added basis for node/flow creation + node layout

gallery/test.typ

@@ -0,0 +1,7 @@
+#import "../src/lib.typ": *
+
+#diagram({
+  _flow("Wages", 1500, "Budget")
+  _flow("Other", 250, "Budget")
+  _flow("Budget", 450, "Taxes")
+}, 10cm)

src/diagram.typ

@@ -0,0 +1,180 @@
+#import "@preview/cetz:0.3.0": canvas, draw
+
+#let _flow(from, amount, to) = {
+  return ((
+    type: "flow",
+    from: from,
+    to: to,
+    amount: amount
+  ),)
+}
+
+#let _node(name, display-name: auto, color: auto) = {
+  return ((
+    type: "node",
+    name: name,
+    display-name: if display-name == auto {
+      name
+    } else {
+      display-name
+    },
+    color: color,
+    is-src: false,
+    is-dst: false,
+    sources: (),
+    targets: (),
+    max-depth: 0,
+    total: (
+      "in": 0,
+      "out": 0,
+      "max": 0
+    )
+  ),)
+}
+
+#let process-depth(nodes, flows, node, visited: ()) = {
+  let next-depth = node.max-depth + 1
+  let total-depth = node.max-depth
+  let depth
+  for flow in node.targets {
+    if flow.to in visited {
+      panic("Loop")
+    }
+    nodes.at(flow.to).max-depth = calc.max(
+      nodes.at(flow.to).max-depth,
+      next-depth
+    )
+
+    (depth, nodes) = process-depth(nodes, flows, nodes.at(flow.to), visited: visited + (flow.to,))
+    total-depth = calc.max(total-depth, depth)
+  }
+  return (total-depth, nodes)
+}
+
+#let diagram(
+  elmts,
+  height,
+  min-spacing: 1cm
+) = {
+  let columns = ()
+  let nodes = (:)
+  let flows = ()
+
+  for elmt in elmts {
+    if elmt.type == "node" {
+      nodes.insert(elmt.name, elmt)
+    } else if elmt.type == "flow" {
+      flows.push(elmt)
+    }
+  }
+
+  for flow in flows {
+    if not flow.from in nodes {
+      nodes.insert(flow.from, _node(flow.from).first())
+    }
+    if not flow.to in nodes {
+      nodes.insert(flow.to, _node(flow.to).first())
+    }
+    nodes.at(flow.from).is-src = true
+    nodes.at(flow.from).targets.push(flow)
+    nodes.at(flow.to).is-dst = true
+    nodes.at(flow.to).sources.push(flow)
+  }
+
+  for (nid, node) in nodes.pairs() {
+    let tot-in = node.targets.map(t => t.amount).sum(default: 0)
+    let tot-out = node.sources.map(t => t.amount).sum(default: 0)
+    nodes.at(nid).total = (
+      "in": tot-in,
+      "out": tot-out,
+      "max": calc.max(tot-in, tot-out),
+    )
+  }
+
+  let total-depth = 0
+  let d
+  for node in nodes.values().filter(n => n.is-src and not n.is-dst) {
+    (d, nodes) = process-depth(nodes, flows, node)
+    total-depth = calc.max(total-depth, d)
+  }
+
+  columns = ((),) * (total-depth + 1)
+  let column-totals = (0,) * columns.len()
+  for (key, node) in nodes.pairs() {
+    columns.at(node.max-depth).push(key)
+    column-totals.at(node.max-depth) += node.total.max
+  }
+
+  //total-depth
+  [
+    *nodes*: #nodes
+
+    *total-depth*: #total-depth
+
+    *columns*: #columns
+
+    *column-totals*: #column-totals
+  ]
+  //flows
+
+  let h-factor = calc.min(
+    ..columns.zip(column-totals).map(((col, total)) => {
+      let available-h = height - (col.len() - 1) * min-spacing
+      return available-h / total
+    })
+  )
+
+  let colors = (red, orange, yellow, green, blue, purple).map(c => c.lighten(50%))
+
+  canvas({
+    let c = 0
+    for (i, column) in columns.enumerate() {
+      let x = i * 3
+      let total = column.map(n => nodes.at(n).total.max).sum()
+      let total-h = total * h-factor
+      let remaining-h = height - total-h
+      let spacing = remaining-h / (column.len() + 1)
+
+      let y = -spacing
+      for (j, nid) in column.enumerate() {
+        let node = nodes.at(nid)
+
+        let h = h-factor * node.total.max
+        draw.rect(
+          (x, y),
+          (x + 1, y - h),
+          name: nid,
+          fill: colors.at(c)
+        )
+        c += 1
+
+        if node.is-src and not node.is-dst {
+          draw.content(
+            nid + ".west",
+            anchor: "east",
+            node.display-name,
+            padding: 5pt
+          )
+        } else if node.is-src and node.is-dst {
+          draw.content(
+            nid + ".center",
+            anchor: "center",
+            node.display-name,
+            padding: 5pt,
+            frame: "rect",
+            fill: white.transparentize(20%)
+          )
+        } else if not node.is-src and node.is-dst {
+          draw.content(
+            nid + ".east",
+            anchor: "west",
+            node.display-name,
+            padding: 5pt
+          )
+        }
+
+        y -= spacing + h
+      }
+    }
+  })
+}

src/lib.typ

@@ -0,0 +1,2 @@
+#import "diagram.typ": diagram
+#import "diagram.typ": _flow, _node