Changes

* John Hobby's page: http://cm.bell-labs.com/who/hobby/MetaPost.html* Current development: http://foundry.supelec.fr/projects/metapost/ MetaPost is a graphical programming language, based on Donald Knuth's MetaFont. Normally MP graphics are converted to PostScript and used with dvips, but ConTeXt can use it directly with PDF (see the[http://www.pragma-ade.com/general/sources/mptopdf.pdf MPtoPDFMP to PDF]manual). MetaPost is ConTeXt's "native" graphics mode, see [[MetaFun]].

* [http://www.ctan.org/tex-archive/graphics/metapost/contrib/macros/metaobj/ MetaObj] - object-oriented drawing, see also the page about [[MetaObj and Labels]]

== Using MP Testing plain MetaPost ==To test whether MetaPost is installed on your system, create a file called {{code|test.mp}}:  beginfig(1) draw fullcircle scaled 3cm ; endfig ; end ; * apply MetaPost on the testfile  mp test.mp or mpost test.mp * that should create a postscript file test.1* open test.1 with a postscript viewer like Ghostview, Okular, … You should see a circle. == Testing MetaPost embedded in ConTeXt == If MetaPost is installed on your system and working correctly, you can   \starttext \startMPcode draw fullcircle scaled 3cm; \stopMPcode \stoptext * for mkii you need to have write18 support enabled and run texexec --pdf test.tex * for mkiv run context test.tex * that should create a pdf file test.pdf* open test.pdf with a pdf viewer like Adobe Acrobat, Okular... You should see a circle. == Text in MetaPost == Text that is typeset using `textext` or `btex … etex` adapts to the body font. However, when `label("Foo", pair)` or `"Foo" infont defaultfont` is used, which is not the recommended way, the text is typeset using the font `MetafunDefault`, which can be changed if desired. Example: <context mode="mkiv" source="yes" text="Gives:">\starttext \startMPcode label("Foo", origin); draw textext("Bar") yshifted -LineHeight; \stopMPcode  \definefontsynonym [MetafunDefault] [Bold*default]  \switchtobodyfont [pagella, 18pt]  \startMPcode label("Foo", origin); draw textext("Foo") yshifted -LineHeight; \stopMPcode\stoptext</context> The first recommended way to typeset text is to use the `textext` macro and change the font using {{cmd |setupMPinstance}}. == Repetition of a Text Element to Fill a Bar Using textext == Imagine you want to create a frame which consists out of one glyph or a combination of different glyphs in order to make a decorative border. For this purpose a usable graphicseries of such elements should be placed on the bar as pictures, evenly spaced. Such Probably you want to have at the end of the bar a graphic different glyph inserted as a picture too. The following code is calculated anew each time it working but the last picture is usednot the expected glyph. An exampleOne would expect 14 times the "?" and at the end of the bar a "*": <context mode="mkiv" source="yes" text="Gives:">\starttext \startMPpage picture PicA ; PicA := textext("*"); picture PicB ; PicB := textext("?");  numeric Step ; Step := 2cm div bbwidth(PicB) ;  for i = 1 upto Step : draw PicB shifted (i*5mm,0) ; endfor ; draw PicA ; \stopMPpage\stoptext</context> What you get is 15 "?" but no "*"!

In order to get this corrected one needs to calculate the boundingbox of the "?" on beforehand. Hans Hagen provided this solution on 14-10-2014. <context mode="mkiv" source="yes" text="Gives:">\starttext \startMPcalculation path PicX ; PicX := boundingbox textext("?") ; \stopMPcalculation  \startMPpage picture PicA ; PicA := textext("*"); picture PicB ; PicB := textext("?");  numeric Step ; Step := 2cm div bbwidth(PicX) ; % numeric Step ; Step := 2cm div bbwidth(PicB) ;  for i = 1 upto Step : draw PicB shifted (i*5mm,0) ; endfor ; draw PicA ; \stopMPpage\stoptext </context> Now you get 14 "?" and the "*". === A Full Example === <texcodecontext mode="mkiv" source="yes" text="Gives:">\startuseMPgraphicsetupbodyfont[8pt] \defineoverlay[Myframe][\reuseMPgraphic{nameFrame}] fill \setuppapersize[A8][A8] \setuplayout [topspace=5mm, backspace=5mm, height=middle, width=middle, header=0pt, footer=0pt] \starttext % ======== Definition of the frame in Metafun ==========\startMPcalculation path PicX ; PicX := boundingbox textext("= : =") ;\stopMPcalculation \startreusableMPgraphic{Frame} numeric u,v,xshift,yshift,picwidth,remnant,nelements;  u := OverlayWidth; v := OverlayHeight; path p,w; p := unitsquare xscaled u yscaled v; w := fullcircle scaled 5cm withcolor 8pt; picture Edgepic,Linepic[]; color edgedotcolor,linelementcolorA; edgedotcolor := blue; linelementcolorA := red;  Linepic[1] := textext("\stopuseMPgraphicrotate[rotation=90]{= : =}"); Linepic[2] := textext("= : ="); Edgepic := textext("o"); %Calculations for the horizontal frame-element placement: % In order to make this work, the width of the line element needs to be calculated on beforehand. % path PicX; PicX := textext(")("); picwidth := bbwidth(PicX); nelements := u div picwidth; remnant := u mod picwidth; xshift := picwidth + remnant/nelements;   Linepic[3] := Linepic[2] shifted (0.5*picwidth,0);

\useMPgraphic{name} for a = llcorner p, ulcorner p :< for i = 1 upto nelements : draw Linepic[3] shifted ((xpart a + (i-1)*xshift),ypart a) withcolor linelementcolorA; endfor; endfor; %Calculations for the vertical frame-element placement: picheight := bbwidth(PicX); nelements := v div picheight; remnant := v mod picheight; yshift := picheight + remnant/texcode>nelements; Linepic[4]:= Linepic[1] shifted (0,0.5*picheight); for a = llcorner p, lrcorner p : for i = 1 upto nelements: draw Linepic[4] shifted (xpart a,ypart a + (i-1)*yshift) withcolor linelementcolorA; endfor; endfor;

As said for i = llcorner p, this graphic is calculated each time it is placedlrcorner p, which can be time consuming. Apart from the time aspectulcorner p, this also means that the graphic itself is incorporated many times. Thereforeurcorner p : fill w shifted (xpart i, for graphics that don’t changeypart i) withcolor white; draw Edgepic shifted (xpart i, CONTEXT provides reusable graphics:ypart i) withcolor edgedotcolor; endfor;

<texcode>\startreusableMPgraphic{name}% For frame-element positioning checking:% fill fullcircle scaled 200pt withcolor .625yellowdraw p;%

See also section 3\startframedtext [width=0.3 of [[manual:metafun-s8\textwidth,height=0.pdf|MetaFun manual]8\textheight,frame=off,background=Myframe, align={middle,lohi}] The butterfly counts not months but moments, and has time enough. \blank {\tfx Rabindranath Tagore}\stopframedtext\stoptext