 4 },
    { 0x1800, 5 },
    { 0x1400, 6 },
    { 0x1000, 6 },
    { 0x0800, 7 }, /* 10 */
    { 0x0a00, 7 },
    { 0x0e00, 7 },
    { 0x0400, 8 },
    { 0x0700, 8 },
    { 0x0c00, 9 },
    { 0x05c0, 10 },
    { 0x0600, 10 },
    { 0x0200, 10 },
    { 0x0ce0, 11 },
    { 0x0d00, 11 }, /* 20 */
    { 0x0d80, 11 },
    { 0x06e0, 11 },
    { 0x0500, 11 },
    { 0x02e0, 11 },
    { 0x0300, 11 },
    { 0x0ca0, 12 },
    { 0x0cb0, 12 },
    { 0x0cc0, 12 },
    { 0x0cd0, 12 }, 
    { 0x0680, 12 }, /* 30 */
    { 0x0690, 12 }, 
    { 0x06a0, 12 }, 
    { 0x06b0, 12 }, 
    { 0x0d20, 12 }, 
    { 0x0d30, 12 }, 
    { 0x0d40, 12 }, 
    { 0x0d50, 12 }, 
    { 0x0d60, 12 }, 
    { 0x0d70, 12 },
    { 0x06c0, 12 }, /* 40 */ 
    { 0x06d0, 12 }, 
    { 0x0da0, 12 }, 
    { 0x0db0, 12 }, 
    { 0x0540, 12 }, 
    { 0x0550, 12 }, 
    { 0x0560, 12 }, 
    { 0x0570, 12 }, 
    { 0x0640, 12 }, 
    { 0x0650, 12 },
    { 0x0520, 12 }, /* 50 */ 
    { 0x0530, 12 }, 
    { 0x0240, 12 }, 
    { 0x0370, 12 }, 
    { 0x0380, 12 }, 
    { 0x0270, 12 }, 
    { 0x0280, 12 }, 
    { 0x0580, 12 }, 
    { 0x0590, 12 }, 
    { 0x02b0, 12 },
    { 0x02c0, 12 }, /* 60 */ 
    { 0x05a0, 12 }, 
    { 0x0660, 12 }, 
    { 0x0670, 12 }, 
/* ---------------- */
    { 0x03c0, 10 }, /* 64 */
    { 0x0c80, 12 }, /* 128 */
    { 0x0c90, 12 }, /* 192 */
    { 0x05b0, 12 }, /* 256 */
    { 0x0330, 12 }, /* 320 */
    { 0x0340, 12 },
    { 0x0350, 12 }, /* 448 */
    { 0x0360, 13 }, /* 512 */
    { 0x0368, 13 },
    { 0x0250, 13 }, /* 640 */
    { 0x0258, 13 }, /* 704 */
    { 0x0260, 13 },
    { 0x0268, 13 },
    { 0x0390, 13 },
    { 0x0398, 13 },
    { 0x03a0, 13 },
    { 0x03a8, 13 },
    { 0x03b0, 13 },
    { 0x03b8, 13 },
    { 0x0290, 13 },
    { 0x0298, 13 },
    { 0x02a0, 13 },
    { 0x02a8, 13 },
    { 0x02d0, 13 },
    { 0x02d8, 13 }, /* 1600 */
    { 0x0320, 13 }, /* 1664 */
    { 0x0328, 13 }, /* 1728 */
/* -------------------------------- */
};

static
initCCITTTables() {
    register cnt, bits, value;
    int nBits, index;

    if (whiteCountTable != (short *)0) return;

