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When using the "grid" geometry manager in a Tk application to place a number of, say, buttons it can be a little confusing when the number of widgets is not an exact multiple of the number of rows or columns constraining the layout. I came up with a small module that calculates the "x" and "y" for each widget, returning a ref to an AoA of widget positions. Here is the module:-

# Module to calculate item positions for the Tk Grid geometry # manager, returning the results as an anonymous AoA such that the # data structure represents [ [ item 0 row, item0 column ], [ item 1 # row, item 1 column ] ... [ item n row, item n column ] ]. The Grid # geometry manager numbers rows and columns from zero. # # Subroutine references are only created for fitting elements to a # number of columns. When fitting to rows the same routines can be # used but each pair of elements, "x" and "y" if you will, have to # be reversed, see the two fitToRows.....() subroutines below. # # When arranging items to fit a certain number of columns and the # items are ordered along the rows the algorithm is simple, keep # filling rows until you run out of items, the last row might be # short but that's fine. # # However, things get more complicated when fitting to columns and the # order is down the columns as well. Just filling columns until you # run out of items no longer works in all cases. For example, if we # want to fit nine items to four columns we will need three rows (two # times four is only eight) but filling columns willy-nilly means we # run out of items before we get to the fourth column, leaving it # empty. Instead we have to calculate how many columns will be full # ones from items modulo columns, the number of rows being the # truncated division of items by columns, with one row added if the # modulo was positive. # # ========== package GridLayout; # ========== use strict; use warnings; # Only integer maths required. # use integer; # Set up Exporter to make subroutines available. # use Exporter qw{ import }; our @EXPORT_OK = qw{ fitToColsHSort fitToColsVSort fitToRowsHSort fitToRowsVSort }; our %EXPORT_TAGS = ( ALL => [ @EXPORT_OK ], ); # Subroutine to calculate grid positions of elements that are to be # fitted to a number of columns with the element order sorted # vertically. # # ----------------- my $rcColsSortAligned = sub # ----------------- { # Get number of items and number of columns to fit them to then #initialise the anonymous AoA tha will be returned. # my( $nItems, $colsToFit ) = @_; my $raOrder = []; # Calculate the number of rows required; we are using integer # arithmetic so dividing number of items by number of columns # gives an "at least" number for rows. However, if number of # items modulo number of columns is positive then we need # another row which will contain that number of full columns # with the remaining columns being one item shorter. If not, al +l # columns are full so set number of full columns to match colum +ns # to fit. # my $nRows = $nItems / $colsToFit; my $nFullCols = $nItems % $colsToFit; $nRows ++ if $nFullCols; $nFullCols ||= $colsToFit; # Populate the columns that are full, looping row within column +. # foreach my $col ( 0 .. $nFullCols - 1 ) { foreach my $row ( 0 .. $nRows - 1 ) { push @{ $raOrder }, [ $row, $col ]; } } # If all columns are full columns then we are done, return the # anonymous AoA. # return $raOrder if $nFullCols == $colsToFit; # For the remaining columns populate all but the last row. Loop # row within column again. # foreach my $col ( $nFullCols .. $colsToFit - 1 ) { foreach my $row ( 0 .. $nRows - 2 ) { push @{ $raOrder }, [ $row, $col ]; } } # Now all columns are populated we can return the anonymous AoA +. # return $raOrder; }; # Subroutine to calculate grid positions of elements that are to be # fitted to a number of columns with the element order sorted # horizontally. # # ----------------- my $rcColsSortOpposed = sub # ----------------- { # Get number of items and number of columns to fit them to then #initialise the anonymous AoA that will be returned. # my( $nItems, $colsToFit ) = @_; my $raOrder = []; # When fitting items to, say, four columns the row number will # be the truncated integer division of item number by number of # columns. So, items 0, 1, 2 and 3 go into row 0, then 4, 5, 6 # and 7 into row 1 etc. The column position is simply the item # number modulo the number of columns, cycling 0, 1, 2, 3, 0, 1 +, # 2, 3 etc. # foreach my $item ( 0 .. ( $nItems - 1 ) ) { push @{ $raOrder }, [ $item / $colsToFit, $item % $colsToFit ]; } # Now all columns are populated we can return the anonymous AoA +. # return $raOrder; }; # Exported subroutines # ==================== # # Fit $nItems items into $nCols columns with items ordered along # the rows. # # -------------- sub fitToColsHSort # -------------- { my( $nItems, $nCols ) = @_; # We are fitting to columns so the anonymous AoA returned by # $rcColsSortOpposed->() is all that's needed. # return $rcColsSortOpposed->( $nItems, $nCols ); } # Fit $nItems items into $nCols columns with items ordered down # the columns. # # -------------- sub fitToColsVSort # -------------- { my( $nItems, $nCols ) = @_; # We are fitting to columns so the anonymous AoA returned by # $rcColsSortAligned->() is all that's needed. # return $rcColsSortAligned->( $nItems, $nCols ); } # Fit $nItems items into $nRows rows with items ordered along # the rows. # # -------------- sub fitToRowsHSort # -------------- { my( $nItems, $nRows ) = @_; # We are fitting to rows so the anonymous AoA returned by # $rcColsSortAligned->() has to be modified by swapping the # row and column values for each item. # return [ map { [ reverse @{ $_ } ] } @{ $rcColsSortAligned->( $nItems, $nRows ) } ]; } # Fit $nItems items into $nRows rows with items ordered down # the columns. # # -------------- sub fitToRowsVSort # -------------- { my( $nItems, $nRows ) = @_; # We are fitting to rows so the anonymous AoA returned by # $rcColsSortOpposed->() has to be modified by swapping the # row and column values for each item. # return [ map { [ reverse @{ $_ } ] } @{ $rcColsSortOpposed->( $nItems, $nRows ) } ]; } 1;

