Blob.cs

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// Copyright (c) 2014 Silicon Studio Corp. (http://siliconstudio.co.jp)
// This file is distributed under GPL v3. See LICENSE.md for details.
using System;
using System.Runtime.InteropServices;
using SiliconStudio.Core;
using SiliconStudio.Core.IO;

namespace SiliconStudio.Core.Storage
{
    /// <summary>
    /// Stores immutable binary content.
    /// </summary>
    public class Blob : ReferenceBase
    {
        private readonly ObjectDatabase objectDatabase;
        private readonly IntPtr content;
        private readonly int size;
        private readonly ObjectId objectId;

        protected Blob(ObjectDatabase objectDatabase, ObjectId objectId)
        {
            this.objectDatabase = objectDatabase;
            this.objectId = objectId;
        }

        internal Blob(ObjectDatabase objectDatabase, ObjectId objectId, IntPtr content, int size)
            : this(objectDatabase, objectId)
        {
            this.size = size;
            this.content = Marshal.AllocHGlobal(size);
            Utilities.CopyMemory(this.content, content, size);
        }

        internal Blob(ObjectDatabase objectDatabase, ObjectId objectId, NativeStream stream)
            : this(objectDatabase, objectId)
        {
            this.size = (int)stream.Length;
            this.content = Marshal.AllocHGlobal(this.size);
            stream.Read(this.content, this.size);
        }

        /// <summary>
        /// Gets the size.
        /// </summary>
        /// <value>
        /// The size.
        /// </value>
        public int Size
        {
            get { return size; }
        }

        /// <summary>
        /// Gets the content.
        /// </summary>
        /// <value>
        /// The content.
        /// </value>
        public IntPtr Content
        {
            get { return content; }
        }

        /// <summary>
        /// Gets the <see cref="ObjectId"/>.
        /// </summary>
        /// <value>
        /// The <see cref="ObjectId"/>.
        /// </value>
        public ObjectId ObjectId
        {
            get { return objectId; }
        }

        internal ObjectDatabase ObjectDatabase
        {
            get { return objectDatabase; }
        }

        /// <summary>
        /// Gets a <see cref="NativeStream"/> over the <see cref="Content"/>.
        /// </summary>
        /// It will keeps a reference to the <see cref="Blob"/> until disposed.
        /// <returns>A <see cref="NativeStream"/> over the <see cref="Content"/>.</returns>
        public NativeStream GetContentStream()
        {
            return new BlobStream(this);
        }

        /// <inheritdoc/>
        protected override void Destroy()
        {
            objectDatabase.DestroyBlob(this);
            Marshal.FreeHGlobal(this.content);
        }
    }
}