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kimageformats/src/imageformats/chunks.cpp
Mirco Miranda 463da81fad IFF: support for PCHG chunk 
Highlights:
- Adds support for a new palette changer chunk. Some test cases attached to #38 .
- Fixes the reading of ILBMs with the mask (test case: [cyclone.iff](/uploads/d8734d2155fd0d21f7b003b37e0d1259/cyclone.iff)).
- Adds support for HAM5 encoding.
- Adds more test cases created using [HAM Converter](http://mrsebe.bplaced.net/blog/wordpress/).
- Adds support for Atari STE RAST chunk outside FORM one (test case: [fish.iff](/uploads/c461cf4b6a1423cec60fbce645d9fd07/fish.iff)).

NOTE: I contacted Sebastiano Vigna, the author of the PCHG chunk specifications, and he provided me with:
- Some images to test the code (but I can't include them in the test cases).
- Permission to use [his code](https://vigna.di.unimi.it/amiga/PCHGLib.zip) without restrictions: Huffman decompression was achieved by converting `FastDecomp.a` via AI.

Closes #38
2025-09-08 15:39:50 +00:00

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/*
This file is part of the KDE project
SPDX-FileCopyrightText: 2025 Mirco Miranda <mircomir@outlook.com>
SPDX-License-Identifier: LGPL-2.0-or-later
*/
#include "chunks_p.h"
#include "packbits_p.h"
#include <QBuffer>
#include <QColor>
#include <QDataStream>
#ifdef QT_DEBUG
Q_LOGGING_CATEGORY(LOG_IFFPLUGIN, "kf.imageformats.plugins.iff", QtDebugMsg)
#else
Q_LOGGING_CATEGORY(LOG_IFFPLUGIN, "kf.imageformats.plugins.iff", QtWarningMsg)
#endif
#define RECURSION_PROTECTION 10
#define BITPLANES_HAM_MAX 8
#define BITPLANES_HAM_MIN 5
#define BITPLANES_HALFBRIDE_MAX 8
#define BITPLANES_HALFBRIDE_MIN 1
static QString dataToString(const IFFChunk *chunk)
{
if (chunk == nullptr || !chunk->isValid()) {
return {};
}
auto dt = chunk->data();
for (; dt.endsWith(char()); dt = dt.removeLast());
return QString::fromUtf8(dt).trimmed();
}
IFFChunk::~IFFChunk()
{
}
IFFChunk::IFFChunk()
: _chunkId{0}
, _size{0}
, _align{2}
, _dataPos{0}
, _recursionCnt{0}
{
}
bool IFFChunk::operator ==(const IFFChunk &other) const
{
if (chunkId() != other.chunkId()) {
return false;
}
return _size == other._size && _dataPos == other._dataPos;
}
bool IFFChunk::isValid() const
{
auto cid = chunkId();
if (cid.isEmpty()) {
return false;
}
// A “type ID”, “property name”, “FORM type”, or any other IFF
// identifier is a 32-bit value: the concatenation of four ASCII
// characters in the range “ ” (SP, hex 20) through “~” (hex 7E).
// Spaces (hex 20) should not precede printing characters;
// trailing spaces are OK. Control characters are forbidden.
if (cid.at(0) == ' ') {
return false;
}
for (auto &&c : cid) {
if (c < ' ' || c > '~')
return false;
}
return true;
}
qint32 IFFChunk::alignBytes() const
{
return _align;
}
bool IFFChunk::readStructure(QIODevice *d)
{
auto ok = readInfo(d);
if (recursionCounter() > RECURSION_PROTECTION - 1) {
ok = ok && IFFChunk::innerReadStructure(d); // force default implementation (no more recursion)
} else {
ok = ok && innerReadStructure(d);
}
if (ok) {
ok = d->seek(nextChunkPos());
}
return ok;
}
QByteArray IFFChunk::chunkId() const
{
return QByteArray(_chunkId, 4);
}
quint32 IFFChunk::bytes() const
{
return _size;
}
const QByteArray &IFFChunk::data() const
{
return _data;
}
const IFFChunk::ChunkList &IFFChunk::chunks() const
{
return _chunks;
}
quint8 IFFChunk::chunkVersion(const QByteArray &cid)
{
if (cid.size() != 4) {
return 0;
}
if (cid.at(3) >= char('2') && cid.at(3) <= char('9')) {
return quint8(cid.at(3) - char('0'));
}
return 1;
}
bool IFFChunk::isChunkType(const QByteArray &cid) const
{
if (chunkId() == cid) {
return true;
}
if (chunkId().startsWith(cid.left(3)) && IFFChunk::chunkVersion(cid) > 1) {
return true;
}
return false;
}
bool IFFChunk::readInfo(QIODevice *d)
{
if (d == nullptr || d->read(_chunkId, 4) != 4) {
return false;
}
if (!IFFChunk::isValid()) {
return false;
}
auto sz = d->read(4);
if (sz.size() != 4) {
return false;
}
_size = ui32(sz.at(3), sz.at(2), sz.at(1), sz.at(0));
_dataPos = d->pos();
return true;
}
QByteArray IFFChunk::readRawData(QIODevice *d, qint64 relPos, qint64 size) const
{
if (!seek(d, relPos)) {
return{};
}
if (size == -1) {
size = _size;
}
auto read = std::min(size, _size - relPos);
return d->read(read);
}
bool IFFChunk::seek(QIODevice *d, qint64 relPos) const
{
if (d == nullptr) {
return false;
}
return d->seek(_dataPos + relPos);
}
bool IFFChunk::innerReadStructure(QIODevice *)
{
return true;
}
void IFFChunk::setAlignBytes(qint32 bytes)
{
_align = bytes;
}
qint64 IFFChunk::nextChunkPos() const
{
auto pos = _dataPos + _size;
if (auto align = pos % alignBytes())
pos += alignBytes() - align;
return pos;
}
IFFChunk::ChunkList IFFChunk::search(const QByteArray &cid, const QSharedPointer<IFFChunk> &chunk)
{
return search(cid, ChunkList() << chunk);
}
IFFChunk::ChunkList IFFChunk::search(const QByteArray &cid, const ChunkList &chunks)
{
IFFChunk::ChunkList list;
for (auto &&chunk : chunks) {
if (chunk->chunkId() == cid)
list << chunk;
list << IFFChunk::search(cid, chunk->_chunks);
}
return list;
}
bool IFFChunk::cacheData(QIODevice *d)
{
if (bytes() > 8 * 1024 * 1024) {
return false;
}
_data = readRawData(d);
return _data.size() == _size;
}
void IFFChunk::setChunks(const ChunkList &chunks)
{
_chunks = chunks;
}
qint32 IFFChunk::recursionCounter() const
{
return _recursionCnt;
}
void IFFChunk::setRecursionCounter(qint32 cnt)
{
_recursionCnt = cnt;
}
IFFChunk::ChunkList IFFChunk::innerFromDevice(QIODevice *d, bool *ok, IFFChunk *parent)
{
auto tmp = false;
if (ok == nullptr) {
ok = &tmp;
}
*ok = false;
if (d == nullptr) {
return {};
}
auto alignBytes = qint32(2);
auto recursionCnt = qint32();
auto nextChunkPos = qint64();
if (parent) {
alignBytes = parent->alignBytes();
recursionCnt = parent->recursionCounter();
nextChunkPos = parent->nextChunkPos();
}
if (recursionCnt > RECURSION_PROTECTION) {
return {};
}
IFFChunk::ChunkList list;
for (; !d->atEnd() && (nextChunkPos == 0 || d->pos() < nextChunkPos);) {
auto cid = d->peek(4);
QSharedPointer<IFFChunk> chunk;
if (cid == ABIT_CHUNK) {
chunk = QSharedPointer<IFFChunk>(new ABITChunk());
} else if (cid == ANNO_CHUNK) {
chunk = QSharedPointer<IFFChunk>(new ANNOChunk());
} else if (cid == AUTH_CHUNK) {
chunk = QSharedPointer<IFFChunk>(new AUTHChunk());
} else if (cid == BEAM_CHUNK) {
chunk = QSharedPointer<IFFChunk>(new BEAMChunk());
} else if (cid == BMHD_CHUNK) {
chunk = QSharedPointer<IFFChunk>(new BMHDChunk());
} else if (cid == BODY_CHUNK) {
chunk = QSharedPointer<IFFChunk>(new BODYChunk());
} else if (cid == CAMG_CHUNK) {
chunk = QSharedPointer<IFFChunk>(new CAMGChunk());
} else if (cid == CAT__CHUNK) {
chunk = QSharedPointer<IFFChunk>(new CATChunk());
} else if (cid == CMAP_CHUNK) {
chunk = QSharedPointer<IFFChunk>(new CMAPChunk());
} else if (cid == CMYK_CHUNK) {
chunk = QSharedPointer<IFFChunk>(new CMYKChunk());
} else if (cid == COPY_CHUNK) {
chunk = QSharedPointer<IFFChunk>(new COPYChunk());
} else if (cid == CTBL_CHUNK) {
chunk = QSharedPointer<IFFChunk>(new CTBLChunk());
} else if (cid == DATE_CHUNK) {
chunk = QSharedPointer<IFFChunk>(new DATEChunk());
} else if (cid == DPI__CHUNK) {
chunk = QSharedPointer<IFFChunk>(new DPIChunk());
} else if (cid == EXIF_CHUNK) {
chunk = QSharedPointer<IFFChunk>(new EXIFChunk());
} else if (cid == FOR4_CHUNK) {
chunk = QSharedPointer<IFFChunk>(new FOR4Chunk());
} else if (cid == FORM_CHUNK) {
chunk = QSharedPointer<IFFChunk>(new FORMChunk());
} else if (cid == FVER_CHUNK) {
chunk = QSharedPointer<IFFChunk>(new FVERChunk());
} else if (cid == HIST_CHUNK) {
chunk = QSharedPointer<IFFChunk>(new HISTChunk());
} else if (cid == ICCN_CHUNK) {
chunk = QSharedPointer<IFFChunk>(new ICCNChunk());
} else if (cid == ICCP_CHUNK) {
chunk = QSharedPointer<IFFChunk>(new ICCPChunk());
} else if (cid == NAME_CHUNK) {
chunk = QSharedPointer<IFFChunk>(new NAMEChunk());
} else if (cid == PCHG_CHUNK) {
chunk = QSharedPointer<IFFChunk>(new PCHGChunk());
} else if (cid == RAST_CHUNK) {
chunk = QSharedPointer<IFFChunk>(new RASTChunk());
} else if (cid == RGBA_CHUNK) {
chunk = QSharedPointer<IFFChunk>(new RGBAChunk());
} else if (cid == SHAM_CHUNK) {
chunk = QSharedPointer<IFFChunk>(new SHAMChunk());
} else if (cid == TBHD_CHUNK) {
chunk = QSharedPointer<IFFChunk>(new TBHDChunk());
} else if (cid == VERS_CHUNK) {
chunk = QSharedPointer<IFFChunk>(new VERSChunk());
} else if (cid == XBMI_CHUNK) {
chunk = QSharedPointer<IFFChunk>(new XBMIChunk());
} else if (cid == XMP0_CHUNK) {
chunk = QSharedPointer<IFFChunk>(new XMP0Chunk());
} else { // unknown chunk
chunk = QSharedPointer<IFFChunk>(new IFFChunk());
qCDebug(LOG_IFFPLUGIN) << "IFFChunk::innerFromDevice(): unknown chunk" << cid;
}
// change the alignment to the one of main chunk (required for unknown Maya IFF chunks)
if (chunk->isChunkType(CAT__CHUNK)
|| chunk->isChunkType(FILL_CHUNK)
|| chunk->isChunkType(FORM_CHUNK)
|| chunk->isChunkType(LIST_CHUNK)
|| chunk->isChunkType(PROP_CHUNK)) {
alignBytes = chunk->alignBytes();
} else {
chunk->setAlignBytes(alignBytes);
}
chunk->setRecursionCounter(recursionCnt + 1);
if (!chunk->readStructure(d)) {
*ok = false;
return {};
}
// skip any non-IFF data at the end of the file.