    whiteCountTable = (short *) malloc(sizeof(short) * 8192);
    if (! whiteCountTable) return;
    whiteShiftTable = (char *) malloc(sizeof(char) * 8192);
    if (! whiteShiftTable) {
	goto fail1;
/*
	free(whiteCountTable); whiteCountTable = (short *)0;
	return;
*/
    }
    blackCountTable = (short *) malloc(sizeof(short) * 8192);
    if (! blackCountTable) {
	goto fail2;
/*
	free(whiteShiftTable); whiteShiftTable = (char *)0;
	free(whiteCountTable); whiteCountTable = (short *)0;
	return;
*/
    }
    blackShiftTable = (char *) malloc(sizeof(char) * 8192);
    if (! blackShiftTable) {
	free(blackCountTable); blackCountTable = (short *)0;
fail2:
	free(whiteShiftTable); whiteShiftTable = (char *)0;
fail1:
	free(whiteCountTable); whiteCountTable = (short *)0;
	return;
    }

    for (index = 0; index < 8192; index++) {
	whiteCountTable[index] = -1;
	blackCountTable[index] = -1;
    }

    for (value = 0; value <= 63; value++) {
	nBits = whiteDef[value].nBits;
	bits = whiteDef[value].bits >> 3;
	for (cnt = 1 << (13 - nBits); cnt; cnt--, bits++) {
	    whiteCountTable[bits] = value;
	    whiteShiftTable[bits] = nBits;
	}
	nBits = blackDef[value].nBits;
	bits = blackDef[value].bits >> 3;
	for (cnt = 1 << (13 - nBits); cnt; cnt--, bits++) {
	    blackCountTable[bits] = value;
	    blackShiftTable[bits] = nBits;
	}
    }
    index = value;

    for (; value <= 1728; value += 64) {
	nBits = whiteDef[index].nBits;
	bits = whiteDef[index].bits >> 3;
	for (cnt = 1 << (13 - nBits); cnt; cnt--, bits++) {
	    whiteCountTable[bits] = value;
	    whiteShiftTable[bits] = nBits;
	}
	nBits = blackDef[index].nBits;
	bits = blackDef[index].bits >> 3;
	for (cnt = 1 << (13 - nBits); cnt; cnt--, bits++) {
	    blackCountTable[bits] = value;
	    blackShiftTable[bits] = nBits;
	}
	index++;
    }

    for (; value <= 2560; value += 64) {
	nBits = whiteDef[index].nBits;
	bits = whiteDef[index].bits >> 3;
	for (cnt = 1 << (13 - nBits); cnt; cnt--, bits++) {
	    whiteCountTable[bits] = value;
	    whiteShiftTable[bits] = nBits;
	    blackCountTable[bits] = value;
	    blackShiftTable[bits] = nBits;
	}
	index++;
    }
}

static short 
leftBits[] = {
     0, 0x80, 0xC0, 0xE0, 0xF0, 0xF8, 0xFC, 0xFE, 0xFF
};

__decodeCCITTgroup3__(from, to, len)
    unsigned char *from;
    register unsigned char *to;
{
    register cnt;
    register short *countPtr;
    register char *shiftPtr;
    unsigned bits, bits13;
    int shift, outCount, nBitsLess13;
    int outBitOffset;
    int nLeft, t;

    if (! whiteCountTable) initCCITTTables();
    if (! whiteCountTable) return 0; /* malloc failed */

    countPtr = whiteCountTable;
    shiftPtr = whiteShiftTable;
    outCount = 0;
    outBitOffset = 0;
    bits = *from++;
    bits = (bits << 8) | *from++;
    nBitsLess13 = 3;
    for (;;) {
	bits13 = (bits >> nBitsLess13) & 0x1FFF;
	cnt = countPtr[bits13];
	if (cnt < 0) return;
	shift = shiftPtr[bits13];
	outCount += cnt;
	if (countPtr == blackCountTable) {
	    /* toggle if it was a terminating code */
	    if (cnt < 64) {
		countPtr = whiteCountTable;
		shiftPtr = whiteShiftTable;
	    }

