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diff --git a/doc/context/sources/general/manuals/metafun/metafun-layout.tex b/doc/context/sources/general/manuals/metafun/metafun-layout.tex new file mode 100644 index 000000000..2be7e19ff --- /dev/null +++ b/doc/context/sources/general/manuals/metafun/metafun-layout.tex @@ -0,0 +1,990 @@ +% language=uk +% +% copyright=pragma-ade readme=readme.pdf licence=cc-by-nc-sa + +\startcomponent metafun-layout + +\environment metafun-environment + +\startchapter[title={Enhancing the layout}] + +\startintro + +One of the most powerful and flexible commands of \CONTEXT\ is \type {\framed}. +We can use the background features of this command to invoke and position +graphics that adapt themselves to the current situation. Once understood, +overlays will become a natural part of the \CONTEXT\ users toolkit. + +\stopintro + +\startsection[title={Overlays}] + +\index{overlays} + +Many \CONTEXT\ commands support overlays. The term {\em overlay} is a bit +confusing, since such an overlay in most cases will lay under the text. However, +because there can be many layers on top of each other, the term suits its +purpose. + +When we want to put a \METAPOST\ graphic under some text, we go through a three +step process. First we define the graphic itself: + +\startbuffer +\startuniqueMPgraphic{demo circle} + path p ; + p := fullcircle xscaled \overlaywidth yscaled \overlayheight ; + fill p withcolor .85white ; + draw p withpen pencircle scaled 2pt withcolor .625red ; +\stopuniqueMPgraphic +\stopbuffer + +\typebuffer + +\getbuffer + +This graphic will adapt itself to the width and height of the overlay. Both \type +{\overlaywidth} and \type {\overlayheight} are macros that return a dimension +followed by a space. The next step is to register this graphic as an overlay. + +\startbuffer +\defineoverlay[demo circle][\uniqueMPgraphic{demo circle}] +\stopbuffer + +\typebuffer + +\getbuffer + +We can now use this overlay in any command that provides the \type {\framed} +functionality. Since this graphic is defined as unique, \CONTEXT\ will try to +reuse already calculated and embedded graphics when possible. + +\startbuffer +\framed[background=demo circle]{This text is overlayed.} +\stopbuffer + +\typebuffer + +The background can be set to \type {color}, \type {screen}, an overlay +identifier, like \typ {demo circle}, or a comma separated list of those. + +\startlinecorrection[blank] +\getbuffer +\stoplinecorrection + +The \type {\framed} command automatically draws a ruled box, which can be quite +useful when debugging a graphic. However, in this case we want to turn the frame +off. + +\startbuffer +\framed + [background=demo circle,frame=off] + {This text is overlayed.} +\stopbuffer + +\typebuffer + +\startlinecorrection[blank] +\getbuffer +\stoplinecorrection + +In this case, it would have made sense to either set the \type {offset} to a +larger value, or to set \type {backgroundoffset}. In the latter case, the ellipse +is positioned outside the frame. + +The difference between the three offsets \type {offset}, \type {frameoffset} and +\type {backgroundoffset} is demonstrated in \in {figure} [fig:offsets]. While the +\type {offset} is added to the (natural or specified) dimensions of the content +of the box, the other two are applied to the frame and background and don't add +to the dimensions. + +In the first row we only set the \type {offset}, while in the second row, the +(text) offset is set to \type {3pt}. When not specified, the \type {offset} has a +comfortable default value of \type {.25ex} (some 25\% of the height of an~x). + +\startbuffer +\setupframed + [width=.3\textwidth, + background=demo circle] +\startcombination[3*3] + {\framed[offset=none] {\TeX}} {\tt offset=none} + {\framed[offset=overlay] {\TeX}} {\tt offset=overlay} + {\framed[offset=0pt] {\TeX}} {\tt offset=0pt} + {\framed[offset=1pt] {\TeX}} {\tt offset=1pt} + {\framed[offset=2pt] {\TeX}} {\tt offset=2pt} + {\framed[offset=4pt] {\TeX}} {\tt offset=4pt} + {\framed[offset=3pt] {\TeX}} {\tt offset=3pt} + {\framed[frameoffset=3pt] {\TeX}} {\tt frameoffset=3pt} + {\framed[backgroundoffset=3pt]{\TeX}} {\tt backgroundoffset=3pt} +\stopcombination +\stopbuffer + +\typebuffer + +\placefigure + [here][fig:offsets] + {The three offsets.