/// <summary>
/// Initializes the <see cref="Atom"/> instance from the specified <see cref="IntPtr"/>
/// value.
/// </summary>
/// <param name="fileHandle">The <see cref="IntPtr"/> file handle of the file from which to read this <see cref="Atom"/>.</param>
/// <returns><see langword="true"/> if this <see cref="Atom"/> was successfully initialized; otherwise, <see langword="false"/>.</returns>
internal bool Initialize(IntPtr fileHandle)
{
bool isInitialized = false;
IntPtr rawAtomPointer = NativeMethods.MP4ItmfGetItemsByMeaning(fileHandle, this.Meaning, this.Name);
if (rawAtomPointer != IntPtr.Zero)
{
NativeMethods.MP4ItmfItemList atomItemList = rawAtomPointer.ReadStructure <NativeMethods.MP4ItmfItemList>();
isInitialized = atomItemList.size > 0;
for (int i = 0; i < atomItemList.size; i++)
{
IntPtr itemPointer = atomItemList.elements[i];
NativeMethods.MP4ItmfItem item = itemPointer.ReadStructure <NativeMethods.MP4ItmfItem>();
NativeMethods.MP4ItmfDataList dataList = item.dataList;
for (int j = 0; j < dataList.size; j++)
{
IntPtr dataListItemPointer = dataList.elements[i];
NativeMethods.MP4ItmfData data = dataListItemPointer.ReadStructure <NativeMethods.MP4ItmfData>();
if (data.typeCode == this.DataType)
{
byte[] dataBuffer = data.value.ReadBuffer(data.valueSize);
this.Populate(dataBuffer);
}
}
}
NativeMethods.MP4ItmfItemListFree(rawAtomPointer);
}
return(isInitialized);
}
private static void WriteRawAtom <T>(IntPtr fileHandle, T atom) where T : Atom, new()
{
// Because Generics don't allow inheritable static members, and we
// really don't want to resort to reflection, we can create an instance
// of the appropriate Atom type, only to get the Meaning and Name properties.
// Passing in the parameters leads to potentially getting the strings wrong.
// This solution is hacky in the worst possible way; let's think of a better
// approach.
T templateAtom = new T();
string atomMeaning = templateAtom.Meaning;
string atomName = templateAtom.Name;
IntPtr listPtr = NativeMethods.MP4ItmfGetItemsByMeaning(fileHandle, atomMeaning, atomName);
if (listPtr != IntPtr.Zero)
{
NativeMethods.MP4ItmfItemList list = listPtr.ReadStructure <NativeMethods.MP4ItmfItemList>();
for (int i = 0; i < list.size; i++)
{
IntPtr item = list.elements[i];
NativeMethods.MP4ItmfRemoveItem(fileHandle, item);
}
NativeMethods.MP4ItmfItemListFree(listPtr);
if (atom != null)
{
IntPtr newItemPtr = NativeMethods.MP4ItmfItemAlloc("----", 1);
NativeMethods.MP4ItmfItem newItem = newItemPtr.ReadStructure <NativeMethods.MP4ItmfItem>();
newItem.mean = atom.Meaning;
newItem.name = atom.Name;
NativeMethods.MP4ItmfData data = new NativeMethods.MP4ItmfData();
data.typeCode = atom.DataType;
byte[] dataBuffer = atom.ToByteArray();
data.valueSize = dataBuffer.Length;
IntPtr dataValuePointer = Marshal.AllocHGlobal(dataBuffer.Length);
Marshal.Copy(dataBuffer, 0, dataValuePointer, dataBuffer.Length);
data.value = dataValuePointer;
IntPtr dataPointer = Marshal.AllocHGlobal(Marshal.SizeOf(data));
Marshal.StructureToPtr(data, dataPointer, false);
newItem.dataList.elements[0] = dataPointer;
Marshal.StructureToPtr(newItem, newItemPtr, false);
NativeMethods.MP4ItmfAddItem(fileHandle, newItemPtr);
Marshal.FreeHGlobal(dataPointer);
Marshal.FreeHGlobal(dataValuePointer);
}
}
}