// NOTE: there should be no more chunks after the first (root)
if (nextChunkPos == 0) {
nextChunkPos = chunk->nextChunkPos();
}
list << chunk;
}
*ok = true;
return list;
}
IFFChunk::ChunkList IFFChunk::fromDevice(QIODevice *d, bool *ok)
{
return innerFromDevice(d, ok, nullptr);
}
/* ******************
* *** BMHD Chunk ***
* ****************** */
BMHDChunk::~BMHDChunk()
{
}
BMHDChunk::BMHDChunk() : IFFChunk()
{
}
bool BMHDChunk::isValid() const
{
if (bytes() < 20) {
return false;
}
return chunkId() == BMHDChunk::defaultChunkId();
}
bool BMHDChunk::innerReadStructure(QIODevice *d)
{
return cacheData(d);
}
qint32 BMHDChunk::width() const
{
if (!isValid()) {
return 0;
}
return qint32(ui16(data().at(1), data().at(0)));
}
qint32 BMHDChunk::height() const
{
if (!isValid()) {
return 0;
}
return qint32(ui16(data().at(3), data().at(2)));
}
QSize BMHDChunk::size() const
{
return QSize(width(), height());
}
qint32 BMHDChunk::left() const
{
if (!isValid()) {
return 0;
}
return qint32(ui16(data().at(5), data().at(4)));
}
qint32 BMHDChunk::top() const
{
if (!isValid()) {
return 0;
}
return qint32(ui16(data().at(7), data().at(6)));
}
quint8 BMHDChunk::bitplanes() const
{
if (!isValid()) {
return 0;
}
return quint8(data().at(8));
}
BMHDChunk::Masking BMHDChunk::masking() const
{
if (!isValid()) {
return BMHDChunk::Masking::None;
}
return BMHDChunk::Masking(quint8(data().at(9)));
}
BMHDChunk::Compression BMHDChunk::compression() const
{
if (!isValid()) {
return BMHDChunk::Compression::Uncompressed;
}
return BMHDChunk::Compression(data().at(10));
}
qint16 BMHDChunk::transparency() const
{
if (!isValid()) {
return 0;
}
return i16(data().at(13), data().at(12));
}
quint8 BMHDChunk::xAspectRatio() const
{
if (!isValid()) {
return 0;
}
return quint8(data().at(14));
}
quint8 BMHDChunk::yAspectRatio() const
{
if (!isValid()) {
return 0;
}
return quint8(data().at(15));
}
quint16 BMHDChunk::pageWidth() const
{
if (!isValid()) {
return 0;
}
return ui16(data().at(17), data().at(16));
}
quint16 BMHDChunk::pageHeight() const
{
if (!isValid()) {
return 0;
}
return ui16(data().at(19), data().at(18));
}
quint32 BMHDChunk::rowLen() const
{
return ((quint32(width()) + 15) / 16) * 2;
}
/* ******************
* *** CMAP Chunk ***
* ****************** */
CMAPChunk::~CMAPChunk()
{
}
CMAPChunk::CMAPChunk() : IFFChunk()
{
}
bool CMAPChunk::isValid() const
{
return chunkId() == CMAPChunk::defaultChunkId();
}
qint32 CMAPChunk::count() const
{
if (!isValid()) {
return 0;
}
return bytes() / 3;
}
QList<QRgb> CMAPChunk::palette(bool halfbride) const
{
auto p = innerPalette();
if (!halfbride) {
return p;
}
auto tmp = p;
for (auto &&v : tmp) {
p << qRgb(qRed(v) / 2, qGreen(v) / 2, qBlue(v) / 2);
}
return p;
}
bool CMAPChunk::innerReadStructure(QIODevice *d)
{
return cacheData(d);
}
QList<QRgb> CMAPChunk::innerPalette() const
{
QList<QRgb> l;
auto &&d = data();
for (qint32 i = 0, n = count(); i < n; ++i) {
auto i3 = i * 3;
l << qRgb(d.at(i3), d.at(i3 + 1), d.at(i3 + 2));
}
return l;
}
/* ******************
* *** CMYK Chunk ***
* ****************** */
CMYKChunk::~CMYKChunk()
{
}
CMYKChunk::CMYKChunk() : CMAPChunk()
{
}
bool CMYKChunk::isValid() const
{
return chunkId() == CMYKChunk::defaultChunkId();
}
qint32 CMYKChunk::count() const
{
if (!isValid()) {
return 0;
}
return bytes() / 4;
}
QList<QRgb> CMYKChunk::innerPalette() const
{
QList<QRgb> l;
auto &&d = data();
for (qint32 i = 0, n = count(); i < n; ++i) {
auto i4 = i * 4;
auto C = quint8(d.at(i4)) / 255.;
auto M = quint8(d.at(i4 + 1)) / 255.;
auto Y = quint8(d.at(i4 + 2)) / 255.;
auto K = quint8(d.at(i4 + 3)) / 255.;
l << QColor::fromCmykF(C, M, Y, K).toRgb().rgb();
}
return l;
}
/* ******************
* *** CAMG Chunk ***
* ****************** */
CAMGChunk::~CAMGChunk()
{
}
CAMGChunk::CAMGChunk() : IFFChunk()
{
}
bool CAMGChunk::isValid() const
{
if (bytes() != 4) {
return false;
}
return chunkId() == CAMGChunk::defaultChunkId();
}
CAMGChunk::ModeIds CAMGChunk::modeId() const
{
if (!isValid()) {
return CAMGChunk::ModeIds();
}
return CAMGChunk::ModeIds(ui32(data().at(3), data().at(2), data().at(1), data().at(0)));
}
bool CAMGChunk::innerReadStructure(QIODevice *d)
{
return cacheData(d);
}
/* ******************
* *** DPI Chunk ***
* ****************** */
DPIChunk::~DPIChunk()
{
}
DPIChunk::DPIChunk() : IFFChunk()
{
}
bool DPIChunk::isValid() const
{
if (dpiX() == 0 || dpiY() == 0) {
return false;
}
return chunkId() == DPIChunk::defaultChunkId();
}
quint16 DPIChunk::dpiX() const
{
if (bytes() < 4) {
return 0;
}
return i16(data().at(1), data().at(0));
}
quint16 DPIChunk::dpiY() const
{
if (bytes() < 4) {
return 0;
}
return i16(data().at(3), data().at(2));
}
qint32 DPIChunk::dotsPerMeterX() const
{
return qRound(dpiX() / 25.4 * 1000);
}
qint32 DPIChunk::dotsPerMeterY() const
{
return qRound(dpiY() / 25.4 * 1000);
}
bool DPIChunk::innerReadStructure(QIODevice *d)
{
return cacheData(d);
}
/* ******************
* *** XBMI Chunk ***
* ****************** */
XBMIChunk::~XBMIChunk()
{
}
XBMIChunk::XBMIChunk() : DPIChunk()
{
}
bool XBMIChunk::isValid() const
{
if (dpiX() == 0 || dpiY() == 0) {
return false;
}
return chunkId() == XBMIChunk::defaultChunkId();
}
quint16 XBMIChunk::dpiX() const
{
if (bytes() < 6) {
return 0;
}
return i16(data().at(3), data().at(2));
}
quint16 XBMIChunk::dpiY() const
{
if (bytes() < 6) {
return 0;
}
return i16(data().at(5), data().at(4));
}
XBMIChunk::PictureType XBMIChunk::pictureType() const
{
if (bytes() < 6) {
return PictureType(-1);
}
return PictureType(i16(data().at(1), data().at(0)));
}
/* ******************
* *** BODY Chunk ***
* ****************** */
BODYChunk::~BODYChunk()
{
}
BODYChunk::BODYChunk() : IFFChunk()
{
}
bool BODYChunk::isValid() const
{
return chunkId() == BODYChunk::defaultChunkId();
}
// For each RGB value, a LONG-word (32 bits) is written:
// with the 24 RGB bits in the MSB positions; the "genlock"
// bit next, and then a 7 bit repeat count.
