qpkmhandler.cpp

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// Copyright (C) 2017 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
 
#include "qpkmhandler_p.h"
#include "qtexturefiledata_p.h"
 
#include <QFile>
#include <QDebug>
#include <QSize>
#include <qendian.h>
 
//#define ETC_DEBUG
 
QT_BEGIN_NAMESPACE
 
static const int qpkmh_headerSize = 16;
 
struct PkmType
{
    quint32 glFormat;
    quint32 bytesPerBlock;
};
 
static constexpr PkmType typeMap[5] = {
    { 0x8D64,  8 },   // GL_ETC1_RGB8_OES
    { 0x9274,  8 },   // GL_COMPRESSED_RGB8_ETC2
    { 0, 0 },         // unused (obsolete)
    { 0x9278, 16},    // GL_COMPRESSED_RGBA8_ETC2_EAC
    { 0x9276,  8 }    // GL_COMPRESSED_RGB8_PUNCHTHROUGH_ALPHA1_ETC2
};
 
QPkmHandler::~QPkmHandler() = default;
 
bool QPkmHandler::canRead(const QByteArray &suffix, const QByteArray &block)
{
    Q_UNUSED(suffix);
 
    return block.startsWith("PKM ");
}
 
QTextureFileData QPkmHandler::read()
{
    QTextureFileData texData;
 
    if (!device())
        return texData;
 
    QByteArray fileData = device()->readAll();
    if (fileData.size() < qpkmh_headerSize || !canRead(QByteArray(), fileData)) {
        qCDebug(lcQtGuiTextureIO, "Invalid PKM file %s", logName().constData());
        return QTextureFileData();
    }
    texData.setData(fileData);
 
    const char *rawData = fileData.constData();
 
    // ignore version (rawData + 4 & 5)
 
    // texture type
    quint16 type = qFromBigEndian<quint16>(rawData + 6);
    if (type >= sizeof(typeMap)/sizeof(typeMap[0])) {
        qCDebug(lcQtGuiTextureIO, "Unknown compression format in PKM file %s", logName().constData());
        return QTextureFileData();
    }
    texData.setGLFormat(0);                    // 0 for compressed textures
    texData.setGLInternalFormat(typeMap[type].glFormat);
    //### setBaseInternalFormat
 
    // texture size
    texData.setNumLevels(1);
    texData.setNumFaces(1);
    const int bpb = typeMap[type].bytesPerBlock;
    QSize paddedSize(qFromBigEndian<quint16>(rawData + 8), qFromBigEndian<quint16>(rawData + 10));
    texData.setDataLength((paddedSize.width() / 4) * (paddedSize.height() / 4) * bpb);
    QSize texSize(qFromBigEndian<quint16>(rawData + 12), qFromBigEndian<quint16>(rawData + 14));
    texData.setSize(texSize);
 
    texData.setDataOffset(qpkmh_headerSize);
 
    if (!texData.isValid()) {
        qCDebug(lcQtGuiTextureIO, "Invalid values in header of PKM file %s", logName().constData());
        return QTextureFileData();
    }
 
    texData.setLogName(logName());
 
#ifdef ETC_DEBUG
    qDebug() << "PKM file handler read" << texData;
#endif
    return texData;
}
 
QT_END_NAMESPACE