/// <summary>
/// Gets a list of the meta-data block ids.
/// </summary>
/// <param name="type">The meta-data block type.</param>
/// <param name="contentType">The meta-data block content type.</param>
/// <returns>A list of the meta-data block ids.</returns>
/// <exception cref="HeifException">Could not get all of the meta-data block ids.</exception>
/// <exception cref="ObjectDisposedException">The object has been disposed.</exception>
public IReadOnlyList <HeifItemId> GetMetadataBlockIds(string type = null, string contentType = null)
{
VerifyNotDisposed();
int count = LibHeifNative.heif_image_handle_get_number_of_metadata_blocks(this.imageHandle, type);
if (count == 0)
{
return(Array.Empty <HeifItemId>());
}
var ids = new HeifItemId[count];
unsafe
{
fixed(HeifItemId *ptr = ids)
{
int filledCount = LibHeifNative.heif_image_handle_get_list_of_metadata_block_IDs(this.imageHandle,
type,
ptr,
count);
if (filledCount != count)
{
ExceptionUtil.ThrowHeifException(Resources.CannotGetAllMetadataBlockIds);
}
}
}
// The type must be defined in order to filter by content type.
if (type != null && contentType != null)
{
var matchingItems = new List <HeifItemId>();
for (int i = 0; i < ids.Length; i++)
{
var id = ids[i];
var metadataContentType = LibHeifNative.heif_image_handle_get_metadata_content_type(this.imageHandle, id);
if (contentType.Equals(metadataContentType.GetStringValue(), StringComparison.Ordinal))
{
matchingItems.Add(id);
}
}
return(matchingItems);
}
else
{
return(ids);
}
}