} + {\getbuffer} + +As the first row in \in {figure} [fig:offsets] demonstrates, instead of a value, +one can pass a keyword. The \type {overlay} keyword implies that there is no +offset at all and that the lines cover the content. With \type {none} the frame +is drawn tight around the content. When the offset is set to \type {0pt} or more, +the text is automatically set to at least the height of a line. You can turn this +feature off by saying \type {strut=off}. More details can be found in the +\CONTEXT\ manual. + +In \in {figure} [fig:all offsets] we have set {offset} to \type {3pt}, \type +{frameoffset} to \type {6pt} and \type {backgroundoffset} to \type {9pt}. Both +the frame and background offset are sort of imaginary, since they don't +contribute to the size of the box. + +\startbuffer +\ruledhbox + {\framed + [offset=3pt,frameoffset=6pt,backgroundoffset=9pt, + background=screen,backgroundscreen=.85] + {Welcome in the hall of frame!}} +\stopbuffer + +\typebuffer + +\placefigure + [here][fig:all offsets] + {The three offsets.} + {\getbuffer} + +\stopsection + +\startsection[title={Overlay variables}] + +The communication between \TEX\ and embedded \METAPOST\ graphics takes place by +means of some macros. + +\starttabulate[|l|p|] +\HL +\NC overlay status macro \NC meaning \NC \NR +\HL +\NC \tex {overlaywidth} \NC the width of the graphic, as + calculated from the actual + width and background offset \NC \NR +\NC \tex {overlayheight} \NC the height of the graphic, as + calculated from the actual + height, depth and background + offset \NC \NR +\NC \tex {overlaydepth} \NC the depth of the graphic, if + available \NC \NR +\NC \tex {overlaycolor} \NC the background color, if given \NC \NR +\NC \tex {overlaylinecolor} \NC the color of the frame \NC \NR +\NC \tex {overlaylinewidth} \NC the width of the frame \NC \NR +\HL +\stoptabulate + +The dimensions of the overlay are determined by dimensions of the background, +which normally is the natural size of a \type {\framed}. When a background offset +is specified, it is added to \type {overlayheight} and \type {overlaywidth}. + +Colors can be converted by \type {\MPcolor} and in addition to the macros +mentioned, you can use all macros that expand into a dimension or dimen register +prefixed by the \TEX\ primitive \type {\the} (this and other primitives are +explained in \quotation {The \TeX book}, by Donald Knuth). + +\stopsection + +\startsection[title={Stacking overlays}] + +A background can be a gray scale (\type {screen}), a color (\type {color}), a +previously defined overlay identifier, or any combination of these. The next +assignments are therefore valid: + +\starttyping +\framed[background=color,backgroundcolor=red]{...} +\framed[background=screen,backgroundscreen=.8]{...} +\framed[background=circle]{...} +\framed[background={color,cow},backgroundcolor=red]{...} +\framed[background={color,cow,grid},backgroundcolor=red]{...} +\stoptyping + +In the last three cases of course you have to define \type {circle}, \type {cow} +and \type {grid} as overlay. These items are packed in a comma separated list, +which has to be surrounded by \type {{}}. + +\stopsection + +\startsection[title={Foregrounds}] + +\startbuffer[a] +\startuniqueMPgraphic{backfore} + draw fullcircle + xscaled \overlaywidth yscaled \overlayheight + withpen pencircle scaled 2pt + withcolor .625yellow ; +\stopuniqueMPgraphic + +\defineoverlay[backfore][\uniqueMPgraphic{backfore}] +\stopbuffer + +\startbuffer[b] +\framed + [background=backfore,backgroundoffset=4pt] + {one, two, three, \unknown} +\stopbuffer + +\startbuffer[c] +\framed + [background={foreground,backfore},backgroundoffset=4pt] + {one, two, three, \unknown} +\stopbuffer + +The overlay system is actually a system of layers. Sometimes we are confronted +with a situation in which we want the text behind another layer. This can be +achieved by explicitly placing the foreground layer, as in \in {figure} +[fig:foreground]. + +\getbuffer[a] + +\placefigure + [here][fig:foreground] + {Foreground material moved backwards.