//
// See also: https://wiki.amigaos.net/wiki/RGBN_and_RGB8_IFF_Image_Data
inline qint64 rgb8Decompress(QIODevice *input, char *output, qint64 olen)
{
qint64 j = 0;
for (qint64 available = olen; j < olen; available = olen - j) {
auto pos = input->pos();
auto ba4 = input->read(4);
if (ba4.size() != 4) {
break;
}
auto cnt = qint32(ba4.at(3) & 0x7F);
if (cnt * 3 > available) {
if (!input->seek(pos))
return -1;
break;
}
for (qint32 i = 0; i < cnt; ++i) {
output[j++] = ba4.at(0);
output[j++] = ba4.at(1);
output[j++] = ba4.at(2);
}
}
return j;
}
// For each RGB value, a WORD (16-bits) is written: with the
// 12 RGB bits in the MSB (most significant bit) positions;
// the "genlock" bit next; and then a 3 bit repeat count.
// If the repeat count is greater than 7, the 3-bit count is
// zero, and a BYTE repeat count follows. If the repeat count
// is greater than 255, the BYTE count is zero, and a WORD
// repeat count follows. Repeat counts greater than 65536 are
// not supported.
//
// See also: https://wiki.amigaos.net/wiki/RGBN_and_RGB8_IFF_Image_Data
inline qint32 rgbnCount(QIODevice *input, quint8 &R, quint8& G, quint8 &B)
{
auto ba2 = input->read(2);
if (ba2.size() != 2)
return 0;
R = ba2.at(0) & 0xF0;
R = R | (R >> 4);
G = ba2.at(0) & 0x0F;
G = G | (G << 4);
B = ba2.at(1) & 0xF0;
B = B | (B >> 4);
auto cnt = ba2.at(1) & 7;
if (cnt == 0) {
auto ba1 = input->read(1);
if (ba1.size() != 1)
return 0;
cnt = quint8(ba1.at(0));
}
if (cnt == 0) {
auto baw = input->read(2);
if (baw.size() != 2)
return 0;
cnt = qint32(quint8(baw.at(0))) << 8 | quint8(baw.at(1));
}
return cnt;
}
inline qint64 rgbNDecompress(QIODevice *input, char *output, qint64 olen)
{
qint64 j = 0;
for (qint64 available = olen; j < olen; available = olen - j) {
quint8 R = 0, G = 0, B = 0;
auto pos = input->pos();
auto cnt = rgbnCount(input, R, G, B);
if (cnt * 3 > available || cnt == 0) {
if (!input->seek(pos))
return -1;
break;
}
for (qint32 i = 0; i < cnt; ++i) {
output[j++] = R;
output[j++] = G;
output[j++] = B;
}
}
return j;
}
QByteArray BODYChunk::strideRead(QIODevice *d, qint32 y, const BMHDChunk *header, const CAMGChunk *camg, const CMAPChunk *cmap, const IPALChunk *ipal, const QByteArray& formType) const
{
if (!isValid() || header == nullptr || d == nullptr) {
return {};
}
auto isRgbN = formType == RGBN_FORM_TYPE;
auto isRgb8 = formType == RGB8_FORM_TYPE;
auto isPbm = formType == PBM__FORM_TYPE;
auto lineCompressed = isRgbN || isRgb8 ? false : true;
auto readSize = strideSize(header, formType);
auto bufSize = readSize;
if (isRgbN) {
bufSize = std::max(quint32(65536 * 3), readSize);
}
if (isRgb8) {
bufSize = std::max(quint32(127 * 3), readSize);
}
for (auto nextPos = nextChunkPos(); !d->atEnd() && d->pos() < nextPos && _readBuffer.size() < readSize;) {
QByteArray buf(bufSize, char());
qint64 rr = -1;
if (header->compression() == BMHDChunk::Compression::Rle) {
// WARNING: The online spec says it's the same as TIFF but that's
// not accurate: the RLE -128 code is not a noop.
rr = packbitsDecompress(d, buf.data(), buf.size(), true);
} else if (header->compression() == BMHDChunk::Compression::RgbN8) {
if (isRgb8)
rr = rgb8Decompress(d, buf.data(), buf.size());
else if (isRgbN)
rr = rgbNDecompress(d, buf.data(), buf.size());
} else if (header->compression() == BMHDChunk::Compression::Uncompressed) {
rr = d->read(buf.data(), buf.size()); // never seen
} else {
qCDebug(LOG_IFFPLUGIN) << "BODYChunk::strideRead(): unknown compression" << header->compression();
}
if ((rr != readSize && lineCompressed) || (rr < 1))
return {};
_readBuffer.append(buf.data(), rr);
}
auto planes = _readBuffer.left(readSize);
_readBuffer.remove(0, readSize);
if (isPbm) {
return pbm(planes, y, header, camg, cmap, ipal);
}
if (isRgb8) {
return rgb8(planes, y, header, camg, cmap, ipal);
}
if (isRgbN) {
return rgbN(planes, y, header, camg, cmap, ipal);
}
return deinterleave(planes, y, header, camg, cmap, ipal);
}
bool BODYChunk::resetStrideRead(QIODevice *d) const
{
_readBuffer.clear();
return seek(d);
}
CAMGChunk::ModeIds BODYChunk::safeModeId(const BMHDChunk *header, const CAMGChunk *camg, const CMAPChunk *cmap)
{
if (camg) {
return camg->modeId();
}
if (header == nullptr) {
return CAMGChunk::ModeIds();
}
auto cmapCount = cmap ? cmap->count() : 0;
auto bitplanes = header->bitplanes();
if (bitplanes >= BITPLANES_HALFBRIDE_MIN && bitplanes <= BITPLANES_HALFBRIDE_MAX) {
if (cmapCount == (1 << (header->bitplanes() - 1)))
return CAMGChunk::ModeIds(CAMGChunk::ModeId::HalfBrite);
}
if (bitplanes >= BITPLANES_HAM_MIN && bitplanes <= BITPLANES_HAM_MAX) {
if (cmapCount == (1 << (header->bitplanes() - 2)))
return CAMGChunk::ModeIds(CAMGChunk::ModeId::Ham);
}
return CAMGChunk::ModeIds();
}
quint32 BODYChunk::strideSize(const BMHDChunk *header, const QByteArray& formType) const
{
// RGB8 / RGBN
if (formType == RGB8_FORM_TYPE || formType == RGBN_FORM_TYPE) {
return header->width() * 3;
}
// PBM
if (formType == PBM__FORM_TYPE) {
auto rs = header->width() * header->bitplanes() / 8;
if (rs & 1)
++rs;
return rs;
}
// ILBM
auto sz = header->rowLen() * header->bitplanes();
if (header->masking() == BMHDChunk::Masking::HasMask)
sz += header->rowLen();
return sz;
}
QByteArray BODYChunk::pbm(const QByteArray &planes, qint32, const BMHDChunk *header, const CAMGChunk *, const CMAPChunk *, const IPALChunk *) const
{
if (planes.size() != strideSize(header, PBM__FORM_TYPE)) {
return {};
}
if (header->bitplanes() == 8) {
// The data are contiguous.
return planes;
}
return {};
}
QByteArray BODYChunk::rgb8(const QByteArray &planes, qint32, const BMHDChunk *header, const CAMGChunk *, const CMAPChunk *, const IPALChunk *) const
{
if (planes.size() != strideSize(header, RGB8_FORM_TYPE)) {
return {};
}
return planes;
}
QByteArray BODYChunk::rgbN(const QByteArray &planes, qint32, const BMHDChunk *header, const CAMGChunk *, const CMAPChunk *, const IPALChunk *) const
{
if (planes.size() != strideSize(header, RGBN_FORM_TYPE)) {
return {};
}
return planes;
}
QByteArray BODYChunk::deinterleave(const QByteArray &planes, qint32 y, const BMHDChunk *header, const CAMGChunk *camg, const CMAPChunk *cmap, const IPALChunk *ipal) const
{
if (planes.size() != strideSize(header, ILBM_FORM_TYPE)) {
return {};
}
auto rowLen = qint32(header->rowLen());
auto bitplanes = header->bitplanes();
auto modeId = BODYChunk::safeModeId(header, camg, cmap);
QByteArray ba;
switch (bitplanes) {
case 1: // gray, indexed and rgb Ham mode
case 2:
case 3:
case 4:
case 5:
case 6:
case 7:
case 8:
if ((modeId & CAMGChunk::ModeId::Ham) && (cmap) &&
(bitplanes >= BITPLANES_HAM_MIN && bitplanes <= BITPLANES_HAM_MAX)) {
// From A Quick Introduction to IFF.txt:
//
// Amiga HAM (Hold and Modify) mode lets the Amiga display all 4096 RGB values.
