检测点是否在MKPolygon覆盖范围内

Question

我希望能够判断tap是否在MKPolygon中.

我有一个MKPolygon:

CLLocationCoordinate2D  points[4];

points[0] = CLLocationCoordinate2DMake(41.000512, -109.050116);
points[1] = CLLocationCoordinate2DMake(41.002371, -102.052066);
points[2] = CLLocationCoordinate2DMake(36.993076, -102.041981);
points[3] = CLLocationCoordinate2DMake(36.99892, -109.045267);

MKPolygon* poly = [MKPolygon polygonWithCoordinates:points count:4];

[self.mapView addOverlay:poly];  

//create UIGestureRecognizer to detect a tap
UITapGestureRecognizer *tapRecognizer = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(foundTap:)];
tapRecognizer.numberOfTapsRequired = 1;
tapRecognizer.numberOfTouchesRequired = 1;
[self.mapView addGestureRecognizer:tapRecognizer];

它只是科罗拉多州的基本轮廓.

我得到了lat/long转换设置:

-(IBAction)foundTap:(UITapGestureRecognizer *)recognizer
{
    CGPoint point = [recognizer locationInView:self.mapView];

    CLLocationCoordinate2D tapPoint = [self.mapView convertPoint:point toCoordinateFromView:self.view];
}

但如果我的分接点在MKPolygon内,我不确定如何技术.似乎没有办法做这个检查,所以我猜我需要将MKPolygon转换为CGRect并使用CGRectContainsPoint.

MKPolygon有一个.points属性,但我似乎无法让它们退出.

有什么建议？

编辑:

以下两种解决方案均适用于iOS 6或更低版本,但在iOS 7中有效.在iOS 7中,该polygon.path属性始终返回NULL.安娜女士非常友好地提供了另一个SO问题的解决方案.它涉及从多边形点创建自己的路径以进入CGPathContainsPoint().

我的多边形的图像:

Answer 1

我创建了这个MKPolygon类别,以防有人想要使用它.似乎运作良好.您必须考虑内部多边形(即多边形中的孔):

@interface MKPolygon (PointInPolygon)
  -(BOOL) pointInPolygon:(CLLocationCoordinate2D) point mapView: (MKMapView*) mapView;
@end

@implementation MKPolygon (PointInPolygon)

-(BOOL) pointInPolygon:(CLLocationCoordinate2D) point mapView: (MKMapView*) mapView {
    MKMapPoint mapPoint = MKMapPointForCoordinate(point);
    MKPolygonView * polygonView = (MKPolygonView*)[mapView viewForOverlay:self];
    CGPoint polygonViewPoint = [polygonView pointForMapPoint:mapPoint];
    return CGPathContainsPoint(polygonView.path, NULL, polygonViewPoint, NO) && 
        ![self pointInInteriorPolygons:point mapView:mapView];
}

-(BOOL) pointInInteriorPolygons:(CLLocationCoordinate2D) point mapView: (MKMapView*) mapView {
    return [self pointInInteriorPolygonIndex:0 point:point mapView:mapView];
}

-(BOOL) pointInInteriorPolygonIndex:(int) index point:(CLLocationCoordinate2D) point mapView: (MKMapView*) mapView {
    if(index >= [self.interiorPolygons count])
        return NO;
    return [[self.interiorPolygons objectAtIndex:index] pointInPolygon:point mapView:mapView] || [self pointInInteriorPolygonIndex:(index+1) point:point mapView:mapView];
}

@end

Answer 2

你的foundTap方法:

-(IBAction)foundTap:(UITapGestureRecognizer *)recognizer
{
    CGPoint point = [recognizer locationInView:self.mapView];

    CLLocationCoordinate2D tapPoint = [self.mapView convertPoint:point toCoordinateFromView:self.view];

    [self pointInsideOverlay:tapPoint];

    if (isInside) 
     {
       ....
     }
}

以下是从上一个调用以检查该点是否在叠加层内的方法:

-(void)pointInsideOverlay:(CLLocationCoordinate2D )tapPoint 
{
    isInside = FALSE; 

    MKPolygonView *polygonView = (MKPolygonView *)[mapView viewForOverlay:polygonOverlay];

    MKMapPoint mapPoint = MKMapPointForCoordinate(tapPoint);

    CGPoint polygonViewPoint = [polygonView pointForMapPoint:mapPoint];

    BOOL mapCoordinateIsInPolygon = CGPathContainsPoint(polygonView.path, NULL, polygonViewPoint, NO);

        if ( !mapCoordinateIsInPolygon )

