feat(geobase): create box functions, also related to (#96)

dart/geobase/lib/src/base/coordinates/box.dart

@@ -4,11 +4,35 @@
 //
 // Docs: https://github.com/navibyte/geospatial
 
+import 'dart:math' as math;
+
 import '/src/utils/tolerance.dart';
 
 import 'position.dart';
 import 'positionable.dart';
 
+/// Creates a new bounding box from [minX], [minY], [maxX] and [maxY] values.
+///
+/// Optional [minZ] and [maxZ] for 3D boxes, and [minM] and [maxM] for
+/// measured boxes can be provided too.
+///
+/// For projected or cartesian bounding boxes (`ProjBox`), coordinates axis are
+/// applied as is.
+///
+/// For geographic bounding boxes (`GeoBox`), coordinates are applied as:
+/// `minX` => `west`, `minY` => `south`, `minZ` => `minElev`, `minM` => `minM`,
+/// `maxX` => `east`, `maxY` => `north`, `maxZ` => `maxElev`, `maxM` => `maxM`
+typedef CreateBox<T extends Box> = T Function({
+  required num minX,
+  required num minY,
+  num? minZ,
+  num? minM,
+  required num maxX,
+  required num maxY,
+  num? maxZ,
+  num? maxM,
+});
+
 /// A base interface for axis-aligned bounding boxes with min & max coordinates.
 ///
 /// This interface defines min and max coordinate values only for the m axis.
@@ -121,8 +145,8 @@ abstract class Box extends Positionable {
   /// Returns true if this bounding box intesects with [other] box.
   ///
   /// X ja y (or lon and lat) are always compared on intersection calculation.
-  /// 
-  /// This and [other] must equal on [is3D] and [isMeasured] properties. Z (or 
+  ///
+  /// This and [other] must equal on [is3D] and [isMeasured] properties. Z (or
   /// elev) is further compared when both has z coordinates, and m is compared
   /// when both has m coordinates.
   bool intersects(Box other) => Box.testIntersects(this, other);
@@ -136,8 +160,8 @@ abstract class Box extends Positionable {
   /// Returns true if this bounding box intesects with [point].
   ///
   /// X ja y (or lon and lat) are always compared on intersection calculation.
-  /// 
-  /// This and [point] must equal on [is3D] and [isMeasured] properties. Z (or 
+  ///
+  /// This and [point] must equal on [is3D] and [isMeasured] properties. Z (or
   /// elev) is further compared when both has z coordinates, and m is compared
   /// when both has m coordinates.
   bool intersectsPoint(Position point) => Box.testIntersectsPoint(this, point);
@@ -173,6 +197,57 @@ abstract class Box extends Positionable {
     }
   }
 
+  /// A minimum bounding box created by [factory], calculated from [positions].
+  /// 
+  /// Throws FormatException if cannot create (ie. [positions] is empty).
+  static R createBoxFrom<R extends Box>(
+    Iterable<Position> positions,
+    CreateBox<R> factory,
+  ) {
+    // calculate mininum and maximum coordinates
+    num? minX, minY, minZ, minM;
+    num? maxX, maxY, maxZ, maxM;
+    var isFirst = true;
+    for (final cp in positions) {
+      if (isFirst) {
+        minX = cp.x;
+        minY = cp.y;
+        minZ = cp.optZ;
+        minM = cp.optM;
+        maxX = cp.x;
+        maxY = cp.y;
+        maxZ = cp.optZ;
+        maxM = cp.optM;
+      } else {
+        minX = math.min(minX!, cp.x);
+        minY = math.min(minY!, cp.y);
+        minZ = cp.is3D && minZ != null ? math.min(minZ, cp.z) : null;
+        minM = cp.isMeasured && minM != null ? math.min(minM, cp.m) : null;
+        maxX = math.max(maxX!, cp.x);
+        maxY = math.max(maxY!, cp.y);
+        maxZ = cp.is3D && maxZ != null ? math.max(maxZ, cp.z) : null;
+        maxM = cp.isMeasured && maxM != null ? math.max(maxM, cp.m) : null;
+      }
+      isFirst = false;
+    }
+
+    if(isFirst) {
+      throw const FormatException('Positions should not be empty.');
+    }
+
+    // create a new bounding box
+    return factory.call(
+      minX: minX!,
+      minY: minY!,
+      minZ: minZ,
+      minM: minM,
+      maxX: maxX!,
+      maxY: maxY!,
+      maxZ: maxZ,
+      maxM: maxM,
+    );
+  }
+
   /// True if [box1] and [box2] equals by testing all coordinate values.
   static bool testEquals(Box box1, Box box2) =>
       box1.minX == box2.minX &&

dart/geobase/lib/src/base/coordinates/geobox.dart

@@ -70,6 +70,31 @@ class GeoBox extends Box {
         _maxElev = maxElev,
         _maxM = maxM;
 