// In HAM mode, the bits in the two last planes describe an R G or B
// modification to the color of the previous pixel on the line to create the
// color of the current pixel. So a 6-plane HAM picture has 4 planes for
// specifying absolute color pixels giving up to 16 absolute colors which would
// be specified in the ILBM CMAP chunk. The bits in the last two planes are
// color modification bits which cause the Amiga, in HAM mode, to take the RGB
// value of the previous pixel (Hold and), substitute the 4 bits in planes 0-3
// for the previous color's R G or B component (Modify) and display the result
// for the current pixel. If the first pixel of a scan line is a modification
// pixel, it modifies the RGB value of the border color (register 0). The color
// modification bits in the last two planes (planes 4 and 5) are interpreted as
// follows:
// 00 - no modification. Use planes 0-3 as normal color register index
// 10 - hold previous, replacing Blue component with bits from planes 0-3
// 01 - hold previous, replacing Red component with bits from planes 0-3
// 11 - hold previous. replacing Green component with bits from planes 0-3
ba = QByteArray(rowLen * 8 * 3, char());
auto pal = cmap->palette();
if (ipal) {
auto tmp = ipal->palette(y);
if (tmp.size() == pal.size())
pal = tmp;
}
// HAM 6: 2 control bits+4 bits of data, 16-color palette
//
// HAM 8: 2 control bits+6 bits of data, 64-color palette
//
// HAM 5: 1 control bit (and 1 hardwired to zero)+4 bits of data
// (red and green modify operations are unavailable)
auto ctlbits = bitplanes > 5 ? 2 : 1;
auto max = (1 << (bitplanes - ctlbits)) - 1;
quint8 prev[3] = {};
for (qint32 i = 0, cnt = 0; i < rowLen; ++i) {
for (qint32 j = 0; j < 8; ++j, ++cnt) {
quint8 idx = 0, ctl = 0;
for (qint32 k = 0, msk = (1 << (7 - j)); k < bitplanes; ++k) {
if ((planes.at(k * rowLen + i) & msk) == 0)
continue;
if (k < bitplanes - ctlbits)
idx |= 1 << k;
else
ctl |= 1 << (bitplanes - k - 1);
}
if (ctl && ctlbits == 1) {
ctl <<= 1; // HAM 5 has only 1 control bit and the LSB is always 0
}
switch (ctl) {
case 1: // red
prev[0] = idx * 255 / max;
break;
case 2: // blue
prev[2] = idx * 255 / max;
break;
case 3: // green
prev[1] = idx * 255 / max;
break;
default:
if (idx < pal.size()) {
prev[0] = qRed(pal.at(idx));
prev[1] = qGreen(pal.at(idx));
prev[2] = qBlue(pal.at(idx));
} else {
qCWarning(LOG_IFFPLUGIN) << "BODYChunk::deinterleave(): palette index" << idx << "is out of range";
}
break;
}
auto cnt3 = cnt * 3;
ba[cnt3] = char(prev[0]);
ba[cnt3 + 1] = char(prev[1]);
ba[cnt3 + 2] = char(prev[2]);
}
}
} else if ((modeId & CAMGChunk::ModeId::HalfBrite) && (cmap) &&
(bitplanes >= BITPLANES_HALFBRIDE_MIN && bitplanes <= BITPLANES_HALFBRIDE_MAX)) {
// From A Quick Introduction to IFF.txt:
//
// In HALFBRITE mode, the Amiga interprets the bit in the
// last plane as HALFBRITE modification. The bits in the other planes are
// treated as normal color register numbers (RGB values for each color register
// is specified in the CMAP chunk). If the bit in the last plane is set (1),
// then that pixel is displayed at half brightness. This can provide up to 64
// absolute colors.
ba = QByteArray(rowLen * 8, char());
auto palSize = cmap->count();
for (qint32 i = 0, cnt = 0; i < rowLen; ++i) {
for (qint32 j = 0; j < 8; ++j, ++cnt) {
quint8 idx = 0, ctl = 0;
for (qint32 k = 0, msk = (1 << (7 - j)); k < bitplanes; ++k) {
if ((planes.at(k * rowLen + i) & msk) == 0)
continue;
if (k < bitplanes - 1)
idx |= 1 << k;
else
ctl = 1;
}
if (idx < palSize) {
ba[cnt] = ctl ? idx + palSize : idx;
} else {
qCWarning(LOG_IFFPLUGIN) << "BODYChunk::deinterleave(): palette index" << idx << "is out of range";
}
}
}
} else {
// From A Quick Introduction to IFF.txt:
//
// If the ILBM is not HAM or HALFBRITE, then after parsing and uncompacting if
// necessary, you will have N planes of pixel data. Color register used for
// each pixel is specified by looking at each pixel thru the planes. I.e.,
// if you have 5 planes, and the bit for a particular pixel is set in planes
// 0 and 3:
//
// PLANE 4 3 2 1 0
// PIXEL 0 1 0 0 1
//
// then that pixel uses color register binary 01001 = 9
ba = QByteArray(rowLen * 8, char());
for (qint32 i = 0; i < rowLen; ++i) {
for (qint32 k = 0, i8 = i * 8; k < bitplanes; ++k) {
auto v = planes.at(k * rowLen + i);
auto msk = 1 << k;
if (v & (1 << 7))
ba[i8] |= msk;
if (v & (1 << 6))
ba[i8 + 1] |= msk;
if (v & (1 << 5))
ba[i8 + 2] |= msk;
if (v & (1 << 4))
ba[i8 + 3] |= msk;
if (v & (1 << 3))
ba[i8 + 4] |= msk;
if (v & (1 << 2))
ba[i8 + 5] |= msk;
if (v & (1 << 1))
ba[i8 + 6] |= msk;
if (v & 1)
ba[i8 + 7] |= msk;
}
}
}
break;
case 24: // rgb
case 32: // rgba (SView5 extension)
// From A Quick Introduction to IFF.txt:
//
// If a deep ILBM (like 12 or 24 planes), there should be no CMAP
// and instead the BODY planes are interpreted as the bits of RGB
// in the order R0...Rn G0...Gn B0...Bn
//
// NOTE: This code does not support 12-planes images
ba = QByteArray(rowLen * bitplanes, char());
for (qint32 i = 0, cnt = 0, p = bitplanes / 8; i < rowLen; ++i) {
for (qint32 j = 0; j < 8; ++j)
for (qint32 k = 0; k < p; ++k, ++cnt) {
auto k8 = k * 8;
auto msk = (1 << (7 - j));
if (planes.at(k8 * rowLen + i) & msk)
ba[cnt] |= 0x01;
if (planes.at((1 + k8) * rowLen + i) & msk)
ba[cnt] |= 0x02;
if (planes.at((2 + k8) * rowLen + i) & msk)
ba[cnt] |= 0x04;
if (planes.at((3 + k8) * rowLen + i) & msk)
ba[cnt] |= 0x08;
if (planes.at((4 + k8) * rowLen + i) & msk)
ba[cnt] |= 0x10;
if (planes.at((5 + k8) * rowLen + i) & msk)
ba[cnt] |= 0x20;
if (planes.at((6 + k8) * rowLen + i) & msk)
ba[cnt] |= 0x40;
if (planes.at((7 + k8) * rowLen + i) & msk)
ba[cnt] |= 0x80;
}
}
break;
case 48: // rgb (SView5 extension)
case 64: // rgba (SView5 extension)
// From https://aminet.net/package/docs/misc/ILBM64:
//
// Previously, the IFF-ILBM fileformat has been
// extended two times already, for 24 bit and 32 bit
// image data:
//
// 24 bit -> 24 planes composing RGB 8:8:8 true color
// 32 bit -> 32 planes composing RGBA 8:8:8:8 true color
// plus alpha
//
// The former extension quickly became a common one,
// while the latter until recently mainly had been
// used by some NewTek software.
//
// Now the following - as a consequent logical extension
// of the previously mentioned definitions - is introduced
// by SView5-Library:
//
// 48 bit -> 48 planes composing RGB 16:16:16 true color
// 64 bit -> 64 planes composing RGBA 16:16:16:16 true color
// plus alpha
//
// The resulting data is intended to allow direct transformation
// from the PNG format into the Amiga (ILBM) bitmap format.
ba = QByteArray(rowLen * 64, char()); // the RGBX QT format is 64-bits
const qint32 order[] = { 1, 0, 3, 2, 5, 4, 7, 6 };
for (qint32 i = 0, cnt = 0, p = bitplanes / 8; i < rowLen; ++i) {
for (qint32 j = 0; j < 8; ++j, cnt += 8) {
for (qint32 k = 0; k < p; ++k) {
auto k8 = k * 8;
auto msk = (1 << (7 - j));
auto idx = cnt + order[k];
if (planes.at(k8 * rowLen + i) & msk)
ba[idx] |= 0x01;
if (planes.at((1 + k8) * rowLen + i) & msk)
ba[idx] |= 0x02;
if (planes.at((2 + k8) * rowLen + i) & msk)
ba[idx] |= 0x04;
if (planes.at((3 + k8) * rowLen + i) & msk)
ba[idx] |= 0x08;
if (planes.at((4 + k8) * rowLen + i) & msk)
ba[idx] |= 0x10;
if (planes.at((5 + k8) * rowLen + i) & msk)
ba[idx] |= 0x20;
if (planes.at((6 + k8) * rowLen + i) & msk)
ba[idx] |= 0x40;
if (planes.at((7 + k8) * rowLen + i) & msk)
ba[idx] |= 0x80;
}
if (p == 6) { // RGBX wants unused X data set to 0xFF
ba[cnt + 6] = char(0xFF);
ba[cnt + 7] = char(0xFF);
}
}
}
break;
}
return ba;
}
/* ******************
* *** ABIT Chunk ***
* ****************** */
ABITChunk::~ABITChunk()
{
}
ABITChunk::ABITChunk() : BODYChunk()
{
}
bool ABITChunk::isValid() const
{
return chunkId() == ABITChunk::defaultChunkId();
}
QByteArray ABITChunk::strideRead(QIODevice *d, qint32 y, const BMHDChunk *header, const CAMGChunk *camg, const CMAPChunk *cmap, const IPALChunk *ipal, const QByteArray& formType) const
{
if (!isValid() || header == nullptr || d == nullptr) {
return {};
}
if (header->compression() != BMHDChunk::Compression::Uncompressed || formType != ACBM_FORM_TYPE) {
return {};
}
// convert ABIT data to an ILBM line on the fly
auto ilbmLine = QByteArray(strideSize(header, formType), char());
auto rowSize = header->rowLen();
auto height = header->height();
if (y >= height) {
return {};
}
for (qint32 plane = 0, planes = qint32(header->bitplanes()); plane < planes; ++plane) {
if (!seek(d, qint64(plane) * rowSize * height + y * rowSize))
return {};
auto offset = qint64(plane) * rowSize;
if (offset + rowSize > ilbmLine.size())
return {};
if (d->read(ilbmLine.data() + offset, rowSize) != rowSize)
return {};
}
// decode the ILBM line
QBuffer buf;
buf.setData(ilbmLine);
if (!buf.open(QBuffer::ReadOnly)) {
return {};
}
return BODYChunk::strideRead(&buf, y, header, camg, cmap, ipal, ILBM_FORM_TYPE);
}
bool ABITChunk::resetStrideRead(QIODevice *d) const
{
return BODYChunk::resetStrideRead(d);
}
/* **********************
* *** FORM Interface ***
* ********************** */
IFOR_Chunk::~IFOR_Chunk()
{
}
IFOR_Chunk::IFOR_Chunk() : IFFChunk()
{
}
QImageIOHandler::Transformation IFOR_Chunk::transformation() const
{
auto exifs = IFFChunk::searchT<EXIFChunk>(chunks());
if (!exifs.isEmpty()) {
auto exif = exifs.first()->value();
if (!exif.isEmpty())
return exif.transformation();
}
return QImageIOHandler::Transformation::TransformationNone;
}
QImage::Format IFOR_Chunk::optionformat() const
{
auto fmt = this->format();
if (fmt == QImage::Format_Indexed8) {
if (auto ipal = searchIPal()) {
fmt = ipal->hasAlpha() ? FORMAT_RGBA_8BIT : FORMAT_RGB_8BIT;
}
}
return fmt;
}
const IPALChunk *IFOR_Chunk::searchIPal() const
{
const IPALChunk *ipal = nullptr;
auto beam = IFFChunk::searchT<BEAMChunk>(this);
if (!beam.isEmpty()) {
ipal = beam.first();
}
auto ctbl = IFFChunk::searchT<CTBLChunk>(this);
if (!ctbl.isEmpty()) {
ipal = ctbl.first();
}
auto sham = IFFChunk::searchT<SHAMChunk>(this);
if (!sham.isEmpty()) {
ipal = sham.first();
}
auto rast = IFFChunk::searchT<RASTChunk>(this);
if (!rast.isEmpty()) {
ipal = rast.first();
}
auto pchg = IFFChunk::searchT<PCHGChunk>(this);
if (!pchg.isEmpty()) {
ipal = pchg.first();
}
if (ipal && ipal->isValid()) {
return ipal;
}
return nullptr;
}
/* ******************
* *** FORM Chunk ***
* ****************** */
FORMChunk::~FORMChunk()
{
}
FORMChunk::FORMChunk() : IFOR_Chunk()
{
}
bool FORMChunk::isValid() const
{
return chunkId() == FORMChunk::defaultChunkId();
}
bool FORMChunk::isSupported() const
{
return format() != QImage::Format_Invalid;
}
bool FORMChunk::innerReadStructure(QIODevice *d)
{
if (bytes() < 4) {
return false;
}
_type = d->read(4);
auto ok = true;
// NOTE: add new supported type to CATChunk as well.