} + {\setupframed[linewidth=1pt]% + \startcombination + {\getbuffer[b]} {frame on top layer} + {\getbuffer[c]} {frame on bottom layer} + \stopcombination} + +The graphic layer is defined as follows: + +\typebuffer[a] + +The two framed texts have a slightly different definition. The leftmost graphic +is defined as: + +\typebuffer[b] + +The rightmost graphic is specified as: + +\typebuffer[c] + +The current values of the frame color and frame width are passed to the overlay. +It often makes more sense to use colors defined at the document level, if only to +force consistency. + +\startbuffer +\startuniqueMPgraphic{super ellipse} + path p ; p := unitsquare + xscaled \overlaywidth yscaled \overlayheight + superellipsed .85 ; + pickup pencircle scaled \overlaylinewidth ; + fill p withcolor \MPcolor{\overlaycolor} ; + draw p withcolor \MPcolor{\overlaylinecolor} ; +\stopuniqueMPgraphic + +\defineoverlay[super ellipse][\uniqueMPgraphic{super ellipse}] +\stopbuffer + +\typebuffer \getbuffer + +This background demonstrates that a super ellipse is rather well suited as frame. + +\startbuffer +\framed + [background=super ellipse, + frame=off, + width=3cm, + align=middle, + framecolor=darkyellow, + rulethickness=2pt, + backgroundcolor=darkgray] + {\white This is a\\Super Ellipsed\\sentence.} +\stopbuffer + +\typebuffer + +Such a super ellipse looks quite nice and is a good candidate for backgrounds, +for which the superness should be at least~.85. + +\startlinecorrection[blank] +\getbuffer +\stoplinecorrection + +\stopsection + +\startsection[title={Typesetting graphics}] + +I have run into people who consider it kind of strange when you want to use \TEX\ +for non||mathematical typesetting. If you agree with them, you may skip this +section with your eyes closed. + +One of the \CONTEXT\ presentation styles (number 15, tagged as balls) stepwise +builds screens full of sentences, quotes or concepts, packages in balloons and +typesets them as a paragraph. We will demonstrate that \TEX\ can typeset graphics +using the following statement. + +% \let\processword\relax + +\startbuffer[lions] +\processwords{As you may know, \TEX's ambassador is a lion, while {\METAFONT} +is represented by a lioness. It is still unclear if they have a relationship, +but if so, and if a cub is born, may it enjoy \METAFUN.} +\stopbuffer + +\startquotation +\def\processwords#1{#1}\getbuffer[lions] +\stopquotation + +The low level \CONTEXT\ macro \type {\processwords} provides a mechanism to treat +the individual words of its argument. The macro is called as follows: + +\typebuffer[lions] + +In order to perform a task, you should also define a macro \type {\processword}, +which takes one argument. The previous quote was typeset with the following +definition in place: + +\starttyping +\def\processword#1{#1} +\stoptyping + +A slightly more complicated definition is the following: + +\startbuffer +\def\processword#1{\noindent\framed{#1}\space} +\stopbuffer + +\typebuffer \getbuffer + +We now get: + +\blank\getbuffer[lions]\blank + +If we can use \type {\framed}, we can also use backgrounds. + +\startbuffer +\def\processword#1% + {\noindent\framed[frame=off,background=lions]{#1} } +\stopbuffer + +\typebuffer \getbuffer + +We can add a supperellipsed frame using the following definition: + +\startbuffer +\startuniqueMPgraphic{lions a} + path p ; p := fullsquare + xyscaled (\overlaywidth,\overlayheight) superellipsed .85 ; + pickup pencircle scaled 1pt ; + fill p withcolor .850white ; draw p withcolor .625yellow ; +\stopuniqueMPgraphic + +\defineoverlay[lions][\uniqueMPgraphic{lions a}] +\stopbuffer + +\typebuffer \getbuffer + +\bgroup \blank \veryraggedright\getbuffer[lions]\unskip \blank \egroup + +\startbuffer +\startuseMPgraphic{lions b} + path p ; p := fullsquare + xyscaled (\overlaywidth,\overlayheight) randomized 5pt ; + pickup pencircle scaled 1pt ; + fill p withcolor .850white ; draw p withcolor .625yellow ; +\stopuseMPgraphic + +\defineoverlay[lions][\uniqueMPgraphic{lions b}] +\stopbuffer + +\typebuffer \getbuffer + +\bgroup \blank \veryraggedcenter\getbuffer[lions]\unskip \blank \egroup + +\startbuffer +\startuniqueMPgraphic{lions c} + path p ; p := fullsquare + xyscaled (\overlaywidth,\overlayheight) squeezed 2pt ; + pickup pencircle scaled 1pt ; + fill p withcolor .850white ; draw p withcolor .625yellow ; +\stopuniqueMPgraphic + +\defineoverlay[lions][\uniqueMPgraphic{lions c}] +\stopbuffer + +\typebuffer \getbuffer + +\bgroup \blank \veryraggedleft\getbuffer[lions]\unskip \blank \egroup + +These paragraphs were typeset with the following settings. + +\starttyping +\setupalign[broad, right] % == \veryraggedright +\setupalign[broad, middle] % == \veryraggedcenter +\setupalign[broad, left] % == \veryraggedleft +\stoptyping + +The \type {broad} increases the raggedness. We defined three different graphics +(a, b and c) because we want some to be unique, which saves some processing. Of +course we don't reuse the random graphics. In the definition of \type +{\processword} we have to use \type {\noindent} because otherwise \TEX\ will put +each graphic on a line of its own. Watch the space at the end of the macro. + +\stopsection + +\startsection[title={Graphics and macros}] + +Because \TEX's typographic engine and \METAPOST's graphic engine are separated, +interfacing between them is not as natural as you may expect. In \CONTEXT\ we +have tried to integrate them as much as possible, but using the interface is not +always as convenient as it should be. What method you follow, depends on the +problem at hand. + +The official \METAPOST\ way to embed \TEX\ code into graphics is to use \typ +{btex ... etex}. As soon as \CONTEXT\ writes the graphic data to the intermediate +\METAPOST\ file, it looks for these commands. When it has encountered an \type +{etex}, \CONTEXT\ will make sure that the text that is to be typeset by \TEX\ is +{\em not} expanded. This is what you may expect, because when you would embed +those commands in a stand||alone graphic, they would also not be expanded, if +only because \METAPOST\ does not know \TEX. With expansion we mean that \TEX\ +commands are replaced by their meaning (which can be quite extensive). + +{\em Users of \CONTEXT\ MKIV\ can skip the next paragraph}. + +When \METAPOST\ sees a \type {btex} command, it will consult a so called \type +{mpx} file. This file holds the \METAPOST\ representation of the text typeset by +\TEX. Before \METAPOST\ processes a graphic definition file, it first calls +another program that filters the \type {btex} commands from the source file, and +generates a \TEX\ file from them. This file is then processed by \TEX, and after +that converted to a \type {mpx} file. In \CONTEXT\ we let \TEXEXEC\ take care of +this whole process. + +Because the \typ {btex ... etex} commands are filtered from the raw \METAPOST\ +source code, they cannot be part of macro definitions and loop constructs. When +used that way, only one instance would be found, while in practice multiple +instances may occur. + +This drawback is overcome by \METAFUN's \type {textext} command. This command +still uses \typ {btex ... etex} but writes these commands to a separate job +related file each time it is used. \footnote {It took the author a while to find +out that there is a \METAPOST\ module called \type {tex.mp} that provides a +similar feature, but with the disadvantage that each text results in a call to +\TEX. Each text goes into a temporary file, which is then included and results in +\METAPOST\ triggering \TEX.