We introduced one way to retrieve revit thumbnail in post: http://blog.revitapp.com/2010/07/revit-thumbnails/. However, we found that that tool has some unknown issue which will make Revit crash.
Here we introduce another class to get the file preview (including Revit thumbnail):
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
using System.Drawing;
using System.Runtime.InteropServices;
using System.Drawing.Imaging;
namespace RevitApp
{
internal class ThumbnailCreator : IDisposable
{
// Fields
private IMalloc alloc;
private Size desiredSize;
private bool disposed;
private Bitmap thumbnail;
// Methods
public ThumbnailCreator()
{
this.desiredSize = new Size(128, 128);
}
public ThumbnailCreator(int width, int height)
{
desiredSize = new Size(128, 128);
desiredSize.Width = width;
desiredSize.Height = height;
}
public void Dispose()
{
if (!this.disposed)
{
if (this.alloc != null)
{
Marshal.ReleaseComObject(this.alloc);
}
this.alloc = null;
if (this.thumbnail != null)
{
this.thumbnail.Dispose();
}
this.disposed = true;
}
}
~ThumbnailCreator()
{
this.Dispose();
}
private bool getThumbNail(string file, IntPtr pidl, IShellFolder item)
{
bool CS;
IntPtr hBmp = IntPtr.Zero;
IExtractImage extractImage = null;
try
{
if (Path.GetFileName(PathFromPidl(pidl)).ToUpper().Equals(Path.GetFileName(file).ToUpper()))
{
int prgf;
IUnknown iunk = null;
Guid iidExtractImage = new Guid(“BB2E617C-0920-11d1-9A0B-00C04FC2D6C1″);
item.GetUIObjectOf(IntPtr.Zero, 1, ref pidl, ref iidExtractImage, out prgf, ref iunk);
extractImage = (IExtractImage)iunk;
if (extractImage != null)
{
SIZE sz = new SIZE
{
cx = this.desiredSize.Width,
cy = this.desiredSize.Height
};
StringBuilder location = new StringBuilder(260, 260);
int priority = 0;
int requestedColourDepth = 0×20;
EIEIFLAG flags = EIEIFLAG.IEIFLAG_SCREEN | EIEIFLAG.IEIFLAG_ASPECT;
int uFlags = (int)flags;
extractImage.GetLocation(location, location.Capacity, ref priority, ref sz, requestedColourDepth, ref uFlags);
extractImage.Extract(out hBmp);
if (hBmp != IntPtr.Zero)
{
this.thumbnail = Image.FromHbitmap(hBmp);
}
Marshal.ReleaseComObject(extractImage);
extractImage = null;
}
return true;
}
CS = false;
}
catch (Exception)
{
if (hBmp != IntPtr.Zero)
{
UnManagedMethods.DeleteObject(hBmp);
}
if (extractImage != null)
{
Marshal.ReleaseComObject(extractImage);
}
throw;
}
return CS;
}
public Bitmap GetThumbNail(string file)
{
if (!File.Exists(file) && !Directory.Exists(file))
{
throw new FileNotFoundException(string.Format(“The file ‘{0}’ does not exist”, file), file);
}
if (this.thumbnail != null)
{
this.thumbnail.Dispose();
this.thumbnail = null;
}
IShellFolder folder = getDesktopFolder;
if (folder != null)
{
IntPtr pidlMain;
try
{
int cParsed;
int pdwAttrib;
string filePath = Path.GetDirectoryName(file);
folder.ParseDisplayName(IntPtr.Zero, IntPtr.Zero, filePath, out cParsed, out pidlMain, out pdwAttrib);
}
catch (Exception)
{
Marshal.ReleaseComObject(folder);
throw;
}
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)
{
Marshal.ReleaseComObject(folder);
