The Guido Engine A toolbox for music scores rendering

Transcription

1 Th Guido Engin A toolbo for music scors rndring C. Dudin, D. Fobr, S. Ltz nd Y. Orlry Grm Cntr ntionl d crtion musicl Lyon, Frnc dudin, fobr, ltz, orlry@grm.fr Abstrct Th Guido Music Nottion formt (GMN) is gnrl purpos forml lngug for rprsnting scor lvl music in pltform indpndnt plin tt nd humn rdbl wy. Bsd on this music rprsnttion formt, th GuidoLib provids gnric, portbl librry nd API for th grphicl rndring of musicl scors. This ppr givs n introduction to th music nottion formt nd to th Guido grphic scor rndring ngin. An mpl of ppliction, th GuidoScnComposr, is nt prsntd. Kywords Guido, Music nottion, scor lyout. 1 Introduction Computr music hs strtd to invstigt music scor rndring vry rly [1][2][3]. Music nottion cods such s DARMS [4], SCORE [5] or MusDt [6] hv bn dsignd to ddrss rprsnttionl issus nd gv birth to ssocitd progrms (such s th SCORE Nottion Progrm, widly usd in ngrving during th 1980s nd 1990s) nd long history of drivd or ltrnt formts. Now, commrcil music publishing softwr ist for mor dcd nd ctully provid sophistictd but compl solutions for music ngrving. Along ths closd solutions, th toolbo pproch hs bn invstigtd vry rly [7]. Howvr, vry fw systms hv rchd mturity: th Common Music Nottion systm [8] could b considrd s th bst chivmnt. Mor rcntly, th Eprssiv Nottion Pckg (ENP) [9] introducd nothr promising pproch; both systms r Lisp bsd nvironmnts. Anothr solution consists in dsigning compilrs for producing music shts from ttul music dscription. MusiXTEX is mong ths tools: it is st of TEX mcros to typst music nottion. Sinc MusiXTEX is powrful but hrd to lrn, prprocssors such s PMX nd M-T hv bn dsignd to fcilitt music input nd lyout. A mor rcnt inititiv is Lilypond [10], n opn sourc softwr prtilly implmntd in th lngug Schm, its input music rprsnttion formt is simpl nd intuitiv, it includs utomtic lyout cpbilitis. Both systms produc PostScript, EPS or PDF fils. Bsd th Guido Music Nottion formt, th GuidoLib projct is opn sourc, crosspltform C/C++ librry tht provids scor lyout nd rndring cpbilitis to its clint pplictions. Th music nottion formt is vry clos to th Lylipond formt. Th GuidoLib minly diffrs from th compilrs pproch in tht it llows to mbd music scor rndring cpbilitis into stndlon pplictions nd to crt scors dynmiclly. This ppr introducs first th Guido Music Nottion formt, nt th Guido Engin nd th Guido librry API r prsntd. Th lst sction prsnts th Qt support for Guido, long with concrt mpl of Guido-Qt ppliction, th GuidoScnComposr. 2 Th Guido Music Nottion formt Th Guido Music Nottion formt (GMN) [11] [12] hs bn dsignd by H. Hoos nd K. Hml mor thn tn yrs go. It is gnrl purpos forml lngug for rprsnting scor lvl music in pltform indpndnt plin tt nd humn rdbl wy. It is bsd on concptully simpl but powrful formlism: its dsign concntrts on gnrl musicl concpts (s opposd to grphicl fturs). A ky ftur of th Guido dsign is dqucy which mns tht simpl musicl concpts should b rprsntd in simpl wy nd only compl notions should rquir compl rprsnttions.

