[Refactor] Split functions out to file (#713)

Splits code out from `LGraphCanvas`.

src/canvas/measureSlots.ts

@@ -0,0 +1,75 @@
+import type { Point } from "@/interfaces"
+import type { LGraphNode } from "@/LGraphNode"
+
+import { isInRectangle } from "@/measure"
+
+/**
+ * returns the INDEX if a position (in graph space) is on top of a node input slot
+ */
+export function isOverNodeInput(
+  node: LGraphNode,
+  canvasx: number,
+  canvasy: number,
+  slot_pos?: Point,
+): number {
+  const { inputs } = node
+  if (inputs) {
+    for (const [i, input] of inputs.entries()) {
+      const link_pos = node.getConnectionPos(true, i)
+      let is_inside = false
+      // TODO: Find a cheap way to measure text, and do it on node label change instead of here
+      // Input icon width + text approximation
+      const width =
+        20 + ((input.label?.length ?? input.localized_name?.length ?? input.name?.length) || 3) * 7
+      is_inside = isInRectangle(
+        canvasx,
+        canvasy,
+        link_pos[0] - 10,
+        link_pos[1] - 10,
+        width,
+        20,
+      )
+      if (is_inside) {
+        if (slot_pos) {
+          slot_pos[0] = link_pos[0]
+          slot_pos[1] = link_pos[1]
+        }
+        return i
+      }
+    }
+  }
+  return -1
+}
+
+/**
+ * returns the INDEX if a position (in graph space) is on top of a node output slot
+ */
+export function isOverNodeOutput(
+  node: LGraphNode,
+  canvasx: number,
+  canvasy: number,
+  slot_pos?: Point,
+): number {
+  const { outputs } = node
+  if (outputs) {
+    for (let i = 0; i < outputs.length; ++i) {
+      const link_pos = node.getConnectionPos(false, i)
+      const is_inside = isInRectangle(
+        canvasx,
+        canvasy,
+        link_pos[0] - 10,
+        link_pos[1] - 10,
+        40,
+        20,
+      )
+      if (is_inside) {
+        if (slot_pos) {
+          slot_pos[0] = link_pos[0]
+          slot_pos[1] = link_pos[1]
+        }
+        return i
+      }
+    }
+  }
+  return -1
+}