[svgPathPen] Improve writing out numbers

Open behdad opened this issue 1 year ago • 1 comments

See: https://github.com/fonttools/fonttools/pull/3543#issuecomment-2140398555

May 30 '24 17:05 behdad

Currently:

fonttools pens.svgPathPen AdobeVFPrototype.otf A

generates output using integers only:

<g transform="translate(0 918) scale(1 -1)"><path d="M5 0H235V40L125 55H105L5 40V0ZM71 0H118L322 599H299L500 0H593L363 675H303L71 0ZM170 219H472L456 265H186L170 219ZM383 0H653V40L529 55H509L383 40V0Z"/></g>

As soon as I set any --variations, even to the default, it switches to float because the variation calculations happen in float:

fonttools pens.svgPathPen AdobeVFPrototype.otf A --variations wght=100

<g transform="translate(0 918) scale(1 -1)"><path d="M12.0 0H210.0V20.0L113.0 26.0H99.0L12.0 20.0V0.0ZM85.0 0.0H114.0L325.0 667.0L308.0 657.0L524.0 0.0H556.0L327.0 684.0H307.0L85.0 0.0ZM173.0 247.0H468.0L460.0 267.0H182.0L173.0 247.0ZM403.0 0.0H651.0V20.0L537.0 26.0H523.0L403.0 20.0V0.0Z"/></g>

And if I set non-default location, I get multiple unnecessary digits of float:

fonttools pens.svgPathPen AdobeVFPrototype.otf A --variations wght=400

<g transform="translate(0 918) scale(1 -1)"><path d="M5.205617204267097 0H234.3831483871987V40.781345376214965L125.24674064512051 55.781345376214965H105.37011096768077L5.205617204267099 40.781345376214965V0.0ZM70.75325935487949 0.0H118.45235784938762L321.7121359140261 598.3420249463453L297.8896670969577 595.463384086606L497.1624825811141 0.0H594.6038141932834L364.8916782792573 674.0541608603713H302.42427182805216L70.7532593548795 0.0ZM169.91775311829318 217.39618580671666H472.3289875268274L455.95887655914663 264.0952843012248H185.95887655914663L169.9177531182932 217.3961858067167ZM381.3139389250099 2.842170943040401e-14H653.4934812902411V40.65797505365474L529.2467406451206 55.65797505365474H506.5737169896483L381.31393892500984 40.65797505365474V2.842170943040401e-14Z"/></g>

That's clearly not ideal. Before I committed (accidentally actually) the following change: https://github.com/fonttools/fonttools/commit/42d6b6b4fedf51dd741d3134da74df04339335b4 but it was reverted.

Cosimo wanted me to update the callsites, not change default behavior. I realized now that I didn't actually change the default behavior of the pen, just the cmdline tool. And I still think that was the correct change. CORRECTION: I had changed the pen default.

But I also propose adding a new named argument to the pen to Do The Right Thing, without each client having to write this lambda.

May 30 '24 17:05 behdad