Am 22.09.24 um 09:06 schrieb Peter Münster:
On Sat, Sep 21 2024, Henning Hraban Ramm wrote:
How can a converter function access …
– the final (scaled) size of a placed image
Hi,
I use "figures.current().request" in my module (here attached).
– the original pixel size of an image ?
I use img.scan() for that.
Hi Peter,
are you sure that your code works with LMTX?
Find attached my version.
It seems to work, but only for the first instance of an image, not for
different sizes of the same image – makes sense WRT efficiency, but
might give wrong results for some uses.
Here’s my test code:
"""
\loadluafile[grph-downsample.lua]
\setupexternalfigure[
location={local,global,default},
conversion=lowres.jpg,
resolution=20,
]
\starttext
\useexternalfigure[zapf][https://upload.wikimedia.org/wikipedia/commons/d/dd/Hermann_Zapf_signing.jpg]
\useexternalfigure[lino][https://upload.wikimedia.org/wikipedia/commons/b/bd/Linotype-vorne-deutsches-museum.jpg]
\externalfigure[zapf][width=.5tw]
\externalfigure[lino][height=.3th]
\externalfigure[zapf][height=.5th]
\stoptext
"""
Hrabanif not modules then modules = { } end modules ['grph-downsample'] = {
version = 1.103,
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"
}
local format = string.format
local report = logs.reporter("DOWNSAMPLE")
local function sample_down(oldname, newname, resolution)
report("sample_down %s to %s (%s)", oldname, newname, resolution)
local request = figures.current().request
-- this is probably the original pixel size
local width = request.width
local height = request.height
-- width/height are integer in sp or a boolean
local TEXpt = 65536
local inch = 72.27
if resolution == "" then -- or (not width and not height) then
report("Nothing to do (missing resolution): %s, %s, %s dpi, %s x %s px",
oldname, newname, resolution, width, height)
return
else
report("Requested: %s, %s, %s dpi, %s x %s px", oldname, newname,
resolution, width, height)
end
-- MkIV:
-- local image = img.scan{filename = oldname}
-- LMTX:
local image = figures.getinfo(oldname,1)
image = image.status.private
local xy = image.xsize / image.ysize -- size ratio
if (not width and not height) then
-- no size requested? use default width
-- probably wrong…
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)
report("image size %dx%dpx. requested %dx%dpt at %ddpi.", image.xsize,
image.ysize, width, height, resolution)
local xsize = math.floor(resolution * width / inch)
local ysize = math.floor(resolution * height / inch)
report("resize %dx%dpx to %dx%dpx:", image.xsize, image.ysize, xsize, ysize)
if xsize < image.xsize or ysize < image.ysize then
-- maybe add a tolerance of 20% (don’t downsample if the difference is
marginal)
local s = format("gm convert -resize %dx%d -resample %dx%d \"%s\" \"%s\"",
xsize, ysize, resolution, resolution, oldname, newname)
report("calling: %s", s)
os.execute(s)
else
report("Nothing to do (image smaller than requested): %s, %s, %s dpi, %d x
%d px", oldname, newname, resolution, width, height)
report("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 {}
-- use \setupexternalfigure[conversion=lowres.jpg]:
figures.converters[s]["lowres." .. s] = sample_down
-- use without setup:
--figures.converters[s].default = sample_down
--figures.converters[s].pdf = sample_down -- gets used
end
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