	    /* draw cnt black bits */
	    if (cnt) {
		if (outBitOffset) {
		    nLeft = 8 - outBitOffset;
		    if (cnt < nLeft) nLeft = cnt;
		    t = leftBits[nLeft] >> outBitOffset;
		    *to |= t;
		    cnt -= nLeft;
		    outBitOffset += nLeft;
		    if (outBitOffset >= 8) {
			to++;
			outBitOffset -= 8;
		    }
		}
		if (cnt > 256) {
		    while ((int)to & 3) {
			*to++ = 0xFF;
			cnt -= 8;
		    }
		    while (cnt >= 32) {
			(*(long *)to) = 0xFFFFFFFF;
			to += 4;
			cnt -= 32;
		    }
		}
		while (cnt >= 8) {
		    *to++ = 0xFF;
		    cnt -= 8;
		}
		*to |= leftBits[cnt];
		outBitOffset += cnt;
	    }
	} else {
	    /* toggle if it was a terminating code */
	    if (cnt < 64) {
		countPtr = blackCountTable;
		shiftPtr = blackShiftTable;
	    }

	    /* skip cnt bits */
	    to += cnt >> 3;
	    outBitOffset += cnt & 7;
	    if (outBitOffset >= 8) {
		to++;
		outBitOffset -= 8;
	    }
	}
	if (outCount >= len) return 1;

	nBitsLess13 -= shift;
	while (nBitsLess13 < 0) {
	    bits = (bits << 8) | *from++;
	    nBitsLess13 += 8;
	}
    }
}

/*
 * LZW decompression
 */
struct buffer {
	struct buffer *prev;
	unsigned char chars[8192 - 4];
};
        
__decodeLZW__(from, to, inCount)
    unsigned char *from;
    unsigned char *to;
{
    register unsigned code;
    unsigned char **strings;
    short *stringLen;
    struct buffer *scratchBuffer;
    struct buffer *newBuffer;
    unsigned char *scratchPtr;
    int nScratch;
    unsigned nextCode, oldCode;
    register unsigned bits;
    int nBits, mask, shift;
    int i;
    int len;
    int codeLen = 9;

    scratchBuffer = (struct buffer *)malloc(sizeof(struct buffer));
    if (! scratchBuffer) return 0;

    strings = (unsigned char **)malloc(sizeof(unsigned char *) * 4096);
    if (! strings) {
	free(scratchBuffer);
	return 0;
    }
    stringLen = (short *)malloc(sizeof(short) * 4096);
    if (! stringLen) {
	free(strings);
	free(scratchBuffer);
	return 0;
    }

    scratchBuffer->prev = (struct buffer *)0;
    scratchPtr = scratchBuffer->chars;
    nScratch = sizeof(scratchBuffer->chars);

    for (i = 0; i < 256; i++) {
	*scratchPtr = i;
	strings[i] = scratchPtr++;
	stringLen[i] = 1;
    }

    nextCode = 258;
    nScratch -= 256;
    mask = 0x1FF;
    nBits = 0;
    bits = 0;
    while (inCount) {
	/* fetch code */
	while (nBits < codeLen) {
	    bits = (bits<<8) | *from++;
	    inCount--;
	    nBits += 8;
	}
	shift = nBits - codeLen;
	code = (bits >> shift) & mask;
	bits &= ~(mask << shift);
	nBits -= codeLen;
	if (code == 257) break;
	if (code == 256) {
	    if (! inCount)
		break;

	    /* free stuff */
	    while (scratchBuffer->prev) {
		newBuffer = scratchBuffer;
		scratchBuffer = scratchBuffer->prev;
		free(newBuffer);
	    }
	    /* reset everything */
	    scratchPtr = scratchBuffer->chars + 256;
	    nScratch = sizeof(scratchBuffer->chars) - 256;
	    codeLen = 9;
	    nextCode = 258;
	    mask = 0x1FF;
	    /* fetch code */
	    while (nBits < codeLen) {
		bits = (bits<<8) | *from++;
		inCount--;
		nBits += 8;
	    }
	    shift = nBits - codeLen;
	    code = (bits >> shift) & mask;
	    bits &= ~(mask << shift);
	    nBits -= codeLen;
	    if (code == 257) break;
	    /* add to output */
	    *to++ = code;
	    oldCode = code;
	} else {
	    if (code < nextCode) {
		/* writeString(string[code]) */
		len = stringLen[code];
		bcopy(strings[code], to, len);
		to += len;

