C＃通过windows api从文件中获取缩略图
Windows资源pipe理器能够显示文件的缩略图。 这些缩略图由核心和第三方shell程序扩展提供。
我知道如何扩展shell来为Windows提供缩略图。
我想要做的是通过使用C＃的shell从系统上的任何文件检索缩略图。 这可能吗？
基本上，我正在写一个自定义的文件浏览器，我想显示缩略图，并不可能parsing地球上的每个文件，使自己的缩略图。
澄清：许多答案似乎围绕网页缩略图，或缩放图像。 但那不是我想要的。 我想要的是要求Windows的这些文件types的缩略图表示：.DOC，.PDF，.3DM，.DWG …和mabye约十多个。 我不想自己parsing，渲染和缩略图，因为Windows已经知道如何。
我发布的代码实际上是可行的，也许可以简化并清理一下。
今天跑了这个 – 这已经过了几个月了，但是它为我完成了工作（在Win7上，提取MPEG-4文件的缩略图）：
- 来源： https ： //github.com/dbarros/WindowsAPICodePack
- Nuget： https ：//www.nuget.org/packages/WindowsAPICodePack-Shell
码：
ShellFile shellFile = ShellFile.FromFilePath(pathToYourFile); Bitmap shellThumb = shellFile.Thumbnail.ExtraLargeBitmap; 希望它有帮助！
SharePoint中的Microsoft Office缩略图位于http://msdn.microsoft.com/zh-cn/library/aa289172(VS.71).aspx 。 正是你想要的。 （我使用http://www.developerfusion.com/tools/convert/vb-to-csharp/将VB.NET代码转换为C＃没有任何困难。;
关于您在答案中发布的代码， 使用 http://www.vbaccelerator.com/home/net/code/libraries/Shell_Projects/Thumbnail_Extraction/article.asp中; 的Shell进行缩略图提取是源代码的原始文章。 我相信几乎所有的IExtractImage示例（您发现search）都基于这篇文章的代码，由于命名约定，评论等等，从原来的。 由于这篇文章是从2003年4月开始的，因此它带有一些非标准的（非.NET）编码习惯。 我做了一些基本的testing，并且有垃圾回收问题，释放非托pipe资源问题和其他清理问题。 因此，我强烈build议避免该条中的代码。 而且，代码的结构化使得维护变得困难。
在2005年7月的MSDN上有一个简洁的版本，在http://msdn.microsoft.com/en-us/library/aa289172(VS.71).aspx中称为SharePoint中的Microsoft Office缩略图 。 此代码和文章的代码共享相似之处，这使我相信使用Shell文章缩略图提取是SharePoint文章的基础。 GetThumbnailImage的VB.NET版本忽略了longestEdge参数，但是C ++版本使用它并logging了ORIGSIZE和QUALITY标志的使用。 此外，该代码演示了如何使用.NET的FreeCoTaskMem而不是Shell的IMalloc和SHGetMalloc 。
IExtractImage与文件，文件夹和其他名称空间对象一起使用。 MSDN代码与隐藏文件一起使用，而vbAccelerator代码则需要将SHCONTF_INCLUDEHIDDEN添加到EnumObjects调用中。 另外，vbAccelerator枚举查找指定文件的shell文件夹的对象，这似乎是浪费时间。 这可能需要find用于GetUIObjectOf调用的正确“相对”PIDL。
ShellThumbnail（工作在进行中）
完整的示例项目位于self.aspx/.Public/ShellThumbnail.html 。
Imports System.Runtime.InteropServices Namespace Shell ''' <summary> ''' Generates a thumbnail of a folder's picture or a file's image. ''' </summary> ''' <remarks>This is the "Folder's Picture" and not the "Folder's Icon"! Use SHGetFileInfo to generate the thumbnail for a folder's icon or for a file that does not have a thumbnail handler.</remarks> ''' <reference>Microsoft Office Thumbnails in SharePoint at http://msdn.microsoft.com/en-us/library/aa289172%28VS.71%29.aspx.</reference> Public Class ShellThumbnail 'TODO - Work out the details for image size and IEIFLAG handling. #Region " Determining Thumbnail Size and Quality [documentation] " 'http://support.microsoft.com/kb/835823 'Determining Thumbnail Size and Quality 'Browse to HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer. Create or modify two DWORDs called ThumbnailSize and ThumbnailQuality. For ThumbnailSize set the value in pixels, with the default being 96. For ThumbnailQuality set the value as a number that represents the percentage quality between 50 and 100. 'http://www.pctools.com/guides/registry/detail/1066/ (modified) ' User Key: [HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer] 'System Key: [HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Explorer] 'Value Name: ThumbnailSize, ThumbnailQuality ' Data Type: REG_DWORD (DWORD Value) 'Value Data: Size in pixels (32-255), Quality Percentage (50-100) 'Microsoft® Windows® XP Registry Guide 'Jerry Honeycutt '09/11/2002 'Microsoft Press 'http://www.microsoft.com/mspress/books/sampchap/6232.aspx#118 '<H3><I><A name=118></A>Thumbnails</I></H3>The Thumbnails category controls the 'quality of thumbnails in Windows Explorer. Table 5-10 describes the values for 'Image Quality and Size. Create values that you don't see in the registry. The 'default value for <CODE>ThumbnailQuality</CODE> is <CODE>0x5A</CODE>. The 'default value for <CODE>ThumbnailSize</CODE> is <CODE>0x60</CODE>. Keep in mind 'that higher quality and larger thumbnails require more disk space, which is not 'usually a problem, but they also take longer to display. Changing the quality 'does not affect thumbnails that already exist on the file system. '<P><B>Table 5-10 </B><I>Values in Thumbnails</I> '<P> '<TABLE border=0 cellSpacing=1 cellPadding=4 width="100%"> '<TBODY> '<TR> '<TD bgColor=#999999 vAlign=top><B>Setting</B></TD> '<TD bgColor=#999999 vAlign=top><B>Name</B></TD> '<TD bgColor=#999999 vAlign=top><B>Type</B></TD> '<TD bgColor=#999999 vAlign=top><B>Data</B></TD></TR> '<TR> '<TD bgColor=#cccccc 'vAlign=top><CODE><B>HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer</B></CODE></TD> '<TD bgColor=#cccccc vAlign=top> </TD> '<TD bgColor=#cccccc vAlign=top> </TD> '<TD bgColor=#cccccc vAlign=top> </TD></TR> '<TR> '<TD bgColor=#cccccc vAlign=top><CODE>Image Quality</CODE></TD> '<TD bgColor=#cccccc vAlign=top><CODE>ThumbnailQuality</CODE></TD> '<TD bgColor=#cccccc vAlign=top><CODE>REG_DWORD</CODE></TD> '<TD bgColor=#cccccc vAlign=top><CODE>0x32 - 0x64</CODE></TD></TR> '<TR> '<TD bgColor=#cccccc vAlign=top><CODE>Size (pixels)</CODE></TD> '<TD bgColor=#cccccc vAlign=top><CODE>ThumbnailSize</CODE></TD> '<TD bgColor=#cccccc vAlign=top><CODE>REG_DWORD</CODE></TD> '<TD bgColor=#cccccc vAlign=top><CODE>0x20 - 0xFF</CODE></TD></TR></TBODY></TABLE></P> #End Region Public Shared ReadOnly DefaultThumbnailSize As New System.Drawing.Size(96, 96) Public Const DefaultColorDepth As Integer = 32 ''' <summary> ''' Used to request an image from an object, such as an item in a Shell folder. ''' </summary> ''' <param name="path">An absolute path to a file or folder.</param> Public Shared Function ExtractImage(ByVal path As String) As Bitmap Return ExtractImage(path, System.Drawing.Size.Empty, DefaultColorDepth, 0) End Function ''' <summary> ''' Used to request an image from an object, such as an item in a Shell folder. ''' </summary> ''' <param name="path">An absolute path to a file or folder.</param> ''' <param name="size"></param> Public Shared Function ExtractImage(ByVal path As String, ByVal size As System.Drawing.Size) As Bitmap Return ExtractImage(path, size, DefaultColorDepth, 0) End Function ''' <summary> ''' Used to request an image from an object, such as an item in a Shell folder. ''' </summary> ''' <param name="path">An absolute path to a file or folder.</param> ''' <param name="size"></param> ''' <param name="recommendedColorDepth">The recommended color depth in units of bits per pixel. The default is 32.</param> Public Shared Function ExtractImage(ByVal path As String, ByVal size As System.Drawing.Size, ByVal recommendedColorDepth As Integer) As Bitmap Return ExtractImage(path, size, recommendedColorDepth, 0) End Function ''' <summary> ''' Used to request an image from an object, such as an item in a Shell folder. ''' </summary> ''' <param name="path">An absolute path to a file or folder.