Could you add to your application:
It could be helpful with handling pdf encoded technical drawings (while application can handle tiff files)
the best location for raising requests per documentation is
Found a bug? Have feature request? Use issue tracker .https://github.com/sumatrapdfreader/sumatrapdf/issues
However it is useful to discuss options here in the forum
Your 2nd & 3rd points re printing are valid
However sumatraPDF as a page “viewer” uses a simplistic method for printing images of each page
I dont think that in half a century of working with CADD / technical drawings I have needed a simple viewer app to deal with “mirror” for text or comic book images (SumatraPDFs main target)
try reading these backwards
(-: eramthgin a eb dluow gnildnah TNOF
It is best that blueprints or tiff reversed images are normalised prior to inserion into technical manuals with a link to the original or included in the portfolio along with a right reading rendition
I’m actually wondering what he meant by “mirror view”. I’ve seen “split view” sometimes being called “mirror view” because in that one half mirrors the other (presumably for comparison purposes or something).
Age is telling on me
Back in the days of helio / diazo printing, blueprints and microfilm it was common to see technical images reversed or mirrored
The first serious format for storing such images was TIFF which could in its meta tags store the orientation much like exif in more modern jpegs which at that time were normally lossy whereas tiff was usually lossless.
In that case I agree with your observation:
Adding code specifically to deal with images that are the document creator’s responsibility to orient properly seems like overkill to me.
Thanks for reply.
Mirror view is useful when drawing editor is an ass and gives inverted (for me) projection of a part. It is a time saving and simple solution for that problem.
I dont think that in half a century of working with CADD / technical drawings I have needed a simple viewer app to deal with “mirror” for text or comic book images (SumatraPDFs main target)
I don’t mean “text”. I mean gaphics mainly. And yes - it is used often.
It could be also useful for printing on transparencies since nowadays it’s not used on obsolete projectors but as cliches for pad printing plates.
Oh. I forgot to mention. Not only mirror view but also print as a mirror 
Your observations are valid that 1st and 3rd angle views, can as I have observed in recent years lead to buildings erected 180 degrees from intended or even a bridge built inside out !!
Also in electronics etc it is customary to use reverse etching
I would say much smaller scale: coolant hoses in cars and their indexes at their ends - on drawing they coming from “inside” of the drawing. I need make an mirror image so I can stick that end directly to drawing so i can take an angle of an index.
Now you can see my point of view.
Digressing: Come on. It’s a simple transpositioning of pixels. I’m sure you can do it
@grappas
I note you have raised an issue on GitHub, Thanks
I have added a back link to this thread for your fuller explanation
I am not the “author” so it will be for him to give the official response(s) on GitHub
Also it would be good if you are learning anything related to technical drawings.Take this CAD draw for making a lathe CNC program for example:
I do have to make a point table to make the corresponding CNC program. However, it is harder if it is not aligned properly, where the mirror function actually comes into play. Rotate 180 degrees and mirror it, and the job gets easier. And even if I wasn’t learning it is still useful to align the piece the way it’s going to get mechanized. Another reason why this would be actually really useful.
Working myself in engineering I have too often seen the dangers of misreading mirrored text, you should always ask the draughtsman to draw it the way you need it!
180 and mirrored
I can do that myself, a quick snip and using honeyview to rotate and mirror the image. Thing is that you need to mechanize the whole piece, with two grabs, first to make the first half, the second one to do the other half. And as far as I know, it is incredibly uncommon giving the drawing duplicated so you have an easier time figuring out the points. Which is another use case where a mirroring function would be really nice, so with 3 shortcuts I can have the piece the best way possible .