		/* add( string[oldcode] + first(string[code]) ) */
		len = stringLen[oldCode] + 1;
		if (nScratch < len) {
		    newBuffer = (struct buffer *)malloc(sizeof(struct buffer));
		    if (! newBuffer) goto out;
		    newBuffer->prev = scratchBuffer;
		    scratchBuffer = newBuffer;
		    scratchPtr = scratchBuffer->chars;
		    nScratch = sizeof(scratchBuffer->chars);
		}
		stringLen[nextCode] = len;
		strings[nextCode] = scratchPtr;
		bcopy(strings[oldCode], scratchPtr, len-1);
		scratchPtr += len-1;
		*scratchPtr++ = strings[code][0];
		nScratch -= len;
	    } else {
		/* writeString(string[oldCode] + first(string[oldCode]) ) */
		len = stringLen[oldCode];
		bcopy(strings[oldCode], to, len);
		to += len;
		*to++ = strings[oldCode][0];

		/* add( string[oldcode] + first(string[oldCode]) ) */
		len++;
		if (nScratch < len) {
		    newBuffer = (struct buffer *)malloc(sizeof(struct buffer));
		    if (! newBuffer) goto out;
		    newBuffer->prev = scratchBuffer;
		    scratchBuffer = newBuffer;
		    scratchPtr = scratchBuffer->chars;
		    nScratch = sizeof(scratchBuffer->chars);
		}
		stringLen[nextCode] = len;
		strings[nextCode] = scratchPtr;
		bcopy(strings[oldCode], scratchPtr, len-1);
		scratchPtr += len-1;
		*scratchPtr++ = strings[oldCode][0];
		nScratch -= len;
	    }
	    oldCode = code;
	    nextCode++;
	    if (nextCode >= 511)
		if (nextCode == 511) {
		    codeLen = 10;
		    mask = 0x3FF;
		} else if (nextCode >= 1023)
		    if (nextCode == 1023) {
			codeLen = 11;
			mask = 0x7FF;
		    } else 
			if (nextCode == 2047) {
			    codeLen = 12;
			    mask = 0xFFF;
			}
	}
    }
out: ;
    /* free stuff */
    while (scratchBuffer) {
	newBuffer = scratchBuffer;
	scratchBuffer = scratchBuffer->prev;
	free(newBuffer);
    }

    free(strings);
    free(stringLen);

    return 1;
}

/*
 * delta decoding (TIFF predictor = 2)
 */
__decodeDelta__(bytes, width, height)
    register unsigned char *bytes;
{
	register w;
	unsigned char r, g, b;

	while (height--) {
	    r = g = b = 0;
	    for (w = width; w; w--) {
		r += *bytes;
		*bytes++ = r;
		g += *bytes;
		*bytes++ = g;
		b += *bytes;
		*bytes++ = b;
	    }
	}
}

/*
 * GIF decompression
 */
__decodeGIF__(from, to, inCount, initialCodeLen)
    unsigned char *from;
    unsigned char *to;
{
    register unsigned code;
    unsigned short *prefix;
    unsigned short *suffix;
    unsigned short *outCode;
    int outCount;
    unsigned maxCode, oldCode, fin, inCode, curCode;
    register unsigned bits;
    register int nBits, mask, shift;
    int i;
    int len;
    int endCode, clearCode, freeCode;
    int codeLen = initialCodeLen;
    static int ranges[] = {0, 1, 2, 4, 8, 16, 32, 64,
			   128, 256, 512, 1024, 2048 };