if (_type == ILBM_FORM_TYPE) {
setChunks(IFFChunk::innerFromDevice(d, &ok, this));
} else if (_type == PBM__FORM_TYPE) {
setChunks(IFFChunk::innerFromDevice(d, &ok, this));
} else if (_type == ACBM_FORM_TYPE) {
setChunks(IFFChunk::innerFromDevice(d, &ok, this));
} else if (_type == RGB8_FORM_TYPE) {
setChunks(IFFChunk::innerFromDevice(d, &ok, this));
} else if (_type == RGBN_FORM_TYPE) {
setChunks(IFFChunk::innerFromDevice(d, &ok, this));
}
return ok;
}
QByteArray FORMChunk::formType() const
{
return _type;
}
QImage::Format FORMChunk::format() const
{
auto headers = IFFChunk::searchT<BMHDChunk>(chunks());
if (headers.isEmpty()) {
return QImage::Format_Invalid;
}
if (auto &&h = headers.first()) {
auto cmaps = IFFChunk::searchT<CMAPChunk>(chunks());
if (cmaps.isEmpty()) {
auto cmyks = IFFChunk::searchT<CMYKChunk>(chunks());
for (auto &&cmyk : cmyks)
cmaps.append(cmyk);
}
auto camgs = IFFChunk::searchT<CAMGChunk>(chunks());
auto modeId = BODYChunk::safeModeId(h, camgs.isEmpty() ? nullptr : camgs.first(), cmaps.isEmpty() ? nullptr : cmaps.first());
if (h->bitplanes() == 13) {
return FORMAT_RGB_8BIT; // NOTE: with a little work you could use Format_RGB444
}
if (h->bitplanes() == 24 || h->bitplanes() == 25) {
return FORMAT_RGB_8BIT;
}
if (h->bitplanes() == 48) {
return QImage::Format_RGBX64;
}
if (h->bitplanes() == 32) {
return QImage::Format_RGBA8888;
}
if (h->bitplanes() == 64) {
return QImage::Format_RGBA64;
}
if (h->bitplanes() >= 1 && h->bitplanes() <= 8) {
if (h->bitplanes() >= BITPLANES_HAM_MIN && h->bitplanes() <= BITPLANES_HAM_MAX) {
if (modeId & CAMGChunk::ModeId::Ham)
return FORMAT_RGB_8BIT;
}
if (!cmaps.isEmpty()) {
return QImage::Format_Indexed8;
}
return QImage::Format_Grayscale8;
}
qCDebug(LOG_IFFPLUGIN) << "FORMChunk::format(): Unsupported" << h->bitplanes() << "bitplanes";
}
return QImage::Format_Invalid;
}
QSize FORMChunk::size() const
{
auto headers = IFFChunk::searchT<BMHDChunk>(chunks());
if (headers.isEmpty()) {
return {};
}
return headers.first()->size();
}
/* ******************
* *** FOR4 Chunk ***
* ****************** */
FOR4Chunk::~FOR4Chunk()
{
}
FOR4Chunk::FOR4Chunk() : IFOR_Chunk()
{
}
bool FOR4Chunk::isValid() const
{
return chunkId() == FOR4Chunk::defaultChunkId();
}
qint32 FOR4Chunk::alignBytes() const
{
return 4;
}
bool FOR4Chunk::isSupported() const
{
return format() != QImage::Format_Invalid;
}
bool FOR4Chunk::innerReadStructure(QIODevice *d)
{
if (bytes() < 4) {
return false;
}
_type = d->read(4);
auto ok = true;
if (_type == CIMG_FOR4_TYPE) {
setChunks(IFFChunk::innerFromDevice(d, &ok, this));
} else if (_type == TBMP_FOR4_TYPE) {
setChunks(IFFChunk::innerFromDevice(d, &ok, this));
}
return ok;
}
QByteArray FOR4Chunk::formType() const
{
return _type;
}
QImage::Format FOR4Chunk::format() const
{
auto headers = IFFChunk::searchT<TBHDChunk>(chunks());
if (headers.isEmpty()) {
return QImage::Format_Invalid;
}
return headers.first()->format();
}
QSize FOR4Chunk::size() const
{
auto headers = IFFChunk::searchT<TBHDChunk>(chunks());
if (headers.isEmpty()) {
return {};
}
return headers.first()->size();
}
/* ******************
* *** CAT Chunk ***
* ****************** */
CATChunk::~CATChunk()
{
}
CATChunk::CATChunk() : IFFChunk()
{
}
bool CATChunk::isValid() const
{
return chunkId() == CATChunk::defaultChunkId();
}
QByteArray CATChunk::catType() const
{
return _type;
}
bool CATChunk::innerReadStructure(QIODevice *d)
{
if (bytes() < 4) {
return false;
}
_type = d->read(4);
auto ok = true;
// supports the image formats of FORMChunk.
if (_type == ILBM_FORM_TYPE) {
setChunks(IFFChunk::innerFromDevice(d, &ok, this));
} else if (_type == PBM__FORM_TYPE) {
setChunks(IFFChunk::innerFromDevice(d, &ok, this));
} else if (_type == ACBM_FORM_TYPE) {
setChunks(IFFChunk::innerFromDevice(d, &ok, this));
} else if (_type == RGB8_FORM_TYPE) {
setChunks(IFFChunk::innerFromDevice(d, &ok, this));
} else if (_type == RGBN_FORM_TYPE) {
setChunks(IFFChunk::innerFromDevice(d, &ok, this));
}
return ok;
}
/* ******************
* *** TBHD Chunk ***
* ****************** */
TBHDChunk::~TBHDChunk()
{
}
TBHDChunk::TBHDChunk()
{
}
bool TBHDChunk::isValid() const
{
if (bytes() != 24 && bytes() != 32) {
return false;
}
return chunkId() == TBHDChunk::defaultChunkId();
}
qint32 TBHDChunk::alignBytes() const
{
return 4;
}
qint32 TBHDChunk::width() const
{
if (!isValid()) {
return 0;
}
return i32(data().at(3), data().at(2), data().at(1), data().at(0));
}
qint32 TBHDChunk::height() const
{
if (!isValid()) {
return 0;
}
return i32(data().at(7), data().at(6), data().at(5), data().at(4));
}
QSize TBHDChunk::size() const
{
return QSize(width(), height());
}
qint32 TBHDChunk::left() const
{
if (bytes() != 32) {
return 0;
}
return i32(data().at(27), data().at(26), data().at(25), data().at(24));
}
qint32 TBHDChunk::top() const
{
if (bytes() != 32) {
return 0;
}
return i32(data().at(31), data().at(30), data().at(29), data().at(28));
}
TBHDChunk::Flags TBHDChunk::flags() const
{
if (!isValid()) {
return TBHDChunk::Flags();
}
return TBHDChunk::Flags(ui32(data().at(15), data().at(14), data().at(13), data().at(12)));
}
qint32 TBHDChunk::bpc() const
{
if (!isValid()) {
return 0;
}
return ui16(data().at(17), data().at(16)) ? 2 : 1;
}
qint32 TBHDChunk::channels() const
{
if ((flags() & TBHDChunk::Flag::RgbA) == TBHDChunk::Flag::RgbA) {
return 4;
}
if ((flags() & TBHDChunk::Flag::Rgb) == TBHDChunk::Flag::Rgb) {
return 3;
}
return 0;
}
quint16 TBHDChunk::tiles() const
{
if (!isValid()) {
return 0;
}
return ui16(data().at(19), data().at(18));
}
QImage::Format TBHDChunk::format() const
{
// Support for RGBA and RGB only for now.
if ((flags() & TBHDChunk::Flag::RgbA) == TBHDChunk::Flag::RgbA) {
if (bpc() == 2)
return QImage::Format_RGBA64;
else if (bpc() == 1)
return QImage::Format_RGBA8888;
} else if ((flags() & TBHDChunk::Flag::Rgb) == TBHDChunk::Flag::Rgb) {
if (bpc() == 2)
return QImage::Format_RGBX64;
else if (bpc() == 1)
return FORMAT_RGB_8BIT;
}
return QImage::Format_Invalid;
}
TBHDChunk::Compression TBHDChunk::compression() const
{
if (!isValid()) {
return TBHDChunk::Compression::Uncompressed;
}
return TBHDChunk::Compression(ui32(data().at(23), data().at(22), data().at(21), data().at(20)));
}
bool TBHDChunk::innerReadStructure(QIODevice *d)
{
return cacheData(d);
}
/* ******************
* *** RGBA Chunk ***
* ****************** */
RGBAChunk::~RGBAChunk()
{
}
RGBAChunk::RGBAChunk()
{
}
bool RGBAChunk::isValid() const
{
if (bytes() < 8) {
return false;
}
return chunkId() == RGBAChunk::defaultChunkId();
}
qint32 RGBAChunk::alignBytes() const
{
return 4;
}
bool RGBAChunk::isTileCompressed(const TBHDChunk *header) const
{
if (!isValid() || header == nullptr) {
return false;
}
return qint64(header->channels()) * size().width() * size().height() * header->bpc() > qint64(bytes() - 8);
}
QPoint RGBAChunk::pos() const
{
return _posPx;
}
QSize RGBAChunk::size() const
{
return _sizePx;
}
// Maya version of IFF uses a slightly different algorithm for RLE compression.
