[Gtk2hs-users] Trying to find / report a bug or two

[Brett G. G. <gi...@cp...>]

Hi Axel, Duncan, et. al.

I tried going to Trac to look at the bug list to see if some issues I'm
having were reported. However, the reports give me a "Maximum recursion
limit exceeded error" and then python spews its traceback.  (If you
like, I can include that for you)

(Long bug related stuff below....)

The search didn't seem to find anything relevant.

The first is to do with layoutGetPixelExtents.

I've had to do the following:

getTextExtent :: PangoLayout -> String ->
                 IO (Int,Int)
getTextExtent playout txt 
    = do playout `layoutSetText` (hackMinusToSpace txt)
         (Rectangle xl yl wl hl, Rectangle x y w h) <-
layoutGetPixelExtents playout
         let ext = (abs (w-x) ,abs (h-y))
         return ext

and 
hackMinusToSpace :: String -> String
hackMinusToSpace [] = []
hackMinusToSpace ('-':ss) = 'a':hackMinusToSpace ss
hackMinusToSpace (a:ss) = a:hackMinusToSpace ss

to get the correct size for text strings. It seems when a text string
contains '-', the values for wl and w go rather wonky - values like
290873 and such returned for 5-8 character strings. With the hack, life
is lovely.

Second has to do with TreeList / listStoreAppend...

Following one of the examples, I created a tree model with 
 -- create the tree model
createTreeAndStore = do
  mainView <- treeViewNew
  skel <- emptyListSkel
  
  let createTextColumn name = do
        (attr, _, set) <- listSkelAddAttribute skel cellText
        column <- newTreeViewColumn
        column `treeViewColumnSetTitle` name
        mainView `treeViewAppendColumn` column
        renderer <- treeViewColumnNewText column True True
        renderer `treeViewColumnAssociate` [attr]
        return set

  -- create the various columns in both the model and view
  setLineNo <- createTextColumn "Line"
  setIns    <- createTextColumn "Instruction"
  
  store <- newListStore skel
  mainView `treeViewSetModel` store
  return (mainView, store, setLineNo, setIns)

and then actually use that as:

setPageData :: [Instruction OurBasis] -> Int -> 
               IO TreeView
setPageData  ins ip
    = do (tv, store, setLineno, setIns) <- createTreeAndStore
         tv `treeViewSetHeadersVisible` True
         sel <- treeViewGetSelection tv
         sel `treeSelectionSetMode` SelectionNone
-- TODO - This inner loop seems to crash at random times. 
         mapM_ (\(ln, txt) -> 
                    do iter <- listStoreAppend store
                       setLineno iter ln 
                       setIns iter txt
                       return ()
                       ) $
                 zip (List.map show [ip..])  (List.map show ins)
         print " SPD: Created and returning tree model"
         return tv

As the TODO comment says - the inner loop just seems to crash sometimes.
These windows have anywhere from 5 - 500 lines. Longer ones seem to
crash more regularly.  I have changed this to just a big text box where
I format the output text with Text.Printf and I've not had a crash in
the last few weeks since I did that.  Any thoughts on this one?

Thanks

-- 
Brett G. Giles
Grad Student - Category Theory 
gi...@cp...
http://pages.cpsc.ucalgary.ca/~gilesb