    prefix = (unsigned short *)malloc(sizeof(short) * 4096);
    if (! prefix) return 0;
    suffix  = (unsigned short *)malloc(sizeof(short) * 4096);
    if (! suffix) {
	free(prefix);
	return 0;
    }
    outCode = (unsigned short *)malloc(sizeof(short) * 4096);
    if (! outCode) {
	free(prefix);
	free(suffix);
	return 0;
    }
    clearCode = ranges[codeLen]; /* 256 */
    endCode = clearCode + 1;     /* 257 */
    freeCode = clearCode + 2;    /* 258 */
    maxCode = clearCode << 1;    /* 512 */
    outCount = 0;

    mask = maxCode - 1;          /* 1FF */
    nBits = 0;
    bits = 0;
    while (inCount) {
	/* fetch code */
	while (nBits < codeLen) {
	    bits = bits | (*from++ << nBits);
	    inCount--;
	    nBits += 8;
	}
	code = bits & mask;
	bits >>= codeLen;
	nBits -= codeLen;
	if (code == endCode) break;
	if (code == clearCode) {
	    if (! inCount)
		break;

	    codeLen = initialCodeLen;
	    maxCode = clearCode<<1;
	    mask = maxCode - 1;
	    freeCode = clearCode + 2;  

	    /* fetch code */
	    while (nBits < codeLen) {
		bits = bits | (*from++ << nBits);
		inCount--;
		nBits += 8;
	    }
	    code = bits & mask;
	    bits >>= codeLen;
	    nBits -= codeLen;
	    if (code == endCode) break;
	    /* add to output */
	    *to++ = code;
	    oldCode = fin = curCode = code;
	} else {
	    curCode = inCode = code;
	    if (curCode >= freeCode) {
		curCode = oldCode;
		outCode[outCount++] = fin;
	    }

	    while (curCode >= clearCode) {
		if (outCount > 1024) {
		    goto out;
		}
		outCode[outCount++] = suffix[curCode];
		curCode = prefix[curCode];
	    }

	    fin = curCode;
	    outCode[outCount++] = fin;

	    for (i = outCount - 1; i >= 0; i--)
		*to++ = outCode[i];
	    outCount = 0;

	    prefix[freeCode] = oldCode;
	    suffix[freeCode] = fin;
	    oldCode = inCode;

	    freeCode++;
	    if (freeCode >= maxCode) {
		if (codeLen < 12) {
		    codeLen++;
		    maxCode *= 2;
		    mask = (1 << codeLen) - 1;
		}
	    }
	}
    }
out: ;
    free(prefix);
    free(suffix);
    free(outCode);

    return 1;
}

%}
! !

!ImageReader class methodsFor:'documentation'!

copyright
"
 COPYRIGHT (c) 1991 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.
"
!

version
"
$Header: /cvs/stx/stx/libview/ImageReader.st,v 1.16 1995-03-18 05:11:27 claus Exp $
"
!

documentation
"
    Abstract class to provide common functions for image-readers 
    (i.e. TIFFReader, GIFReader etc.)

    ImageReaders are created temporary to read an image from a stream.
    They read the stream and collect all relevant information internally.
    Once done with reading, the actual image object is created and
    data filled in from the imageReaders collected info.

    See implementation of fromStream: in concrete subclasses.
    The public interfaces are:
	 <ConcreteReaderClass> fromFile:aFilename
    or:
	 <ConcreteReaderClass> fromStream:aStream

    However, usually this is done indirectly through
	Image fromFile:aFileName
    which tries to find an appropriate readerClass by the fileNames
    extension (i.e. .tiff, .gif etc.) and/or by asking the readers
    if they know about the format of the file (see #isValidImageFile:).
"
! !

!ImageReader class methodsFor:'i/o support'!

streamReadingFile:aFilename
    "return a stream to read aFilename.
     If the filename ends with '.Z' or '.gz', return a stream
     to a pipe for the uncompressor. Otherwise, return a stream to read
     the file directly."

    |inStream name|

    name := aFilename asString.
    ((name endsWith:'.Z') or:[name endsWith:'.gz']) ifTrue:[
	inStream := PipeStream readingFrom:'gunzip < ' , name.
	inStream isNil ifTrue:[
	    inStream := PipeStream readingFrom:'uncompress < ' , name.
	]
    ] ifFalse:[
	inStream := aFilename asFilename readStream.
    ].
    inStream isNil ifTrue:[
	'IMGREADER: open error on: ' errorPrint. aFilename errorPrintNL. 
    ].
    ^ inStream
! !