2 2.1 Bsic concpts Bsic Guido nottion covrs th rprsnttion of nots, rsts, ccidntls, singl nd multivoicd music nd th most common concpts from convntionl music nottion such s clfs, mtr, ky, slurs, tis, bming, stm dirctions, tc. Nots r spcifid by thir nm ( b c d f g h), optionl ccidntls ( # nd & for shrp nd flt), n optionl octv numbr nd n optionl durtion. Durtion is spcifid in on of th forms: * num / dnom dotting * num dotting / dnom dotting whr num nd dnom r positiv intgrs nd dotting is ithr mpty,., or.., with th sm smntic thn th music nottion. Whn num or dnom is omittd, it is ssumd to b 1. Th durtion rprsnts whol not frctionl. Whn omittd, optionl not dscription prts r ssumd to b qul to th prvious spcifiction bfor in th currnt squnc. Chords r dscribd using comm sprtd nots nclosd in brckts.g c,, g 2.2 Guido tgs Tgs r usd to rprsnt dditionl musicl informtion, such s slurs, clfs, kys, tc. A bsic tg hs on of th forms: \tgnm \tgnm<prm-list> whr prm-list is list of string or numricl rgumnts, sprtd by comms (, ). In ddition, tg my hv tim rng nd b pplid to sris of nots (lik slurs, tis tc.); th corrsponding form is: \tgnm(not-sris) \tgnm<prm-list>(not-sris) Th following GMN cod illustrts th concision of th nottion; figur 1 rprsnts th corrsponding Guido ngin output. [ \mtr<"4/4"> \ky<-2> c d & f/8 g ] & bb 4 4 _ \ Figur 1: A simpl GMN mpl 2.3 Nots squncs nd sgmnts A not squnc is of th form [tggd-nots] whr tggd-nots is sris of nots, tgs, nd tggd rngs sprtd by spcs. Not squncs rprsnt singl-voicd scors. Not sgmnts rprsnt multi-voicd scors; thy r dnotd by sq-list whr sq-list is list of not squncs sprtd by comms s shown by th mpl blow: [\stff<1> \stmsup \mtr<"2/4"> \bm(g2/32 /16 c*3/32) c/8 \bm(1/16 c2 f) \bm(g/32 d/16 h1*3/32) d2/8 \bm(h1/16 d2 g)], [\stff<1>\stmsdown g1/8 \bm(g/16 d f ) /8 \bm(/16 g h)], [\stff<2> \stmsup \mtr<"2/4"> 0 f h c1], [\stff<2>\stmsdown f0 d g ] Th corrsponding Guido ngin output is givn by figur 2. & 2 4? 2 4. j. j \ _X! Û \ Figur 2: A multi-voics mpl Additionlly, th dvncd Guido spcifiction (not covrd by this ppr) provids ct formtting of th scor. 3 Th Guido Engin Bsd on th Guido Music Nottion formt nd initilly dsignd by Ki Rnz, th Guido Engin provids grphicl rndring of musicl scors, including utomtic lyout cpbilitis. At Grm s inititiv, th ngin hs bn rshpd undr th form of portbl librry nd bcm n opn sourc projct in 2002, covrd by th GNU LGPL licns nd hostd on SourcForg. Sinc 2002, th Guido ngin hs bn mintind nd tndd by Grm. Th Guido Engin oprts on mmory rprsnttion of th GMN formt: th Guido Abstrct Rprsnttion (GAR). This rprsnttion is trnsformd stp by stp to produc grphicl scor pgs. Two kinds of procssing r first pplid to th GAR: GAR to GAR trnsformtions which rprsnts logicl lyout trnsformtion: prt of th lyout (such s bming for mpl) my b computd from th GAR s wll s prssd in GAR, th GAR is convrtd into Guido Smntic Norml Form (GSNF). Th GSNF is

