A '''geometry manager''' manages the placement and layout of the elements of a [GUI]. ** See Also ** [Comparing Geometry Managers]: [http://wiki.tcl.tk/38909%|%A Program In Tcl/Tk To Demonstrate The Three Geometry Managers : pack, grid and place]: [Stacking Order]: an aspect of geometry management ** Reading ** [http://groups.google.com/d/msg/comp.lang.tcl/O890hopUMTE/y5Wpwr_UP_sJ%|%Windownamager geometry problem] , [comp.lang.tcl] ,2002-06-04: [KBK] gives a good description of the requested versus the actual geometry of a widget ** [Tk] geometry managers ** [place]: precise placement of a widget in absolute coordinates, for when you want to roll your own geometry manager [pack]: widgets flow around each other in the available space [grid]: available space is devided into numbers sectors to which widgets are either manually or automatically assigned. Somewhat more direct and intuitive than [pack]. The [text] and [canvas] widgets also have a limited capability to manage the geometry of child widgets (without using place, pack or grid). For example, [BWidget] constructs a scrollable frame megawidget by creating a frame as an embedded window of a canvas. ** Other Geometry Managers ** [BLT]'s table geometry manager: [layout]: a Tk front-end that calls the standard geometry managers with a different interface [Tix]'s form geometry manager: [TkVSform]: does geometry management (along with other things) for its forms [GRIDPLUS2]: is a screen layout package built on the Tk [grid] manager [making your own geometry manager]: ** Description ** Choose [grid] for tabular layouts, and when there's no good reason to choose something else. Choose [pack] if you're used to the web browser box model, and the flow makes sense to you. Choose [place] when you want as little help as possible managing the layout. ** Introspection ** Introspection on geometry managers is possible: ====== winfo manager $widget ====== Notice that ====== winfo manager $toplevel ====== returns the special value, `wm`. ** Horizontal Stretch of One Widget, But No Vertical Stretch of Either Widget ** [Harald Kirsch]: Is it possible with place to position a widget .f.bot just below another widget .f.top such that the following holds: 1. If the container .f is resized vertically, both widgets keep their natural height and keep sticked to the top of .f 1. If .f is resized horizontally, .f.top keeps it natural width and stays sticked to the left border of .f while .f.bot resizes itself to stretch over the whole width of .f. Please note that 2 seems to make it impossible to use the sibling-trick mentioned in the place-manual. I would probably get the above done with place, if I knew a way of extracting the natural width and height of widgets which are [[place]]d. Neither [[... cget -width]] nor [[winfo width ...]] deliver anything useful - except if I call update before calling winfo. '''ANSWER''' - DKF You need to use [[winfo reqwidth]]. Code that satisfies your request follows: ====== # Basic Setup frame .f -bg red label .f.top -text "I'm top" -bg yellow label .f.bot -text "I'm bot" -bg white pack .f -fill both -expand 1 # Geometry Manager Magic set w1 [winfo reqwidth .f.top] set w2 [winfo reqwidth .f.bot] if {$w1<$w2} {set w1 $w2} set h [expr {[winfo reqheight .f.top]+[winfo reqheight .f.bot]}] .f configure -width $w1 -height $h place .f.top -x 0 -y 0 place .f.bot -x 0 -y [winfo reqheight .f.top] -relwidth 1 ====== Did you know that you can also achieve the same effect using `grid`? ====== # Basic Setup frame .f -bg red label .f.top -text "I'm top" -bg yellow label .f.bot -text "I'm bot" -bg white pack .f -fill both -expand 1 # Geometry Manager Magic grid .f.top -sticky w grid .f.bot -sticky ew grid columnconfigure .f 0 -weight 1 grid rowconfigure .f 2 -weight 1 -minsize 0 ====== And also `[pack]`? ====== # Basic Setup frame .f -bg red label .f.top -text "I'm top" -bg yellow label .f.bot -text "I'm bot" -bg white pack .f -fill both -expand 1 # Geometry Manager Magic pack .f.top -side top -anchor w pack .f.bot -side top -anchor nw -fill x -expand 