!ImageReader class methodsFor:'image reading'!

fromStream:aStream
    "read an image (in my format) from aStream"

    |reader|

    reader := self new fromStream:aStream.
    reader notNil ifTrue:[
	^ reader image
    ].
    ^ nil
!

fromFile:aFileName
    "read an image (in my format) from aFileName. 
     Return the image or nil on error."

    |result inStream|

    inStream := self streamReadingFile:aFileName.
    inStream isNil ifTrue:[
	'IMGREADER: file open error' errorPrintNL.
	^ nil
    ].
    result := self fromStream:inStream.
    inStream close.
    ^ result

    "
     XPMReader fromFile:'bitmaps/ljet.xpm'
     XBMReader fromFile:'bitmaps/SBrowser.xbm'
    " 
! !

!ImageReader class methodsFor:'image writing'!

save:anImage onFile:aFileName
    "save the image in my format on aFileName"

    ^ (self basicNew) save:anImage onFile:aFileName
! !

!ImageReader class methodsFor:'testing'!

isValidImageFile:aFileName
    "return true, if aFileName contains an image this
     reader understands - must be redefined in concrete subclasses."

    ^ false
! !

!ImageReader class methodsFor:'constants'!

reverseBits
    "return a table filled with bit reverse information.
     To convert from msbit-first to lsbit-first bytes, use
     the value as index into the table, retrieving the reverse
     value. Since indexing must start at 1, use (value + 1) as
     index."

    |val "{ Class: SmallInteger }" |

    ReverseBits isNil ifTrue:[
	ReverseBits := ByteArray new:256.
	0 to:255 do:[:i |
	    val := 0.
	    (i bitTest:16r01) ifTrue:[val := val bitOr:16r80].
	    (i bitTest:16r02) ifTrue:[val := val bitOr:16r40].
	    (i bitTest:16r04) ifTrue:[val := val bitOr:16r20].
	    (i bitTest:16r08) ifTrue:[val := val bitOr:16r10].
	    (i bitTest:16r10) ifTrue:[val := val bitOr:16r08].
	    (i bitTest:16r20) ifTrue:[val := val bitOr:16r04].
	    (i bitTest:16r40) ifTrue:[val := val bitOr:16r02].
	    (i bitTest:16r80) ifTrue:[val := val bitOr:16r01].
	    ReverseBits at:(i + 1) put:val
	]
    ].
    ^ ReverseBits
! !

!ImageReader class methodsFor:'cleanup'!

lowSpaceCleanup
    "cleanup things we do not need"

    ReverseBits := nil
! !

!ImageReader class methodsFor:'decompression support'!

decompressCCITT3From:srcBytes into:dstBytes startingAt:offset count:count 
    "decompress CCITT Group 3 compressed image data.
     count bytes from srcBytes are decompressed into dstBytes.
     Calls primitive c function for speed"
%{
    if (__isByteArray(srcBytes) 
     && __isByteArray(dstBytes)
     && __bothSmallInteger(offset, count)) {
	if (__decodeCCITTgroup3__(_ByteArrayInstPtr(srcBytes)->ba_element,
			      _ByteArrayInstPtr(dstBytes)->ba_element
			      + _intVal(offset) - 1,
			      _intVal(count))) {
	    RETURN ( self );
	}
    }
%}
.
    self primitiveFailed
!

decompressLZWFrom:srcBytes count:count into:dstBytes startingAt:offset
    "decompress LZW (tiff) compressed image data.
     count bytes from srcBytes are decompressed into dstBytes.
     Calls primitive c function for speed"
%{
    if (__isByteArray(srcBytes) 
     && __isByteArray(dstBytes)
     && __bothSmallInteger(offset, count)) {
	if (__decodeLZW__(_ByteArrayInstPtr(srcBytes)->ba_element,
		      _ByteArrayInstPtr(dstBytes)->ba_element
		      + _intVal(offset) - 1,
		      _intVal(count))) {
	    RETURN ( self );
	}
    }
%}
.
    self primitiveFailed
!