Here is a test script that demonstrates its use:-

#!/usr/bin/perl # use strict; use warnings; # Use Tk GUI widgets and GridLayout.pm module for calculating widget # positions for the "grid" geometry manager. # use Tk; use GridLayout qw{ :ALL }; # Set up constants for widget creation and the "pack" geometry manager +. # use constant { RIDGE => q{ridge}, FLAT => q{flat}, RAISED => q{raised}, Y => q{y}, LEFT => q{left}, RIGHT => q{right}, TOP => q{top}, BOTTOM => q{bottom}, }; # Set up some default GUI appearance options. # my $bgColour = q{LightSteelBlue3}; my %commonFrameOpts = ( -background => $bgColour, -relief => RIDGE, -borderwidth => 2, ); my %commonLabelOpts = ( -foreground => q{NavyBlue}, -background => q{LemonChiffon}, -relief => FLAT, -borderwidth => 2, -padx => 5, -pady => 5, ); my %commonButtonOpts = ( -background => q{grey35}, -foreground => q{yellow2}, -activebackground => q{grey45}, -activeforeground => q{yellow}, -disabledforeground => q{grey55}, ); my %commonRadioButtonOpts = ( -width => 6, -selectcolor => q{red}, -relief => RAISED, -borderwidth => 2, -padx => 5, -pady => 5, ); # Create non-resizeable main window and set title. # my $mainWin = MainWindow->new( -background => $bgColour, ); $mainWin->resizable( 0, 0 ); $mainWin->title( q{Fit columns and rows} ); # Get screen height in pixels and set the font size to suit the # resolution. # my $screenHeight = $mainWin->screenheight(); my $fontSize = 8; $fontSize = 10 if $screenHeight >= 1024; $fontSize = 12 if $screenHeight >= 1536; $mainWin->optionAdd( q{*font} => qq{courier $fontSize} ); # Default to arranging buttons by columns. Create a frame for the labe +l # and the buttons for choosing rows or columns. # my $rowsOrColumns = 1; my $rowColFrame = $mainWin->Frame( %commonFrameOpts, )->pack( -side => TOP, -fill => Y, -expand => 1, ); # Create label and associated text variable. # my $rsRowColText = \ do { my $dummy }; $rowColFrame->Label( %commonLabelOpts, -textvariable => $rsRowColText, )->pack( -side => TOP, ); # Create a flat-relief frame within the "rows/columns" frame for the # buttons making the choice. # my $chooseRowColFrame = $rowColFrame->Frame( %commonFrameOpts, -relief => FLAT, )->pack( -side => TOP, -fill => Y, -expand => 1, ); # Create the radiobuttons with the &arrangeButtons callback. # $chooseRowColFrame->Radiobutton( %commonRadioButtonOpts, -text => q{Rows}, -width => 7, -value => 0, -variable => \ $rowsOrColumns, -command => \ &arrangeButtons, )->pack( -side => LEFT, -padx => 5, -pady => 5, ); $chooseRowColFrame->Radiobutton( %commonRadioButtonOpts, -text => q{Columns}, -width => 7, -value => 1, -variable => \ $rowsOrColumns, -command => \ &arrangeButtons, )->pack( -side => LEFT, -padx => 5, -pady => 5, ); # Default to sorting buttons horizontally. Create a frame for the labe +l # and the buttons for choosing sort direction. # my $sortDirection = 0; my $directionFrame = $mainWin->Frame( %commonFrameOpts, )->pack( -side => TOP, -fill => Y, -expand => 1, ); # Create label and associated text variable. # my $rsDirectionText = \ do { my $dummy }; $directionFrame->Label( %commonLabelOpts, -textvariable => $rsDirectionText, )->pack( -side => TOP, ); # Create a flat-relief frame within the "horizontal/vertical" frame fo +r # the buttons making