this.Allocator.Free(pidlMain);
throw;
}
if (item != null)
{
IEnumIDList idEnum = null;
try
{
item.EnumObjects(IntPtr.Zero, ESHCONTF.SHCONTF_NONFOLDERS | ESHCONTF.SHCONTF_FOLDERS, ref idEnum);
}
catch (Exception)
{
Marshal.ReleaseComObject(folder);
this.Allocator.Free(pidlMain);
throw;
}
if (idEnum != null)
{
IntPtr pidl = IntPtr.Zero;
bool complete = false;
while (!complete)
{
int fetched;
if (idEnum.Next(1, ref pidl, out fetched) != 0)
{
pidl = IntPtr.Zero;
complete = true;
}
else if (this.getThumbNail(file, pidl, item))
{
complete = true;
}
if (pidl != IntPtr.Zero)
{
this.Allocator.Free(pidl);
}
}
Marshal.ReleaseComObject(idEnum);
}
Marshal.ReleaseComObject(item);
}
this.Allocator.Free(pidlMain);
}
Marshal.ReleaseComObject(folder);
}
return this.thumbnail;
}
private static string PathFromPidl(IntPtr pidl)
{
StringBuilder path = new StringBuilder(260, 260);
if (UnManagedMethods.SHGetPathFromIDList(pidl, path) != 0)
{
return path.ToString();
}
return string.Empty;
}
// Properties
#region Properties
private IMalloc Allocator
{
get
{
if (!this.disposed && (this.alloc == null))
{
UnManagedMethods.SHGetMalloc(out this.alloc);
}
return this.alloc;
}
}
public Size DesiredSize
{
get
{
return this.desiredSize;
}
set
{
this.desiredSize = value;
}
}
public Bitmap ThumbNail
{
get
{
return this.thumbnail;
}
}
private static IShellFolder getDesktopFolder
{
get
{
IShellFolder ppshf;
UnManagedMethods.SHGetDesktopFolder(out ppshf);
return ppshf;
}
}
#endregion
#region COMDefinitions
// Nested Types
private enum EIEIFLAG
{
IEIFLAG_ASPECT = 4,
IEIFLAG_ASYNC = 1,
IEIFLAG_CACHE = 2,
IEIFLAG_GLEAM = 0×10,
IEIFLAG_NOBORDER = 0×100,
IEIFLAG_NOSTAMP = 0×80,
IEIFLAG_OFFLINE = 8,
IEIFLAG_ORIGSIZE = 0×40,
IEIFLAG_QUALITY = 0×200,
IEIFLAG_SCREEN = 0×20
}
[Flags]
private enum ESFGAO
{
SFGAO_CANCOPY = 1,
SFGAO_CANDELETE = 0×20,
SFGAO_CANLINK = 4,
SFGAO_CANMOVE = 2,
SFGAO_CANRENAME = 0×10,
SFGAO_CAPABILITYMASK = 0×177,
SFGAO_COMPRESSED = 0×4000000,
SFGAO_CONTENTSMASK = -2147483648,
SFGAO_DISPLAYATTRMASK = 0xf0000,
SFGAO_DROPTARGET = 0×100,
SFGAO_FILESYSANCESTOR = 0×10000000,
SFGAO_FILESYSTEM = 0×40000000,
SFGAO_FOLDER = 0×20000000,
SFGAO_GHOSTED = 0×80000,
SFGAO_HASPROPSHEET = 0×40,
SFGAO_HASSUBFOLDER = -2147483648,
SFGAO_LINK = 0×10000,
SFGAO_READONLY = 0×40000,
SFGAO_REMOVABLE = 0×2000000,
SFGAO_SHARE = 0×20000,
SFGAO_VALIDATE = 0×1000000
}
[Flags]
private enum ESHCONTF
{
SHCONTF_FOLDERS = 0×20,
SHCONTF_INCLUDEHIDDEN = 0×80,
SHCONTF_NONFOLDERS = 0×40
}
[Flags]
private enum ESHGDN
{
SHGDN_FORADDRESSBAR = 0×4000,
SHGDN_FORPARSING = 0×8000,
SHGDN_INFOLDER = 1,
SHGDN_NORMAL = 0
}
[Flags]
private enum ESTRRET
{
STRRET_WSTR,
STRRET_OFFSET,
STRRET_CSTR
}
[ComImport, Guid("000214F2-0000-0000-C000-000000000046"), InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
private interface IEnumIDList
{
[PreserveSig]
int Next(int celt, ref IntPtr rgelt, out int pceltFetched);
void Skip(int celt);
void Reset();
void Clone(ref ThumbnailCreator.IEnumIDList ppenum);
}
