问题
I need to implement an IFilter in Delphi 2010 that can search through Office 2007 docx files and return the text found in the document.
The ifilter also needs to use the IPersistStream interface.
Thanks
回答1:
You don't want to implement an IFilter to parse an Office 2007 docx. You want to use Microsoft's already written IFilter objects, so that you can learn the contents of a docx file.
Then you use standard IFilter mechanisms to parse the file contents:
procedure TForm1.ProcessFile(filename: string);
var
Filter: IFilter;
hr: HRESULT;
chunk: PSTAT_CHUNK;
// attr: FULLPROPSPEC;
flags: ULONG;
c: Cardinal;
buffer: WideString;
begin
Log('Processing "'+filename+'"');
Log('Calling LoadIFilter');
filter := LoadIFilter(filename);
if filter = nil then
begin
Log('filter is null; leaving');
Exit;
end;
try
Log('Calling filter.Init(IFILTER_INIT_INDEXING_ONLY)');
hr := filter.Init(IFILTER_INIT_INDEXING_ONLY, 0, nil, flags);
OleCheck(hr);
Log('Init returned sucessfully, looking for chunks...');
while True do
begin
New(chunk);
try
hr := filter.GetChunk(chunk);
if Failed(hr) then
begin
Log('No more chunks: '+IntToHex(hr, 8)+' ('+GetChunkHresultToStr(hr)+')');
Break;
end;
Log('== Got chunk. ChunkType='+IntToStr(chunk.flags)+' (1=text, 2=value) ==');
if (chunk.Flags and CHUNK_TEXT) = CHUNK_TEXT then
begin
c := 2048;
SetLength(buffer, c);
hr := filter.GetText(c, PWideChar(buffer));
if Succeeded(hr) then
begin
Log('=== Got text ===');
SetLength(buffer, c);
Log(buffer);
while Succeeded(hr) do
begin
c := 2048;
SetLength(buffer, c);
hr := filter.GetText(c, PWideChar(buffer));
if Succeeded(hr) then
begin
SetLength(buffer, c);
Log('==== Really long chunk, here''s the next 2048 characters ====');
Log(buffer);
end;
end;
end
else
begin
Log('Could not get text from chunk: '+IntToHex(hr, 8)+' ('+GetChunkHResultToStr(hr)+')');
Log(' It might be a "Value" chunk, meaning i should call filter.GetValue rather than filter.GetText. But i''m too lazy');
end;
end
else if (chunk.flags and CHUNK_VALUE) = CHUNK_VALUE then
begin
Log('This is a "VALUE" chunk. i''m not going to read anything out of it cause it''s too hard :(');
end
else
Log('Unknown chunk type');
finally
Dispose(chunk);
end;
end; //end while true getting chunks
finally
filter := nil;
end;
end;
Where Windows already provides the code that loads an IFilter for a specified filename:
function TForm1.LoadIFilter(const filename: WideString): IFilter;
var
hr: HRESULT;
unk: IUnknown;
begin
hr := ntQuery.LoadIFilter(PWideChar(filename), nil, unk);
OleCheck(hr);
Result := unk as IFilter;
end;
IFilter declarations unit:
unit Filter;
interface
uses
Windows, SysUtils, Classes, ActiveX;
type
IFILTER_INIT = TOleEnum;
const
IFILTER_INIT_CANON_PARAGRAPHS = 1;
IFILTER_INIT_HARD_LINE_BREAKS = 2;
IFILTER_INIT_CANON_HYPHENS = 4;
IFILTER_INIT_CANON_SPACES = 8;
IFILTER_INIT_APPLY_INDEX_ATTRIBUTES = 16;
IFILTER_INIT_APPLY_OTHER_ATTRIBUTES = 32;
IFILTER_INIT_INDEXING_ONLY = 64;
IFILTER_INIT_SEARCH_LINKS = 128;
type
IFILTER_FLAGS = TOleEnum;
const
IFILTER_FLAGS_OLE_PROPERTIES = 1;
type
CHUNKSTATE = TOleEnum;
const
CHUNK_TEXT = $01;
CHUNK_VALUE = $02;
type
CHUNK_BREAKTYPE = TOleEnum;
const
CHUNK_NO_BREAK = 0;
CHUNK_EOW = 1;
CHUNK_EOS = 2;
CHUNK_EOP = 3;
CHUNK_EOC = 4;
type
FILTERREGION = packed record
idChunk: ULONG;
cwcStart: ULONG;
cwcExtent: ULONG;
end;
tagFILTERREGION = FILTERREGION;
const
PRSPEC_LPWSTR = 0;
PRSPEC_PROPID = 1;
type
PROPID = ULONG;
type
PROPSPEC = packed record
ulKind: ULONG;
case integer of
0: (prid: PROPID);
1: (lpws: PWideChar);
end;
tagPROPSPEC = PROPSPEC;
type
FULLPROPSPEC = packed record
guidPropSet: TGUID;
psProperty: PROPSPEC;
end;
tagFULLPROPSPEC = FULLPROPSPEC;
PFULLPROPSPEC = ^FULLPROPSPEC;
type
STAT_CHUNK = packed record
idChunk: ULONG;
breakType: CHUNK_BREAKTYPE;
flags: CHUNKSTATE;
locale: LCID;
attribute: FULLPROPSPEC;
idChunkSource: ULONG;
cwcStartSource: ULONG;
cwcLenSource: ULONG;
end;
tagSTAT_CHUNK = STAT_CHUNK;
PSTAT_CHUNK = ^STAT_CHUNK;
// From filtererr.h
const
FILTER_E_END_OF_CHUNKS = HRESULT($80041700);
//
// MessageId: FILTER_E_NO_MORE_TEXT
//
// MessageText:
//
// No more text available in chunk.
