Add support for circular flag rendering

[Jutier]

At the moment, if I want to render a flag as a circle (maybe it's too niche), there isn't a global or consistent solution because the aspect ratio of flags isn't constant. This becomes particularly problematic when dealing with flags that require specific adjustments for centering or clipping.

I believe it would be better to implement this feature on an individual basis for each flag, as centering isn't always the best approach for certain designs. By doing this, we would also be exposed to the width and height variables.

Here's an example of how this could be implemented:

// br 7:10
- #let flag-br(height:.65em) = {
+ #let flag-br(height:.65em, circle: false) = {
    box(
+    // I'm only using it with clip, most of those properties should be unset if circle == false
+    clip: circle,
+    radius: 50%,
+    width: height,
+    height: height,
+    // Usually this should be (width - height)/2
+    inset: (left: -(3/14)*height),
      rect(height:height, width:10/7*height, fill:rgb("00923e"))
      + place(
        polygon(
          fill:rgb("ffcb00"),
          ((1.7/20)*height*10/7,(height/-2)),
          ((1/2)*height*10/7,-(14-1.7)/14*height),
          (((20-1.7)/20)*height*10/7,(height/-2)),
          ((1/2)*height*10/7,-1.7/14*height),
          )
      )
      + place(
          dy:-3/4*height,
          dx:(10/7/2-1/4)*height,
          image("coat of arms/BR.svg", height:height/2))
    )
}

[samrenault]

Hello,

Unfortunately I don't see an easy way that could work for all flags. As usual flags are standardised in a rectangle, this upgrade needs to be done specifically for each flag and we need find the "center" of each flag. Unless there is a common way to transform rectangular into a circle, it seems a bit too complex to implement (with the current Typst version).

[Jutier]

You're right, getting a circle in the center is easy, the problem would be that most flags when circular are not centered, but have an offset.

I'm not sure if this is something that would be easier at any point in time, that's why I figured it would be something "ok" to solve at this point.

I don't see a way to globally implement this, no matter how it's done, it would need at least an offset variable available at each flag, kinda like the dimensions are as of now.

This would be boring to implement, since I couldn't find any reference to this online, but (and I'm not proficient with typst) we could just leave the function in there to expect this parameter, and hopefully with time people share the offsets.

Hopefully it made sense, I'll try to see if I can implement something like this, if you're open to it.