decompressGIFFrom:srcBytes count:count into:dstBytes startingAt:offset codeLen:codeLen
    "decompress GIF compressed image data.
     count bytes from srcBytes are decompressed into dstBytes.
     Calls primitive c function for speed"
%{
    if (__isByteArray(srcBytes) 
     && __isByteArray(dstBytes)
     && __bothSmallInteger(codeLen, offset)
     && __isSmallInteger(count)) {
	if (__decodeGIF__(_ByteArrayInstPtr(srcBytes)->ba_element,
		      _ByteArrayInstPtr(dstBytes)->ba_element
		      + _intVal(offset) - 1,
		      _intVal(count),
		      _intVal(codeLen))) {
	    RETURN ( self );
	}
    }
%}
.
    self primitiveFailed
!

decodeDelta:step in:data width:width height:height
    "perform NeXT special predictor delta decoding inplace in data.
     Calls primitive c function for speed"

    (step ~~ 3) ifTrue:[
	^ self error:'only rgb pictures supported'
    ].

%{
    if (__isByteArray(data)
     && __bothSmallInteger(width, height)) {
	__decodeDelta__(_ByteArrayInstPtr(data)->ba_element,
		    _intVal(width), _intVal(height));
	RETURN ( self );
    }
%}
.
    self primitiveFailed
! !

!ImageReader methodsFor:'accessing'!

image
    "return the image represented by myself"

    |image depth|

    depth := self bitsPerPixel.
    image := (Image implementorForDepth:depth) new.
    image width:width.
    image height:height.
    image photometric:photometric.
    image samplesPerPixel:samplesPerPixel.
    image bitsPerSample:bitsPerSample.
    image colorMap:colorMap.
    image data:data.
    ^ image
!

height 
    ^ height
!

photometric
    ^ photometric
!

width
    ^ width
!

samplesPerPixel
    ^ samplesPerPixel
!

data 
    ^ data
!

colorMap
    ^ colorMap
!

bitsPerSample
    ^ bitsPerSample
!

bitsPerPixel
    "return the number of bits per pixel"

    ^ (bitsPerSample inject:0 into:[:sum :i | sum + i])
! !

!ImageReader methodsFor:'image writing'!

save:image onFile:aFileName
    "save image in my format on aFile"

    ^ self subclassResponsibility
! !

!ImageReader methodsFor:'image reading'!

fromStream:aStream
    "read imagedata in my format from aStream"

    ^ self subclassResponsibility
! !

!ImageReader methodsFor:'i/o support'!

readLong
    "return the next 4-byte long, honoring the byte-order"

    ^ inStream nextLongMSB:(byteOrder ~~ #lsb)
!

readShort
    "return the next 2-byte short, honoring the byte-order"

    ^ inStream nextUnsignedShortMSB:(byteOrder ~~ #lsb)
!

readShortLong
    "return the next 2-byte short, honoring the byte-order.
     There are actually 4 bytes read, but only 2 looked at."

    |bytes val|

    bytes := ByteArray new:4.
    inStream nextBytes:4 into:bytes.
    (byteOrder == #lsb) ifTrue:[
	val := bytes at:2.
	val := val * 256 + (bytes at:1)
    ] ifFalse:[
	val := bytes at:3.
	val := val * 256 + (bytes at:4)
    ].
    ^ val
!

writeLong:anInteger
    "write a 4-byte long, honoring the byte-order."

    outStream nextPutLong:anInteger MSB:(byteOrder ~~ #lsb)
!

writeShort:anInteger
    "write a 2-byte short, honoring the byte-order."

    outStream nextPutShort:anInteger MSB:(byteOrder ~~ #lsb)
! !