/// <summary>
/// Creates a <see cref="HeifReader" /> instance from the specified file.
/// </summary>
/// <param name="path">The path.</param>
/// <returns>
/// The created <see cref="HeifReader" /> instance.
/// </returns>
/// <exception cref="ArgumentNullException"><paramref name="path" /> is null.</exception>
/// <exception cref="ArgumentException"><paramref name="path" /> is empty, contains only whitespace or contains invalid characters.</exception>
/// <exception cref="FileNotFoundException">The file specified by <paramref name="path" /> does not exist.</exception>
/// <exception cref="IOException">An I/O error occurred.</exception>
/// <exception cref="System.Security.SecurityException">The caller does not have the required permission.</exception>
/// <exception cref="UnauthorizedAccessException">The access requested is not permitted by the operating system for the specified path.</exception>
public static HeifReader CreateFromFile(string path)
{
HeifReader reader;
FileStream fileStream = null;
try
{
fileStream = new FileStream(path, FileMode.Open, FileAccess.Read, FileShare.Read);
if (!fileStream.CanSeek)
{
throw new IOException(Properties.Resources.FileStreamDoesNotSupportSeeking);
}
if (fileStream.Length <= HeifStreamReader.MaxReadBufferSize)
{
byte[] bytes = CopyStreamToByteArray(fileStream);
reader = new HeifByteArrayReader(bytes);
}
else
{
reader = new HeifStreamReader(fileStream, ownsStream: true);
fileStream = null;
}
}
finally
{
fileStream?.Dispose();
}
return(reader);
}
/// <summary>
/// Creates a <see cref="HeifReader"/> instance from the specified stream, and optionally takes ownership of the stream.
/// </summary>
/// <param name="stream">The stream.</param>
/// <param name="ownsStream"><see langword="true"/> if the writer owns the stream; otherwise, <see langword="false"/>.</param>
/// <returns>The created <see cref="HeifReader"/> instance.</returns>
/// <exception cref="ArgumentNullException"><paramref name="stream"/> is null.</exception>
/// <exception cref="IOException">An I/O error occurred.</exception>
public static HeifReader CreateFromStream(Stream stream, bool ownsStream)
{
Validate.IsNotNull(stream, nameof(stream));
HeifReader reader;
// If the stream is a MemoryStream with an accessible buffer we can avoid
// having to copy data to a temporary buffer when reading from the stream.
// This check excludes types that are derived from MemoryStream because they may invalidate the
// underlying buffer when the stream is disposed.
if (stream.GetType() == typeof(MemoryStream) && ((MemoryStream)stream).TryGetBuffer(out var buffer))
{
reader = new HeifByteArrayReader(buffer);
// The documentation for GetBuffer indicates that the buffer remains valid after the MemoryStream is disposed.
if (ownsStream)
{
stream.Dispose();
}
}
else
{
if (stream.Length <= HeifStreamReader.MaxReadBufferSize)
{
byte[] bytes = CopyStreamToByteArray(stream);
if (ownsStream)
{
stream.Dispose();
}
reader = new HeifByteArrayReader(bytes);
}
else
{
reader = new HeifStreamReader(stream, ownsStream);
}
}
return(reader);
}