Add extra columns when converting text to table in Writer

[Lodev]

Hi,


We're trying to implement a new feature in Writer.  When converting text 
to table in Writer, users here want to add additional columns so that 
they don't need to manually add it after creating.

We've implemented the Convert Text To Table dialog, adding a spin button 
to let users choose how many columns they want to add, and fill the 
selected value in SwConvertTableDlg::GetValues() in 
sw/source/ui/table/convert.cxx.  We also add a new variable in 
SwInsertTableOptions (sw/inc/itabenum.hxx) .

We also found that (hope it's correct) the core implementation might be 
in SwNodes::TextToTable() in sw/source/core/docnode/ndtbl.cxx.  We knew 
that the for loop

     for( nLines = 0, nBoxes = 0;
         aSttIdx.GetIndex() < aEndIdx.GetIndex();
         aSttIdx += SwNodeOffset(2), nLines++, nBoxes = 0 )

is the main implementation that creates the table from the text. Each 
row of the table was done created after this:

         pBox = new SwTableBox( pBoxFormat, *pSttNd, pLine );
         pLine->GetTabBoxes().insert( pLine->GetTabBoxes().begin() + 
nBoxes++, pBox );
         if( nMaxBoxes < nBoxes )
             nMaxBoxes = nBoxes;

So we tried to add empty columns, but so far couldn't get it right.  The 
copilot on Github told us that we should create a start node, an empty 
text node, and an end node and insert it to the end of the row.  But it 
kept giving us illusion code.  Either methods that don't exist, or type 
that can't be converted, and when we got it compiled successfully, it 
kept crashing at

SwTableBox(pBoxFormat, *pSttNd, pLine);

with a message (in console) telling us that "In which table is the box?"

Could anyone please give us some instructions and hints about what we 
should do if we want to add (a certain number of) empty cells after each 
row?


Thanks for your help.

Lodev