//
const
FILTER_E_NO_MORE_TEXT = HRESULT($80041701);
//
// MessageId: FILTER_E_NO_MORE_VALUES
//
// MessageText:
//
// No more property values available in chunk.
//
const
FILTER_E_NO_MORE_VALUES = HRESULT($80041702);
//
// MessageId: FILTER_E_ACCESS
//
// MessageText:
//
// Unable to access object.
//
const
FILTER_E_ACCESS = HRESULT($80041703);
//
// MessageId: FILTER_W_MONIKER_CLIPPED
//
// MessageText:
//
// Moniker doesn't cover entire region.
//
const
FILTER_W_MONIKER_CLIPPED = HRESULT($80041704);
//
// MessageId: FILTER_E_NO_TEXT
//
// MessageText:
//
// No text in current chunk.
//
const
FILTER_E_NO_TEXT = HRESULT($80041705);
//
// MessageId: FILTER_E_NO_VALUES
//
// MessageText:
//
// No values in current chunk.
//
const
FILTER_E_NO_VALUES = HRESULT($80041706);
//
// MessageId: FILTER_E_EMBEDDING_UNAVAILABLE
//
// MessageText:
//
// Unable to bind IFilter for embedded object.
//
const
FILTER_E_EMBEDDING_UNAVAILABLE = HRESULT($80041707);
//
// MessageId: FILTER_E_LINK_UNAVAILABLE
//
// MessageText:
//
// Unable to bind IFilter for linked object.
//
const
FILTER_E_LINK_UNAVAILABLE = HRESULT($80041708);
//
// MessageId: FILTER_S_LAST_TEXT
//
// MessageText:
//
// This is the last text in the current chunk.
//
const
FILTER_S_LAST_TEXT = HRESULT($00041709);
//
// MessageId: FILTER_S_LAST_VALUES
//
// MessageText:
//
// This is the last value in the current chunk.
//
const
FILTER_S_LAST_VALUES = HRESULT($0004170A);
//
// MessageId: FILTER_E_PASSWORD
//
// MessageText:
//
// File was not filtered due to password protection.
//
const
FILTER_E_PASSWORD = HRESULT($8004170B);
//
// MessageId: FILTER_E_UNKNOWNFORMAT
//
// MessageText:
//
// The document format is not recognized by the flter.
//
const
FILTER_E_UNKNOWNFORMAT = HRESULT($8004170C);
const
IID_IFilter: TGUID = '{89BCB740-6119-101A-BCB7-00DD010655AF}';
type
IFilter = interface(IUnknown)
['{89BCB740-6119-101A-BCB7-00DD010655AF}']
function Init(grfFlags: ULONG; cAttributes: ULONG; aAttributes: PFULLPROPSPEC; out pFlags: ULONG): HResult; stdcall;
function GetChunk(pStat: PSTAT_CHUNK): HResult; stdcall;
function GetText(var pcwcBuffer: ULONG; awcBuffer: PWideChar): HResult; stdcall;
function GetValue(out ppPropValue: PROPVARIANT): HResult; stdcall;
function BindRegion(origPos: FILTERREGION; riid: TGUID; out ppUnk): HResult; stdcall;
end;
implementation
end.
回答2:
If you seek out the old Borland/CodeGear newsgroups, then you may find references to an IFilter implementation by "Soluciones Vulcano" which has reference to develop.shorterpath.com which still seems to exist. Beyond that, I've never seen any other implementation component, and I've not yet managed to look at it myself.
来源：https://stackoverflow.com/questions/3251935/delphi-ifilter-implementation