1 ====== ---- [DKF]: Many widgets have `'''-width'''` and `'''-height'''` options, but those do not usually give useful results when read (for the purposes of geometry management.) `[winfo width]` and `[winfo height]` would be more useful you'd think, but in fact they only ever report the ''current'' size of a widget, which is initially zero as there hasn't been time to work it out yet (since interaction with geometry managers is performed on idle updates.) To get the info you need for GM, you need `winfo reqheight` and `winfo reqwidth` commands, which report what size widgets would prefer to be. The other thing you need to watch out for if you are doing any fancy geometry mangling (unlike the simple example above) is the `''''''` event. This lets you find out when the enclosing widget changes in size due to whatever GM is managing ''it''. A sophisticated example that uses the configure events is available at [http://www.cs.man.ac.uk/~fellowsd/tcl/#scripts/notebook]. ---- [KBK]: You also need to include `'''update idletasks'''` in the case where another geometry manager is managing the `winfo reqwidth` or `winfo reqheight` of the widget. It is possible that the requested size is zero because a subordinate geometry manager hasn't had the chance to work out the size. ** Using Text Widget As a Flowing Geometry Manager ** [Michail Richardson]: Is it possible with pack to position a series of widgets in a frame such that if they all fit in the horizontal space, then they are arranged that way. Otherwise, they are folded like text. A sort of message window for frames. This is so that a series of radiobuttons that exceeds the width of the user's screen can properly be displayed, in, e.g. tkGnats. (The list of buttons is determined at run-time) [KBK]: Sure. Window them in a text widget. There's an example in the "Widget Tour" that comes with Tk that does just what you're asking. [escargo]: This sounds like the Java flow layout. ** Using `[pack]` and `[grid]` Together ** [Lars H]: In the following example, the main structure uses `[grid]`, but the "toolbar" frame on the top uses `[pack]` internally. Widgets named something ending in `_c` are [canvas]es, ending in `_h` horizontal [scrollbar]s, and those ending in _v are vertical scrollbars. ====== set t [toplevel .rulebrowser] wm title $t "Rule browser" # First create some things to manage foreach c_ [list $t.left_ $t.right_] { scrollbar ${c_}h -orient horiz -command [list ${c_}c xview] scrollbar ${c_}v -command [list ${c_}c yview] canvas ${c_}c -width 200 -height 400 -relief solid -borderwidth 1\ -xscrollcommand [list ${c_}h set] -yscrollcommand [list ${c_}v set]\ -scrollregion {0 0 300 500} } # Then start managing grid $t.left_c -row 2 -column 0 -sticky nsew grid $t.right_c -row 2 -column 3 -sticky nsew grid $t.left_v -row 2 -column 1 -sticky ns grid $t.right_v -row 2 -column 4 -sticky ns grid $t.left_h -row 3 -column 0 -sticky ew grid $t.right_h -row 3 -column 3 -sticky ew grid rowconfigure $t 2 -weight 1 grid columnconfigure $t 0 -weight 1 grid columnconfigure $t 3 -weight 1 canvas $t.arrow_c -width 20 -height 20 $t.arrow_c create line {0 10 20 10} -arrow last -width 2 grid $t.arrow_c -row 2 -column 2 scrollbar $t.text_v -command [list $t.text_t yview] text $t.text_t -height 5 -yscrollcommand [list $t.text_v set] grid $t.text_t - - - -row 1 -column 0 -sticky nsew grid $t.text_v -row 1 -column 4 -sticky ns set bg grey90 frame $t.f -background $bg grid $t.f - - - - -row 0 -column 0 -sticky ew pack [button $t.f.prev -text "Prev" -highlightbackground $bg] -side left pack [button $t.f.next -text "Next" -highlightbackground $bg] -side left pack [button $t.f.go -text "Go" -highlightbackground $bg] -side right pack [entry $t.f.go_e -width 4] -side right pack [label $t.f.go_l -text "Rule" -background $bg] -side right ====== ** Misc ** [escargo]: Is there any way to tell which of the commands (or potentially procedures) act as geometry managers? (This is in some respects an [Introspection] question as well.) [escargo] 2003-07-01: Apparently not. Darn. <> GUI