[ComImport, InterfaceType(ComInterfaceType.InterfaceIsIUnknown), Guid("BB2E617C-0920-11d1-9A0B-00C04FC2D6C1")]
private interface IExtractImage
{
void GetLocation([Out, MarshalAs(UnmanagedType.LPWStr)] StringBuilder pszPathBuffer, int cch, ref int pdwPriority, ref ThumbnailCreator.SIZE prgSize, int dwRecClrDepth, ref int pdwFlags);
void Extract(out IntPtr phBmpThumbnail);
}
[ComImport, Guid("00000002-0000-0000-C000-000000000046"), InterfaceType(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();
}
[ComImport, InterfaceType(ComInterfaceType.InterfaceIsIUnknown), Guid("000214E6-0000-0000-C000-000000000046")]
private interface IShellFolder
{
void ParseDisplayName(IntPtr hwndOwner, IntPtr pbcReserved, [MarshalAs(UnmanagedType.LPWStr)] string lpszDisplayName, out int pchEaten, out IntPtr ppidl, out int pdwAttributes);
void EnumObjects(IntPtr hwndOwner, [MarshalAs(UnmanagedType.U4)] ThumbnailCreator.ESHCONTF grfFlags, ref ThumbnailCreator.IEnumIDList ppenumIDList);
void BindToObject(IntPtr pidl, IntPtr pbcReserved, ref Guid riid, ref ThumbnailCreator.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 ThumbnailCreator.ESFGAO rgfInOut);
void GetUIObjectOf(IntPtr hwndOwner, int cidl, ref IntPtr apidl, ref Guid riid, out int prgfInOut, ref ThumbnailCreator.IUnknown ppvOut);
void GetDisplayNameOf(IntPtr pidl, [MarshalAs(UnmanagedType.U4)] ThumbnailCreator.ESHGDN uFlags, ref ThumbnailCreator.STRRET_CSTR lpName);
void SetNameOf(IntPtr hwndOwner, IntPtr pidl, [MarshalAs(UnmanagedType.LPWStr)] string lpszName, [MarshalAs(UnmanagedType.U4)] ThumbnailCreator.ESHCONTF uFlags, ref IntPtr ppidlOut);
}
[ComImport, InterfaceType(ComInterfaceType.InterfaceIsIUnknown), Guid("00000000-0000-0000-C000-000000000046")]
private interface IUnknown
{
[PreserveSig]
IntPtr QueryInterface(ref Guid riid, out IntPtr pVoid);
[PreserveSig]
IntPtr AddRef();
[PreserveSig]
IntPtr Release();
}
[StructLayout(LayoutKind.Sequential)]
private struct SIZE
{
public int cx;
public int cy;
}
[StructLayout(LayoutKind.Explicit, CharSet = CharSet.Auto)]
private struct STRRET_ANY
{
// Fields
[FieldOffset(4)]
public IntPtr pOLEString;
[FieldOffset(0)]
public ThumbnailCreator.ESTRRET uType;
}
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Auto, Pack = 4)]
private struct STRRET_CSTR
{
public ThumbnailCreator.ESTRRET uType;
[MarshalAs(UnmanagedType.ByValArray, SizeConst = 520)]
public byte[] cStr;
}
private class UnManagedMethods
{
// Methods
[DllImport("gdi32", CharSet = CharSet.Auto)]
internal static extern int DeleteObject(IntPtr hObject);
[DllImport("shell32", CharSet = CharSet.Auto)]
internal static extern int SHGetDesktopFolder(out ThumbnailCreator.IShellFolder ppshf);
[DllImport("shell32", CharSet = CharSet.Auto)]
internal static extern int SHGetMalloc(out ThumbnailCreator.IMalloc ppMalloc);
[DllImport("shell32", CharSet = CharSet.Auto)]
internal static extern int SHGetPathFromIDList(IntPtr pidl, StringBuilder pszPath);
}
#endregion
}
}
. Anyway, if I can find some time, I can take a look at this problem.
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