} After the first \METAPOST\ run, this file is merged +with the original file, and \METAPOST\ is called again. So, at the cost of an +additional run, we can use text typeset by \TEX\ in a more versatile way. Because +\METAPOST\ runs are much faster than \TEX\ runs, the price to pay in terms of run +time is acceptable. Unlike \typ {btex ... etex}, the \TEX\ code in \type +{textext} command is expanded, but as long as \CONTEXT\ is used this is seldom a +problem, because most commands are somewhat protected. + +If we define a graphic with text to be typeset by \TEX, there is a good chance +that this text is not frozen but passes as argument. A \TEX||like solution for +passing arbitrary content to such a graphic is the following: \footnote {The \type +{\unexpanded} prefix makes the command robust for being passed as argument. It is not +to be confused with the primitive. We had this feature already when the primitive +showed up and it was considered to be inconvenient for other macro packages to adapt to +the \CONTEXT\ situation. So keep that in mind when you mix macro packages.} + +\startbuffer[def] +\unexpanded\def\RotatedText#1#2% + {\startuseMPgraphic{RotatedText} + draw btex #2 etex rotated #1 ; + \stopuseMPgraphic + \useMPgraphic{RotatedText}} +\stopbuffer + +\typebuffer[def] \getbuffer[def] + +This macro takes two arguments (the \type {#} identifies an +argument): + +\startbuffer[exa] +\RotatedText{15}{Some Rotated Text} +\stopbuffer + +\typebuffer[exa] + +The text is rotated over 15 degrees about the origin in a counterclockwise +direction. + +\startlinecorrection[blank] +\getbuffer[exa] +\stoplinecorrection + +In \CONTEXT\ we seldom pass settings like the angle of rotation in this manner. +You can use \type {\setupMPvariables} to set up graphic||specific variables. Such +a variable can be accessed with \type {\MPvar}. + +\startbuffer[def] +\setupMPvariables[RotatedText][rotation=90] + +\startuseMPgraphic{RotatedText} + draw textext{Some Text} rotated \MPvar{rotation} ; +\stopuseMPgraphic +\stopbuffer + +\typebuffer[def] \getbuffer[def] + +An example: + +\startbuffer[exa] +\RotatedText{-15}{Some Rotated Text} +\stopbuffer + +\typebuffer[exa] + +\startlinecorrection[blank] +\getbuffer[exa] +\stoplinecorrection + +In a similar fashion we can isolate the text. This permits us to use the same +graphics with different settings. + +\startbuffer[def] +\setupMPvariables[RotatedText][rotation=270] + +\setMPtext{RotatedText}{Some Text} + +\startuseMPgraphic{RotatedText} + draw \MPbetex{RotatedText} rotated \MPvar{rotation} ; +\stopuseMPgraphic +\stopbuffer + +\typebuffer[def] \getbuffer[def] + +This works as expected: + +\startbuffer[exa] +\RotatedText{165}{Some Rotated Text} +\stopbuffer + +\typebuffer[exa] + +\startlinecorrection[blank] +\getbuffer[exa] +\stoplinecorrection + +It is now a small step towards an encapsulating macro (we assume that you are +familiar with \TEX\ macro definitions). + +\startbuffer[def] +\def\RotatedText[#1]#2% + {\setupMPvariables[RotatedText][#1]% + \setMPtext{RotatedText}{#2}% + \useMPgraphic{RotatedText}} + +\setupMPvariables[RotatedText][rotation=90] + +\startuseMPgraphic{RotatedText} + draw \MPbetex{RotatedText} rotated \MPvar{rotation} ; +\stopuseMPgraphic +\stopbuffer + +\typebuffer[def] \getbuffer[def] + +Again, we default to a 90 degrees rotation, and pass both the settings and text +in an indirect way. This method permits you to build complicated graphics and +still keep macros readable. + +\startbuffer[exa] +\RotatedText[rotation=240]{Some Rotated Text} +\stopbuffer + +\typebuffer[exa] + +\startlinecorrection[blank] +\getbuffer[exa] +\stoplinecorrection + +You may wonder why we don't use the variable mechanism to pass the text. The main +reason is that the text mechanism offers a few more features, one of which is +that it passes the text straight on, without the danger of unwanted expansion of +embedded macros. Using \type {\setMPtext} also permits you to separate \TEX\ and +\METAPOST\ code and reuse it multiple times (imagine using the same graphic in a +section head command). + +There are three ways to access a text defined with \type {\setMPtext}. Imagine +that we have the following definitions: + +\startbuffer +\setMPtext {1} {Now is this \TeX\ or not?} +\setMPtext {2} {See what happens here.} +\setMPtext {3} {Text streams become pictures.