Set default CameraFit maxZoom values to null

The other parameters for CameraFit all have default values which will
not cause changes to the calculated CameraFit (i.e. padding is zero,
forceIntegerZoomLevel is false). Setting maxZoom to null makes it
consistent with the other parameters in that it will not affect the
calculated CameraFit. I chose null over double.infinity as in my opinion
the intent is clearer, no maximum.

lib/src/map/camera/camera_fit.dart

@@ -24,7 +24,7 @@ abstract class CameraFit {
   const factory CameraFit.bounds({
     required LatLngBounds bounds,
     EdgeInsets padding,
-    double maxZoom,
+    double? maxZoom,
     bool forceIntegerZoomLevel,
   }) = FitBounds._;
 
@@ -35,7 +35,7 @@ abstract class CameraFit {
   const factory CameraFit.insideBounds({
     required LatLngBounds bounds,
     EdgeInsets padding,
-    double maxZoom,
+    double? maxZoom,
     bool forceIntegerZoomLevel,
   }) = FitInsideBounds._;
 
@@ -51,7 +51,7 @@ abstract class CameraFit {
   const factory CameraFit.coordinates({
     required List<LatLng> coordinates,
     EdgeInsets padding,
-    double maxZoom,
+    double? maxZoom,
     bool forceIntegerZoomLevel,
   }) = FitCoordinates._;
 
@@ -68,10 +68,10 @@ class FitBounds extends CameraFit {
   /// Defaults to [EdgeInsets.zero].
   final EdgeInsets padding;
 
-  /// Limits the maximum zoom level of the resulting fit.
+  /// Limits the maximum zoom level of the resulting fit if set.
   ///
-  /// Defaults to zoom level 18.
-  final double maxZoom;
+  /// Defaults to null.
+  final double? maxZoom;
 
   /// Whether the zoom level of the resulting fit should be rounded to the
   /// nearest integer level.
@@ -82,7 +82,7 @@ class FitBounds extends CameraFit {
   const FitBounds._({
     required this.bounds,
     this.padding = EdgeInsets.zero,
-    this.maxZoom = 18,
+    this.maxZoom,
     this.forceIntegerZoomLevel = false,
   });
 
@@ -95,7 +95,7 @@ class FitBounds extends CameraFit {
     final paddingTotalXY = paddingTL + paddingBR;
 
     var newZoom = _getBoundsZoom(camera, paddingTotalXY);
-    newZoom = math.min(maxZoom, newZoom);
+    if (maxZoom != null) newZoom = math.min(maxZoom!, newZoom);
 
     final paddingOffset = (paddingBR - paddingTL) / 2;
     final swPoint = camera.project(bounds.southWest, newZoom);
@@ -125,7 +125,10 @@ class FitBounds extends CameraFit {
     CustomPoint<double> pixelPadding,
   ) {
     final min = camera.minZoom ?? 0.0;
-    final max = camera.maxZoom ?? double.infinity;
+    final max = math.min(
+      camera.maxZoom ?? double.infinity,
+      maxZoom ?? double.infinity,
+    );
     final nw = bounds.northWest;
     final se = bounds.southEast;
     var size = camera.nonRotatedSize - pixelPadding;
@@ -167,10 +170,10 @@ class FitInsideBounds extends CameraFit {
   /// Defaults to [EdgeInsets.zero].
   final EdgeInsets padding;
 
-  /// Limits the maximum zoom level of the resulting fit.
+  /// Limits the maximum zoom level of the resulting fit if set.
   ///
-  /// Defaults to zoom level 18.
-  final double maxZoom;
+  /// Defaults to null.
+  final double? maxZoom;
 
   /// Whether the zoom level of the resulting fit should be rounded to the
   /// nearest integer level.
@@ -181,7 +184,7 @@ class FitInsideBounds extends CameraFit {
   const FitInsideBounds._({
     required this.bounds,
     this.padding = EdgeInsets.zero,
-    this.maxZoom = 18,
+    this.maxZoom,
     this.forceIntegerZoomLevel = false,
   });
 
@@ -214,9 +217,9 @@ class FitInsideBounds extends CameraFit {
     }
 
     newZoom = math.max(
-      camera.minZoom ?? 0.0,
+      camera.minZoom ?? double.negativeInfinity,
       math.min(
-        math.min(maxZoom, camera.maxZoom ?? double.infinity),
+        math.min(maxZoom ?? double.infinity, camera.maxZoom ?? double.infinity),
         newZoom,
       ),
     );
@@ -359,10 +362,10 @@ class FitCoordinates extends CameraFit {
   /// Defaults to [EdgeInsets.zero].
   final EdgeInsets padding;
 
-  /// Limits the maximum zoom level of the resulting fit.
+  /// Limits the maximum zoom level of the resulting fit if set.
   ///
-  /// Defaults to zoom level 18.
-  final double maxZoom;
+  /// Defaults to null.
+  final double? maxZoom;
 
   /// Whether the zoom level of the resulting fit should be rounded to the
   /// nearest integer level.
@@ -373,7 +376,7 @@ class FitCoordinates extends CameraFit {
   const FitCoordinates._({
     required this.coordinates,
     this.padding = EdgeInsets.zero,
-    this.maxZoom = 18,
+    this.maxZoom = double.infinity,
     this.forceIntegerZoomLevel = false,
   });
 
@@ -386,7 +389,7 @@ class FitCoordinates extends CameraFit {
     final paddingTotalXY = paddingTL + paddingBR;
 
     var newZoom = _getCoordinatesZoom(camera, paddingTotalXY);
-    newZoom = math.min(maxZoom, newZoom);
+    if (maxZoom != null) newZoom = math.min(maxZoom!, newZoom);
 
     final projectedPoints = [
       for (final coord in coordinates) camera.project(coord, newZoom)
@@ -417,7 +420,10 @@ class FitCoordinates extends CameraFit {
     CustomPoint<double> pixelPadding,
   ) {
     final min = camera.minZoom ?? 0.0;
-    final max = camera.maxZoom ?? double.infinity;
+    final max = math.min(
+      camera.maxZoom ?? double.infinity,
+      maxZoom ?? double.infinity,
+    );
     var size = camera.nonRotatedSize - pixelPadding;
     // Prevent negative size which results in NaN zoom value later on in the calculation
     size = CustomPoint(math.max(0, size.x), math.max(0, size.y));