If it doesn't fit on the display, just allow zooming and panning ... That will even let it work on plain CGA.
On Thu, Aug 13, 2026 at 11:39 AM Jim Hall via Freedos-devel < [email protected]> wrote: > Jim Hall wrote: > >> Ultimately, a virtual dot matrix printer should support "half dot" > >> print head vertical movement too, so you can print at very high > >> resolution. > [..] > > On Thu, Aug 13, 2026 at 10:13 AM Alain Mouette wrote: > > > > I've been trying to figure out a good method to do that on screen. > > > > Some Dot-matrix had a possibility (mine had) to advance the paper > > by a half dot and pront overlapping dots... But I believe it will > > hava a poor aspect on screen as dots really were intended to overlap > > and it would me messy on screen > > I think I know of a way to do it if I'm writing to a PGM file. But it > doesn't extend to DOS graphics. > > > If it's PGM: Each "dot" actually takes up a 3x3 grid, where the center > is basically black and you have a partial gray value for each of the 8 > boxes around it. This is easy if you're doing it in PGM, because if > "0" is black and "15" is pure white, then different values of "gray" > are just division. > > Each "dot" 3x3 grid actually overlaps the previous "dot" 3x3 grid. > Let's say one "dot" is this 3x3 grid, where "1" is the center and "o" > are the 8 squares around it: > > ooo > o1o > ooo > > ..then the adjacent "dot" is another 3x3 grid that overlaps the last > column of the previous "dot." Let's show the overlapping dots as "O": > > ooOoo > o1O2o > ooOoo > > ..and so on for other dots. If I'm just printing out two rows of two dots: > > ooOoo > o1O2o > OOOO > o3O4o > ooOoo > > > HOWEVER, this is probably not possible in SVGA graphics, just based on > resolution. If I assume a "page" is 510 "dots" wide (8.5 inches) and > 660 "dots" long (11 inches), that's easy to do in SVGA (XRES > 1024x768). I'll run out of room if I want to display a single page > WITH THAT METHOD in portrait view in 1024x768. > > So I think the easiest way to do this is one "dot" per pixel, and > square pixels. Then a page is 510x660 pixels, which easily fits on > 1024x768. > > > _______________________________________________ > Freedos-devel mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/freedos-devel >
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