%%
%% Ein Beispiel der DANTE-Edition
%%
%% 1. Auflage
%%
%%
%% Copyright (C) 2013 Herbert Voss
%%
%% It may be distributed and/or modified under the conditions
%% of the LaTeX Project Public License, either version 1.3
%% of this license or (at your option) any later version.
%%
%% See
http://www.latex-project.org/lppl.txt for details.
%%
%%
%% ====
% Show page(s) 1
%%
\input CTdefault.tex
%StartShownPreambleCommands
\startluacode
local format = string.format
local concat = table.concat
function document.TestBitmap(nx,ny)
nx = math.round(nx/65536)
ny = math.round(ny/65536)
nx = 2 * math.round(nx/2)
ny = 2 * math.round(ny/2)
local r = { }
local dx = 255/nx
local dy = 255/ny
for i=1,ny/2 do
local n = i*dy
local c = { }
for j=1,nx/2 do c[#c+1] = format("%02x",j*dx+n) end
for j=nx/2,1,-1 do c[#c+1] = format("%02x",j*dx+n) end
c = concat(c,"",1,nx)
r[#r+1] = c
end
for i=ny/2,1,-1 do
local n = i*dy
local c = { }
for j=1,nx/2 do c[#c+1] = format("%02x",j*dx+n) end
for j=nx/2,1,-1 do c[#c+1] = format("%02x",j*dx+n) end
c = concat(c,"",1,nx)
r[#r+1] = c
end
r = concat(r,"\r",1,ny)
figures.bitmapimage {data=r,xresolution=nx,yresolution=ny}
end
\stopluacode
%StopShownPreambleCommands
\starttext
\defineoverlay[BitMess][{\scale[width=\dimexpr\overlaywidth+2ex,
height=\dimexpr\overlayheight+2ex]{\ctxlua{%
document.TestBitmap(\number\dimexpr\overlaywidth,
\number\dimexpr\overlayheight)}}}]
\framed[width=10cm,height=10cm,frame=off,
background={BitMess,color},backgroundcolor=white]{test}
\stoptext
