6FutureDirectionsThisthesishaspresentedtwoprototypesthatwereimplementedforcomposingcomplexdocumentcontent,oneprototypeforgraphicalstyleandtheotherfortableformattingwithgridsandconstraints.Theseexperimentsledtomanyimplementationissuesandseveralnewresearchproblems.TheimplementationissuesarosefromadesiretoprovideintegratedandinteractiveillustrationandtabularcompositiontoolsintheTiogaandCedarenvironmentsatXeroxPARC.Theresearchproblemsfollowfromadesiretounifythetwoapproachesintothesamedocumentmodelandtoextendtherangeoffunctionalityinbothapproaches.Thischapteroutlinessomeofthesefutureproblemsandissues,inparticularacomprehensivedocumentframework,interactiveuserinterfacesfortheprototypes,variousproblemswithgraphicalstyleandtableformatting,andaproposalforconsideringrule-basedexpertsystemsupportforproblemsindocumentcomposition.6.1DocumentModelThedocumentmodelhasbeenacommonthreadthroughthetwoprototypesforgraphicalstyleandtableformatting.Thisexperienceshouldbegeneralizedintoadocumentmodelthatcanintegratearbitraryclassesofdocumentcontentbymorerigorouslydefiningtheobjectinterfacefortheeditorandtheformatter.Aninteractiveeditorforsuchadocumentmodelwouldcoordinatevariousspecialpurposeeditorsforeachclassofdocumentcontent6-1p\d gWn g g>;#q;o"o% -1"5 ?9g gL#)R,46=AD75 go #^'t* 38 B D5 g !s$*0-4+ 0 g  &*,/4a7< .k gQrH.k.kq(.k.k8").34x9G;K?B|,9 g hAp'&,8/z1~69>E* g   %)D/+5`9;?' g %o& 29 % g l c"$ -u32:o>)#p g;} #^$+|., 6 >!= g!#+} s gq:"&(H/4H:=d g 6Z"-%p) 26f >D g !&* -3:? ge (o.16=~@.C q g  %*s-#02]:?% ? g C%+b.157?t)()*hTVm$6FUTUREDIRECTIONS6-2andwouldprovidesharedundo/redofacilities.Severaldifficultiesarisewithdesigningacoordinatedusermodelofinteraction,specifyingthenotionofselectioninnontextualobjects,andarbitratinginteractionrequestsbetweenoverlappingobjects.AmoregeneraldocumentstructurethanahierarchicalonesimilartotheabstractdocumentobjectmodelfromKimura[Kimura,thesis]shouldbeconsideredtoincorporateobjectswitharbitraryinterlinking,suchasfootnotes,floatingfiguresortableswithseveralreferences,andrunningheaders.6.2GraphicalStyleThegraphicalstyleprototypewouldbenefitfromaninteractivedesignenvironmentforspecifyingstyles.ThenotionofinteractivepropertysheetsfromtheXeroxStarcanbeextendedtosupportstylesbynaminggroupsofpropertiesandbymanagingdictionariesofstylerules.Additionalgraphicdesigntoolsforlayoutsandrenderingalgorithmspecificationsarenecessary.Otheruserinterfaceissuesarediscussedbelow.Thesuiteofillustrationrenderingalgorithmsinthegraphicalstyleprototypeprovidesabasisforanextensiblemechanismforaddingnewalgorithms.Initialusesofthismechanismmightbetoaddnewalgorithmsforborderpatterns,shadowsontextobjects,orspecialcolorhighlights.Revealingdifferentlevelsofdetailasastyleattributewhenchangingmediacouldberequestedasanadditionalviewspecification,similartolevelclippingwhenpresentinghierarchicaldocuments.Theideasofgraphicalstyleshouldbeincorporatedintoanewillustrationsystem,perhapsbasedontheGriffinuserinterfaceandeditingmodel.ThisnewillustratorcouldincorporatelayoutconstraintsbyutilizingconstraintsasdemonstratedintheJuno[Nelson,Juno]andGob[Zabula-Salelles,GOB]illustrationsystemsandasincorporatedinthetableformattingprototypedescribedinthisthesis.6.3TableFormatterImplementationThetableformattingprototypeneedsseveralimplementationimprovements.Thecornerstitchingdatastructureimplementationshouldbereplacedbyadynamictopologicaldatastructuresothattheinsertanddeleteeditingoperationsareimplementedwithoutcopying.Theminimalrepaintingalgorithmuf !v"ff$uf(v)ff*ltfEfFfG)q^ g (V /5 =A\ g1 ?!