[wdb] The procedure canvasdump provides an easy way to save and restore contents of a canvas. Simplifies copying of canvas contents.

Example of storing:
======
% set canvasContents [canvasdump .c]
canvas {
  list\
    [$canvas create rectangle {10.0 10.0 100.0 100.0} -fill yellow -width 5.0]\
    [$canvas create oval {50.0 50.0 150.0 150.0} -fill red -width 5.0]
}
======
Restoring:
======
% toplevel .top
.top
% pack [canvas .top.c]
% apply $canvasContents .top.c
1 2
% # .top.c contains drawing of .c; result is list of IDs
======
Code:
======
proc canvasdump canvas {
  set items ""
  foreach item [$canvas find all] {
    set cmd create
    lappend cmd [$canvas type $item]
    set coords {}
    foreach x [$canvas coords $item] {
      lappend coords [expr [format %f $x]]
    }
    lappend cmd $coords
    foreach li [$canvas itemconfigure $item] {
      lassign $li key - - def val
      if {$def != $val} then {
        if {$key eq "-image"} then {
          set image [$canvas itemcget $item -image]
          set file [$image cget -file]
          append cmd " $key " [subst -nocommand {[image create photo -file "$file"]}]
        } else {
          append cmd " $key " [list $val]
        }
      }
    }
    lappend items "    \[\$canvas $cmd\]"
  }
  set lines [join $items \\\n]\n
  concat canvas "{\n  list\\\n$lines}"
}
======

<<categories>>Canvas