Arjen Markus (17 may 2013) The traditional presentation method is rather linear: just start at the first slide and then scroll down page by page. A more fancy way is to jump around amid a multi-dimensional arrangement of slides. The program below, while not offering all the formatting features of contemporary presentation software (in fact there is only a single formatting option), is an experiment with navigating through a set of slides in a non-linear fashion.
Whether presenting stuff in this way really has added value, I do not know, but it does offer the following navigational possibilities:
It is a rather basic program and the example is mostly empty, but it demonstrates some interesting aspects. For instance, you could set up a single slide show that has one or more sidetracks - for different types of audiences or if you need to elaborate some topic.
Some notes:
# slideshow2d.tcl -- # Experiment with a slideshow that allows more advanced navigation # than just up and down a page # namespace eval 2DShow { variable window variable slide variable default variable position namespace export startingSlide defaultFontColor titleFontColor slide plain show link returnTo } # startingSlide -- # Set the slide to start with # # Arguments: # key Key for the starting slide # proc ::2DShow::startingSlide {key} { variable slide set slide(startSlide) $key } # returnTo -- # Register a slide to return to via Escape # # Arguments: # key Key for the starting slide # proc ::2DShow::returnTo {key} { variable slide set slide(returnTo) $key } # defaultFontColor -- # Set the default font and colour # # Arguments: # font Description of the default font # color Colour name # proc ::2DShow::defaultFontColor {font color} { variable default set default(text,font) $font set default(text,color) $color } # titleFontColor -- # Set the font and colour for the title # # Arguments: # font Description of the font # color Colour name # proc ::2DShow::titleFontColor {font color} { variable default set default(title,font) $font set default(title,color) $color } # slide -- # Define the contents of a slide # # Arguments: # key Keyword identifying the slide # title Title for the slide # cmds Series of commands defining the slide # proc ::2DShow::slide {key title cmds} { variable slide variable default set slide($key,title) $title set slide($key,cmds) $cmds if { ! [info exists slide(startSlide)] } { startingSlide $key } } # link -- # Define the link from one slide to the next # # Arguments: # direction Direction to show the "to" slide at - determines navigation key # from Keyword identifying the "from" slide # to Keyword identifying the "to" slide # proc ::2DShow::link {direction from to} { variable slide set slide($from,$direction) $to } # plain -- # Define plain text # # Arguments: # text Text to be shown # args Options (-font, -color) # proc ::2DShow::plain {text args} { variable slide variable default variable position variable window foreach {opt value} [list -font $default(text,font) -color $default(text,color)] { set option($opt) $value } foreach {opt value} $args { set option($opt) $value } set x $position(x) set y $position(y) foreach line [split $text \n] { set line [string trim $line] $window create text $x $y -text $line -font $option(-font) -fill $option(-color) -anchor nw incr y [font metrics $option(-font) -linespace] } set position(y) $y } # show -- # Show the indicated slide # # Arguments: # key Key to the slide to be shown # proc ::2DShow::show {key} { variable slide variable position variable default variable window set position(x) 30 set position(y) 30 set position(left) 5 set position(top) 5 set position(right) [$window cget -width] set position(xcentre) [expr {[$window cget -width]/2}] set position(bottom) [$window cget -height] set position(ycentre) [expr {[$window cget -height]/2}] $window delete all $window create text $position(x) $position(y) -text $slide($key,title) \ -font $default(title,font) -fill $default(title,color) -anchor nw incr position(y) [font metrics $default(title,font) -linespace] eval $slide($key,cmds) foreach link {nw n ne e se s sw w} \ tlink {nw n ne s se s sw n} \ angle {0 0 0 90 0 0 0 90} \ x {left xcentre right right right xcentre left left} \ y {top top top ycentre bottom bottom bottom ycentre} \ press1 {Home Up Prior Right Next Down End Left} \ press2 {7 8 9 6 3 2 1 4} { bind $window <Key-$press1> {} bind $window <Key-$press2> {} if { [info exists slide($key,$link)] } { set forward $slide($key,$link) if { [info exists slide($forward,title)] } { set item [$window create text $position($x) $position($y) -text $slide($forward,title) \ -anchor $tlink -angle $angle] $window bind $item <ButtonPress> [list ::2DShow::show $forward] bind $window <Key-$press1> [list ::2DShow::show $forward] bind $window <Key-$press2> [list ::2DShow::show $forward] } } } # # "Escape" lets us go back ... # if { [info exists slide(returnTo)] } { bind $window <Key-Escape> [list show $slide(returnTo)] } else { bind $window <Key-Escape> [list show $slide(startSlide)] } } # main -- # Get it all started # namespace import ::2DShow::* set ::2DShow::window .c pack [canvas $::2DShow::window -width 400 -height 400 -bg white] focus $::2DShow::window titleFontColor "Helvetica 14 bold" black defaultFontColor "Helvetica 12" black # # Define a simple slide show # slide Start "Starting the show ..." { plain { This is just a start Nothing really fancy at the moment } plain "But there is more to come!" -color red plain "For instance: click on \"middle-left\"" } slide middle-left middle-left {plain {Something to return to}; returnTo middle-left} slide middle-right middle-right {} slide top-left top-left {} slide top-centre top-centre {} slide top-right top-right {} slide bottom-left bottom-left {} slide bottom-centre bottom-centre {} slide bottom-right bottom-right {} slide explain-middle-left "Explain middle-left" { plain {The previous slide illustrates that we can register various slides to return to} -color blue } link w Start middle-left link e Start middle-right link nw Start top-left link n Start top-centre link ne Start top-right link sw Start bottom-left link s Start bottom-centre link se Start bottom-right link e middle-left explain-middle-left link w middle-left Start show "Start"