</param> ''' <param name="size"></param> ''' <param name="recommendedColorDepth">The recommended color depth in units of bits per pixel. The default is 32.</param> Private Shared Function ExtractImage(ByVal path As String, ByVal size As System.Drawing.Size, ByVal recommendedColorDepth As Integer, ByVal flags As IEIFLAG) As Bitmap Dim oResult As Bitmap = Nothing Dim oDesktopFolder As IShellFolder = Nothing Dim hParentIDL As IntPtr Dim hIDL As IntPtr Dim oParentFolder As IShellFolder Dim hParentFolder As IntPtr Dim oExtractImage As IExtractImage Dim hExtractImage As IntPtr 'Divide the file name into a path and file/folder name. Dim sFolderName As String = System.IO.Path.GetDirectoryName(path) Dim sBaseName As String = System.IO.Path.GetFileName(path) 'Get the desktop IShellFolder. If SHGetDesktopFolder(oDesktopFolder) <> Missico.Win32.S_OK Then Throw New System.Runtime.InteropServices.COMException End If 'Get the parent folder for the specified path. oDesktopFolder.ParseDisplayName(IntPtr.Zero, IntPtr.Zero, sFolderName, 0, hParentIDL, 0) oDesktopFolder.BindToObject(hParentIDL, IntPtr.Zero, ShellGUIDs.IID_IShellFolder, hParentFolder) oParentFolder = CType(Marshal.GetTypedObjectForIUnknown(hParentFolder, GetType(IShellFolder)), IShellFolder) 'Get the file/folder's IExtractImage oParentFolder.ParseDisplayName(IntPtr.Zero, IntPtr.Zero, sBaseName, 0, hIDL, 0) oParentFolder.GetUIObjectOf(IntPtr.Zero, 1, New IntPtr() {hIDL}, ShellGUIDs.IID_IExtractImage, IntPtr.Zero, hExtractImage) 'Free the pidls. The Runtime Callable Wrappers (RCW) should automatically release the COM objects. Marshal.FreeCoTaskMem(hParentIDL) Marshal.FreeCoTaskMem(hIDL) Marshal.FinalReleaseComObject(oParentFolder) Marshal.FinalReleaseComObject(oDesktopFolder) If hExtractImage = IntPtr.Zero Then 'There is no handler for this file, which is odd. I believe we should default the file's type icon. Debug.WriteLine(String.Format("There is no thumbnail for the specified file '{0}'.", path), "ShellThumbnail.ExtractImage") Else oExtractImage = CType(Marshal.GetTypedObjectForIUnknown(hExtractImage, GetType(IExtractImage)), IExtractImage) 'Set the size and flags Dim oSize As Missico.Win32.SIZE 'must specify a size Dim iFlags As IEIFLAG = flags Or IEIFLAG.IEIFLAG_ORIGSIZE Or IEIFLAG.IEIFLAG_QUALITY Or IEIFLAG.IEIFLAG_ASPECT If size.IsEmpty Then oSize.cx = DefaultThumbnailSize.Width oSize.cy = DefaultThumbnailSize.Height Else oSize.cx = size.Width oSize.cy = size.Height End If Dim hBitmap As IntPtr Dim sPath As New System.Text.StringBuilder(Missico.Win32.MAX_PATH, Missico.Win32.MAX_PATH) oExtractImage.GetLocation(sPath, sPath.Capacity, 0, oSize, recommendedColorDepth, iFlags) 'if the specified path is to a folder then IExtractImage.Extract fails. Try oExtractImage.Extract(hBitmap) Catch ex As System.Runtime.InteropServices.COMException 'clear the handle since extract failed hBitmap = IntPtr.Zero Debug.WriteLine(String.Format("There is no thumbnail for the specified folder '{0}'.", path), "ShellThumbnail.ExtractImage") Finally Marshal.FinalReleaseComObject(oExtractImage) End Try If Not hBitmap.Equals(IntPtr.Zero) Then 'create the image from the handle oResult = System.Drawing.Bitmap.FromHbitmap(hBitmap) 'dump the properties to determine what kind of bitmap is returned 'Missico.Diagnostics.ObjectDumper.Write(oResult) 'Tag={ } 'PhysicalDimension={Width=96, Height=96} 'Size={Width=96, Height=96} 'Width=96 'Height=96 'HorizontalResolution=96 'VerticalResolution=96 'Flags=335888 'RawFormat={ } 'PixelFormat=Format32bppRgb 'Palette={ } 'FrameDimensionsList=... 'PropertyIdList=... 'PropertyItems=... Missico.Win32.DeleteObject(hBitmap) 'release the handle End If End If Return oResult End Function End Class End Namespace