&( 1 9X<1AjZ g-1 ^#Q& . 6=JXb g s"*'/6:U; DV/ g$)n.2r8V/V/9!>qV/BS g  !'M+1 ;>Q g {!&O* / 7:A@sJ gfqFC%*024G6 >D g  %)h.0 8?pDMBb g@6$&&+,903 8>m@~ @0 g  "b$s(F-W 5;u@D= g M$K .b1, 9~>A; g.!8 !f( 135=@6 gx0 %9-069 B4` g 2"$&*3- 58=2. gf &*L 2:AiE/ g^1#R*[/R364=?- g ) !'X)\-J38 + g M (Pa $X), 59$:> &^ g2g}"V'+2Q5;A5D$, g u !2&7 .p07; ?u! g r!! %q!(,?r0!!0v:Tq!>{  gf !Y#]&6*M 2k9ASCW gsl g q6 T&+}0 < _ g<& 17X9@LB, g  &(!+.X26(; g k5 !1'?.|18i @ETVm$6FUTUREDIRECTIONS6-3forincrementalinteractiveupdatestotheThehandlingofconstraintsfortablesshouldgracefullysolvetwosetsofrowandcolumnconstraintswhentheconstraintsdonotinteract,butshouldsolvethecombinedconstraintproblemwhentheydo.Thischangewouldpermittheefficientlayoutofamajorityoftabledesignswhileenablingsophisticatedtabledesignstospecifygridmodulesthatweresquareoranyotherspecifiedaspectratio.Additionaltypographycapabilitieswillalsobenecessarytomaketheprototypefullyfunctional.Forexample,thecapabilitytocenterasetofalignedboxeswithingridlinesmentionedinChapter5.Implementingaspreadsheetapplicationbasedonthetableformattingschemewouldstresstheperformanceoftheimplementationandrevealstrategiesfordealingwithrepetitivestructures.Itwouldalsobeanopportunitytoimplementautomaticcomputationofcarry-forwardtableentries,automaticinsertionofcontinuationandsummaryheadings,andvariousstyleattributesforimprovingthereadabilityoflargetables.Itwouldbedesirabletoacceptatabledesignprespecifiedbyadesignerorprecomputedfromaprototypicaltable.Suchacompletelyspecifiedtablelayoutshouldberecognizedtoavoidcomputingthedimensionsofanimmensenumberoftableentries.Theimplementationwouldrequirestrategiesfordealingwithtableentriesthatdonotconformtotheprespecifieddesign,atleastbyreportingthem.6.4TableFormattingAlgorithmsDetermininganaestheticallypleasingtablelayoutremainsasignificantresearchproblem.Thegridstructurepresentedinthisthesisprovidesabasisfordealingwiththeproblem.Balancingtheamountofwhitespacewithinatablecanbeachievedbymanipulatingthepositionofgridlines.Somepossiblestrategiesmightbetoincreasethecolumnwidthwhilereducingtherowheight(orviceversa)ortofoldasinglelongcolumnintoseveralshorterones.Ausefulconjecturetoproveempiricallywouldbewhethertableentrieshavearowdepththatincreasesmonotonicallywithdecreasingcolumnwidth.Themonotonicrelationshipwouldpermitefficientsearchstrategies.Somegraphicdesignprinciplescanbeexpressedintermsofconstraintsongridlines,suchasforcingtableentriestobeequalwidthorequalheightwhentheyare`almost'equal.uf !v"ff$uf(v)ff*ltfEfFfG)q^ g  &7(<+/58 @IB\ g c #&)N,2 :?0Z g  _#`(,/7r ? Xb g!L&P+.}49;=bCV/ g}H!s +;/R57!<@ S g%L").~P  )),]/2 9W;\?N g #*- 5(7-<%=@B$L g-%'.I ] $ -%14;7;* GZ g?D (!*2- 8<%A E( g  (p*2/7247: @HB gI %' 2D6[<@ g:K " )P039=n D> g]6 b!s%;x|!&(I,_1 :=">E9X g q %*3.W/ 8>C7& g cg"+!- 68;A4 gxT (,-02 :<B2 g}/%.'3* 3A8:>@0 gs)g g  q% a $+a/w4|:< #[ g!e(H/149@.AE!( g2 k(*02 ;Q@pA gt %'./0@38=9 g L"%+0h4;>A gOnr N%(.27=(B_ gQ IN (}-/63:I?CD- g{i &*) 17= g "'.b3t ;@9 g  .&(,. 