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Windowsの任意のファイルのサムネイルを抽出します

さまざまなサイズの画像だけでなく、任意のファイルからサムネイルを抽出する最も効率的な方法は何ですか？

私は全体を見てきましたが、その中で最も有望なのはWindows API ShellFileでしたが、これは正しくインストールされていないようです。私はWindows7を使用しています。

c#.netthumbnails
19
matinau

少し前に、WinAPIからサムネイルをロードするThumbnailProviderを作成しました。透明な画像をサポートします。これは実装です：

using System;
using System.Drawing;
using System.Drawing.Imaging;
using System.Runtime.InteropServices;
using System.IO;

    namespace ThumbnailGenerator
    {
        [Flags]
        public enum ThumbnailOptions
        {
            None = 0x00,
            BiggerSizeOk = 0x01,
            InMemoryOnly = 0x02,
            IconOnly = 0x04,
            ThumbnailOnly = 0x08,
            InCacheOnly = 0x10,
        }

        public class WindowsThumbnailProvider
        {
            private const string IShellItem2Guid = "7E9FB0D3-919F-4307-AB2E-9B1860310C93";

            [DllImport("Shell32.dll", CharSet = CharSet.Unicode, SetLastError = true)]
            internal static extern int SHCreateItemFromParsingName(
                [MarshalAs(UnmanagedType.LPWStr)] string path,
                // The following parameter is not used - binding context.
                IntPtr pbc,
                ref Guid riid,
                [MarshalAs(UnmanagedType.Interface)] out IShellItem shellItem);

            [DllImport("gdi32.dll")]
            [return: MarshalAs(UnmanagedType.Bool)]
            internal static extern bool DeleteObject(IntPtr hObject);

            [ComImport]
            [InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
            [Guid("43826d1e-e718-42ee-bc55-a1e261c37bfe")]
            internal interface IShellItem
            {
                void BindToHandler(IntPtr pbc,
                    [MarshalAs(UnmanagedType.LPStruct)]Guid bhid,
                    [MarshalAs(UnmanagedType.LPStruct)]Guid riid,
                    out IntPtr ppv);

                void GetParent(out IShellItem ppsi);
                void GetDisplayName(SIGDN sigdnName, out IntPtr ppszName);
                void GetAttributes(uint sfgaoMask, out uint psfgaoAttribs);
                void Compare(IShellItem psi, uint hint, out int piOrder);
            };

            internal enum SIGDN : uint
            {
                NORMALDISPLAY = 0,
                PARENTRELATIVEPARSING = 0x80018001,
                PARENTRELATIVEFORADDRESSBAR = 0x8001c001,
                DESKTOPABSOLUTEPARSING = 0x80028000,
                PARENTRELATIVEEDITING = 0x80031001,
                DESKTOPABSOLUTEEDITING = 0x8004c000,
                FILESYSPATH = 0x80058000,
                URL = 0x80068000
            }

            internal enum HResult
            {
                Ok = 0x0000,
                False = 0x0001,
                InvalidArguments = unchecked((int)0x80070057),
                OutOfMemory = unchecked((int)0x8007000E),
                NoInterface = unchecked((int)0x80004002),
                Fail = unchecked((int)0x80004005),
                ElementNotFound = unchecked((int)0x80070490),
                TypeElementNotFound = unchecked((int)0x8002802B),
                NoObject = unchecked((int)0x800401E5),
                Win32ErrorCanceled = 1223,
                Canceled = unchecked((int)0x800704C7),
                ResourceInUse = unchecked((int)0x800700AA),
                AccessDenied = unchecked((int)0x80030005)
            }

            [ComImportAttribute()]
            [GuidAttribute("bcc18b79-ba16-442f-80c4-8a59c30c463b")]
            [InterfaceTypeAttribute(ComInterfaceType.InterfaceIsIUnknown)]
            internal interface IShellItemImageFactory
            {
                [PreserveSig]
                HResult GetImage(
                [In, MarshalAs(UnmanagedType.Struct)] NativeSize size,
                [In] ThumbnailOptions flags,
                [Out] out IntPtr phbm);
            }

            [StructLayout(LayoutKind.Sequential)]
            internal struct NativeSize
            {
                private int width;
                private int height;

                public int Width { set { width = value; } }
                public int Height { set { height = value; } }
            };

            [StructLayout(LayoutKind.Sequential)]
            public struct RGBQUAD
            {
                public byte rgbBlue;
                public byte rgbGreen;
                public byte rgbRed;
                public byte rgbReserved;
            }

            public static Bitmap GetThumbnail(string fileName, int width, int height, ThumbnailOptions options)
            {
                IntPtr hBitmap = GetHBitmap(Path.GetFullPath(fileName), width, height, options);

                try
                {
                    // return a System.Drawing.Bitmap from the hBitmap
                    return GetBitmapFromHBitmap(hBitmap);
                }
                finally
                {
                    // delete HBitmap to avoid memory leaks
                    DeleteObject(hBitmap);
                }
            }

            public static Bitmap GetBitmapFromHBitmap(IntPtr nativeHBitmap)
            {
                Bitmap bmp = Bitmap.FromHbitmap(nativeHBitmap);

                if (Bitmap.GetPixelFormatSize(bmp.PixelFormat) < 32)
                    return bmp;

                return CreateAlphaBitmap(bmp, PixelFormat.Format32bppArgb);
            }

            public static Bitmap CreateAlphaBitmap(Bitmap srcBitmap, PixelFormat targetPixelFormat)
            {
                Bitmap result = new Bitmap(srcBitmap.Width, srcBitmap.Height, targetPixelFormat);