这可能有助于：
这包括Shell API，并允许您执行几乎所有的shell可以（包括渲染缩略图）。
这是一个我在互联网上search的课程。 它看起来像原来的代码来自http://www.experts-exchange.com/Programming/Languages/C_Sharp/Q_21789724.html ，但我不能看到它给予适当的归属。 我在这里find了源代码： http : //www.vbforums.com/showthread.php?t=527704
这里有一个正确的COM调用的类，在这里为后代转载：
using System; using System.Diagnostics; using System.Drawing; using System.IO; using System.Runtime.InteropServices; using System.Text; namespace RMA.Shell { public class ShellThumbnail : IDisposable { [Flags] private enum ESTRRET { STRRET_WSTR = 0, STRRET_OFFSET = 1, STRRET_CSTR = 2 } [Flags] private enum ESHCONTF { SHCONTF_FOLDERS = 32, SHCONTF_NONFOLDERS = 64, SHCONTF_INCLUDEHIDDEN = 128, } [Flags] private enum ESHGDN { SHGDN_NORMAL = 0, SHGDN_INFOLDER = 1, SHGDN_FORADDRESSBAR = 16384, SHGDN_FORPARSING = 32768 } [Flags] private enum ESFGAO { SFGAO_CANCOPY = 1, SFGAO_CANMOVE = 2, SFGAO_CANLINK = 4, SFGAO_CANRENAME = 16, SFGAO_CANDELETE = 32, SFGAO_HASPROPSHEET = 64, SFGAO_DROPTARGET = 256, SFGAO_CAPABILITYMASK = 375, SFGAO_LINK = 65536, SFGAO_SHARE = 131072, SFGAO_READONLY = 262144, SFGAO_GHOSTED = 524288, SFGAO_DISPLAYATTRMASK = 983040, SFGAO_FILESYSANCESTOR = 268435456, SFGAO_FOLDER = 536870912, SFGAO_FILESYSTEM = 1073741824, SFGAO_HASSUBFOLDER = -2147483648, SFGAO_CONTENTSMASK = -2147483648, SFGAO_VALIDATE = 16777216, SFGAO_REMOVABLE = 33554432, SFGAO_COMPRESSED = 67108864, } private enum EIEIFLAG { IEIFLAG_ASYNC = 1, IEIFLAG_CACHE = 2, IEIFLAG_ASPECT = 4, IEIFLAG_OFFLINE = 8, IEIFLAG_GLEAM = 16, IEIFLAG_SCREEN = 32, IEIFLAG_ORIGSIZE = 64, IEIFLAG_NOSTAMP = 128, IEIFLAG_NOBORDER = 256, IEIFLAG_QUALITY = 512 } [StructLayout(LayoutKind.Sequential, Pack = 4, Size = 0, CharSet = CharSet.Auto)] private struct STRRET_CSTR { public ESTRRET uType; [MarshalAs(UnmanagedType.ByValArray, SizeConst = 520)] public byte[] cStr; } [StructLayout(LayoutKind.Explicit, CharSet = CharSet.Auto)] private struct STRRET_ANY { [FieldOffset(0)] public ESTRRET uType; [FieldOffset(4)] public IntPtr pOLEString; } [StructLayoutAttribute(LayoutKind.Sequential)] private struct SIZE { public int cx; public int cy; } [ComImport(), Guid("00000000-0000-0000-C000-000000000046")] [InterfaceType(ComInterfaceType.InterfaceIsIUnknown)] private interface IUnknown { [PreserveSig()] IntPtr QueryInterface(ref Guid riid, ref IntPtr pVoid); [PreserveSig()] IntPtr AddRef(); [PreserveSig()] IntPtr Release(); } [ComImportAttribute()] [GuidAttribute("00000002-0000-0000-C000-000000000046")] [InterfaceTypeAttribute(ComInterfaceType.InterfaceIsIUnknown)] private interface IMalloc { [PreserveSig()] IntPtr Alloc(int cb); [PreserveSig()] IntPtr Realloc(IntPtr pv, int cb); [PreserveSig()] void Free(IntPtr pv); [PreserveSig()] int GetSize(IntPtr pv); [PreserveSig()] int DidAlloc(IntPtr pv); [PreserveSig()] void HeapMinimize(); } [ComImportAttribute()] [GuidAttribute("000214F2-0000-0000-C000-000000000046")] [InterfaceTypeAttribute(ComInterfaceType.InterfaceIsIUnknown)] private interface IEnumIDList { [PreserveSig()] int Next(int celt, ref