69K<A D g  tx$M(+/49<? c gTVm$16FUTUREDIRECTIONS6-4Wewouldliketoinvestigatehowtoapplythetablealignmenttechniquestomathematicalnotationandpagelayout.Manytwo-dimensionalnotationshavepositioningandalignmentrequirementssimilartotables.Forinstance,matrixnotationisobviouslysimilartoasmalltable,andcenteredlimitsaboveasummationoperatorshareacommonalignment.Whentwoormoresummationnotationsappearinthesamemathematicalsegment,wemaywishthatthecorrespondingpartsarealignedtogetheronacommongridline.Similarly,correspondingalignmentwouldbedesirableforlargefractionswithcomplexnumeratoranddenominatorexpressions,formatriceswithsimilarnumbersofrows,andforintegrationoperatorswithlimits.Pagelayouthaslongusedagridstructuretodescribetherelationshipsamongpartsofthepage.Pageandtablelayoutcouldshareinteractivegraphicdesigntoolsforcreatingthegridstructureandexpressingthealignmentrelationships.Treatingpagesasatablelayoutwouldrequiredefininganewkindoftableentryforflowingtextfromonepagetoanother,possiblyrelatedtothemechanismsinvolvedinthespreadsheetsystemproposedinSection6.3.6.5UserInterfaceDesignThecrucialrequirementhereistodevelopanappropriateusermodelforinteractivelyspecifyinggraphicdesignintentionsforlayoutandstyle.Thespecificationofstylesheetsthroughthemetaphorofprogrammingmacrocommandsforadocumentcompositionsystemisneitherinteractivenorintuitive.Interactivegraphicdesigntoolsareneededtosupportthegraphicdesignertoexpresstheirintentionswithintheirowndesignframework.Thegridstructureprovidesametaphorcommontothegraphicdesigndiscipline.TheinteractivetechniquesimplementedinNEWSWHOLE[Tilbrook,NEWSWHOLE]provideideasforrubber-bandgridlines,measurementrules,andgravityfornearbyplacementofobjects.Theuseofatemplatetorefertoapredefinedtablelayoutorillustrationlayoutwouldsimplifytheconstructionofrepeateddesigns.Theconstraintsystemusedintheprototypefortablelayoutneedsaninteractivespecificationtool.Techniquesarenecessaryforidentifyingalignmentrelationshipsamongasetofgridlines.Specialarrangementsmayhavetobewrittenintheexpressionlanguageunlessasuitableinteractivespecificationtechniquecanbedeveloped.uf !v"ff$uf(v)ff*ltfEfFfG)q^ %(*/N2'6>= F-\ g  R$@*L/;vBZ g 1 )/N1S7:DA Xb g!#$)@-17<<A V/ g!K( 058;?bS g" ,*3 59>=@pQ g )? #*L,.48i< O g )#&6-1/3:>iMf gx !t *-=37{<CK4 g &A)H-`#B$(/17}:V E g#'+0#49 AC g>!Y$+. 69A g  "8$=%).39@Ah?c g;Lb]#O&*-13:E@F=1 g@ :!>$ ,2^9;Als6 g.Qq2,t !%'?)C/x1 :>6CG/ g  x#^( 0227;(@- g  &)103A =+ g] y )/(06 >A )c g z#&k,)..4<7<C'1 g2 "&*t/ $*y$%%,358>! g > C (~ 2yr4}!!5!>  g q !;# -~05? ?bC g !$ *.034m;4=9A4C8` g  (;-?2D8;x D. g!'  #&(0Z3 7!<%@ g l "G +-5(7 @+ g sa!r$)/ 9=PA?CC g  %*,B2] :b ^ ge TVm$.6FUTUREDIRECTIONS6-56.6ExpertStyleRulesTheapplicationofexpertsystemsandknowledgerepresentationstotheproblemofdocumentformattingarebutagleamintheresearcher'seye.Capturingthestylerulesusedingraphicdesignandbookpublishingmaybeaproductiveapproachtowardsaestheticandeffectivepagelayout.Therearecertainlymanystylemanualstochoosefromfortheknowledgebase.Thegridstructureusedinthetableformattingprototypedescribedheremayserveasausefulrepresentationforthearealayoutproblemsthataretheprincipaldomainofgraphicdesign.uf !v"ff$uf(v)ff*ltfEfFfG)s^ gqZ "(,4F?AX g $'*,025 >V g7"$*/3&7V ?uCEgTN g !(+26<A`R g "$ )w-0<3;[@CO gJ+/  (=/7$:>|BDM gQ !%-*21o47:qA_K gx^TVm$ TIMESROMAN TIMESROMANY HELVETICA TIMESROMAN TIMESROMAN TIMESROMANY TIMESROMAN Q j/![]<>Beach>Thesis>Chapter6.TiogaMonday, May 6, 1985 1:31 pm PDT