Fix dashed and dotted lines in EPS export

EPS of dashed and dotted lines export badly. This modifies the EPS file to fix them.

Description

I was very frustrated at not being able to export dashed and dotted lines in EPS format, as they come out weird. Finally I found a post somewhere on the internet that suggested editing a certain part of the EPS file to fix it. This is a function which, given the name of the EPS file, will modify the length of the 'dot', making it look better in the image.

I've found it useful to automatically add this function to my standard 'save figure' script, so it is always run.

In EPS file:
/DO { [.5 dpi2point mul 4 dpi2point mul] 0 setdash } bdef

It seems the optimal numbers to go in the EPS file depend on the thickness of the line being drawn. This code changes only the .5 which corresponds to the length of the 'dot'. The number 4 controls the space between the dots. Setting both equal to 1 seems to work well with a Matlab line thickness of 1.5.

• Acknowledgements: This submission has inspired the following:; export_fig
• MATLAB release: MATLAB 7.4 (R2007a)
• Other requirements: Should work on all platforms, but only tested on a mac.

[Ronco Badsmith]

This is a great fix. Thanks for the upload!

[Rich Germuska]

Nice one.

For those still using legacy versions e.g. 6.0 release 12, just replace strfind() with findstr() as appropriate.

Works nicely on WinXP Pro.

[Klaas van 't Veld]

Outstanding fix of a very annoying problem. I modified the script a bit to make it more flexible, adding arguments "dotlen" and "dotgap"

  function fix_dottedline(filename,dotlen,gaplen)

adding these lines at the top

  dotstr = ['[' num2str(dotlen)];
  gapstr = ['mul ' num2str(gaplen)];

and changing the replacement operations (for both the DO and DD lines) to

  thisLine = regexprep(thisLine,'[.5',dotstr);
  thisLine = regexprep(thisLine,'mul 4',gapstr);

That way you can play around with dot lengths and gap lengths until everything is just perfect.

[Oliver Woodford]

This is a great idea. I haven't downloaded the file because I found the functionality first in fixPSlinestyle. However, you gave me the idea of automatically changing dash length with line width. This functionality is now available in my print_pdf and print_eps functions, so manual tinkering on a figure by figure basis is no longer needed.

[Oliver Woodford]

See fix_lines (http://www.mathworks.com/matlabcentral/fileexchange/23604) for an equivalent function which automatically changes dash length according to line width.