the choice. # my $chooseDirectionFrame = $directionFrame->Frame( %commonFrameOpts, -relief => FLAT, )->pack( -side => TOP, -fill => Y, -expand => 1, ); # Create the radiobuttons with the &arrangeButtons callback. # $chooseDirectionFrame->Radiobutton( %commonRadioButtonOpts, -text => q{Horizontal}, -width => 10, -value => 0, -variable => \ $sortDirection, -command => \ &arrangeButtons, )->pack( -side => LEFT, -padx => 5, -pady => 5, ); $chooseDirectionFrame->Radiobutton( %commonRadioButtonOpts, -text => q{Vertical}, -width => 10, -value => 1, -variable => \ $sortDirection, -command => \ &arrangeButtons, )->pack( -side => LEFT, -padx => 5, -pady => 5, ); # Default to arranging 9 buttons, prepare a frame to hold the buttons # that choose how many items to arrange. # my $numItems = 9; my $itemCountFrame = $mainWin->Frame( %commonFrameOpts, )->pack( -side => TOP, -fill => Y, -expand => 1, ); # Create label and associated text variable. # my $rsItemsText = \ do { my $dummy }; $itemCountFrame->Label( %commonLabelOpts, -textvariable => $rsItemsText, )->pack( -side => TOP, ); # Create a flat-relief frame within the "item count" frame for # the buttons making the choice. # my $chooseItemsFrame = $itemCountFrame->Frame( %commonFrameOpts, -relief => FLAT, )->pack( -side => TOP, -fill => Y, -expand => 1, ); # Allow a choice of from 2 to 31 items to display, selected by # radiobuttons arranged in a grid. For this straighforward rectangular # layout of 5 x 6 radiobuttons some simple arithmetic suffices to # calculate the grid positions, no need for the GridLayout module. # for ( 2 .. 31 ) { $chooseItemsFrame->Radiobutton( %commonRadioButtonOpts, -text => $_, -value => $_, -variable => \ $numItems, -width => 3, -command => \ &arrangeButtons, )->grid( -row => ( ( $_ - 2 ) / 5 ), -column => ( ( $_ - 2 ) % 5 ), -padx => 5, -pady => 5, ); } # Default to arranging in 4 columns, create frame for choosing how # many rows or columns to arrange. # my $numRowsOrCols = 4; my $rowColCountFrame = $mainWin->Frame( %commonFrameOpts, )->pack( -side => TOP, -fill => Y, -expand => 1, ); # Create label and associated text variable. # my $rsRowColCountText = \ do { my $dummy }; $rowColCountFrame->Label( %commonLabelOpts, -textvariable => $rsRowColCountText, )->pack( -side => TOP, ); # Create a flat-relief frame within the "rows/columns count" frame for # the buttons making the choice. # my $chooseColumnsFrame = $rowColCountFrame->Frame( %commonFrameOpts, -relief => FLAT, )->pack( -side => TOP, -fill => Y, -expand => 1, ); # Create the radiobuttons, 2 through 7, with the &arrangeButtons callb +ack. # for (2 .. 7) { $chooseColumnsFrame->Radiobutton( %commonRadioButtonOpts, -text => $_, -value => $_, -width => 3, -variable => \ $numRowsOrCols, -command => \ &arrangeButtons, )->pack( -side => LEFT, -padx => 5, -pady => 5, ); } # The items being arranged according to the choices made are simple bu +ttons # here and we keep track of them in an anonymous hash updated by the # &arrangeButtons() subroutine. They will be displayed in the $buttonF +rame # frame which we create now. # my $rhButtons = {}; my $buttonFrame = $mainWin->Frame( %commonFrameOpts, )->pack( -side => TOP, -fill => Y, -expand => 1, ); # Finally create a control button frame to hold the "Quit" button. # my $controlButtonFrame = $mainWin->Frame( %commonFrameOpts, -relief => FLAT, )->pack( -side => TOP, ); $controlButtonFrame->Button( %commonButtonOpts, -text => q{Quit}, -command => sub { $mainWin->destroy(); }, )->pack( -side => RIGHT, -padx => 5, -pady => 5, ); # Call arrangeButtons() to display the default button arrangement then # enter the main loop and await events. # arrangeButtons(); MainLoop(); # Subroutine called to arrange (before MainLoop()) or re-arrange (as # a widget callback) buttons depending on choices made on row or # column constraint, row or column count and sorting direction. # # -------------- sub arrangeButtons # -------------- { # Destroy any existing buttons and clear the buttons hash. # foreach my $button ( keys %{ $rhButtons } ) { $rhButtons->{ $button }->destroy() if Exists( $rhButtons->{ $button } ); delete $rhButtons->{ $button }; } # Call routines to set label text for each of the four categories # that the user might change. # setRowOrColumnText(); setDirectionText(); setItemsText(); setRowColCountText(); # Get the button order as an anonymous AoA by calling the appropri +ate # subroutine depending on whether we are constrained by the number + of # rows or of columns and whether buttons are sorted vertically or # horizontally. # my $raButtonOrder = $rowsOrColumns ? ( $sortDirection ? fitToColsVSort( $numItems, $numRowsOrCols ) : fitToColsHSort( $numItems, $numRowsOrCols ) ) : ( $sortDirection ? fitToRowsVSort( $numItems, $numRowsOrCols ) : fitToRowsHSort( $numItems, $numRowsOrCols ) ); # Create the chosen number of buttons, keeping track of them in # the $rhButtons anonymous hash. Place them using the calculated # grid positions. Numbering the buttons from zero makes things # more obvious when looking at the algorithms in the GridLayout # module. The buttons are dumb and do nothing when clicked. # foreach my $buttonNo ( 0 .. $numItems - 1 ) { my $buttonName = q{Button_} . $buttonNo; $rhButtons->{ $buttonName } = $buttonFrame->Button( %commonButtonOpts, -text => qq{Button $buttonNo}, -width => 9, )->grid( -row => $raButtonOrder->[ $buttonNo ]->[ 0 ], -column => $raButtonOrder->[ $buttonNo ]->[ 1 ], -padx => 5, -pady => 5, ); } } # Subroutine to update the sorting direction text label. # # ---------------- sub setDirectionText # ---------------- { ${ $rsDirectionText } = q{... sorting } . ( qw{ horizontally vertically } )[ $sortDirection ] . q{ ...}; } # Subroutine to update the number of items text label. # # ------------ sub setItemsText # ------------ { ${ $rsItemsText } = qq{... fit $numItems items ...}; } # Subroutine to update the number of rows or columns text label. # # ------------------ sub setRowColCountText # ------------------ { ${ $rsRowColCountText } = qq{... to $numRowsOrCols } . ( qw{ rows columns } )[ $rowsOrColumns ]; } # Subroutine to update the arrange by rows or columns text label. # # ------------------ sub setRowOrColumnText # ------------------ { ${ $rsRowColText } = q{By } . ( qw{ Rows Columns } )[ $rowsOrColumns ] . q{ ...}; }

I'm posting this in the hope that someone might find it useful.

Update: Corrected typo.

Cheers,

JohnGG


In reply to Routines to help place widgets using Tk "grid" GM by johngg

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