3 cnonicl form such tht diffrnt smnticlly quivlnt prssions hv th sm GSNF. This GSNF is finlly convrtd into Guido Grphic Rprsnttion (GGR) tht contins th ncssry lyout informtion nd is dirctly usd to drw th music scor. This finl stp notbly includs spcing nd pg brking lgorithms [13]. Not tht lthough th GMN formt llows for curt music formtting using dvncd Guido (s figur 3), th Guido Engin provids powrful utomtic lyout cpbilitis. 4 Th Guido Librry Th Guido Librry is implmntd is in C++ but th srvics of Guido Engin r vilbl using C API. 4.1 Scor lyout Th librry provids functions to prs GMN fil nd to crt th corrsponding GAR nd GGR. GAR nd GGR r rfrncd by opqu hndls which r usd s rgumnts of ny function tht oprts on scor. For mpl: GuidoPrs (const chr * filnm) provids convrsion of GMN fil into GGR hndl rturnd s th function rsult. This hndl my b nt usd to drw th scor using th GuidoOnDrw function. A typicl cod to drw scor from its GMN dscription is givn blow (s sction 4.6 for VGDvic informtion): void DrwGMNFil (chr* filnm, VGDvic* dvic) // dt structur for ngin initiliztion // uss fonts "guido2" nd "tims" GuidoInitDsc gd = dvic, 0, "guido2", "tims" ; // Initilis th Guido Engin first GuidoInit (&gd); // dclr dt structur for drwing GuidoOnDrwDsc dsc; // nd prs th GMN fil to gt GGR hndl // dirctly stord in th drwing struct dsc.hndl = GuidoPrs (filnm); // nt stup th drwing prmtrs // (s th documnttion for mor dtils) dsc.hdc = dvic; // th output dvic dsc.pg = 1; // th pg to drw dsc.updtrgion.rs = tru; dsc.scroll = dsc.scrolly = 0; dsc.zoom = 1; // no zoom dsc.siz = dsc.sizy = 0; // nd finlly drws th scor GuidoOnDrw (&dsc); 4.2 Scor pgs ccss Th rsult of th scor lyout is st of pgs which siz my b dynmiclly chngd ccording to n ppliction or usr nds. Th librry provids th ncssry to chng th pg siz, to qury scor pgs count, or th pg numbr corrsponding to givn music dt. Not tht only on pg is drwn by th GuidoOnDrw function. 4.3 Engin sttings Scor lyout lgorithms r controlld by st of prmtrs which r globl to th Guido ngin. Th librry provids n API to qury nd modify ths prmtrs. It includs optiml pg fill control, springs nd spc forc control, systms distnc nd systms distribution. 4.4 Th Guido Fctory Th Guido Engin my b fdd with computr gnrtd music using th Guido Fctory. Th Guido Fctory API provids st of functions to crt GAR from scrtch nd to convrt it into GGR. Th Guido Fctory is stt mchin tht oprts on implicit currnt lmnts: for mpl, onc you opn voic (GuidoFctoryOpnVoic()), it bcoms th currnt voic nd ll subsqunt crtd vnts r implicitly ddd to this currnt voic. Th Guido Fctory stt includs th currnt scor, voic, chord, not (or rst) nd tg. Som lmnts of th fctory stt rflcts th Guido forml spcifiction; unlss othrwis spcifid, nw nots will implicitly crry th currnt durtion nd octv. A music scor dynmic construction is vry clos to th ttul Guido dscription: th Fctory API hndls GAR objcts tht hv on to on rltionship with th nottion formt. Onc th scor hs bn dynmiclly built, cll to GuidoFctoryClosMusic() rturns Guido hndl to GAR, dirctly usbl with GuidoFctoryMkGR(), which rturns Guido hndl to GGR, dirctly usbl with th min srvics of th librry. Logicl lyout is prformd bfor rturning th GAR hndl nd grphicl lyout is prformd bfor rturning th GGR hndl. 4.5 Grphic Mppings Along with th GGR, th Guido Engin mintins tr of grphicl lmnts for ch pg of th scor, s illustrtd by figur 4. Ech lmnt hs bounding bo nd dt. Positions

