Re: drops module (draft)

[Hans Hagen <pragma@wxs.nl>]

On 12/6/2012 7:05 PM, Aditya Mahajan wrote:

> I always thought that shadows were possible to do in PDF (after all TikZ
> does it using some type of PDF primitives). Since you are the PDF
> expert, I am interested in knowing why you choose to go the ImageMagic
> route.

not so efficient but it shows a bit what bitmaps can do

\starttext

\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

\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

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                                           Hans Hagen | PRAGMA ADE
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                                              | www.pragma-pod.nl
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