Re: Looking for help for clipboard in Math

Hi Michael,

and another report:

I found, what I did wrong. I had used GetTree() and not realized, that 
it does not only return a pointer but actually performs a "pop".
For text clipboard content I have followed your tip with SvMemoryStream 
and utl::OInputStreamWrapper.
So now I can import from clipboard, if the clipboard is of MIME type 
"application/mathml+xml" or if it is of type FORMAT_STRING and is 
actually a math-fragment.

But now I have this problem:
I start module Math with a fresh document, I write a formula into the 
command window (e.g. a^2+b^2) and then try to save as *.mml.
I get the errors cited below. I have not used any operations with the 
clipboard. A build from current trunk does not have this error, so it 
must be something, which I have introduced. But I do not know, what are 
possible causes and where to start.

Errormessages:

Locking problem.
Sharing violation while accessing the object.


Error: An error or a warning has occurred during XML import/export!
Error-Id: 0x60040004
    Flags: 6 ERRROR SEVERE
    Class: 4 API
    Number: 4
Parameters:
Exception-Message: io exception during writing
 From File 
c:/AOO_debugbuild_420/trunk/main/xmloff/source/core/xmlerror.cxx at Line 193

 Error: cached Sequence not written From File 
C:/AOO_debugbuild_420/trunk/main/sax/source/expatwrap/saxwriter.cxx at 
Line 164


Kind regards
Regina


Michael Stahl schrieb:
> On 06.06.2015 22:03, Regina Henschel wrote:
> > Hi Michael,
> >
> > thank-you for looking at my problems.
> >
> > Michael Stahl schrieb:
> > > On 05.06.2015 01:44, Regina Henschel wrote:
> > > > Hi all,
> > > >
> > > > I struggle with the clipboard. My goal is to import MathML in module
> > > > Math from clipboard, similar as it is imported from file. But I'm stuck.
> > > > Therefore some questions:
> > [skipped a lot of text]
> >
> > Helpful comments. Looking around I think, the connection to the OS is
> > done in /main/dtrans/source/win32/
> >
> > I have found the table m_TranslTable, which refers the SOT_FORMATSTR_IDs
> > from exchange.cxx. I'll try what happens, when I add the MathML format
> > there too. I had already added it in exchange.cxx, but that was not
> > enough to be recognized. [I need some time for that. I will report back,
> > when I have finished.]
>
> that sounds plausible.
>
> > > > (5)
> > > > I try to use SmViewShell::InsertFrom(SfxMedium &rMedium). It seems to
> > > > work, but when the process arrives at SmXMLImport::endDocument(void),
> > > > the node tree is empty.  Any tips, what I might have missed?
> > >
> > > how do you prepare the SfxMedium?  i'm not sure if it requires an actual
> > > file, or if it can read from an input stream (XInputStream); it probably
> > > can't read from a Sequence<sal_Int8> buffer directly...
> > >
> > > there is a SfxMedium::setStreamToLoadFrom() which looks promising.
> >
> > I have used:
> >
> > TransferableDataHelper aDataHelper(
> > TransferableDataHelper::CreateFromSystemClipboard(GetEditWindow()) );
> > uno::Reference < io::XInputStream > xStrm;
> > aDataHelper.GetInputStream( nId, xStrm );
> > SfxMedium* pClipboardMedium = new SfxMedium();
> > SfxMedium aClipboardMedium = *pClipboardMedium;
>
> this is probably not a good idea: the aClipboardMedium is now a copy of
> pClipboardMedium (using the copy-constructor), so any modification to
> aClipboardMedium will not be visible if you use pClipboardMedium.
>
> if you need a pointer, better do it the other way around, and use "&
> aClipbardMedium" when needed.
>
> > aClipboardMedium.setStreamToLoadFrom( xStrm, sal_True /*bIsReadOnly*/ );
> > InsertFrom(aClipboardMedium);
>
> oh, nice, the TransferableDataHelper can already get you a stream.
>
> > When I then proof it with
> >
> > SvStream* pStream = aClipboardMedium.GetInStream();
> > ...
> > sal_uLong nBytesRead = pStream->Read( aBuffer, nBufferSize );
> > printf("%s \n", aBuffer);
> >
> > I can see, that the stream contains the expected MathML-source in case
> > the clipboard viewer lists the clipboard format "application/mathml+xml".
>
> ok, so we can read the data.
>
> do you re-wind the stream with Seek() after this debug output?  perhaps
> the import filter reads from the current position, which is going to be
> in the middle or at the end of the stream after this.
>
> > In addition I have set the filter by
> >
> > const SfxFilter* pMathFilter = SfxFilter::GetFilterByName(
> > String::CreateFromAscii(MATHML_XML) );
> > aClipboardMedium.SetFilter(pMathFilter);
> >
> > so that
> >
> > if ( rFltName.EqualsAscii(MATHML_XML) )
> >
> > in InsertFrom becomes true
>
> it looks like SmXMLImportWrapper is using the usual xmloff XML-parsing
> stuff.
>
> so i would try to check if the root element of the MathML document is
> being recognized; set a breakpoint or add a SAL_DEBUG output in the
> right CreateChildContext() method...
>
> this is apparently SmXMLImport::CreateContext() - which should create a
> SmXMLDocContext_Impl, since there's not going to be a "office" namespace.
>
> most of the work is going on in the CreateChildContext() and
> EndElement() overrides in various child classes of SmXMLImportContext;
> basically xmloff maintains a stack of contexts, one for each currently
> open XML element; it then calls StartElement() / CreateChildContext() /
> EndElement() etc. on the context that is on top of the stack.
>
> this means it's quite annoying to step through the import with a
> debugger, since a lot of it is various abstraction layers that are not
> very interesting but you still have to step through them; it's best to
> set breakpoints in the "interesting" places and only start stepping into
> the lower layers as a last resort if you have no idea why the
> interesting place is not reached.
>
> > > you can create an input stream from the buffer via SvMemoryStream and
> > > then wrap that in utl::OInputStreamWrapper.
> >
> > You mean, it will be possible to use the "Unicode-Text"? That would
> > help, when copying from Websites. But first I need to solve the problem,
> > that I get no node-tree, and the problem to detect the clipboard correctly.
>
> no, i meant how to convert the clipboard Sequence<sal_Int8> to an input
> stream, but i missed that TransferableDataHelper::GetInputStream()
> already does this for you :)
>
>
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