Hi Doug, At 2023-06-04T06:59:55-0400, Douglas McIlroy wrote: > >> Does anyone have a recipe for including a bitmap image in a groff > >> document? I wish to assure that on a raster-printing device the > >> bitmap is appropriately aligned with that of the device. > > > There is a PSPIC macro which is part of the MM macros (groff_mm) > > which I use to pull in a picture. > > I use PSPIC regularly. It is capable of scaling images, but this is > not the same as aligning bitmaps. I would like to assure that a > 1000x1000 bitmap, say, occupies exactly 1000x1000 pixels on the > display, regardless of the physical size of a pixel. A misaligned > bitmap produces unwanted artifacts such as. Moiré patterns. > > Of course, on a very high resolution device 1000x1000 pixels may be an > extreme eye test, but I can deal with that if necessary.
There doesn't appear to be a troff drawing command for this purpose, and no groff device control command tag for it, either. Maybe it would be a nice thing to have. According to this: https://stackoverflow.com/questions/15167454/how-include-img-in-postscript My guess is that you can wrap the guidance above into GNU troff's "ps: exec" device control command to get what you want. grops(1) says: Device control commands grops recognizes device control commands produced by the \X escape sequence, but interprets only those that begin with a "ps:" tag. \X'ps: exec code' Execute the arbitrary PostScript commands code. The PostScript currentpoint is set to the groff drawing position when the \X escape sequence is interpreted before executing code. The origin is at the top left corner of the page; x coordinates increase to the right, and y coordinates down the page. A procedure u is defined that converts groff basic units to the coordinate system in effect (provided the user doesn't change the scale). For example, .nr x 1i \X'ps: exec \nx u 0 rlineto stroke' draws a horizontal line one inch long. [...] Since PostScript has machinery for this purpose, I would guess PDF does too. TeX DVI reportedly does not.[1] Maybe someone on this list with experience embedding PostScript commands into GNU troff documents can advise further; I don't have such yet. It might be convenient to expose a new device control command extension for this purpose; we could name its tag 'raster:', maybe. Possibly it would take an argument identifying the image format to follow. The easiest thing to do at first would be to support only "native", say, and require the user to pass only the format that the device expects. I suspect we could finagle such a raster graphics extension into the X11 devices, if someone wanted to go to the trouble (I imagine just dumping the meaty part of an XPM file into GNU troff output, albeit with each line prefixed with '+' as described in groff_out(5)). I don't have any idea about the lbp or lj4 devices. (I don't know if I mentioned this to the list, but about a year ago I was able to test groff Git HEAD on a laser printer that accepts a LaserJet 4 input stream (HP PCL/PDL, I suppose), and it worked fine.) The most interesting possibility for my own nefarious plans would be to support this on terminal devices by converting images to Sixel graphics[2] in the output driver. Regards, Branden [1] https://tex.stackexchange.com/questions/547408/how-to-put-a-picture-inside-a-dvi-file [2] https://en.wikipedia.org/wiki/Sixel
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