IntPtr rgelt, ref int pceltFetched); void Skip(int celt); void Reset(); void Clone(ref IEnumIDList ppenum); } [ComImportAttribute()] [GuidAttribute("000214E6-0000-0000-C000-000000000046")] [InterfaceTypeAttribute(ComInterfaceType.InterfaceIsIUnknown)] private interface IShellFolder { void ParseDisplayName(IntPtr hwndOwner, IntPtr pbcReserved, [MarshalAs(UnmanagedType.LPWStr)]string lpszDisplayName, ref int pchEaten, ref IntPtr ppidl, ref int pdwAttributes); void EnumObjects(IntPtr hwndOwner, [MarshalAs(UnmanagedType.U4)]ESHCONTF grfFlags, ref IEnumIDList ppenumIDList); void BindToObject(IntPtr pidl, IntPtr pbcReserved, ref Guid riid, ref IShellFolder ppvOut); void BindToStorage(IntPtr pidl, IntPtr pbcReserved, ref Guid riid, IntPtr ppvObj); [PreserveSig()] int CompareIDs(IntPtr lParam, IntPtr pidl1, IntPtr pidl2); void CreateViewObject(IntPtr hwndOwner, ref Guid riid, IntPtr ppvOut); void GetAttributesOf(int cidl, IntPtr apidl, [MarshalAs(UnmanagedType.U4)]ref ESFGAO rgfInOut); void GetUIObjectOf(IntPtr hwndOwner, int cidl, ref IntPtr apidl, ref Guid riid, ref int prgfInOut, ref IUnknown ppvOut); void GetDisplayNameOf(IntPtr pidl, [MarshalAs(UnmanagedType.U4)]ESHGDN uFlags, ref STRRET_CSTR lpName); void SetNameOf(IntPtr hwndOwner, IntPtr pidl, [MarshalAs(UnmanagedType.LPWStr)]string lpszName, [MarshalAs(UnmanagedType.U4)] ESHCONTF uFlags, ref IntPtr ppidlOut); } [ComImportAttribute(), GuidAttribute("BB2E617C-0920-11d1-9A0B-00C04FC2D6C1"), InterfaceTypeAttribute(ComInterfaceType.InterfaceIsIUnknown)] private interface IExtractImage { void GetLocation([Out(), MarshalAs(UnmanagedType.LPWStr)] StringBuilder pszPathBuffer, int cch, ref int pdwPriority, ref SIZE prgSize, int dwRecClrDepth, ref int pdwFlags); void Extract(ref IntPtr phBmpThumbnail); } private class UnmanagedMethods { [DllImport("shell32", CharSet = CharSet.Auto)] internal extern static int SHGetMalloc(ref IMalloc ppMalloc); [DllImport("shell32", CharSet = CharSet.Auto)] internal extern static int SHGetDesktopFolder(ref IShellFolder ppshf); [DllImport("shell32", CharSet = CharSet.Auto)] internal extern static int SHGetPathFromIDList(IntPtr pidl, StringBuilder pszPath); [DllImport("gdi32", CharSet = CharSet.Auto)] internal extern static int DeleteObject(IntPtr hObject); } ~ShellThumbnail() { Dispose(); } private IMalloc alloc = null; private bool disposed = false; private Size _desiredSize = new Size(100, 100); private Bitmap _thumbNail; public Bitmap ThumbNail { get { return _thumbNail; } } public Size DesiredSize { get { return _desiredSize; } set { _desiredSize = value; } } private IMalloc Allocator { get { if (!disposed) { if (alloc == null) { UnmanagedMethods.SHGetMalloc(ref alloc); } } else { Debug.Assert(false, "Object has been disposed."); } return alloc; } } public Bitmap GetThumbnail(string fileName) { if (string.IsNullOrEmpty(fileName)) return null; if (!File.Exists(fileName) && !Directory.Exists(fileName)) { throw new FileNotFoundException(string.Format("The file '{0}' does not exist", fileName), fileName); } if (_thumbNail != null) { _thumbNail.Dispose(); _thumbNail = null; } IShellFolder folder = null; try { folder = getDesktopFolder; } catch (Exception ex) { throw ex; } if (folder != null) { IntPtr pidlMain = IntPtr.Zero; try { int cParsed = 0; int pdwAttrib = 0; string filePath = Path.GetDirectoryName(fileName); folder.ParseDisplayName(IntPtr.Zero, IntPtr.Zero, filePath, ref cParsed, ref pidlMain, ref pdwAttrib); } catch (Exception ex) { Marshal.ReleaseComObject(folder); throw ex; } if (pidlMain != IntPtr.Zero) { Guid iidShellFolder = new Guid("000214E6-0000-0000-C000-000000000046"); IShellFolder item = null; try { folder.BindToObject(pidlMain, IntPtr.Zero, ref iidShellFolder, ref item); } catch (Exception ex) { Marshal.ReleaseComObject(folder); Allocator.Free(pidlMain); throw ex; } if (item != null) { IEnumIDList idEnum = null; try { item.EnumObjects(IntPtr.Zero, (ESHCONTF.SHCONTF_FOLDERS | ESHCONTF.SHCONTF_NONFOLDERS), ref idEnum); } catch (Exception ex) { Marshal.ReleaseComObject(folder); Allocator.Free(pidlMain); throw ex; } if (idEnum != null) { int hRes = 0; IntPtr pidl = IntPtr.Zero; int fetched = 0; bool complete = false; while (!complete) { hRes = idEnum.Next(1, ref pidl, ref fetched); if (hRes != 0) { pidl = IntPtr.Zero; complete = true; } else { if (_getThumbNail(fileName, pidl, item)) { complete = true; } } if (pidl != IntPtr.Zero) { Allocator.Free(pidl); } } Marshal.ReleaseComObject(idEnum); } Marshal.ReleaseComObject(item); } Allocator.Free(pidlMain); } Marshal.ReleaseComObject(folder); } return ThumbNail; } private bool _getThumbNail(string file, IntPtr pidl, IShellFolder item) { IntPtr hBmp = IntPtr.Zero; IExtractImage extractImage = null; try { string pidlPath = PathFromPidl(pidl); if (Path.GetFileName(pidlPath).ToUpper().Equals(Path.GetFileName(file).ToUpper())) { IUnknown iunk = null; int prgf = 0; Guid iidExtractImage = new Guid("BB2E617C-0920-11d1-9A0B-00C04FC2D6C1"); item.GetUIObjectOf(IntPtr.Zero, 1, ref pidl, ref iidExtractImage, ref prgf, ref iunk); extractImage = (IExtractImage)iunk; if (extractImage != null) { Console.WriteLine("Got an IExtractImage object!"); SIZE sz = new SIZE(); sz.cx = DesiredSize.Width; sz.cy = DesiredSize.Height; StringBuilder location = new StringBuilder(260, 260); int priority = 0; int requestedColourDepth = 32; EIEIFLAG flags = EIEIFLAG.IEIFLAG_ASPECT | EIEIFLAG.IEIFLAG_SCREEN; int uFlags = (int)flags; try { extractImage.GetLocation(location, location.Capacity, ref priority, ref sz, requestedColourDepth, ref uFlags); extractImage.Extract(ref hBmp); } catch (System.Runtime.InteropServices.COMException ex) { } if (hBmp != IntPtr.Zero) { _thumbNail = Bitmap.FromHbitmap(hBmp); } Marshal.ReleaseComObject(extractImage); extractImage = null; } return true; } else { return false; } } catch (Exception ex) { if (hBmp != IntPtr.Zero) { UnmanagedMethods.DeleteObject(hBmp); } if (extractImage != null) { Marshal.ReleaseComObject(extractImage); } throw ex; } } private string PathFromPidl(IntPtr pidl) { StringBuilder path = new StringBuilder(260, 260); int result = UnmanagedMethods.SHGetPathFromIDList(pidl, path); if (result == 0) { return string.Empty; } else { return path.ToString(); } } private IShellFolder getDesktopFolder { get { IShellFolder ppshf = null; int r = UnmanagedMethods.SHGetDesktopFolder(ref ppshf); return ppshf; } } public void Dispose() { if (!disposed) { if (alloc != null) { Marshal.ReleaseComObject(alloc); } alloc = null; if (_thumbNail != null) { _thumbNail.Dispose(); } disposed = true; } } } }
XP / 2003不支持Windows API代码包缩略图调用。
不完全是你问的，但这里是一个打开Thumbs.db文件的项目 。
维基百科的文章有更多的信息在哪里可以find缩略图在Vista＆7。
您应该使用Windows GDI +来获取这些缩略图，就像这样 。
