GARbro-mirror/ArcFormats/WebP/ImageWEBP.cs

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2016-05-20 08:01:40 +08:00
//! \file ImageWEBP.cs
//! \date Wed Apr 06 07:16:39 2016
//! \brief Google WEBP image format.
//
// Copyright (C) 2016 by morkt
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to
// deal in the Software without restriction, including without limitation the
// rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
// sell copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
// IN THE SOFTWARE.
//
using System;
using System.ComponentModel.Composition;
using System.IO;
using System.Windows.Media;
using GameRes.Utility;
namespace GameRes.Formats.Google
{
internal class WebPMetaData : ImageMetaData
{
public WebPFeature Flags;
public bool IsLossless;
public long DataOffset;
public int DataSize;
public long AlphaOffset;
public int AlphaSize;
}
[Flags]
internal enum WebPFeature : uint
{
Fragments = 0x0001,
Animation = 0x0002,
Xmp = 0x0004,
Exif = 0x0008,
Alpha = 0x0010,
Iccp = 0x0020,
}
[Export(typeof(ImageFormat))]
public class WebPFormat : ImageFormat
{
public override string Tag { get { return "WEBP"; } }
public override string Description { get { return "Google WebP image format"; } }
public override uint Signature { get { return 0; } }
public override ImageMetaData ReadMetaData (Stream stream)
{
if (0x46464952 != FormatCatalog.ReadSignature (stream)) // 'RIFF'
return null;
var header = new byte[0x10];
if (8 != stream.Read (header, 0, 8))
return null;
if (!Binary.AsciiEqual (header, 4, "WEBP"))
return null;
bool found_vp8x = false;
var info = new WebPMetaData();
int chunk_size;
for (;;)
{
if (8 != stream.Read (header, 0, 8))
return null;
chunk_size = LittleEndian.ToInt32 (header, 4);
int aligned_size = (chunk_size + 1) & ~1;
if (!found_vp8x && Binary.AsciiEqual (header, 0, "VP8X"))
{
found_vp8x = true;
if (chunk_size < 10)
return null;
if (chunk_size > header.Length)
header = new byte[chunk_size];
if (chunk_size != stream.Read (header, 0, chunk_size))
return null;
info.Flags = (WebPFeature)LittleEndian.ToUInt32 (header, 0);
info.Width = 1 + GetUInt24 (header, 4);
info.Height = 1 + GetUInt24 (header, 7);
if ((long)info.Width * info.Height >= (1L << 32))
return null;
continue;
}
if (Binary.AsciiEqual (header, 0, "VP8 ") || Binary.AsciiEqual (header, 0, "VP8L"))
{
info.IsLossless = header[3] == 'L';
info.DataOffset = stream.Position;
info.DataSize = chunk_size;
if (!found_vp8x)
{
if (chunk_size < 10 || 10 != stream.Read (header, 0, 10))
return null;
if (header[3] != 0x9D || header[4] != 1 || header[5] != 0x2A)
return null;
if (0 != (header[0] & 1)) // not a keyframe
return null;
info.Width = LittleEndian.ToUInt16 (header, 6) & 0x3FFFu;
info.Height = LittleEndian.ToUInt16 (header, 8) & 0x3FFFu;
}
break;
}
if (Binary.AsciiEqual (header, 0, "ALPH"))
{
info.AlphaOffset = stream.Position;
info.AlphaSize = chunk_size;
}
stream.Seek (aligned_size, SeekOrigin.Current);
}
if (0 == info.Width || 0 == info.Height)
return null;
return info;
}
static uint GetUInt24 (byte[] src, int offset)
{
return (uint)(src[offset] | src[offset+1] << 8 | src[offset+2] << 16);
}
public override ImageData Read (Stream stream, ImageMetaData info)
{
using (var reader = new WebPDecoder (stream, (WebPMetaData)info))
{
reader.Decode();
return ImageData.Create (info, reader.Format, null, reader.Output);
}
}
public override void Write (Stream file, ImageData image)
{
throw new NotImplementedException ("WebPFormat.Write not implemented");
}
}
}