} +\stopbuffer + +\typebuffer \getbuffer + +The \type {\MPbetex} macro returns a \typ {btex ... etex} construct. The \type +{\MPstring} returns the text as a \METAPOST\ string, between quotes. The raw text +can be fetched with \type {\MPtext}. + +\startbuffer +\startMPcode + picture p ; p := \MPbetex {1} ; + picture q ; q := textext( \MPstring{2} ) ; + picture r ; r := thelabel("\MPtext {3}",origin) ; + + for i=p, boundingbox p : draw i withcolor .625red ; endfor ; + for i=q, boundingbox q : draw i withcolor .625yellow ; endfor ; + for i=r, boundingbox r : draw i withcolor .625white ; endfor ; + + currentpicture := currentpicture scaled 2 ; + draw origin + withpen pencircle scaled 5.0mm withcolor white ; + draw origin + withpen pencircle scaled 2.5mm withcolor black ; + draw boundingbox currentpicture + withpen pencircle scaled .1mm + dashed evenly ; +\stopMPcode +\stopbuffer + +\typebuffer + +The first two lines return text typeset by \TEX, while the last line leaves this +to \METAPOST. + +\startlinecorrection[blank] +\getbuffer +\stoplinecorrection + +If you watch closely, you will notice that the first (red) alternative is +positioned with the baseline on the origin. + +\startbuffer +\startMPcode + picture p ; p := \MPbetex {1} ; + picture q ; q := textext.origin( \MPstring{2} ) ; + picture r ; r := thelabel.origin("\MPtext {3}",origin) ; + + for i=p, boundingbox p : draw i withcolor .625red ; endfor ; + for i=q, boundingbox q : draw i withcolor .625yellow ; endfor ; + for i=r, boundingbox r : draw i withcolor .625white ; endfor ; + + currentpicture := currentpicture scaled 2 ; + draw origin withpen pencircle scaled 5.0mm + withcolor white ; + draw origin withpen pencircle scaled 2.5mm + withcolor black ; + draw boundingbox currentpicture + withpen pencircle scaled .1mm + dashed evenly ; +\stopMPcode +\stopbuffer + +\typebuffer + +This draws: + +\startlinecorrection[blank] +\getbuffer +\stoplinecorrection + +This picture demonstrates that we can also position \type {textext}'s and \type +{label}'s on the baseline. For this purpose the repertoire of positioning +directives (\type {top}, \type {lft}, etc.) is extended with an \type {origin} +directive. Another extra positioning directive is \type {raw}. This one does not +do any positioning at all. + +\starttyping +picture q ; q := textext.origin( \MPstring{2} ) ; +picture r ; r := thelabel.origin("\MPtext {3}",origin) ; +\stoptyping + +We will now apply this knowledge of text inclusion in graphics to a more advanced +example. The next definitions are the answer to a question on the \CONTEXT\ +mailinglist with regards to framed texts with titles. + +\startbuffer[a] +\defineoverlay[FunnyFrame][\useMPgraphic{FunnyFrame}] + +\defineframedtext[FunnyText][frame=off,background=FunnyFrame] + +\def\StartFrame{\startFunnyText} +\def\StopFrame {\stopFunnyText } + +\def\FrameTitle#1% + {\setMPtext{FunnyFrame}{\hbox spread 1em{\hss\strut#1\hss}}} + +\setMPtext{FunnyFrame}{} % initialize the text variable +\stopbuffer + +\startbuffer[b] +\startuseMPgraphic{FunnyFrame} + picture p ; numeric w, h, o ; + p := textext.rt(\MPstring{FunnyFrame}) ; + w := OverlayWidth ; h := OverlayHeight ; o := BodyFontSize ; + p := p shifted (2o,h-ypart center p) ; draw p ; + drawoptions (withpen pencircle scaled 1pt withcolor .625red) ; + draw (2o,h)--(0,h)--(0,0)--(w,0)--(w,h)--(xpart urcorner p,h) ; + draw boundingbox p ; + setbounds currentpicture to unitsquare xyscaled(w,h) ; +\stopuseMPgraphic +\stopbuffer + +\startbuffer[c1] +\FrameTitle{Zapf (1)} + +\StartFrame +Coming back to the use of typefaces in electronic +publishing: many of the new typographers receive their +knowledge and information about the rules of typography from +books, from computer magazines or the instruction manuals +which they get with the purchase of a PC or software. +\StopFrame +\stopbuffer + +\getbuffer[a,b,c1] + +In this example, the title is positioned on top of the frame. Title and text are +entered as: + +\typebuffer[c1] + +The implementation is not that complicated and uses the frame commands that are +built in \CONTEXT. Instead of letting \TEX\ draw the frame, we use \METAPOST, +which we also use for handling the title. The graphic is defined as follows: + +\typebuffer[b] + +Because the framed title is partly positioned outside the main frame, and because +the main frame