1 files changed, 92 insertions, 0 deletions
diff --git a/lib/multipictureformat.cpp b/lib/multipictureformat.cpp
new file mode 100644
index 0000000..dc31fbb
--- /dev/null
+++ b/lib/multipictureformat.cpp
@@ -0,0 +1,92 @@
+/*
+ * Copyright 2023 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "multipictureformat.h"
+
+namespace ultrahdr {
+size_t calculateMpfSize() {
+  return sizeof(kMpfSig) +                 // Signature
+         kMpEndianSize +                   // Endianness
+         sizeof(uint32_t) +                // Index IFD Offset
+         sizeof(uint16_t) +                // Tag count
+         kTagSerializedCount * kTagSize +  // 3 tags at 12 bytes each
+         sizeof(uint32_t) +                // Attribute IFD offset
+         kNumPictures * kMPEntrySize;      // MP Entries for each image
+}
+
+std::shared_ptr<DataStruct> generateMpf(int primary_image_size, int primary_image_offset,
+                                        int secondary_image_size, int secondary_image_offset) {
+  size_t mpf_size = calculateMpfSize();
+  std::shared_ptr<DataStruct> dataStruct = std::make_shared<DataStruct>(mpf_size);
+
+  dataStruct->write(static_cast<const void*>(kMpfSig), sizeof(kMpfSig));
+#if USE_BIG_ENDIAN_IN_MPF
+  dataStruct->write(static_cast<const void*>(kMpBigEndian), kMpEndianSize);
+#else
+  dataStruct->write(static_cast<const void*>(kMpLittleEndian), kMpEndianSize);
+#endif
+
+  // Set the Index IFD offset be the position after the endianness value and this offset.
+  constexpr uint32_t indexIfdOffset = static_cast<uint16_t>(kMpEndianSize + sizeof(kMpfSig));
+  dataStruct->write32(Endian_SwapBE32(indexIfdOffset));
+
+  // We will write 3 tags (version, number of images, MP entries).
+  dataStruct->write16(Endian_SwapBE16(kTagSerializedCount));
+
+  // Write the version tag.
+  dataStruct->write16(Endian_SwapBE16(kVersionTag));
+  dataStruct->write16(Endian_SwapBE16(kVersionType));
+  dataStruct->write32(Endian_SwapBE32(kVersionCount));
+  dataStruct->write(kVersionExpected, kVersionSize);
+
+  // Write the number of images.
+  dataStruct->write16(Endian_SwapBE16(kNumberOfImagesTag));
+  dataStruct->write16(Endian_SwapBE16(kNumberOfImagesType));
+  dataStruct->write32(Endian_SwapBE32(kNumberOfImagesCount));
+  dataStruct->write32(Endian_SwapBE32(kNumPictures));
+
+  // Write the MP entries.
+  dataStruct->write16(Endian_SwapBE16(kMPEntryTag));
+  dataStruct->write16(Endian_SwapBE16(kMPEntryType));
+  dataStruct->write32(Endian_SwapBE32(kMPEntrySize * kNumPictures));
+  const uint32_t mpEntryOffset =
+      static_cast<uint32_t>(dataStruct->getBytesWritten() -  // The bytes written so far
+                            sizeof(kMpfSig) +                // Excluding the MPF signature
+                            sizeof(uint32_t) +               // The 4 bytes for this offset
+                            sizeof(uint32_t));  // The 4 bytes for the attribute IFD offset.
+  dataStruct->write32(Endian_SwapBE32(mpEntryOffset));
+
+  // Write the attribute IFD offset (zero because we don't write it).
+  dataStruct->write32(0);
+
+  // Write the MP entries for primary image
+  dataStruct->write32(Endian_SwapBE32(kMPEntryAttributeFormatJpeg | kMPEntryAttributeTypePrimary));
+  dataStruct->write32(Endian_SwapBE32(primary_image_size));
+  dataStruct->write32(Endian_SwapBE32(primary_image_offset));
+  dataStruct->write16(0);
+  dataStruct->write16(0);
+
+  // Write the MP entries for secondary image
+  dataStruct->write32(Endian_SwapBE32(kMPEntryAttributeFormatJpeg));
+  dataStruct->write32(Endian_SwapBE32(secondary_image_size));
+  dataStruct->write32(Endian_SwapBE32(secondary_image_offset));
+  dataStruct->write16(0);
+  dataStruct->write16(0);
+
+  return dataStruct;
+}
+
+}  // namespace ultrahdr