如何在两个 MKCooperativeRegion 之间建立并集

Question

我正在尝试在两个 MKCooperativeRegion 之间进行并集。有人知道如何做到这一点吗？

Answer 1

有一个 MKMapRectUnion 函数接受两个 MKMapRect，因此您可以首先将每个 MKCooperativeRegion 转换为 MKMapRect，然后调用该函数（并使用 MKCooperativeRegionForMapRect 函数将结果转换回 MKCooperativeRegion）。

转换方法可能如下所示：

- (MKMapRect)mapRectForCoordinateRegion:(MKCoordinateRegion)coordinateRegion
{
    CLLocationCoordinate2D topLeftCoordinate = 
        CLLocationCoordinate2DMake(coordinateRegion.center.latitude 
                + (coordinateRegion.span.latitudeDelta/2.0), 
            coordinateRegion.center.longitude 
                - (coordinateRegion.span.longitudeDelta/2.0));

    MKMapPoint topLeftMapPoint = MKMapPointForCoordinate(topLeftCoordinate);

    CLLocationCoordinate2D bottomRightCoordinate = 
        CLLocationCoordinate2DMake(coordinateRegion.center.latitude 
                - (coordinateRegion.span.latitudeDelta/2.0), 
            coordinateRegion.center.longitude 
                + (coordinateRegion.span.longitudeDelta/2.0));

    MKMapPoint bottomRightMapPoint = MKMapPointForCoordinate(bottomRightCoordinate);

    MKMapRect mapRect = MKMapRectMake(topLeftMapPoint.x, 
                            topLeftMapPoint.y, 
                            fabs(bottomRightMapPoint.x-topLeftMapPoint.x), 
                            fabs(bottomRightMapPoint.y-topLeftMapPoint.y));

    return mapRect;
}

然后，实际进行并集：

MKCoordinateRegion region1 = ...
MKCoordinateRegion region2 = ...

MKMapRect mapRect1 = [self mapRectForCoordinateRegion:region1];
MKMapRect mapRect2 = [self mapRectForCoordinateRegion:region2];

MKMapRect mapRectUnion = MKMapRectUnion(mapRect1, mapRect2);

MKCoordinateRegion regionUnion = MKCoordinateRegionForMapRect(mapRectUnion);

Answer 2

如果有人正在寻找使用扩展的快速等效项，

extension MKCoordinateRegion {
    func mapRectForCoordinateRegion() -> MKMapRect {
        let dLat = span.latitudeDelta / 2.0
        let dLon = span.longitudeDelta / 2.0

        let topLeft = MKMapPointForCoordinate(
            CLLocationCoordinate2DMake(center.latitude + dLat, center.longitude - dLon))
        let botRight = MKMapPointForCoordinate(
            CLLocationCoordinate2DMake(center.latitude - dLat, center.longitude + dLon))

        return MKMapRectMake(
            topLeft.x,
            topLeft.y,
            fabs(botRight.x - topLeft.x),
            fabs(botRight.y - topLeft.y))
    }

    func unionWith(region: MKCoordinateRegion) -> MKCoordinateRegion {
        let union = MKMapRectUnion(
            self.mapRectForCoordinateRegion(),
            region.mapRectForCoordinateRegion())

        return MKCoordinateRegionForMapRect(union)
    }
}

并且可以像这样使用

let region1 = ...
let region2 = ...

let regionUnion = region1.unionWith(region2)

Answer 3

我在 4.3 和 5.0 上做了一些测试，似乎转换不正确

UIImageView *imageView = [[UIImageView alloc] initWithImage:[[UIImage imageNamed:@"heart.png"] imageByScalingProportionallyToSize:CGSizeMake(100, 100)]];
imageView.frame = CGRectMake(0, 0, 100, 100);
imageView.center = [mapView convertCoordinate:mapView.centerCoordinate toPointToView:canvasView];
[canvasView addSubview:imageView];

MKCoordinateRegion region = [mapView convertRect:imageView.frame toRegionFromView:canvasView];
MKMapRect maprect;
for (int i = 0; i < 5; i ++)
{
    maprect = [mapView mapRectForCoordinateRegion:region];
    NSLog(@"%f, %f, %f, %f", region.center.latitude, region.center.longitude, region.span.latitudeDelta, region.span.longitudeDelta);
    NSLog(@"%f, %f, %f, %f", maprect.origin.x, maprect.origin.y, maprect.size.width, maprect.size.height);
    region = MKCoordinateRegionForMapRect([mapView mapRectForCoordinateRegion:region]);
}

14.718256、-40.078125、63.837150、70.312500

78118912.000000、94811514.406252、52428800.000000、52428799.999997

17.416993、-40.078125、63.837150、70.312500

78118912.000000、91803983.982924、52428800.000000、53344239.567355

20.649080、-40.078125、63.837150、70.312500

78118912.000000、87976363.978412、52428800.000000、54699220.734715

24.548345、-40.078125、63.837150、70.312500

78118912.000000、82962597.189840、52428800.000000、56765991.576236

29.305644、-40.078125、63.837150、70.312500

78118912.000000、76093086.024249、52428800.000000、60073659.997575

Answer 4

//usage >> let regionMerged = [region1, region2,......, regionN].unionRegion

internal extension MKCoordinateRegion {
    var northDegree: CLLocationDegrees { center.latitude + (span.latitudeDelta  / 2) }
    var southDegree: CLLocationDegrees { center.latitude - (span.latitudeDelta  / 2) }
    var eastDegree: CLLocationDegrees { center.longitude + (span.longitudeDelta / 2) }
    var westDegree: CLLocationDegrees { center.longitude - (span.longitudeDelta / 2) }

    var northWestPoint: CLLocationCoordinate2D { CLLocationCoordinate2D(latitude: northDegree, longitude: westDegree) }
    var southEastPoint: CLLocationCoordinate2D { CLLocationCoordinate2D(latitude: southDegree, longitude: eastDegree) }

    var mapRect: MKMapRect {
        let topLeft = northWestPoint
        let bottomRight = southEastPoint

        let a = MKMapPoint(topLeft)
        let b = MKMapPoint(bottomRight)

        return MKMapRect(origin: MKMapPoint(x:min(a.x,b.x),
                                            y:min(a.y,b.y)),
                         size: MKMapSize(width: abs(a.x-b.x),
                                         height: abs(a.y-b.y)))
    }

    static func + (lhs: MKCoordinateRegion, rhs: MKCoordinateRegion) -> MKCoordinateRegion {
        let union = lhs.mapRect + rhs.mapRect
        return union.coordinateRegion
    }
}

internal extension [MKCoordinateRegion] {
    var unionRegion: MKCoordinateRegion {
        self.reduce(MKCoordinateRegion() , +)
    }
}

internal extension MKMapRect {
    static func + (lhs: MKMapRect, rhs: MKMapRect) -> MKMapRect {
        lhs.union(rhs)
    }

    var coordinateRegion: MKCoordinateRegion {
        MKCoordinateRegion(self)
    }
}