Colors and pictures in plain LuaTeX
Colors and pictures in plain LuaTeX
As Knuths TeX had no support for colors or pictures, we have to make our own macros for that. The following macros are perhaps a bit simple, but that also means being easy to adapt to different needs and situations.
Images can be placed with an \image{<file>} macro. It can be preceeded with \imageheight or \imagewidth to set dimensions. If a dimension is set to 0pt, the natural size of the image is used. This is very similar to how it's done in Opmac/OpTeX.
\newdimen\imagewidth \imagewidth=0pt % 0pt gives natural size of image
\newdimen\imageheight \imageheight=0pt
\newtoks\imagedir \imagedir{} % Must end with /, e.g. mypics/
\def\image#1{%
\hbox{%
\saveimageresource
\ifdim\imagewidth=0pt \else width\imagewidth\fi
\ifdim\imageheight=0pt \else height\imageheight\fi
{\the\imagedir#1}%
\useimageresource\lastsavedimageresourceindex
}%
}
% Example: {\imageheight=4cm \image{mypicture.png}}
Colors can be set like this:
% Token for \aftergroup to reset color
\def\colorstackpop{\pdfextension colorstack 0 pop}
% Switch to CMYK color in current group. Expects four values between 0 and 1
\def\setcmykcolor#1{%
\pdfextension colorstack 0 push {#1 k #1 K}%
\aftergroup\colorstackpop
}
% Switch to RGB color in current group. Expects three values between 0 and 1
\def\setrgbcolor#1{%
\pdfextension colorstack 0 push {#1 rg #1 RG}%
\aftergroup\colorstackpop
}
% Color names
\def\black{\setcmykcolor{0 0 0 1}}
\def\blue{\setcmykcolor{1 1 0 0}}
\def\red{\setrgbcolor{0.8 0 0}}
% Example: {\blue This is blue text}
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