+  /// A bounding box from parameters compatible with `CreateBox` function type.
+  GeoBox.create({
+    required num minX,
+    required num minY,
+    num? minZ,
+    num? minM,
+    required num maxX,
+    required num maxY,
+    num? maxZ,
+    num? maxM,
+  })  : _west = minX.toDouble(),
+        _south = minY.toDouble(),
+        _minElev = minZ?.toDouble(),
+        _minM = minM?.toDouble(),
+        _east = maxX.toDouble(),
+        _north = maxY.toDouble(),
+        _maxElev = maxZ?.toDouble(),
+        _maxM = maxM?.toDouble();
+
+  /// A minimum bounding box calculated from [positions].
+  ///
+  /// Throws FormatException if cannot create (ie. [positions] is empty).
+  factory GeoBox.from(Iterable<Geographic> positions) =>
+      Box.createBoxFrom(positions, GeoBox.create);
+
   /// The west coordinate as geographic longitude.
   double get west => _west;
 

dart/geobase/lib/src/base/coordinates/projbox.dart

@@ -4,14 +4,11 @@
 //
 // Docs: https://github.com/navibyte/geospatial
 
-import 'dart:math' as math;
-
 import 'package:meta/meta.dart';
 
 import '/src/base/codes.dart';
 
 import 'box.dart';
-import 'position.dart';
 import 'projected.dart';
 
 /// A bounding box with [minX], [minY], [maxX] and [maxY] coordinates.
@@ -51,47 +48,30 @@ class ProjBox extends Box {
         _maxZ = maxZ,
         _maxM = maxM;
 
-  /// A minimum bounding box calculated from [positions].
-  factory ProjBox.from(Iterable<Position> positions) {
-    // calculate mininum and maximum coordinates
-    num? minX, minY, minZ, minM;
-    num? maxX, maxY, maxZ, maxM;
-    var isFirst = true;
-    for (final cp in positions) {
-      if (isFirst) {
-        minX = cp.x;
-        minY = cp.y;
-        minZ = cp.optZ;
-        minM = cp.optM;
-        maxX = cp.x;
-        maxY = cp.y;
-        maxZ = cp.optZ;
-        maxM = cp.optM;
-      } else {
-        minX = math.min(minX!, cp.x);
-        minY = math.min(minY!, cp.y);
-        minZ = cp.is3D && minZ != null ? math.min(minZ, cp.z) : null;
-        minM = cp.isMeasured && minM != null ? math.min(minM, cp.m) : null;
-        maxX = math.max(maxX!, cp.x);
-        maxY = math.max(maxY!, cp.y);
-        maxZ = cp.is3D && maxZ != null ? math.max(maxZ, cp.z) : null;
-        maxM = cp.isMeasured && maxM != null ? math.max(maxM, cp.m) : null;
-      }
-      isFirst = false;
-    }
+  /// A bounding box from parameters compatible with `CreateBox` function type.
+  const ProjBox.create({
+    required num minX,
+    required num minY,
+    num? minZ,
+    num? minM,
+    required num maxX,
+    required num maxY,
+    num? maxZ,
+    num? maxM,
+  })  : _minX = minX,
+        _minY = minY,
+        _minZ = minZ,
+        _minM = minM,
+        _maxX = maxX,
+        _maxY = maxY,
+        _maxZ = maxZ,
+        _maxM = maxM;
 
-    // create a new bounding box
-    return ProjBox(
-      minX: minX!,
-      minY: minY!,
-      minZ: minZ,
-      minM: minM,
-      maxX: maxX!,
-      maxY: maxY!,
-      maxZ: maxZ,
-      maxM: maxM,
-    );
-  }
+  /// A minimum bounding box calculated from [positions].
+  /// 
+  /// Throws FormatException if cannot create (ie. [positions] is empty).
+  factory ProjBox.from(Iterable<Projected> positions) =>
+      Box.createBoxFrom(positions, ProjBox.create);
 
   @override
   num get minX => _minX;