feat(er-diagram): lay tables out in compact 2D clusters with color

CHANGELOG.md

@@ -12,6 +12,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Connections can now have more than one tag. Assign several tags in the connection form, and filter the welcome list by tag with Match Any or Match All. (#744)
 - Elasticsearch support. Connect to Elasticsearch 7.x and 8.x, browse indices, run Query DSL requests in a console, and edit documents in the data grid. Install from Settings > Plugins. (#1529)
 
+### Changed
+
+- The ER diagram now arranges tables in a compact layout that fills the canvas in both directions, keeps tables linked by foreign keys together, and tints each group of connected tables with its own header color. (#1755)
+
 ### Fixed
 
 - Raw filters in the data grid now apply on document and key-value databases; the typed text was being dropped before it reached the driver. (#1529)

TablePro/Models/ERDiagram/ERClusterAnalyzer.swift

@@ -0,0 +1,73 @@
+import Foundation
+
+enum ERClusterAnalyzer {
+    static func assignClusters(
+        nodes: [ERTableNode],
+        edges: [EREdge],
+        nodeIndex: [String: UUID]
+    ) -> [UUID: Int] {
+        guard !nodes.isEmpty else { return [:] }
+
+        var parent: [UUID: UUID] = [:]
+        var rank: [UUID: Int] = [:]
+        for node in nodes {
+            parent[node.id] = node.id
+            rank[node.id] = 0
+        }
+
+        func find(_ start: UUID) -> UUID {
+            var root = start
+            while let next = parent[root], next != root { root = next }
+            var current = start
+            while let next = parent[current], next != root {
+                parent[current] = root
+                current = next
+            }
+            return root
+        }
+
+        func union(_ lhs: UUID, _ rhs: UUID) {
+            let rootLhs = find(lhs)
+            let rootRhs = find(rhs)
+            guard rootLhs != rootRhs else { return }
+            let rankLhs = rank[rootLhs] ?? 0
+            let rankRhs = rank[rootRhs] ?? 0
+            if rankLhs < rankRhs {
+                parent[rootLhs] = rootRhs
+            } else if rankLhs > rankRhs {
+                parent[rootRhs] = rootLhs
+            } else {
+                parent[rootRhs] = rootLhs
+                rank[rootLhs] = rankLhs + 1
+            }
+        }
+
+        for edge in edges {
+            guard let from = nodeIndex[edge.fromTable],
+                  let to = nodeIndex[edge.toTable],
+                  from != to
+            else { continue }
+            union(from, to)
+        }
+
+        var members: [UUID: [UUID]] = [:]
+        for node in nodes {
+            members[find(node.id), default: []].append(node.id)
+        }
+
+        let nameById = Dictionary(uniqueKeysWithValues: nodes.map { ($0.id, $0.tableName) })
+        let multiNodeComponents = members.values.filter { $0.count >= 2 }
+        let ordered = multiNodeComponents.sorted { lhs, rhs in
+            let lhsKey = lhs.compactMap { nameById[$0] }.min() ?? ""
+            let rhsKey = rhs.compactMap { nameById[$0] }.min() ?? ""
+            return lhsKey < rhsKey
+        }
+
+        var result: [UUID: Int] = [:]
+        for node in nodes { result[node.id] = -1 }
+        for (index, component) in ordered.enumerated() {
+            for member in component { result[member] = index }
+        }
+        return result
+    }
+}