How to make .slf font file?

Tanveer Qureshi
Tanveer Qureshi Posts: 16
in Font Technology
Hi, 
I am trying to find a way to make .slf font file. Is there any way to make it, or which software helps me with it?

Regards
Tanveer
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Comments

  • Thomas Phinney
    Thomas Phinney Posts: 2,917
    edited January 15
    SLF is an abbreviation for “single line font” which are commonly used for CAD and engraving purposes.

    BUT... there is not a single specific format called “.slf” that I am aware of. Rather, one can make fonts in any of a number of formats, that are engineered to work this way. (Edit: and if there were such a format, it would likely typically be created by conversion from one of the fonts I describe further below.)

    Because of the use of actual or implied close-paths in TrueType and OpenType (both CFF and TTF), a single-line font in these formats will have many contours that would otherwise be problematic. Consider a simple sans-serif capital L... if done with two line segments, the auto-closing would make it a triangle.

    Either you can manually deal with this using extra paths, or you can use a font editor that can deal with it by automatically reversing the path. This is a feature that exists in FontLab specifically to support such “single-line fonts.” It was an export preference even in FontLab Studio 5, I think? In recent versions you would do it with a custom export profile setting, this one here:


  • mitradranirban
    mitradranirban Posts: 34
    Fontforge can create Type 1 font from stroked fonts ( unlike outline fonts like OpenType or Truetype). Can it be considered a single line font?
  • Thomas Phinney
    Thomas Phinney Posts: 2,917
    edited January 15
    No

    That is pretty much the exact opposite: take a line, stroke it, and then export it as a full contour.


  • Tanveer Qureshi
    Tanveer Qureshi Posts: 16
    Hi Thomas, 
    Thanks for the info, but I know the FontLab single-line export method. Someone requested me to create a single-line font file with the extension .slf and just wanted to know what is the process of it. 

    Regards
    Tanveer
  • Erwin Denissen
    Erwin Denissen Posts: 308
    As Thomas pointed out, I am also not aware of a specific .slf file extension for single line fonts.

    But I am aware of .opf fonts. Such fonts are actually regular OpenType fonts, but used with software for electronic cutting machines that supports the .opf font and will not connect the last and first point of each contour. This is against the official OpenType specification, so it is a trick to allow single line fonts with open contours. From what I have heard the extension is only supported by "Sure Cuts A Lot".

    To create such a Single Line Font, export your font with the option to close open contours; in FontCreator it is known as the Single Stroke option. Finally, change the font file extension from .ttf to .opf.

    Here is an article that provides more information about creating single-line fonts:
    How to Make Single-Line Fonts for Engraving and Cutting

    Hope this helps,

    Erwin Denissen
  • Tanveer Qureshi
    Tanveer Qureshi Posts: 16
    Hi Erwin, 
    I checked the link but this didn't help me out. Also, .opf works in     Pazzles InVue, Make the Cut and Sure Cuts a Lot software as I tried that. 

    ~Tanveer
  • jeremy tribby
    jeremy tribby Posts: 256
    I realize this is a fairly obvious question, but have you tried changing the file extension from .otf or .ttf to .slf? what you're describing almost sounds like your client is accustomed to SLF as an acronym, and maybe mistakenly thinks the file extension needs to reflect that? some of these cutting machines do have proprietary font stacks, though, so it's not impossible that .slf is unique to the hardware they use... you might have an easier time figuring this out if you are able to obtain a known working .slf file from the person requesting it, so you can examine it in a hex editor or similar and see what it actually is
  • Thomas Phinney
    Thomas Phinney Posts: 2,917
    edited January 16
    Agree that checking to see if they actually HAVE an .slf file, and if so examining it, would be a sensible step in this situation.

    When I search for SLF fonts, the only thing I find is a company that claims that SLF is both copyrighted and trademarked by them (lol) ( https://singlelinefonts.com/ ) ... and what is interesting is that they show what formats they include with each sale:
    • TTF - Hairline Width (the description clarifies that this retraces over itself and then closes, like the FontLab feature I described previously)
    • OTF (for FontLab Pad) - Open Type Format 
    • OPF - Open Path Format
    • TF (thick font) Format: Regular Width - Printable version (description clarifies this is just a stroked/expanded version of the font, presumably TTF)
    So, I rather suspect there is no .SLF format, but rather a variety of other options for deploying single line fonts.
  • Tanveer Qureshi
    Tanveer Qureshi Posts: 16
    Hi Jeremy, 
    This makes sense to me as checking the .slf file to examine. 
  • Tanveer Qureshi
    Tanveer Qureshi Posts: 16
    edited January 16
    Hi Thomas, 
    I can make any font in ttf, opf, otf(single line for Illustrator or Indesign only), SVG(for InkScape), SHX(for Cad utilities) but need to check this new file extension. I also tried converting the extension only but I don't have software or machine to test so it's a long process while I make the font and person on the other hand test it with no result. 

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