// To understand how it works I saved images with regular patterns from Photoshop
// and then checked the data. It is basically the same as packbits except for how
// the length is extracted: I don't know if it's a standard variant or not, so
// I'm keeping it private.
inline qint64 rleMayaDecompress(QIODevice *input, char *output, qint64 olen)
{
qint64 j = 0;
for (qint64 rr = 0, available = olen; j < olen; available = olen - j) {
char n;
// check the output buffer space for the next run
if (available < 128) {
if (input->peek(&n, 1) != 1) { // end of data (or error)
break;
}
rr = qint64(n & 0x7F) + 1;
if (rr > available)
break;
}
// decompress
if (input->read(&n, 1) != 1) { // end of data (or error)
break;
}
rr = qint64(n & 0x7F) + 1;
if ((n & 0x80) == 0) {
auto read = input->read(output + j, rr);
if (rr != read) {
return -1;
}
} else {
char b;
if (input->read(&b, 1) != 1) {
break;
}
std::memset(output + j, b, size_t(rr));
}
j += rr;
}
return j;
}
QByteArray RGBAChunk::readStride(QIODevice *d, const TBHDChunk *header) const
{
auto readSize = size().width();
if (readSize == 0) {
return {};
}
// It seems that tiles are compressed independently only if there is space savings.
// The compression method specified in the header is only to indicate the type of
// compression if used.
if (!isTileCompressed(header)) {
// when not compressed, the line contains all channels
readSize *= header->bpc() * header->channels();
QByteArray buf(readSize, char());
auto rr = d->read(buf.data(), buf.size());
if (rr != buf.size()) {
return {};
}
return buf;
}
// compressed
for (auto nextPos = nextChunkPos(); !d->atEnd() && d->pos() < nextPos && _readBuffer.size() < readSize;) {
QByteArray buf(readSize * size().height(), char());
qint64 rr = -1;
if (header->compression() == TBHDChunk::Compression::Rle) {
rr = rleMayaDecompress(d, buf.data(), buf.size());
}
if (rr != buf.size()) {
return {};
}
_readBuffer.append(buf.data(), rr);
}
auto buff = _readBuffer.left(readSize);
_readBuffer.remove(0, readSize);
return buff;
}
/*!
* \brief compressedTile
*
* The compressed tile contains compressed data per channel.
*
* If 16 bit, high and low bytes are treated separately (so I have
* channels * 2 compressed data blocks). First the high ones, then the low
* ones (or vice versa): for the reconstruction I went by trial and error :)
* \param d The device
* \param header The header.
* \return The tile as Qt image.
*/
QImage RGBAChunk::compressedTile(QIODevice *d, const TBHDChunk *header) const
{
QImage img(size(), header->format());
auto bpc = header->bpc();
if (bpc == 1) {
for (auto c = 0, cs = header->channels(); c < cs; ++c) {
for (auto y = 0, h = img.height(); y < h; ++y) {
auto ba = readStride(d, header);
if (ba.isEmpty()) {
return {};
}
auto scl = reinterpret_cast<quint8*>(img.scanLine(y));
for (auto x = 0, w = std::min(int(ba.size()), img.width()); x < w; ++x) {
scl[x * cs + cs - c - 1] = ba.at(x);
}
}
}
} else if (bpc == 2) {
auto cs = header->channels();
if (cs < 4) { // alpha on 64-bit images must be 0xFF
std::memset(img.bits(), 0xFF, img.sizeInBytes());
}
for (auto c = 0, cc = header->channels() * header->bpc(); c < cc; ++c) {
#if Q_BYTE_ORDER == Q_BIG_ENDIAN
auto c_bcp = c / cs; // Not tried
#else
auto c_bcp = 1 - c / cs;
#endif
auto c_cs = (cs - 1 - c % cs) * bpc + c_bcp;
for (auto y = 0, h = img.height(); y < h; ++y) {
auto ba = readStride(d, header);
if (ba.isEmpty()) {
return {};
}
auto scl = reinterpret_cast<quint8*>(img.scanLine(y));
for (auto x = 0, w = std::min(int(ba.size()), img.width()); x < w; ++x) {
scl[x * 4 * bpc + c_cs] = ba.at(x); // * 4 -> Qt RGB 64-bit formats are always 4 channels
}
}
}
}
return img;
}
/*!
* \brief RGBAChunk::uncompressedTile
*
* The uncompressed tile scanline contains the data in
* B0 G0 R0 A0 B1 G1 R1 A1... Bn Gn Rn An format.
* \param d The device
* \param header The header.
* \return The tile as Qt image.
*/
QImage RGBAChunk::uncompressedTile(QIODevice *d, const TBHDChunk *header) const
{
QImage img(size(), header->format());
auto bpc = header->bpc();
if (bpc == 1) {
auto cs = header->channels();
for (auto y = 0, h = img.height(); y < h; ++y) {
auto ba = readStride(d, header);
if (ba.isEmpty()) {
return {};
}
auto scl = reinterpret_cast<quint8*>(img.scanLine(y));
for (auto c = 0; c < cs; ++c) {
for (auto x = 0, w = std::min(int(ba.size() / cs), img.width()); x < w; ++x) {
auto xcs = x * cs;
scl[xcs + cs - c - 1] = ba.at(xcs + c);
}
}
}
} else if (bpc == 2) {
auto cs = header->channels();
if (cs < 4) { // alpha on 64-bit images must be 0xFF
std::memset(img.bits(), 0xFF, img.sizeInBytes());
}
for (auto y = 0, h = img.height(); y < h; ++y) {
auto ba = readStride(d, header);
if (ba.isEmpty()) {
return {};
}
auto scl = reinterpret_cast<quint16*>(img.scanLine(y));
auto src = reinterpret_cast<const quint16*>(ba.data());
for (auto c = 0; c < cs; ++c) {
for (auto x = 0, w = std::min(int(ba.size() / cs / bpc), img.width()); x < w; ++x) {
auto xcs = x * cs;
auto xcs4 = x * 4;
#if Q_BYTE_ORDER == Q_BIG_ENDIAN
scl[xcs4 + cs - c - 1] = src[xcs + c]; // Not tried
#else
scl[xcs4 + cs - c - 1] = (src[xcs + c] >> 8) | (src[xcs + c] << 8);
#endif
}
}
}
}
return img;
}
QImage RGBAChunk::tile(QIODevice *d, const TBHDChunk *header) const
{
if (!isValid() || header == nullptr) {
return {};
}
if (!seek(d, 8)) {
return {};
}
if (isTileCompressed(header)) {
return compressedTile(d, header);
}
return uncompressedTile(d, header);
}
bool RGBAChunk::innerReadStructure(QIODevice *d)
{
auto ba = d->read(8);
if (ba.size() != 8) {
return false;
}
auto x0 = ui16(ba.at(1), ba.at(0));
auto y0 = ui16(ba.at(3), ba.at(2));
auto x1 = ui16(ba.at(5), ba.at(4));
auto y1 = ui16(ba.at(7), ba.at(6));
if (x0 > x1 || y0 > y1) {
return false;
}
_posPx = QPoint(x0, y0);
_sizePx = QSize(qint32(x1) - x0 + 1, qint32(y1) - y0 + 1);
return true;
}
/* ******************
* *** ANNO Chunk ***
* ****************** */
ANNOChunk::~ANNOChunk()
{
}
ANNOChunk::ANNOChunk()
{
}
bool ANNOChunk::isValid() const
{
return chunkId() == ANNOChunk::defaultChunkId();
}
QString ANNOChunk::value() const
{
return dataToString(this);
}
bool ANNOChunk::innerReadStructure(QIODevice *d)
{
return cacheData(d);
}
/* ******************
* *** AUTH Chunk ***
* ****************** */
AUTHChunk::~AUTHChunk()
{
}
AUTHChunk::AUTHChunk()
{
}
bool AUTHChunk::isValid() const
{
return chunkId() == AUTHChunk::defaultChunkId();
}
QString AUTHChunk::value() const
{
return dataToString(this);
}
bool AUTHChunk::innerReadStructure(QIODevice *d)
{
return cacheData(d);
}
/* ******************
* *** COPY Chunk ***
* ****************** */
COPYChunk::~COPYChunk()
{
}
COPYChunk::COPYChunk()
{
}
bool COPYChunk::isValid() const
{
return chunkId() == COPYChunk::defaultChunkId();
}
QString COPYChunk::value() const
{
return dataToString(this);
}
bool COPYChunk::innerReadStructure(QIODevice *d)
{
return cacheData(d);
}
/* ******************
* *** DATE Chunk ***
* ****************** */
DATEChunk::~DATEChunk()
{
}
DATEChunk::DATEChunk()
{
}
bool DATEChunk::isValid() const
{
return chunkId() == DATEChunk::defaultChunkId();
}
QDateTime DATEChunk::value() const
{
if (!isValid()) {
return {};
}
return QDateTime::fromString(QString::fromLatin1(data()), Qt::TextDate);
}
bool DATEChunk::innerReadStructure(QIODevice *d)
{
return cacheData(d);
}
/* ******************
* *** EXIF Chunk ***
* ****************** */
EXIFChunk::~EXIFChunk()
{
}
EXIFChunk::EXIFChunk()
{
}
bool EXIFChunk::isValid() const
{
if (!data().startsWith(QByteArray("Exif\0\0"))) {
return false;
}
return chunkId() == EXIFChunk::defaultChunkId();
}
MicroExif EXIFChunk::value() const
{
if (!isValid()) {
return {};
}
return MicroExif::fromByteArray(data().mid(6));
}
bool EXIFChunk::innerReadStructure(QIODevice *d)
{
return cacheData(d);
}
/* ******************
* *** ICCN Chunk ***
* ****************** */
ICCNChunk::~ICCNChunk()
{
}
ICCNChunk::ICCNChunk()
{
}
bool ICCNChunk::isValid() const
{
return chunkId() == ICCNChunk::defaultChunkId();
}
QString ICCNChunk::value() const
{