4 &? & c _. XÚ h? c _XÚ h J _. # FUGA I J.S.Bch BWV 846 J _XÚ h _XÚ _XÚ h h. # _XÚ h ẊÚh b Figur 3: A compl lyout mpl of th lmnts r stord s pil coordints. Top lft cornr of th scor is t position (0, 0). & 4 4 _X! Û & _ X! Û = 120 = 120 = 120 _X! Û _X! Û _X! Û _X! Û X! Û X! Û X! Û X! Û X X! Û X! Û _E! Û \ Figur 4: Bounding rcts of scor lmnts Th Guido librry provids spcific API to qury th scor mp nd to rtriv lmnts by typ, position nd dt. 4.6 Th Virtul Grphic Systm Th virtul grphic systm is intndd s n bstrct lyr covring pltform dpndncis t grphic lvl. It rprsnts st of bstrct clsss drssing th bsic nds of n ppliction: printing tt, drwing on th scrn or offscrn, tc. Th st of bstrct clsss includs: VGDvic clss: spcilizd on drwing onscrn or offscrn VGFont clss: to covr fonts mngmnt VGSystm clss: to covr lloction of spcific VGDvic nd VGFont objcts. This st of clsss is implmntd for diffrnt trgt pltforms: support is providd for GDI (Windows), Qurtz (Mc OS X), GTK (GNU Linu), OpnGL nd mor rcntly for Qt. 5 Guido Qt support Qt is cross-pltform ppliction dvlopmnt frmwork [14], widly usd for th dvlopmnt of GUI progrms GuidoQt clsss A st of clsss hs bn dvlopd to us th Guido librry with Qt; thy r orgnizd in 3 lyrs (figur 5): low lvl: GDvicQt, GFontQt & GSystmQt: Qt implmnttion of th Virtul Grphic Systm middl lvl: QGuidoPintr: clss tht uss GDvicQt, GFontQt & GSystmQt, nd offrs highr-lvl intrfc high lvl: rdy-to-us Qt clsss tht uss th QGuidoPintr to prs nd drw Guido scors: QGuidoWidgt, QWidgt QGuidoSPgItm & QGuidoM- PgItm, two QGrphicsItm displying, rspctivly, on scor s pg t tim, nd ll th pgs Guido2Img, to port Guido scors to vrious img formts 1 s:

5 Qt Librry QGrphicsItm QWidgt High lvl QGuidoMPgItm QGuidoSPgItm QGuidoWidgt Guido2Img QGuidoItm Mid lvl QGuidoPintr Low lvl GSystmQt GDvicQt GFontQt Figur 5: GuidoQt clss digrm Hr is short mpl using th QGuidoPintr tht shows how to port Guido scor to n img: #includ <QAppliction> #includ <QPintr> #includ <QImg> #includ "QGuidoPintr.h" int min(int rgc, chr* rgv[]) QAppliction pp( rgc, rgv ); //Guido Engin initiliztion QGuidoPintr::strtGuidoEngin(); //Crt QGuidoPintr... QGuidoPintr* p = QGuidoPintr::crt(); //...nd giv it som Guido Music Nottion p->stgmncod( "[c/8 d g d c]" ); //Gt th siz of th scor s first nd only pg int pgind = 1; QSizF s = p->pgsizmm( pgind ); //Crt blnk img, using th siz of th scor QImg img(s.tosiz()*10, QImg::Formt_ARGB32); img.fill( QColor(Qt::whit).rgb() ); //Drw th scor with th QGuidoPintr, vi QPintr. QPintr pintr( &img ); p->drw( &pintr, pgind, img.rct() ); QGuidoPintr::dstroyGuidoPintr( p ); //Dstroy th Guido Engin rsourcs QGuidoPintr::stopGuidoEngin(); img.sv( "myscor.png" ); rturn 0; And hr is nothr mpl showing how to disply Guido Scor using QGuidoWidgt: #includ <QAppliction> #includ "QGuidoWidgt.h" #includ "QGuidoPintr.h" int min(int rgc, chr *rgv[]) QAppliction pp(rgc, rgv); // Guido Engin initiliztion QGuidoPintr::strtGuidoEngin(); // Crt QGuidoWidgt... QGuidoWidgt w; //...nd giv it som Guido Music Nottion w.stgmncod( "[ d c]" ); w.show(); // Tht s it! int rsult = pp.c(); // Dstroy th Guido Engin rsourcs QGuidoPintr::stopGuidoEngin(); rturn rsult; 5.2 Th Guido Scn Composr Th GuidoScnComposr is grphic IDE for Guido, llowing to mnipult Guido scors in grphic scn A Guido Music Nottion lrning tool Th GuidoScnComposr is n ffctiv nvironmnt to lrn th GMN: whn typing GMN, th corrsponding scor is instntly updtd, mking it vry simpl to try diffrnt nottions; hlp pltt (figur 6) lists lrg ssortmnt of Guido prssions nd tgs,

