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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]].

== Troubleshooting plain MetaPost ==* Test if MetaPost With {{cmd|startuseMPgraphic}}, you define a piece of graphics code that is processed anew every time the graphic is installed on your systemplaced with {{cmd|useMPgraphic}}. * create testFurther commands are described at [[MetaPost in ConTeXt]].mp containing this:

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.red: \useMPgraphic{name}

== Troubleshooting MetaPost embedded in ConTeXt == * create test.tex containing this:  \starttext \startMPcode draw fullcircle scaled 3cm ; def\stopMPcode mycolor{.625blue} blue: \stoptext  * for mkii you need to have write18 support enabled and run texexec --pdf test.tex useMPgraphic{name}* for mkiv run </context test.tex  * that should create a pdf file test.pdf* open test.pdf with a pdf viewer like acroread, okular... You should see a circle.>

* [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 in ConTeXt Testing plain MetaPost ==The first way To test whether MetaPost is installed on your system, create a usable graphicfile called {{code|test. Such a graphic is calculated anew each time it is used. An examplemp}}:

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: <texcodecontext mode="mkiv" source="yes" text="Gives:">\startuseMPgraphicstarttext \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 recommended way to typeset text is to use the `textext` macro and change the font using {{namecmd |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 series of such elements should be placed on the bar as pictures, evenly spaced. Probably you want to have at the end of the bar a different glyph inserted as a picture too.  fill fullcircle scaled 5cm withcolor redThe following code is working but the last picture is not the expected glyph. One 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 === <context mode="mkiv" source="yes" text="Gives:">\setupbodyfont[8pt] \defineoverlay[Myframe][\reuseMPgraphic{Frame}] \setuppapersize[A8][A8] \setuplayout [topspace=5mm, backspace=5mm, height=middle, width=middle, header=0pt, footer=0pt] \stopuseMPgraphicstarttext

% ======== Definition of the frame in Metafun ==========\startMPcalculation path PicX ; PicX := boundingbox textext("= : =") ;\stopMPcalculation \useMPgraphicstartreusableMPgraphic{nameFrame}</texcode> numeric u,v,xshift,yshift,picwidth,remnant,nelements;

As said u := OverlayWidth; v := OverlayHeight; path p, this graphic is calculated each time it is placedw; p := unitsquare xscaled u yscaled v; w := fullcircle scaled 8pt; picture Edgepic, which can be time consuming. Apart from the time aspectLinepic[]; color edgedotcolor, this also means that the graphic itself is incorporated many times. Therefore, for graphics that don’t change, CONTEXT provides reusable graphicslinelementcolorA; edgedotcolor := blue; linelementcolorA := red;

<texcode> Linepic[1] := textext("\startreusableMPgraphicrotate[rotation=90]{name= : =}"); fill fullcircle scaled 200pt withcolor 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.625yellow % path PicX; PicX := textext(")(");\stopreusableMPgraphic picwidth := bbwidth(PicX); nelements := u div picwidth; remnant := u mod picwidth; xshift := picwidth + remnant/nelements;

When reusing for a graphic is not so important and you just want to include something inline= llcorner p, you can also use 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 followingvertical frame-element placement: picheight := bbwidth(PicX); nelements := v div picheight; remnant := v mod picheight; yshift := picheight + remnant/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;

<texcode> for i = llcorner p, lrcorner p,ulcorner p,urcorner p :\startMPcode fill fullcircle scaled 200pt w shifted (xpart i,ypart i) withcolor .625yellowwhite;\stopMPcode draw Edgepic shifted (xpart i,ypart i) withcolor edgedotcolor;</texcode> endfor;

See also section 3.3 of [[manual% For frame-element positioning checking:metafun-s.pdf|MetaFun manual]].% draw p;%\stopreusableMPgraphic

% ======= Examples ===

\startframedtext [width=0.8\textwidth,height=0.8\textheight,frame=off,background=Myframe, align={{todo|Enable support for Metapost code when running ConTeXt online. This will allow easy creation of Metapost examplesmiddle,lohi}] The butterfly counts not months but moments, including both source code and resulted figurehas time enough. \blank {\tfx Rabindranath Tagore}}\stopframedtext\stoptext

<texcode>\startMPcode fill fullcircle scaled 200pt withcolor There is some strange cropping going on on the Wiki-implementation. Of course the left frame is in reality equal to the right frame...625yellow;\stopMPcode</texcode>