I want to use the imagemagick
convert command to draw on a image file. I have the image data as raw-text in a buffer and now I would like to run
convert - -draw 'rectangle 0,0,100,100' - on it (the dashes tell convert to use stdin for input and print the data to stdout). If I leave out the
-draw 'rectangle 0,0,100,100' then I can just use
(call-process-region (point-min) (point-max) "convert" t t nil "-" "-") to pass the buffer contents as stdin to the convert program and insert the from
convert returned image data in the buffer (this does not do anything but it works, e.g. I could replace the last
- with a filename to write the resulting image data to a file). However now I want to add the
-draw 'rectangle 0,0,100,100' as an extra argument to
call-process-region but I really can not find (out) how to do this properly. For example I tried
(call-process-region (point-min) (point-max) "convert" t t nil "-" "-draw" "'rectangle 0,0,50,50'" "-") but then I get message
convert: non-conforming drawing primitive definition rectangle 0,0,50,50' @ error/draw.c/RenderMVGContent/4473.`
I tried to run it as a shell-command (i.e. using
/bin/bash -c)? But then I don't know how to pass the buffer contents as input.
So I would like to know how to properly pass the single-quotes string
'rectangle 0,0,100,100' to the command.
(FYI I would like to extend djvu.el to show annotations)