                Rectangle bmpBounds = new Rectangle(0, 0, srcBitmap.Width, srcBitmap.Height);

                BitmapData srcData = srcBitmap.LockBits(bmpBounds, ImageLockMode.ReadOnly, srcBitmap.PixelFormat);

                bool isAlplaBitmap = false;

                try
                {
                    for (int y = 0; y <= srcData.Height - 1; y++)
                    {
                        for (int x = 0; x <= srcData.Width - 1; x++)
                        {
                            Color pixelColor = Color.FromArgb(
                                Marshal.ReadInt32(srcData.Scan0, (srcData.Stride * y) + (4 * x)));

                            if (pixelColor.A > 0 & pixelColor.A < 255)
                            {
                                isAlplaBitmap = true;
                            }

                            result.SetPixel(x, y, pixelColor);
                        }
                    }
                }
                finally
                {
                    srcBitmap.UnlockBits(srcData);
                }

                if (isAlplaBitmap)
                {
                    return result;
                }
                else
                {
                    return srcBitmap;
                }
            }

            private static IntPtr GetHBitmap(string fileName, int width, int height, ThumbnailOptions options)
            {
                IShellItem nativeShellItem;
                Guid shellItem2Guid = new Guid(IShellItem2Guid);
                int retCode = SHCreateItemFromParsingName(fileName, IntPtr.Zero, ref shellItem2Guid, out nativeShellItem);

                if (retCode != 0)
                    throw Marshal.GetExceptionForHR(retCode);

                NativeSize nativeSize = new NativeSize();
                nativeSize.Width = width;
                nativeSize.Height = height;

                IntPtr hBitmap;
                HResult hr = ((IShellItemImageFactory)nativeShellItem).GetImage(nativeSize, options, out hBitmap);

                Marshal.ReleaseComObject(nativeShellItem);

                if (hr == HResult.Ok) return hBitmap;

                throw Marshal.GetExceptionForHR((int)hr);
            }
        }
    }

次に、次の方法で使用できます。

int THUMB_SIZE = 256;
Bitmap thumbnail = WindowsThumbnailProvider.GetThumbnail(
   fileName, THUMB_SIZE, THUMB_SIZE, ThumbnailOptions.None);

使用後はビットマップを Dispose（） する必要があることを忘れないでください。

41
Daniel Peñalba

これは、受け入れられた（素晴らしい）回答の改良版です。以下が変更されました。

  • SetPixel（）の代わりに安全でないコードを使用する->パフォーマンスを大幅に向上させる

  • isAlphaBitmapチェック全体を削除します。そもそもなぜそれが実装されたのかわかりませんが、同じコンテンツを含む2つの画像を区別する理由はありません（何かが変わったかどうかに関係なく、透明度のあるビットマップを返すだけです）

    [Flags]
public enum ThumbnailOptions
{
    None = 0x00,
    BiggerSizeOk = 0x01,
    InMemoryOnly = 0x02,
    IconOnly = 0x04,
    ThumbnailOnly = 0x08,
    InCacheOnly = 0x10
}

public class WindowsThumbnailProvider
{
    private const string IShellItem2Guid = "7E9FB0D3-919F-4307-AB2E-9B1860310C93";

    [DllImport("Shell32.dll", CharSet = CharSet.Unicode, SetLastError = true)]
    internal static extern int SHCreateItemFromParsingName(
        [MarshalAs(UnmanagedType.LPWStr)] string path,
        // The following parameter is not used - binding context.
        IntPtr pbc,
        ref Guid riid,
        [MarshalAs(UnmanagedType.Interface)] out IShellItem shellItem);

    [DllImport("gdi32.dll")]
    [return: MarshalAs(UnmanagedType.Bool)]
    internal static extern bool DeleteObject(IntPtr hObject);

    [DllImport("msvcrt.dll", CallingConvention = CallingConvention.Cdecl)]
    public static extern unsafe IntPtr memcpy(void* dst, void* src, UIntPtr count);

    public static Bitmap GetThumbnail(string fileName, int width, int height, ThumbnailOptions options)
    {
        var hBitmap = GetHBitmap(Path.GetFullPath(fileName), width, height, options);

        try
        {
            // return a System.Drawing.Bitmap from the hBitmap
            return GetBitmapFromHBitmap(hBitmap);
        }
        finally
        {
            // delete HBitmap to avoid memory leaks
            DeleteObject(hBitmap);
        }
    }

    public static Bitmap GetBitmapFromHBitmap(IntPtr nativeHBitmap)
    {
        Bitmap bmp = Image.FromHbitmap(nativeHBitmap);