return dataToString(this);
}
bool ICCNChunk::innerReadStructure(QIODevice *d)
{
return cacheData(d);
}
/* ******************
* *** ICCP Chunk ***
* ****************** */
ICCPChunk::~ICCPChunk()
{
}
ICCPChunk::ICCPChunk()
{
}
bool ICCPChunk::isValid() const
{
return chunkId() == ICCPChunk::defaultChunkId();
}
QColorSpace ICCPChunk::value() const
{
if (!isValid()) {
return {};
}
return QColorSpace::fromIccProfile(data());
}
bool ICCPChunk::innerReadStructure(QIODevice *d)
{
return cacheData(d);
}
/* ******************
* *** FVER Chunk ***
* ****************** */
FVERChunk::~FVERChunk()
{
}
FVERChunk::FVERChunk()
{
}
bool FVERChunk::isValid() const
{
return chunkId() == FVERChunk::defaultChunkId();
}
bool FVERChunk::innerReadStructure(QIODevice *d)
{
return cacheData(d);
}
/* ******************
* *** HIST Chunk ***
* ****************** */
HISTChunk::~HISTChunk()
{
}
HISTChunk::HISTChunk()
{
}
bool HISTChunk::isValid() const
{
return chunkId() == HISTChunk::defaultChunkId();
}
QString HISTChunk::value() const
{
if (!isValid()) {
return {};
}
return QString::fromLatin1(data());
}
bool HISTChunk::innerReadStructure(QIODevice *d)
{
return cacheData(d);
}
/* ******************
* *** NAME Chunk ***
* ****************** */
NAMEChunk::~NAMEChunk()
{
}
NAMEChunk::NAMEChunk()
{
}
bool NAMEChunk::isValid() const
{
return chunkId() == NAMEChunk::defaultChunkId();
}
QString NAMEChunk::value() const
{
return dataToString(this);
}
bool NAMEChunk::innerReadStructure(QIODevice *d)
{
return cacheData(d);
}
/* ******************
* *** VERS Chunk ***
* ****************** */
VERSChunk::~VERSChunk()
{
}
VERSChunk::VERSChunk()
{
}
bool VERSChunk::isValid() const
{
return chunkId() == VERSChunk::defaultChunkId();
}
QString VERSChunk::value() const
{
if (!isValid()) {
return {};
}
return QString::fromLatin1(data());
}
bool VERSChunk::innerReadStructure(QIODevice *d)
{
return cacheData(d);
}
/* ******************
* *** XMP0 Chunk ***
* ****************** */
XMP0Chunk::~XMP0Chunk()
{
}
XMP0Chunk::XMP0Chunk()
{
}
bool XMP0Chunk::isValid() const
{
return chunkId() == XMP0Chunk::defaultChunkId();
}
QString XMP0Chunk::value() const
{
return dataToString(this);
}
bool XMP0Chunk::innerReadStructure(QIODevice *d)
{
return cacheData(d);
}
/* ******************
* *** BEAM Chunk ***
* ****************** */
BEAMChunk::~BEAMChunk()
{
}
BEAMChunk::BEAMChunk()
: IPALChunk()
, _height()
{
}
bool BEAMChunk::isValid() const
{
return chunkId() == BEAMChunk::defaultChunkId();
}
IPALChunk *BEAMChunk::clone() const
{
return new BEAMChunk(*this);
}
bool BEAMChunk::initialize(const QList<QRgb> &, qint32 height)
{
_height = height;
return true;
}
QList<QRgb> BEAMChunk::palette(qint32 y) const
{
auto &&height = _height;
if (height < 1) {
return {};
}
auto bpp = bytes() / height;
if (bytes() != height * bpp) {
return {};
}
auto col = qint32(bpp / 2);
auto &&dt = data();
QList<QRgb> pal;
for (auto c = 0; c < col; ++c) {
// 2 bytes per color (0x0R 0xGB)
auto idx = bpp * y + c * 2;
auto r = quint8(dt[idx] & 0x0F);
auto g = quint8(dt[idx + 1] & 0xF0);
auto b = quint8(dt[idx + 1] & 0x0F);
pal << qRgb(r | (r << 4), (g >> 4) | g, b | (b << 4));
}
return pal;
}
bool BEAMChunk::innerReadStructure(QIODevice *d)
{
return cacheData(d);
}
/* ******************
* *** CTBL Chunk ***
* ****************** */
CTBLChunk::~CTBLChunk()
{
}
CTBLChunk::CTBLChunk() : BEAMChunk()
{
}
bool CTBLChunk::isValid() const
{
return chunkId() == CTBLChunk::defaultChunkId();
}
/* ******************
* *** SHAM Chunk ***
* ****************** */
SHAMChunk::~SHAMChunk()
{
}
SHAMChunk::SHAMChunk()
: IPALChunk()
, _height()
{
}
bool SHAMChunk::isValid() const
{
if (bytes() < 2) {
return false;
}
auto &&dt = data();
if (dt[0] != 0 && dt[1] != 0) {
// In all the sham test cases I have them at zero...
// if they are different from zero I suppose they should
// be interpreted differently from what was done.
return false;
}
return chunkId() == SHAMChunk::defaultChunkId();
}
IPALChunk *SHAMChunk::clone() const
{
return new SHAMChunk(*this);
}
QList<QRgb> SHAMChunk::palette(qint32 y) const
{
auto && height = _height;
if (height < 1) {
return {};
}
auto bpp = 32; // always 32 bytes per palette (16 colors)
auto div = 0;
if (bytes() == quint32(height * bpp + 2)) {
div = 1;
} else if (bytes() == quint32(height / 2 * bpp + 2)) {
div = 2;
}
if (div == 0) {
return {};
}
auto &&dt = data();
QList<QRgb> pal;
for (auto c = 0, col = bpp / 2, idx0 = y / div * bpp + 2; c < col; ++c) {
// 2 bytes per color (0x0R 0xGB)
auto idx = idx0 + c * 2;
auto r = quint8(dt[idx] & 0x0F);
auto g = quint8(dt[idx + 1] & 0xF0);
auto b = quint8(dt[idx + 1] & 0x0F);
pal << qRgb(r | (r << 4), (g >> 4) | g, b | (b << 4));
}
return pal;
}
bool SHAMChunk::initialize(const QList<QRgb> &, qint32 height)
{
_height = height;
return true;
}
bool SHAMChunk::innerReadStructure(QIODevice *d)
{
return cacheData(d);
}
/* ******************
* *** RAST Chunk ***
* ****************** */
RASTChunk::~RASTChunk()
{
}
RASTChunk::RASTChunk()
: IPALChunk()
, _height()
{
}
bool RASTChunk::isValid() const
{
return chunkId() == RASTChunk::defaultChunkId();
}
IPALChunk *RASTChunk::clone() const
{
return new RASTChunk(*this);
}
QList<QRgb> RASTChunk::palette(qint32 y) const
{
auto &&height = _height;
if (height < 1) {
return {};
}
auto bpp = bytes() / height;
if (bytes() != height * bpp) {
return {};
}
auto col = qint32(bpp / 2 - 1);
auto &&dt = data();
QList<QRgb> pal;
for (auto c = 0; c < col; ++c) {
auto idx = bpp * y + 2 + c * 2;
// The Atari ST uses 3 bits per color (512 colors) while the Atari STE
// uses 4 bits per color (4096 colors). This strange encoding with the
// least significant bit set as MSB is, I believe, to ensure hardware
// compatibility between the two machines.
#define H1L(a) ((quint8(a) & 0x7) << 1) | ((quint8(a) >> 3) & 1)
auto r = H1L(dt[idx]);
auto g = H1L(dt[idx + 1] >> 4);
auto b = H1L(dt[idx + 1]);
#undef H1L
pal << qRgb(r | (r << 4), (g << 4) | g, b | (b << 4));
}
return pal;
}
bool RASTChunk::initialize(const QList<QRgb> &, qint32 height)
{
_height = height;
return true;
}
bool RASTChunk::innerReadStructure(QIODevice *d)
{
return cacheData(d);
}
/* ******************
* *** PCHG Chunk ***
* ****************** */
PCHGChunk::~PCHGChunk()
{
}
PCHGChunk::PCHGChunk() : IPALChunk()
{
}
PCHGChunk::Compression PCHGChunk::compression() const
{
if (!isValid()) {
return Compression::Uncompressed;
}
return Compression(ui16(data(), 0));
}
PCHGChunk::Flags PCHGChunk::flags() const
{
if (!isValid()) {
return Flags(Flag::None);
}
return Flags(ui16(data(), 2));
}
qint16 PCHGChunk::startLine() const
{
if (!isValid()) {
return 0;
}
return i16(data(), 4);
}
quint16 PCHGChunk::lineCount() const
{
if (!isValid()) {
return 0;
}
return ui16(data(), 6);
}
quint16 PCHGChunk::changedLines() const
{
if (!isValid()) {
return 0;
}
return ui16(data(), 8);
}
quint16 PCHGChunk::minReg() const
{
if (!isValid()) {
return 0;
}
return ui16(data(), 10);
}
quint16 PCHGChunk::maxReg() const
{
if (!isValid()) {
return 0;
}
return ui16(data(), 12);
}
quint16 PCHGChunk::maxChanges() const
{
if (!isValid()) {
return 0;
}
return ui16(data(), 14);
}
quint32 PCHGChunk::totalChanges() const
{
if (!isValid()) {
return 0;
}
return ui32(data(), 16);
}
bool PCHGChunk::hasAlpha() const
{
return (flags() & PCHGChunk::Flag::UseAlpha) ? true : false;
}
bool PCHGChunk::isValid() const
{
if (bytes() < 20) {
return false;
}
return chunkId() == PCHGChunk::defaultChunkId();
}
IPALChunk *PCHGChunk::clone() const
{
return new PCHGChunk(*this);
}
QList<QRgb> PCHGChunk::palette(qint32 y) const
{
return _palettes.value(y);
}
// ----------------------------------------------------------------------------
// PCHG_FastDecomp reimplementation (Amiga 68k -> portable C++/Qt)
// ----------------------------------------------------------------------------
// This mirrors the original 68k routine semantics:
// - The Huffman tree is stored as a sequence of signed 16-bit words (big-endian)
// and TreeCode points to the *last word* of that sequence.
