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Re: Re: Can nobody help me? Re: selecting a column in a grid

  • To: mathgroup at smc.vnet.net
  • Subject: [mg98345] Re: [mg98312] Re: Can nobody help me? Re: selecting a column in a grid
  • From: "Sjoerd C. de Vries" <sjoerd.c.devries at gmail.com>
  • Date: Mon, 6 Apr 2009 05:04:29 -0400 (EDT)
  • References: <gr6c5c$ppo$1@smc.vnet.net> <200904051040.GAA02679@smc.vnet.net> <FDB93FBE969041DF852D4FEBE63716A4@paulspc>

Paul,

I wouldn't have thought my little program was that difficult to understand. 

If you'd follow the code closely you'd see that it generates a table of
event handlers. Each event handler is wrapped around a piece of styled data.


I've also wrapped a DynamicModule around every table entry, which causes the
variable pos to be localized. If you examine the start of the module you can
see that it is initializes pos with the value {i,j}, i.e. the values of the
indices which are use to build up the table. 

Therefore, each event handler in each table cell has its own value of pos
and this is the reason it knows its own position in the table.

To address your other questions:

myData = {{aasdfpppppppppppp, bbbbbbbbb, c}, {dasdf, "", f}, {gasdf, 
    h, i}};
Dynamic[clickpos]
longest = 
  Select[#, 
     Function[{x}, 
      Composition [StringLength, ToString][x] == 
       Max[Composition [StringLength, ToString] /@ #]], 
     1] & /@ (myData\[Transpose]);
Grid[
 Table[
  DynamicModule[{col = White, pos = {i, j}},
   EventHandler[
    Graphics[
     {
      Text[longest[[j, 1]] // Invisible],
      Text[myData[[i, j]]]
      },
     Background -> Dynamic[col],
     ImageSize -> {Automatic, 14}
     ],
    {"MouseDown" :> (clickpos = pos; col = Red), 
     "MouseUp" :> (col = White)}
    ]
   ], {i, Length[myData]}, {j, Length[myData[[1]]]}
  ], Frame -> All, 
 BaseStyle -> {Editable -> False, Selectable -> False}
 ]