            //we are finding points that are inside the overlay
        {
            isInside = TRUE;
        }
}

Answer 3

确定一个点是否在任意多边形中并非易事，Apple 不将其作为 MKPolygon 的一部分提供也就不足为奇了。您可以访问这些点，这允许您在边缘上进行迭代。

要确定点 p 是否在多边形 s 内，请将每条边视为 s 中的一条有向线段。如果来自 p 的任何固定方向（通常平行于 X 轴或 Y 轴）的射线与该线段相交，则取该射线与该有向线段的叉积的 Z 分量的符号。如果 Z 分量 > 0，则向计数器加 1。如果它 < 0，则减去 1。实现这一点的技巧是避免当边缘几乎平行于光线时出现问题，或者当光线通过一个顶点时（它必须只计算一次，而不是每条边一次） .

当您对 s 中的所有边执行此操作后，您将计算光线与多边形轮廓相交的次数，如果边是从左到右添加的，以及如果是从右到左添加，你减去。如果结果总和为零，则您在多边形之外。否则你就在里面。

有许多可能的优化。其中之一是在更完整的测试之前进行快速边界框测试。另一种方法是拥有一个在所有边缘上都有边界的数据结构，以简单地丢弃不与射线相交的边缘。

编辑： AXB 的 Z 分量（ A 与 B 的叉积）由下式给出：

a.x * b.y - a.y * b.x

因为你关心的只是标志，你可以检查

a.x * b.y > a.y * b.x

Answer 4

我从字符串中的xml文件中获取MKPolygon数据点.我将数据字符串解析为数组点并使用http://alienryderflex.com/polygon/中的方法给出

这个对我有用....

-(BOOL)isPoint:(CLLocationCoordinate2D)findLocation inPloygon:(NSArray*)polygon{

    NSMutableArray *tempPolygon=[NSMutableArray arrayWithArray:polygon];
    int   i, j=(int)tempPolygon.count-1 ;
    bool  oddNodes=NO;
    double x=findLocation.latitude;
    double y=findLocation.longitude;

    for (i=0; i<tempPolygon.count; i++) {
        NSString*coordString=[tempPolygon objectAtIndex:i];
        NSArray*pointsOfCoordString=[coordString componentsSeparatedByString:@","];
        CLLocationCoordinate2D point=CLLocationCoordinate2DMake([[pointsOfCoordString objectAtIndex:1] doubleValue], [[pointsOfCoordString objectAtIndex:0] doubleValue]);
        NSString*nextCoordString=[tempPolygon objectAtIndex:j];
        NSArray*nextPointsOfCoordString=[nextCoordString componentsSeparatedByString:@","];
        CLLocationCoordinate2D nextPoint=CLLocationCoordinate2DMake([[nextPointsOfCoordString objectAtIndex:1] doubleValue], [[nextPointsOfCoordString objectAtIndex:0] doubleValue]);


        if ((point.longitude<y && nextPoint.longitude>=y)
            ||  (nextPoint.longitude<y && point.longitude>=y)) {
            if (point.latitude+(y-point.longitude)/(nextPoint.longitude-point.longitude)*(nextPoint.latitude-point.latitude)<x) {
                oddNodes=!oddNodes; }}
        j=i; }


    return oddNodes;

}

我的多边形(NSArray)对象是字符串,例如 @"-89.860021,44.944266,0"

Answer 5

这在#Swift 4.2 中对我有用：

extension MKPolygon {
    func isCoordinateInsidePolyon(coordinate: CLLocationCoordinate2D) -> Bool {
        let polygonRenderer = MKPolygonRenderer(polygon: self)
        let currentMapPoint: MKMapPoint = MKMapPoint(coor)
        let polygonViewPoint: CGPoint = polygonRenderer.point(for: currentMapPoint)
        if polygonRenderer.path == nil {
            return false
        }else{
            return polygonRenderer.path.contains(polygonViewPoint)
        }
    }
}

Answer 6

感谢@Steve Stomp，这里是Swift 3的更新版本

extension MKPolygon {

    func contains(coordinate: CLLocationCoordinate2D) -> Bool {

        let polygonRenderer = MKPolygonRenderer(polygon: self)
        let currentMapPoint: MKMapPoint = MKMapPointForCoordinate(coordinate)
        let polygonViewPoint: CGPoint = polygonRenderer.point(for: currentMapPoint)

        return  polygonRenderer.path.contains(polygonViewPoint)
    }
}