1 files changed, 132 insertions, 0 deletions
diff --git a/libs/preview_dds_native/src/ddsfile.cpp b/libs/preview_dds_native/src/ddsfile.cpp
new file mode 100644
index 0000000..91dc627
--- /dev/null
+++ b/libs/preview_dds_native/src/ddsfile.cpp
@@ -0,0 +1,132 @@
+#include "ddsfile.h"
+
+#include <QFile>
+
+#include <algorithm>
+#include <cstring>
+
+bool DDSFile::loadFromFile(const QString& path)
+{
+  QFile file(path);
+  if (!file.open(QIODevice::ReadOnly)) {
+    return false;
+  }
+  return parse(file.readAll());
+}
+
+bool DDSFile::loadFromData(const QByteArray& data)
+{
+  return parse(data);
+}
+
+bool DDSFile::parse(const QByteArray& data)
+{
+  const char* ptr = data.constData();
+  int offset      = 0;
+  int size        = data.size();
+
+  // Magic number
+  if (size < 4)
+    return false;
+  uint32_t magic;
+  std::memcpy(&magic, ptr + offset, 4);
+  offset += 4;
+  if (magic != DDS_MAGIC)
+    return false;
+
+  // DDS header
+  if (size - offset < static_cast<int>(sizeof(DDSHeader)))
+    return false;
+  DDSHeader header;
+  std::memcpy(&header, ptr + offset, sizeof(DDSHeader));
+  offset += sizeof(DDSHeader);
+
+  if (header.dwSize != 124)
+    return false;
+
+  // DXT10 extended header
+  DDSHeaderDXT10 dxt10{};
+  bool hasDXT10 = false;
+  if ((header.ddspf.dwFlags & DDPF_FOURCC) &&
+      header.ddspf.dwFourCC == makeFourCC('D', 'X', '1', '0')) {
+    if (size - offset < static_cast<int>(sizeof(DDSHeaderDXT10)))
+      return false;
+    std::memcpy(&dxt10, ptr + offset, sizeof(DDSHeaderDXT10));
+    offset += sizeof(DDSHeaderDXT10);
+    hasDXT10 = true;
+  }
+
+  m_width  = header.dwWidth;
+  m_height = header.dwHeight;
+
+  // Determine GL format
+  m_glFormat = getGLFormat(header.ddspf, hasDXT10 ? &dxt10 : nullptr);
+  if (!m_glFormat.valid) {
+    return false;
+  }
+
+  // Determine DXGI format for size calculations
+  if (hasDXT10) {
+    m_dxgiFormat = dxt10.dxgiFormat;
+  } else if (header.ddspf.dwFlags & DDPF_FOURCC) {
+    m_dxgiFormat = fourCCToDXGI(header.ddspf.dwFourCC);
+  } else {
+    m_dxgiFormat = DXGIFormat::UNKNOWN;
+  }
+
+  // Description
+  m_description = formatDescription(header.ddspf, hasDXT10 ? &dxt10 : nullptr);
+  m_description +=
+      QString(" | %1x%2").arg(m_width).arg(m_height);
+
+  // Cubemap detection
+  m_cubemap  = false;
+  int layers = 1;
+  if (header.dwCaps2 & DDSCAPS2_CUBEMAP) {
+    m_cubemap = true;
+    layers    = 0;
+    if (header.dwCaps2 & DDSCAPS2_CUBEMAP_POSITIVEX) layers++;
+    if (header.dwCaps2 & DDSCAPS2_CUBEMAP_NEGATIVEX) layers++;
+    if (header.dwCaps2 & DDSCAPS2_CUBEMAP_POSITIVEY) layers++;
+    if (header.dwCaps2 & DDSCAPS2_CUBEMAP_NEGATIVEY) layers++;
+    if (header.dwCaps2 & DDSCAPS2_CUBEMAP_POSITIVEZ) layers++;
+    if (header.dwCaps2 & DDSCAPS2_CUBEMAP_NEGATIVEZ) layers++;
+    m_description += " | Cubemap";
+  } else {
+    m_description += " | 2D";
+  }
+
+  // Mipmap count
+  int mipCount = 1;
+  if (header.dwFlags & DDSD_MIPMAPCOUNT) {
+    mipCount = std::max(1u, header.dwMipMapCount);
+  }
+  if (mipCount > 1) {
+    m_description += QString(" | %1 mips").arg(mipCount);
+  }
+
+  // Read pixel data for each face and mip level
+  m_faces.resize(layers);
+  for (int face = 0; face < layers; ++face) {
+    m_faces[face].mips.resize(mipCount);
+    uint32_t w = m_width;
+    uint32_t h = m_height;
+    for (int mip = 0; mip < mipCount; ++mip) {
+      uint32_t dataSize = mipDataSize(m_dxgiFormat, header.ddspf, w, h);
+      if (offset + static_cast<int>(dataSize) > size) {
+        // Truncated file, keep what we have
+        m_faces[face].mips.resize(mip);
+        break;
+      }
+      m_faces[face].mips[mip].width  = w;
+      m_faces[face].mips[mip].height = h;
+      m_faces[face].mips[mip].data =
+          QByteArray(ptr + offset, static_cast<int>(dataSize));
+      offset += dataSize;
+      w = std::max(1u, w / 2);
+      h = std::max(1u, h / 2);
+    }
+  }
+
+  return !m_faces.isEmpty() && !m_faces[0].mips.isEmpty();
+}