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// Copyright (C) 2018 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
static const quint32 DDS_MAGIC = 0x20534444; // 'DDS '
static const quint32 DDS_FOURCC = 4;
#define FOURCC(c0, c1, c2, c3) ((c0) | ((c1) << 8) | ((c2) << 16) | ((c3 << 24)))
struct DDS_PIXELFORMAT {
quint32 size;
quint32 flags;
quint32 fourCC;
quint32 rgbBitCount;
quint32 rBitMask;
quint32 gBitMask;
quint32 bBitMask;
quint32 aBitMask;
};
struct DDS_HEADER {
quint32 size;
quint32 flags;
quint32 height;
quint32 width;
quint32 pitch;
quint32 depth;
quint32 mipMapCount;
quint32 reserved1[11];
DDS_PIXELFORMAT pixelFormat;
quint32 caps;
quint32 caps2;
quint32 caps3;
quint32 caps4;
quint32 reserved2;
};
static quint32 bc1size(const QSize &size)
{
static const quint32 blockSize = 8; // 8 bytes for BC1
const quint32 bytesPerLine = qMax<quint32>(1, (size.width() + 3) / 4) * blockSize;
const quint32 ySize = qMax<quint32>(1, (size.height() + 3) / 4);
return bytesPerLine * ySize;
}
static QByteArrayList loadBC1(const QString &filename, QSize *size)
{
QFile f(filename);
if (!f.open(QIODevice::ReadOnly)) {
qWarning("Failed to open %s", qPrintable(filename));
return QByteArrayList();
}
quint32 magic = 0;
f.read(reinterpret_cast<char *>(&magic), sizeof(magic));
if (magic != DDS_MAGIC) {
qWarning("%s is not a DDS file", qPrintable(filename));
return QByteArrayList();
}
DDS_HEADER header;
f.read(reinterpret_cast<char *>(&header), sizeof(header));
if (header.size != sizeof(DDS_HEADER)) {
qWarning("Invalid DDS header size");
return QByteArrayList();
}
if (header.pixelFormat.size != sizeof(DDS_PIXELFORMAT)) {
qWarning("Invalid DDS pixel format size");
return QByteArrayList();
}
if (!(header.pixelFormat.flags & DDS_FOURCC)) {
qWarning("Invalid DDS pixel format");
return QByteArrayList();
}
if (header.pixelFormat.fourCC != FOURCC('D', 'X', 'T', '1')) {
qWarning("Only DXT1 (BC1) is supported");
return QByteArrayList();
}
QByteArrayList data;
QSize sz(header.width, header.height);
for (quint32 level = 0; level < header.mipMapCount; ++level) {
data.append(f.read(bc1size(sz)));
sz.setWidth(qMax(1, sz.width() / 2));
sz.setHeight(qMax(1, sz.height() / 2));
}
if (size)
*size = QSize(header.width, header.height);
return data;
}
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