will be combined with the text, we need to set the boundingbox +explicitly. This is a way to create so called free figures, where part of the +figure lays beyond the area that is taken into account when positioning the +graphic. The shift + +\starttyping +... shifted (2o,h-ypart center p) +\stoptyping + +ensures that the title is vertically centered over the top line of the main box. + +The macros that use this graphic combine some techniques of defining macros, +using predefined \CONTEXT\ classes, and passing information to graphics. + +\typebuffer[a] + +There is a little bit of low level \TEX\ code involved, like a horizontal box +(\type {\hbox}) that stretches one em||space beyond its natural size (\type +{spread 1em}) with a centered text (two times \type {\hss}). Instead of applying +this spread, we could have enlarged the frame on both sides. + +\startbuffer[b] +\startuseMPgraphic{FunnyFrame} + picture p ; numeric o ; path a, b ; pair c ; + p := textext.rt(\MPstring{FunnyFrame}) ; + a := unitsquare xyscaled(OverlayWidth,OverlayHeight) ; + o := BodyFontSize ; + p := p shifted (2o,OverlayHeight-ypart center p) ; + drawoptions (withpen pencircle scaled 1pt withcolor .625red) ; + b := a randomized (o/2) ; + fill b withcolor .85white ; draw b ; + b := (boundingbox p) randomized (o/8) ; + fill b withcolor .85white ; draw b ; + draw p withcolor black; + setbounds currentpicture to a ; + \stopuseMPgraphic +\stopbuffer + +In the previous graphic we calculated the big rectangle taking the small one into +account. This was needed because we don't use a background fill. The next +definition does, so there we can use a more straightforward approach by just +drawing (and filling) the small rectangle on top of the big one. + +\typebuffer[b] \getbuffer[b] + +\startbuffer[c2] +\FrameTitle{Zapf (2)} + +\StartFrame +There is not so much basic instruction, as of now, as there +was in the old days, showing the differences between good +and bad typographic design. +\StopFrame +\stopbuffer + +\getbuffer[c2] + +Because we use a random graphic, we cannot guarantee beforehand that the left and +right edges of the small shape touch the horizontal lines in a nice way. The next +alternative displaces the small shape plus text so that its center lays on the +line. On the average, this looks better. + +\startbuffer[b] +\startuseMPgraphic{FunnyFrame} + picture p ; numeric o ; path a, b ; pair c ; + p := textext.rt(\MPstring{FunnyFrame}) ; + a := unitsquare xyscaled(OverlayWidth,OverlayHeight) ; + o := BodyFontSize ; + p := p shifted (2o,OverlayHeight-ypart center p) ; + drawoptions (withpen pencircle scaled 1pt withcolor .625red) ; + b := a randomized (o/2) ; + fill b withcolor .85white ; draw b ; + c := center p ; + c := b intersectionpoint (c shifted (0,-o)--c shifted(0,o)) ; + p := p shifted (c-center p) ; + b := (boundingbox p) randomized (o/8) ; + fill b withcolor .85white ; draw b ; + draw p withcolor black; + setbounds currentpicture to a ; + \stopuseMPgraphic +\stopbuffer + +\typebuffer[b] \getbuffer[b] + +\getbuffer[c2] + +Yet another definition uses super ellipsed shapes instead of random ones. We need +a high degree of superness (.95) in order to make sure that the curves don't +touch the texts. + +\startbuffer[b] +\startuseMPgraphic{FunnyFrame} + picture p ; numeric o ; path a, b ; pair c ; + p := textext.rt(\MPstring{FunnyFrame}) ; + o := BodyFontSize ; + a := unitsquare xyscaled(OverlayWidth,OverlayHeight) ; + p := p shifted (2o,OverlayHeight-ypart center p) ; + drawoptions (withpen pencircle scaled 1pt withcolor .625red) ; + b := a superellipsed .95 ; + fill b withcolor .85white ; draw b ; + b := (boundingbox p) superellipsed .95 ; + fill b withcolor .85white ; draw b ; + draw p withcolor black ; + setbounds currentpicture to a ; +\stopuseMPgraphic +\stopbuffer + +\typebuffer[b] \getbuffer[b] + +\startbuffer[c3] +\FrameTitle{Zapf (3)} + +\StartFrame +Many people are just fascinated by their PC's tricks, and +think that a widely||praised program, called up on the +screen, will make everything automatic from now on. +\StopFrame +\stopbuffer + +\getbuffer[c3] + +There are quite some hard coded values in these graphics, like the linewidths, +offsets and colors. Some of these can be fetched from the \type {\framed} +environment either by using \TEX\ macros or dimensions, or by using their +\METAFUN\ counterparts. In the following table we summarize both the available +\METAPOST\ variables and their \TEX\ counterparts. They may be used +interchangeably. + +\starttabulate[|l|Tl|l|] +\HL +\NC \bf \METAPOST\ variable \NC \rm \bf \TEX\ command \NC \bf meaning \NC\NR +\HL +\NC OverlayWidth \NC \string\overlaywidth + \NC current width \NC\NR +\NC OverlayHeight \NC \string\overlayheight + \NC current height \NC\NR +\NC OverlayDepth \NC \string\overlayheight + \NC current depth (often zero) \NC\NR +\NC OverlayColor \NC \string\MPcolor\string{\string\overlaycolor\string} + \NC background color \NC\NR +\NC OverlayLineWidth \NC \string\overlaylinewidth + \NC width of the frame \NC\NR +\NC OverlayLineColor \NC \string\MPcolor\string{\overlaylinecolor\string} + \NC color of the frame \NC\NR +\NC BaseLineSkip \NC \string\the\string\baselineskip + \NC main line distance \NC\NR +\NC LineHeight \NC \string\the\string\baselineskip + \NC idem \NC\NR +\NC BodyFontSize \NC \string\the\string\bodyfontsize + \NC font size of the running text \NC\NR +\NC StrutHeight \NC \string\strutheight + \NC space above the baseline \NC\NR +\NC StrutDepth \NC \string\strutdepth + \NC space below the baseline \NC\NR +\NC ExHeight \NC 1ex + \NC height of an x \NC \NR +\NC EmWidth \NC 1em + \NC width of an m-dash \NC \NR +\HL +\stoptabulate + +\startbuffer[b] +\startuseMPgraphic{FunnyFrame} + picture p ; numeric o ; path a, b ; pair c ; + p := textext.rt(\MPstring{FunnyFrame}) ; + o := BodyFontSize ; + a := unitsquare xyscaled(OverlayWidth,OverlayHeight) ; + p := p shifted (2o,OverlayHeight-ypart center p) ; + pickup pencircle scaled OverlayLineWidth ; + b := a superellipsed .95 ; + fill b withcolor OverlayColor ; + draw b withcolor OverlayLineColor ; + b := (boundingbox p) superellipsed .95 ; + fill b withcolor OverlayColor ; + draw b withcolor OverlayLineColor ; + draw p withcolor black ; + setbounds currentpicture to a ; +\stopuseMPgraphic +\stopbuffer + +\typebuffer[b] \getbuffer[b] + +\startbuffer[d] +\setupframedtexts + [FunnyText] + [backgroundcolor=lightgray, + framecolor=darkred, + rulethickness=2pt, + offset=\bodyfontsize, + before={\blank[big,medium]}, + after={\blank[big]}, + width=\textwidth] +\stopbuffer + +\getbuffer[d,c3] + +We used the following command to pass the settings: + +\typebuffer[d] + +In a real implementation, we should also take care of some additional spacing +before the text, which is why we have added more space before than after the +framed text. + +We demonstrated that when defining graphics that are part of the layout, you need +to have access to information known to the typesetting engine. Take \in {figure} +[fig:penalty]. The line height needs to match the font and the two thin +horizontal lines should match the {\em x}||height. We also need to position the +baseline, being the lowest one of a pair of lines, in such a way that it suits +the proportions of the line as specified by the strut. A strut is an imaginary +large character with no width. You should be aware of the fact that while \TEX\ +works its way top||down, in \METAPOST\ the origin is in the lower left corner. + +\startmode[screen] + +\placefigure + [page][fig:penalty] + {Penalty lines.} + {\typesetfile[mfun-902.tex][page=1,frame=on,height=.85\textheight]} + +\stopmode + +\startnotmode[screen] + +\placefigure + [here][fig:penalty] + {Penalty lines.} + {\typesetfile[mfun-902.tex][page=1,frame=on,height=.50\textheight]} + +\stopnotmode + +\typebuffer[handwrit] + +This code demonstrates the use of \type {LineHeight}, \type {ExHeight}, \type +{StrutHeight} and \type {StrutDepth}. We set the interline spacing to 1.5 so that +we get a bit more loose layout. The variables mentioned are set each time a +graphic is processed and thereby match the current font settings. + +\stopsection + +\stopchapter + +\stopcomponent |