Background using Image Overlay

Background using Image Overlay

[Syed N Haider]

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Hi All
I am new to the Metapost and Context world, and need some help regarding
the inclusion of Metapost graphics in ConTeXt documents. I am trying a very
simple approach, using a graphic as a background. Here's my sample (using a
very basic metapost graphic as a page background in a document):

Metapost:
========
beginfig(0);
theta := 360/7;
radius := 1in;
z0 = origin;
z1 = z0 + dir(90)*radius;
z2 = z0 + dir(90 + theta)*radius;
z3 = z0 + dir(90 + 2*theta)*radius;
z4 = z0 + dir(90 + 3*theta)*radius;
z5 = z0 + dir(90 + 4*theta)*radius;
z6 = z0 + dir(90 + 5*theta)*radius;
z7 = z0 + dir(90 + 6*theta)*radius;
draw z1 -- z2 -- z3 -- z4 -- z5 -- z6 -- z7
-- cycle;
endfig;
end;



ConTeXt (after running mpost on the metapost graphic to generate  the
hexagon.0 file):
=====================================================================

\defineoverlay
[backg]
[{\externalfigure[hexagon.0][width=\overlaywidth,height=\overlayheight]}]

\starttext
\noheaderandfooterlines
\setupbackgrounds[page][background=backg]
%\placefigure
%{none}
%{\externalfigure[hexagon.0][width=12cm]}
\stoptext




Thanks in advance

Syed

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webpage  : http://www.pragma-ade.nl / http://tex.aanhet.net
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Re: Background using Image Overlay

[Wolfgang Schuster]

Am 08.11.2011 um 04:45 schrieb Syed N Haider:

> Hi All
> I am new to the Metapost and Context world, and need some help regarding the inclusion of Metapost graphics in ConTeXt documents. I am trying a very simple approach, using a graphic as a background. Here's my sample (using a very basic metapost graphic as a page background in a document):
> 
> Metapost:
> ========
> beginfig(0);
> theta := 360/7;
> radius := 1in;
> z0 = origin;
> z1 = z0 + dir(90)*radius;
> z2 = z0 + dir(90 + theta)*radius;
> z3 = z0 + dir(90 + 2*theta)*radius;
> z4 = z0 + dir(90 + 3*theta)*radius;
> z5 = z0 + dir(90 + 4*theta)*radius;
> z6 = z0 + dir(90 + 5*theta)*radius;
> z7 = z0 + dir(90 + 6*theta)*radius;
> draw z1 -- z2 -- z3 -- z4 -- z5 -- z6 -- z7
> -- cycle;
> endfig;
> end;
> 
> 
> 
> ConTeXt (after running mpost on the metapost graphic to generate  the hexagon.0 file):
> =====================================================================
> 
> \defineoverlay
> [backg]
> [{\externalfigure[hexagon.0][width=\overlaywidth,height=\overlayheight]}]
> 
> \starttext
> \noheaderandfooterlines
> \setupbackgrounds[page][background=backg]
> %\placefigure
> %{none}
> %{\externalfigure[hexagon.0][width=12cm]}
> \stoptext

With ConTeXt you can include your MetaPost code in the document and the graphic is generated at runtime.

\startuseMPgraphic{hexagon}
theta := 360/7;
radius := 1in;
z0 = origin;
z1 = z0 + dir(90)*radius;
z2 = z0 + dir(90 + theta)*radius;
z3 = z0 + dir(90 + 2*theta)*radius;
z4 = z0 + dir(90 + 3*theta)*radius;
z5 = z0 + dir(90 + 4*theta)*radius;
z6 = z0 + dir(90 + 5*theta)*radius;
z7 = z0 + dir(90 + 6*theta)*radius;
draw (z1 -- z2 -- z3 -- z4 -- z5 -- z6 -- z7 -- cycle) xysized(OverlayWidth,OverlayHeight) ;
\stopuseMPgraphic

\defineoverlay[hexagon][\useMPgraphic{hexagon}]

\setupbackgrounds[page][background=hexagon]

\starttext
\page[empty]
\stoptext

For more information about MetaPost graphics take a look into the MetaFun manual (http://pragma-ade.com/show-man-7.htm) which provides many examples.

Wolfgang
___________________________________________________________________________________
If your question is of interest to others as well, please add an entry to the Wiki!

maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context
webpage  : http://www.pragma-ade.nl / http://tex.aanhet.net
archive  : http://foundry.supelec.fr/projects/contextrev/
wiki     : http://contextgarden.net
___________________________________________________________________________________