Sunday, November 16, 2014

Multipaned container implemented in Tcl/Gnocl

The Gtk+ widget set contains two widgets, GtkHPaned and GtkVPaned which only allow the insertion of two child widgets. One might suppose that if more items are needed then folding boxed in a scrolling window would be adequate. One alternative, as I have used up to date, is the use of nested double panes.

Implementing a new container widget in C using the Gtk+ libraries is possible, but implementing such an beast in Tcl/Gnocl is somewhat less complex.

Over the past couple of evenings I've put together a proof of concept script to get the bare bones of this this megawidget in place. All seems well, although a little bit of easing on the gnocl source code side of things has helped. To this end I've added the geometry subcommand to the gnocl::fixed widget. The effect of this to allowing a single command to return the position and size of child objects placed in a gnocl:fixed container rather than making two separate calls in the script, one for the (x y) position and the other for (width height) size of the child.

As can be seen from this screenshot my test script my paned is somewhat overpopulated.

To test this out locally, download and install the lastet nightly build from SourceForge.

A click and drag of the mouse pointer on the separator bars sees the height of all of the panes resize correctly in real-time.

The next step is to introduce some minium settings, overlap prevention and collapse-expand double click behavious on the separator.


# mypaned-2.tcl
#!/bin/sh
#\
exec tclsh "$0" "$@"

package require Gnocl

set bar 15
set height 50
set width 200
set i 1
set handle_height 5


#---------------
#
#---------------
#
proc my_paned {} {

    set ::container [gnocl::fixed -onAdd {puts HI}]

    set wid [gnocl::eventBox]  ;#-background red]

    # add the first container
    $::container add $wid -x 0 -y 0 -width $::width -height $::height

    lappend ::panes $wid

    return $::container

}

#---------------
#
#---------------
#
proc _resize_above { handle } {

    set box [gnocl::winfo parent $handle]
    set i [lsearch $::handles $handle]
    set above [lindex $::panes $i]
   
    set w [lindex [gnocl::winfo geometry $box] 2]

    # get and process geometry
    foreach {ax ay aw ah} [$box geometry $above] {}
    foreach {hx hy} [$box position $handle] {}

if 0 {
        +---------------+ ay
        |               |
        |     ABOVE     | new height = hy - ay
        |               |
        +---------------+ hy
        |     HANDLE    |
        +---------------+  
}

    $box move $above -x $ax -y $ay -width $aw -height [expr $hy -$ay]
       
}

#---------------
#
#---------------
#
proc _resize_below { handle } {

    set box [gnocl::winfo parent $handle]
    set i [lsearch $::handles $handle]
    set below [lindex $::panes [incr i] ]

    # get and process geometry
    foreach {bx by bw bh} [$box geometry $below] {}
    foreach {hx hy hw hh} [$box geometry $handle] {}

if 0 {
        +---------------+ hy
        |     HANDLE    |
        +---------------+ hy+hh = by
        |               |
        |     BELOW     | new height = (by+bh) - (hy+hh)
        |               |
        +---------------+ by+bh 

}
    $box move $below -x $bx -y [expr $hy + $hh] -width $hw -height [expr ($by+$bh) - ($hy+$hh)]
       
}

#---------------
#
#---------------
#
proc move_handle { handle } {

    # get container
    set box [gnocl::winfo parent $handle]

    # move handle
    set hy1 [_pointer_ypos $handle]
    foreach {hw hh} [$box size $handle] {}
    $box move $handle -x 0 -y [_pointer_ypos $handle] -width $hw -height $hh

    _resize_above $handle
    _resize_below $handle   
       
}

#---------------
#
#---------------
#
proc _pointer_ypos { w } {
    return [expr [lindex [gnocl::winfo pointer [gnocl::winfo toplevel "$w"]] 1] -5]
}


#---------------
#
#---------------
#
proc adjust {w} {
    set i [lsearch $::handles $w]
    set l [expr [llength $::handles] -1]


    set ret "[expr $i] [expr $i+1]" 
       
    return $ret
}

#---------------
#
#---------------
#
proc add_handle { y } {
   
    set wid [ gnocl::eventBox ]
    $wid configure -child [ gnocl::separator ]
   
    set parent [gnocl::winfo parent $::container]
    foreach {a b width c} [gnocl::winfo geometry $parent] {}
   
    set y [expr $y -$::handle_height]
   
    $::container add $wid -x 0 -y $y -width $width -height $::handle_height   

    lappend ::handles $wid
   
    $wid configure -onMotion { move_handle %w }
       
}

#---------------
#
#---------------
#
proc add_pane { } {
   
    set lpane [lindex $::panes end]
   
    foreach {a y w h} [$::container geometry $lpane] {}
   
    set y [expr $y + $h +$::handle_height]
    set wid [gnocl::eventBox ]
   
    $::container add $wid -x 0 -y $y -width $w -height $h

    add_handle $y
   
    incr ::i
   
    lappend ::panes $wid
   
}

#---------------
# test-block
#---------------
#

set paned [my_paned]

gnocl::window -child $paned -height 600 -width 300

add_pane
add_pane
add_pane
add_pane
add_pane
add_pane
add_pane
add_pane

set txt(1) [gnocl::text -wrapMode word] ; $txt(1) lorem
set txt(2) [gnocl::text -wrapMode word] ; $txt(2) lorem
set txt(3) [gnocl::text -wrapMode word] ; $txt(3) lorem
set txt(4) [gnocl::text -wrapMode word] ; $txt(4) lorem

[lindex $panes 0] configure -child $txt(1)
[lindex $panes 1] configure -child [gnocl::label -text ONE]
[lindex $panes 2] configure -child [gnocl::label -text TWO]
[lindex $panes 3] configure -child $txt(2)
[lindex $panes 4] configure -child [gnocl::label -text FOUR]
[lindex $panes 5] configure -child [gnocl::label -text FIVE]
[lindex $panes 6] configure -child $txt(3)
[lindex $panes 7] configure -child [gnocl::label -text SIX]
[lindex $panes 8] configure -child $txt(4)

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