Cheers -- Sjoerd



> -----Original Message-----
> From: Paul Ellsmore [mailto:paul.ellsmore at nanion.co.uk]
> Sent: 05 April 2009 16:44
> To: 'Sjoerd C. de Vries'
> Cc: mathgroup at smc.vnet.net
> Subject: RE: [mg98312] Re: Can nobody help me? Re: selecting a column
> in a grid
> 
> Thanks Sjoerd,
> 
> Unfortunately, this approach has a problem for me, and I have to admit
> I
> don't know why it works at all!
> 
> The following example shows my problem (I think I have adapted your
> code to
> use a user-defined list of data properly):
> myData = {{aasdfpppppppppppp, bbbbbbbbb, c}, {dasdf, "", f},
>        {gasdf, h, i}};
> Dynamic[clickpos]
> Grid[Table[DynamicModule[{col = Black, pos = {i, j}},
>        EventHandler[Style[myData[[i, j]], FontColor -> Dynamic[col]],
>          {"MouseDown" :> (clickpos = pos; col = Red),
>            "MouseUp" :> (col = Black)}]], {i, 3}, {j, 3}],
>  Frame -> All,
>    BaseStyle -> {Editable -> False, Selectable -> False}]
> 
> In the grid that results, the cell selection only works if the mouse is
> clicked inside the text in the cell, not in any whitespace, and the
> empty
> cell cannot be selected at all. This is a problem for me. But how does
> it
> work anyway? Eventhandler seems to be wrapped around the cell contents,
> rather than the cell itself, but why is there a dynamic value of {i,j}
> associated with the cell? I assume that it is something to do with the
> fact
> that pos is defined within Dynamic, but how does the code know what
> value of
> {i,j} is associated with each block of displayed text? Is this some
> normal
> behaviour of Table that I was not aware of, and where would I look to
> find
> more information about this behaviour? More to the point, is there a
> way of
> forcing each CELL to take the value of {i,j}, because this would solve
> my
> problem instantly?
> 
> Incidentally, if you double-click in the empty cell, the whole table
> goes
> blue - why is that?
> 
> Many thanks, but I still cannot believe that such a simple task is
> proving
> to be so complicated.
> 
> Cheers,
> 
> Paul.
> 
> -----Original Message-----
> From: Sjoerd C. de Vries [mailto:sjoerd.c.devries at gmail.com]
> Sent: 05 April 2009 11:40
> To: mathgroup at smc.vnet.net
> Subject: [mg98312] Re: Can nobody help me? Re: selecting a column in a
> grid
> 
> Hi Paul,
> 
> Cool down ;-) Try this for inspiration:
> 
> Dynamic[clickpos]
> Grid[
>  Table[
>   DynamicModule[
>    {col=Black, pos = {i, j}},
>    EventHandler[
>     Style[RandomInteger[{0, 1000000}], FontColor -> Dynamic[col]],
>     {"MouseDown" :> (clickpos = pos; col = Red),
>      "MouseUp" :> (col = Black)}
>     ]
>    ], {i, 5}, {j, 5}]
>  ]
> 
> Cheers -- Sjoerd
> 
> On Apr 4, 3:12 am, "Paul Ellsmore" <paul.ellsm... at nanion.co.uk> wrote:
> > The key point in this problem is that the columns are not equal
> widths, a=
> nd
> > in fact are variable width, depending on the particular data
> displayed. S=
> o I
> > set ItemSize to automatic, so that each column width is defined by
> the da=
> ta.
> > The trouble is that MousePosition gives me coordinates that are a
> linear
> > function of the position in the grid, but the columns are not
> linearly
> > spaced in the Grid, so how do I know which column the mouse is in?
> >
> > I need one of three things, all three of which are beyond my skills:
> >
> > 1) I could get the actual values that ItemSize is set to when
> Automatic i=
> s
> > used. CurrentValue[ItemSize] doesn't work. Anyone got an alternative?
> > 2) I could calculate what values ItemSize will be set to by looking
> at th=
> e
> > type and  number of characters in each grid cell, knowing the font
> size=
> ,
> > font family, cell margins, frame linewidth etc. But I don't have
> access t=
> o
> > the information needed - how many pixels does a Courier Size 10 "n"
> take =
> up?
> > 3) I could use EventHandler in a better way. Currently I wrap it
> around t=
> he
> > whole Grid, but if I could wrap it around a cell, that would work for
> me.=
>  No
> > syntax that I have tried works - should I try using GridBox, or is
> there =
> an
> > obvious better idea?
> >
> > Nobody got any ideas at all? What kind of language is this, where you
> can=
> 't
> > even select a column in a table?
> >
> > Cheers,
> >
> > Paul.
> >
> > -----Original Message-----
> > From: Paul Ellsmore [mailto:paul.ellsm... at nanion.co.uk]
> > Sent: 01 April 2009 11:55
> > Subject:  selecting a column in a grid
> >
> > Hi,
> >
> > I have a tricky problem with a graphical user interface. I have a
> grid of
> > data, and I want to be able to MouseClick in the grid to either
> select a =
> row
> > or a column. Using GUIKit, this is trivial, but I want to be able to
> > distribute my program using PlayerPro, which won't support GUIKit.
> >
> > Selecting a row is straightforward using EventHandler and
> > EventHandlerScaled, since I know how many rows there are and they are
> all
> > one line in height. However, the column widths change according to
> the da=
> ta,
> > since I have set ItemSize to Auto. So is there some way of retrieving
> the
> > actual values used in ItemSize, when Auto is used? I have tried
> > CurrentValue[ItemSize] in many variations, but it always fails.
> >
> > I could, of course, look at the data that will be in the grid, and
> comput=
> e
> > the widths of each column accordingly, and synthesize the values that
> > ItemSize will take. To do that, though, I would need to know what the
> pix=
> el
> > width of a particular text string will be, which varies with font
> family,
> > size etc. Is there an easy way to do this? This is essentially what
> > Mathematica does when ItemSize is set to Auto, but I have no idea how
> to =
> do
> > it myself.
> >
> > Currently I have EventHandler wrapped around the whole grid. Is it
> possib=
> le
> > to wrap it around each individual cell in a grid? I have tried a few
> idea=
> s,
> > but they don't seem to work. The documentation suggests that
> EventHandler
> > can be wrapped around any expression, but that doesn't seem to be the
> cas=
> e,
> > or at least the wrapped expression doesn't seem to display properly
> insid=
> e
> > other constructs, such as Grid, Column etc.
> >
> > Is there some better approach I could take, rather than using
> EventHandle=
> r?
> >
> > All ideas gratefully received.
> >
> > Cheers,
> >
> > Paul.
> >
> > Dr. Paul A. Ellsmore
> >
> > Nanion Limited
> >
> > Oxford Centre for Innovation
> >
> > Mill Street
> >
> > Oxford
> >
> > United Kingdom
> >
> > OX2 0JX
> >
> > Tel: +44 (0) 1865 811175
> >
> > Fax: +44 (0) 1865 248594




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