Re: setupexternalfigures and resoĺution

[Henning Hraban Ramm via ntg-context <ntg-context@ntg.nl>]

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Am 02.09.22 um 10:39 schrieb Keith McKay via ntg-context:
> Thanks for this code Hraban. I tried this last night and it worked 
> really well. I did have one stumbling block when I noticed that those 
> image files with a space in their names were not found, however 
> renaming  without a space solved the problem. Is this a bug or a feature?

The call to gm convert was lacking quoting of the file names. Fixed in 
attachment.

While the code does some downsampling, the calculation is not always 
right, because it doesn’t consider scaling (or something like that).

Hraban

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if not modules then modules = { } end modules ['grph-downsample'] = {
  version   = 1.101,
  comment   = "companion to grph-inc.mkiv",
  author    = "Peter Münster", -- adapted to LMTX by Hraban
  copyright = "PRAGMA ADE / ConTeXt Development Team",
  license   = "see context related readme files"
}

assert(not figures.getinfo2)

figures.getinfo2 = function(name, page) -- [ [NTG-context] Pdf info with Lua/Ctx API ]
 if type(name) == "string" then
   name = { name = name, page = page }
 end

 if name.name then
   local data = figures.push(name)
   local info = figures.identify()

   if info.status.status ~= 0 then
     figures.check() -- !Counts pages here!
   end

   figures.pop()

   return --data
          info
 end
end


local format = string.format
-- figures.cachepaths.path = "cache" -- should be setup-option
local function sample_down(oldname, newname, resolution)
  print("DOWNSAMPLE sample_down " .. oldname .. " to " .. newname)
  local request = figures.current().request
  local width = request.width
  local height = request.height
  if resolution == "" then -- or (not width and not height) then
    print(format("DOWNSAMPLE Nothing to do: %s, %s, %s dpi, %s x %s px", oldname, newname, resolution, width, height))
    return
  end
  local TEXpt = 65536
  local inch = 72.27

  -- MkIV:
  -- local image = img.scan{filename = oldname}

  -- LMTX:
  local image = figures.getinfo(oldname,1)
  image = image.status.private

  local xy = image.xsize / image.ysize
  if (not width and not height) then
    -- no size requested? use default width
    width = 300 * TEXpt
  end
  if not width then
    height = height / TEXpt
    width = height * xy
  end
  if not height then
    width = width / TEXpt
    height = width / xy
  end
  width = math.floor(width)
  height = math.floor(height)
  print(format("DOWNSAMPLE image size %dx%dpx. requested %dx%d?", image.xsize, image.ysize, width, height))
  local xsize = math.floor(resolution * width / inch)
  local ysize = math.floor(resolution * height / inch)
  print(format("DOWNSAMPLE size %d x %d to %d x %d", image.xsize, image.ysize, xsize, ysize))
  if xsize < image.xsize or ysize < image.ysize then
    local s = format("gm convert -resize %dx%d -resample %dx%d \"%s\" \"%s\"",
                     xsize, ysize, resolution, resolution, oldname, newname)
    print("DOWNSAMPLE Conversion: " .. s)
    os.execute(s)
  else
    print(format("DOWNSAMPLE Nothing to do: %s, %s, %s dpi, %d x %d px", oldname, newname, resolution, width, height))
    print(format("DOWNSAMPLE xsize = %d, ysize = %d", xsize, ysize))
  end
end

local formats = {"png", "jpg", "gif"}

for _, s in ipairs(formats) do
  figures.converters[s] = figures.converters[s] or {}
  figures.converters[s]["lowres." .. s] = sample_down
end

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