From 91dd180225200efe28e9553ad495506ee96899c1 Mon Sep 17 00:00:00 2001
From: Johannes Wolf <mail@johannes-wolf.com>
Date: Sun, 13 Oct 2024 17:17:30 +0200
Subject: [PATCH] coordinate: Add register function

---
 src/coordinate.typ               |  9 ++++----
 src/draw.typ                     |  2 +-
 src/draw/util.typ                | 38 ++++++++++++++++++++++++++++++++
 tests/coordinate/custom/test.typ |  5 +----
 4 files changed, 44 insertions(+), 10 deletions(-)

diff --git a/src/coordinate.typ b/src/coordinate.typ
index 382b2e9a2..725d4f9ae 100644
--- a/src/coordinate.typ
+++ b/src/coordinate.typ
@@ -322,11 +322,10 @@
 /// - update (bool): Update the context's last position
 /// -> array
 #let resolve(ctx, ..coordinates, update: true) = {
-  let resolver = ()
-  if type(ctx.resolve-coordinate) == array {
-    resolver += ctx.resolve-coordinate
-  } else if type(ctx.resolve-coordinate) == function {
-    resolver.push(ctx.resolve-coordinate)
+  let resolver = if type(ctx.resolve-coordinate) == array {
+    ctx.resolve-coordinate
+  } else {
+    ()
   }
 
   let result = ()
diff --git a/src/draw.typ b/src/draw.typ
index e46b87de9..cef4e6d2d 100644
--- a/src/draw.typ
+++ b/src/draw.typ
@@ -3,4 +3,4 @@
 #import "draw/styling.typ": set-style, fill, stroke, register-mark
 #import "draw/shapes.typ": circle, circle-through, arc, arc-through, mark, line, grid, content, rect, bezier, bezier-through, catmull, hobby, merge-path
 #import "draw/projection.typ": ortho, on-xy, on-xz, on-yz
-#import "draw/util.typ": assert-version
+#import "draw/util.typ": assert-version, register-coordinate-resolver
diff --git a/src/draw/util.typ b/src/draw/util.typ
index 3f2c0d1df..3d4a99cb6 100644
--- a/src/draw/util.typ
+++ b/src/draw/util.typ
@@ -18,3 +18,41 @@
     return (ctx: ctx)
   },)
 }
+
+/// Push a custom coordinate resolve function to the list of coordinate
+/// resolvers. This resolver is scoped to the current context scope!
+///
+/// A coordinate resolver must be a function of the format `(context, coordinate) => coordinate`. And must _always_ return a valid coordinate or panic, in case of an error.
+///
+/// If multiple resolvers are registered, coordinates get passed through all
+/// resolvers in reverse registering order. All coordinates get paased to cetz'
+/// default coordinate resolvers.
+///
+/// ```typc example
+/// register-coordinate-resolver((ctx, c) => {
+///   if type(c) == dictionary and "log" in c {
+///     c = c.log.map(n => calc.log(n, base: 10))
+///   }
+///   return c
+/// })
+///
+/// circle((log: (10, 0)), radius: .25)
+/// circle((log: (100, 0)), radius: .25)
+/// circle((log: (1000, 0)), radius: .25)
+/// ```
+///
+/// - resolver (function): The resolver function, taking a context and a single coordinate and returning a single coordinate
+#let register-coordinate-resolver(resolver) = {
+  assert.eq(type(resolver), function,
+    message: "Coordinate resolver must be of type function (ctx, coordinate) => coordinate.")
+
+  return (ctx => {
+    if type(ctx.resolve-coordinate) == array {
+      ctx.resolve-coordinate.push(resolver)
+    } else {
+      ctx.resolve-coordinate = (resolver,)
+    }
+
+    return (ctx: ctx)
+  },)
+}
diff --git a/tests/coordinate/custom/test.typ b/tests/coordinate/custom/test.typ
index 930f6c00b..0c2137946 100644
--- a/tests/coordinate/custom/test.typ
+++ b/tests/coordinate/custom/test.typ
@@ -15,10 +15,7 @@
     return coordinate
   }
 
-  set-ctx(ctx => {
-    ctx.resolve-coordinate = log-resolver
-    return ctx
-  })
+  register-coordinate-resolver(log-resolver)
 
   set-style(circle: (radius: .1))
   for i in (.1, 1, 10, 100, 1000, 10000) {