6 so tht no trnl documnttion is ncssry; th GMN tt ditor uss synth highlightr, for clrr GMN rding; import MusicXML nd MusDt (limitd support) scors; port th Guido scors to pdf or n img. Figur 6: Th Guido Hlp pltt A scor grphic composr Th GuidoScnComposr llows to you to compos grphic scns with diffrnt scors: mov, rsiz, copy & pst th scors, to crt grphiclly compl musicl scn, import vrious formts of picturs to nrich th scn, dd ttul nnottions, port th scn to n img or pdf. Figur 7: Th Guido Scn Composr 6 Conclusions Bsd on th Guido Music Nottion formt, th GuidoLib is uniqu opn sourc, pltform-indpndnt librry, for mbdding scor rndring into stndlon ppliction. Th rcnt support of th widly-usd crosspltform Qt librry mks it vn mor ccssibl to softwr dvloprs. In th futur, w pln to tnd th grphicl possibilitis of th GuidoScnComposr giving to usrs mor drwing tools; it would thn bcom n intrsting ppliction to crt tndd modrn music scors. Support of import/port in othr common music scor formts is lso mong our concrns. Finlly, w pln to dd scor composition fturs, lik putting scors in squnc or in prlll, cutting th hd, th til, th top or th bottom voics of scor, trnsposition, or durtion chng, using n homognous pproch, whr scors r both th trgt nd th rgumnt of th oprtions. Th Guido librry is vilbl on Sourcforg t Rfrncs [1] Dvid A. Gombrg. A Computr-Orintd Systm for Music Printing. In Computrs nd th Humnitis, volum 11, pgs Prgmon Prss, [2] Donld Alvin Bird. Music Nottion by Computr. PhD thsis, Indin Univrsity, [3] John S. Gourly, A. Prrish, D. Roush, F. Sol, nd Y. Tin. Computr Formtting of Music. Tchnicl rport OSU- CISRC-2/87-TR3, Dprtmnt of Computr nd Informtion Scinc, Th Ohio Stt Univrsity, [4] E. Slfridg-Fild. DARMS, Its Dilicts, nd Its Uss. In Byond MIDI, Th hndbook of Musicl Cods., pgs MIT Prss, [5] Smith Llnd. SCORE. In Byond MIDI, Th hndbook of Musicl Cods., pgs MIT Prss, [6] Wltr B. Hwltt. MusDt: Multipurpos Rprsnttion. In Slfridg-Fild E., ditor, Byond MIDI, Th hndbook of Musicl Cods., pgs MIT Prss, 1997.

7 [7] Assyg G. nd D. Timis. A ToolBo for Music Nottion. In Procdings of th Intrntionl Computr Music Confrnc, pgs , [8] Bill Schottstdt. Common Music Nottion. In Slfridg-Fild E., ditor, Byond MIDI, Th hndbook of Musicl Cods., pgs MIT Prss, [9] Mik Kuusknkr nd Michl Lurson. ENP - Music Nottion Librry bsd on Common Lisp nd CLOS. In Procdings of th Intrntionl Computr Music Confrnc, pgs ICMA, [10] Hn-Wn Ninhuys nd Jn Niuwnhuizn. LilyPond, systm for utomtd music ngrving. In Procdings of th XIV Colloquium on Musicl Informtics (XIV CIM 2003), My [11] Hoos H., Hml K. A., Rnz K., nd Kilin J. Th GUIDO Music Nottion Formt - Novl Approch for Adqutly Rprsnting Scor-lvl Music. In Procdings of th Intrntionl Computr Music Confrnc, pgs ICMA, [12] H. H. Hoos nd K. A. Hml. Th GUIDO Music Nottion Formt Spcifiction - vrsion 1.0, prt 1: Bsic GUIDO. Tchnicl rport TI 20/97, Tchnisch Univrsitt Drmstdt, [13] Ki Rnz. Algorithms nd Dt Structurs for Music Nottion Systm bsd on GUIDO Music Nottion. PhD thsis, Tchnischn Univrsität Drmstdt, [14] Jsmin Blnchtt nd Mrk Summrfild. C++ GUI Progrmming with Qt 4 (2nd Edition). Prntic Hll, 2008.