// - Bits are consumed MSB-first from 32-bit big-endian longwords of the source.
// - Navigation rules (matching the assembly):
// bit=1: read w = *(a3). If w < 0 then a3 += w (byte-wise) and continue;
// else emit (w & 0xFF) and reset a3 to TreeCode (last word).
// bit=0: predecrement a3 by 2; read w = *a3. If w < 0: continue;
// else if (w & 0x0100) emit (w & 0xFF) and reset a3; else continue.
// - Stop after writing exactly OriginalSize bytes.
//
// This function expects a single QByteArray laid out as:
// [ tree (treeSize bytes, even) | compressed bitstream (... bytes) ]
//
// On any error, logs with qCCritical(LOG_IFFPLUGIN) and returns {}.
// Comments are in English as requested.
// ----------------------------------------------------------------------------
//
// NOTE: Sebastiano Vigna, the author of the PCHG specification and the ASM
// decompression code for the Motorola 68K, gave us permission to use his
// code and recommended that we convert it with AI.
// Read a big-endian 16-bit signed word from a byte buffer
static inline qint16 read_be16(const char* base, int byteIndex, int size)
{
if (byteIndex + 1 >= size)
return 0; // caller must bounds-check; we keep silent here
const quint8 b0 = static_cast<quint8>(base[byteIndex]);
const quint8 b1 = static_cast<quint8>(base[byteIndex + 1]);
return static_cast<qint16>((b0 << 8) | b1);
}
// Read a big-endian 32-bit unsigned long from a byte buffer
static inline quint32 read_be32(const char* base, int byteIndex, int size)
{
if (byteIndex + 3 >= size)
return 0; // caller must bounds-check
const quint8 b0 = static_cast<quint8>(base[byteIndex]);
const quint8 b1 = static_cast<quint8>(base[byteIndex + 1]);
const quint8 b2 = static_cast<quint8>(base[byteIndex + 2]);
const quint8 b3 = static_cast<quint8>(base[byteIndex + 3]);
return (static_cast<quint32>(b0) << 24) |
(static_cast<quint32>(b1) << 16) |
(static_cast<quint32>(b2) << 8) |
static_cast<quint32>(b3);
}
// Core decompressor (tree + compressed stream in one QByteArray)
static QByteArray pchgFastDecomp(const QByteArray& input, int treeSize, int originalSize)
{
// Basic validation
if (treeSize <= 0 || (treeSize & 1)) {
qCCritical(LOG_IFFPLUGIN) << "Invalid treeSize (must be positive and even)" << treeSize;
return {};
}
if (input.size() < treeSize) {
qCCritical(LOG_IFFPLUGIN) << "Input too small for treeSize" << input.size() << treeSize;
return {};
}
if (originalSize < 0) {
qCCritical(LOG_IFFPLUGIN) << "Invalid originalSize" << originalSize;
return {};
}
const char* data = input.constData();
const int totalSize = input.size();
// Tree view (big-endian words)
const int treeBytes = treeSize;
const int treeWords = treeBytes / 2;
if (treeWords <= 0) {
qCCritical(LOG_IFFPLUGIN) << "Tree has zero words";
return {};
}
// Compressed stream
const int srcBase = treeBytes; // offset where bitstream starts
const int srcSize = totalSize - srcBase;
if (srcSize <= 0 && originalSize > 0) {
qCCritical(LOG_IFFPLUGIN) << "No compressed payload present";
return {};
}
QByteArray out;
out.resize(originalSize);
char* outPtr = out.data();
// Emulate a3 pointer to words:
// a2 points to the *last word* => word index (0..treeWords-1)
auto resetA3 = [&]() {
return treeWords - 1; // last word index
};
int a3_word = resetA3();
// Bit reader: loads 32b big-endian and shifts MSB-first
quint32 bitbuf = 0;
int bits = 0; // remaining bits in bitbuf
int srcPos = 0; // byte offset relative to srcBase
auto refill = [&]() -> bool {
if (srcPos + 4 > srcSize) {
qCCritical(LOG_IFFPLUGIN) << "Compressed stream underflow while refilling bit buffer"
<< "srcPos=" << srcPos << "srcSize=" << srcSize;
return false;
}
bitbuf = read_be32(data + srcBase, srcPos, srcSize);
bits = 32;
srcPos += 4;
return true;
};
int produced = 0;
// Main decode loop: produce exactly originalSize bytes
while (produced < originalSize) {
if (bits == 0) {
if (!refill()) {
// Not enough bits to complete output
return {};
}
}
const bool bit1 = (bitbuf & 0x80000000u) != 0u; // MSB before shift
bitbuf <<= 1;
--bits;
if (bit1) {
// Case bit == 1 --> w = *(a3)
if (a3_word < 0 || a3_word >= treeWords) {
qCCritical(LOG_IFFPLUGIN) << "a3 out of bounds (bit=1)" << a3_word;
return {};
}
const int byteIndex = a3_word * 2;
const qint16 w = read_be16(data, byteIndex, treeBytes);
if (w < 0) {
// a3 += w (w is a signed byte offset, must be even)
if (w & 1) {
qCCritical(LOG_IFFPLUGIN) << "Misaligned tree offset (odd)" << w;
return {};
}
const int deltaWords = w / 2; // arithmetic division, w is even in valid streams
const int next = a3_word + deltaWords;
if (next < 0 || next >= treeWords) {
qCCritical(LOG_IFFPLUGIN) << "a3 out of bounds after offset" << next;
return {};
}
a3_word = next;
} else {
// Leaf: emit low 8 bits, reset a3
outPtr[produced++] = static_cast<char>(w & 0xFF);
a3_word = resetA3();
}
} else {
// Case bit == 0 --> w = *--a3 (predecrement)
--a3_word;
if (a3_word < 0) {
qCCritical(LOG_IFFPLUGIN) << "a3 underflow on predecrement";
return {};
}
const int byteIndex = a3_word * 2;
const qint16 w = read_be16(data, byteIndex, treeBytes);
if (w < 0) {
// Internal node: continue with current a3
continue;
}
// Non-negative: check bit #8; if set -> leaf
if ((w & 0x0100) != 0) {
outPtr[produced++] = static_cast<char>(w & 0xFF);
a3_word = resetA3();
} else {
// Not a leaf: continue scanning
continue;
}
}
}
return out;
}
// !Huffman decompression
bool PCHGChunk::initialize(const QList<QRgb> &cmapPalette, qint32 height)
{
auto dt = data().mid(20);
if (compression() == PCHGChunk::Compression::Huffman) {
QDataStream ds(dt);
ds.setByteOrder(QDataStream::BigEndian);
quint32 infoSize;
ds >> infoSize;
quint32 origSize;
ds >> origSize;
dt = pchgFastDecomp(dt.mid(8), infoSize, origSize);
}
if (dt.isEmpty()) {
return false;
}
QDataStream ds(dt);
ds.setByteOrder(QDataStream::BigEndian);
// read the masks
auto lcnt = lineCount();
auto nlw = (lcnt + 31) / 32; // number of LWORD containing the bit mask
QList<quint32> masks;
for (auto i = 0; i < nlw; ++i) {
quint32 mask;
ds >> mask;
masks << mask;
}
if (ds.status() != QDataStream::Ok) {
return false;
}
// read the palettes
auto changesLoaded = qint64();
auto startY = startLine();
auto last = cmapPalette;
auto flgs = flags();
for (auto i = 0; i < lcnt; ++i) {
auto mask = masks.at(i / 32);
if (((mask >> (31 - i % 32)) & 1) == 0) {
_palettes.insert(i + startY, last);
continue; // no palette change for this line
}
QHash<quint16, QRgb> hash;
if (flgs & PCHGChunk::Flag::F12Bit) {
quint8 c16;
ds >> c16;
quint8 c32;
ds >> c32;
for (auto j = 0; j < int(c16); ++j) {
quint16 tmp;
ds >> tmp;
hash.insert(((tmp >> 12) & 0xF), qRgb(((tmp >> 8) & 0xF) * 17, ((tmp >> 4) & 0xF) * 17, ((tmp & 0xF) * 17)));
}
for (auto j = 0; j < int(c32); ++j) {
quint16 tmp;
ds >> tmp;
hash.insert((((tmp >> 12) & 0xF) + 16), qRgb(((tmp >> 8) & 0xF) * 17, ((tmp >> 4) & 0xF) * 17, ((tmp & 0xF) * 17)));
}
} else if (flgs & PCHGChunk::Flag::F32Bit) { // NOTE: missing test case (not tested)
quint16 cnt;
ds >> cnt;
for (auto j = 0; j < int(cnt); ++j) {
quint16 reg;
ds >> reg;
quint8 alpha;
ds >> alpha;
quint8 red;
ds >> red;
quint8 blue;
ds >> blue;
quint8 green;
ds >> green;
hash.insert(reg, qRgba(red, green, blue, flgs & PCHGChunk::Flag::UseAlpha ? alpha : 0xFF));
}
}
if (ds.status() != QDataStream::Ok) {
return false;
}
for (auto i = qsizetype(), n = last.size(); i < n; ++i) {
if (hash.contains(i))
last[i] = hash.value(i);
}
_palettes.insert(i + startY, last);
changesLoaded += hash.size();
}
if (changesLoaded != qint64(totalChanges())) {
qCDebug(LOG_IFFPLUGIN) << "PCHGChunk::innerReadStructure(): palette changes count mismatch!";
}
return true;
}
bool PCHGChunk::innerReadStructure(QIODevice *d)
{
return cacheData(d);
}
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