        if (Image.GetPixelFormatSize(bmp.PixelFormat) < 32)
            return bmp;

        using (bmp)
            return CreateAlphaBitmap(bmp, PixelFormat.Format32bppArgb);
    }

    public static unsafe Bitmap CreateAlphaBitmap(Bitmap srcBitmap, PixelFormat targetPixelFormat)
    {
        var result = new Bitmap(srcBitmap.Width, srcBitmap.Height, targetPixelFormat);

        var bmpBounds = new Rectangle(0, 0, srcBitmap.Width, srcBitmap.Height);
        var srcData = srcBitmap.LockBits(bmpBounds, ImageLockMode.ReadOnly, srcBitmap.PixelFormat);
        var destData = result.LockBits(bmpBounds, ImageLockMode.ReadOnly, targetPixelFormat);

        var srcDataPtr = (byte*) srcData.Scan0;
        var destDataPtr = (byte*) destData.Scan0;

        try
        {
            for (int y = 0; y <= srcData.Height - 1; y++)
            {
                for (int x = 0; x <= srcData.Width - 1; x++)
                {
                    //this is really important because one stride may be positive and the other negative
                    var position = srcData.Stride * y + 4 * x;
                    var position2 = destData.Stride * y + 4 * x;

                    memcpy(destDataPtr + position2, srcDataPtr + position, (UIntPtr) 4);
                }
            }
        }
        finally
        {
            srcBitmap.UnlockBits(srcData);
            result.UnlockBits(destData);
        }

        return result;
    }

    private static IntPtr GetHBitmap(string fileName, int width, int height, ThumbnailOptions options)
    {
        IShellItem nativeShellItem;
        Guid shellItem2Guid = new Guid(IShellItem2Guid);
        int retCode = SHCreateItemFromParsingName(fileName, IntPtr.Zero, ref shellItem2Guid, out nativeShellItem);

        if (retCode != 0)
            throw Marshal.GetExceptionForHR(retCode);

        NativeSize nativeSize = new NativeSize();
        nativeSize.Width = width;
        nativeSize.Height = height;

        IntPtr hBitmap;
        HResult hr = ((IShellItemImageFactory) nativeShellItem).GetImage(nativeSize, options, out hBitmap);

        Marshal.ReleaseComObject(nativeShellItem);

        if (hr == HResult.Ok) return hBitmap;

        throw Marshal.GetExceptionForHR((int) hr);
    }

    [ComImport]
    [InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
    [Guid("43826d1e-e718-42ee-bc55-a1e261c37bfe")]
    internal interface IShellItem
    {
        void BindToHandler(IntPtr pbc,
            [MarshalAs(UnmanagedType.LPStruct)] Guid bhid,
            [MarshalAs(UnmanagedType.LPStruct)] Guid riid,
            out IntPtr ppv);

        void GetParent(out IShellItem ppsi);
        void GetDisplayName(SIGDN sigdnName, out IntPtr ppszName);
        void GetAttributes(uint sfgaoMask, out uint psfgaoAttribs);
        void Compare(IShellItem psi, uint hint, out int piOrder);
    }

    internal enum SIGDN : uint
    {
        NORMALDISPLAY = 0,
        PARENTRELATIVEPARSING = 0x80018001,
        PARENTRELATIVEFORADDRESSBAR = 0x8001c001,
        DESKTOPABSOLUTEPARSING = 0x80028000,
        PARENTRELATIVEEDITING = 0x80031001,
        DESKTOPABSOLUTEEDITING = 0x8004c000,
        FILESYSPATH = 0x80058000,
        URL = 0x80068000
    }

    internal enum HResult
    {
        Ok = 0x0000,
        False = 0x0001,
        InvalidArguments = unchecked((int) 0x80070057),
        OutOfMemory = unchecked((int) 0x8007000E),
        NoInterface = unchecked((int) 0x80004002),
        Fail = unchecked((int) 0x80004005),
        ElementNotFound = unchecked((int) 0x80070490),
        TypeElementNotFound = unchecked((int) 0x8002802B),
        NoObject = unchecked((int) 0x800401E5),
        Win32ErrorCanceled = 1223,
        Canceled = unchecked((int) 0x800704C7),
        ResourceInUse = unchecked((int) 0x800700AA),
        AccessDenied = unchecked((int) 0x80030005)
    }

    [ComImport]
    [Guid("bcc18b79-ba16-442f-80c4-8a59c30c463b")]
    [InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
    internal interface IShellItemImageFactory
    {
        [PreserveSig]
        HResult GetImage(
            [In, MarshalAs(UnmanagedType.Struct)] NativeSize size,
            [In] ThumbnailOptions flags,
            [Out] out IntPtr phbm);
    }

    [StructLayout(LayoutKind.Sequential)]
    internal struct NativeSize
    {
        private int width;
        private int height;

        public int Width
        {
            set { width = value; }
        }

        public int Height
        {
            set { height = value; }
        }
    }

    [StructLayout(LayoutKind.Sequential)]
    public struct RGBQUAD
    {
        public byte rgbBlue;
        public byte rgbGreen;
        public byte rgbRed;
        public byte rgbReserved;
    }
}
5
Snicker