以编程方式清理 Windows 缩略图缓存

Question

我正在编写一个为 Windows 文件夹创建缩略图图标的程序。我想为用户提供一种简单的方法来刷新他们的缩略图缓存。

是否可以通过任何 Windows API 来做到这一点？理想情况下在 C# 中，但更有可能通过包装一些 C++。

如果没有，是否有一种经过批准的方法来确定用户缩略图缓存的位置并手动删除它们。还是最好只启动cleanmgr 并让用户从那里执行？

Answer 1

您可以为 Window 缩略图清理器扩展创建一个主机，该扩展将模拟 cleanmgr 工具。

type
  TThumbnailCleanerCallBack = class(TInterfacedObject, IEmptyVolumeCacheCallBack)
  private
    function ScanProgress(dwlSpaceUsed: UInt64; dwFlags: DWORD; pcwszStatus: LPCWSTR): HRESULT; stdcall;
    function PurgeProgress(dwlSpaceFreed, dwlSpaceToFree: UInt64; dwFlags: DWORD; pcwszStatus: LPCWSTR): HRESULT; stdcall;
  end;

function TThumbnailCleanerCallBack.ScanProgress(dwlSpaceUsed: UInt64; dwFlags: DWORD; pcwszStatus: LPCWSTR): HRESULT;
begin
  Result := S_OK;
end;

function TThumbnailCleanerCallBack.PurgeProgress(dwlSpaceFreed, dwlSpaceToFree: UInt64; dwFlags: DWORD; pcwszStatus: LPCWSTR): HRESULT;
begin
  Result := S_OK;
end;

procedure CleanThumbnailCache;
const
  ThumbnailCleanerCLSID: TGUID = '{889900c3-59f3-4c2f-ae21-a409ea01e605}';
var
  Drives: DWORD;
  Drive: DWORD;
  Letter: Char;
  ThumbnailCleaner: IEmptyVolumeCache;
  Key: HKEY;
  DisplayName: PWideChar;
  Description: PWideChar;
  Flags: DWORD;
  ThumbnailCleanerCallBack: TThumbnailCleanerCallBack;
begin
  Drives := GetLogicalDrives;
  Drive := 1;
  for Letter := 'A' to 'Z' do
    begin
      if Drives and Drive <> 0 then
        begin
          OleCheck(CoCreateInstance(ThumbnailCleanerCLSID, nil, CLSCTX_INPROC_SERVER or CLSCTX_LOCAL_SERVER, IUnknown, ThumbnailCleaner));
          try
            RegOpenKeyEx(HKEY_LOCAL_MACHINE, PWideChar('SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\VolumeCaches\Thumbnail Cache'), 0, KEY_READ, Key);
            try
              DisplayName := nil;
              Description := nil;
              Flags := EVCF_SETTINGSMODE;
              OleCheck(ThumbnailCleaner.Initialize(Key, PWideChar(Letter + ':\'), DisplayName, Description, Flags));
              try
                if Assigned(DisplayName) then CoTaskMemFree(DisplayName);
                if Assigned(Description) then CoTaskMemFree(Description);
                ThumbnailCleanerCallBack := TThumbnailCleanerCallBack.Create;
                OleCheck(ThumbnailCleaner.Purge(UInt64(-1), ThumbnailCleanerCallBack));
              finally
                Flags := 0;
                OleCheck(ThumbnailCleaner.Deactivate(Flags));
              end;
            finally
              RegCloseKey(Key);
            end;
          finally
            ThumbnailCleaner := nil;
          end;
        end;
      Drive := Drive shl 1;
    end;
end;