用背景色绘制GMSPolyline

Question

我看到GMSPolyline协议已经为其笔触颜色定义了color属性，但是有没有一种方法可以遮蔽其多边形的内部（理想情况下是透明）？我正在寻找相当于MKPolygon的Google地图和朋友。

Answer 1

折线与多边形的不同。多义线“没有填充颜色的概念。为要添加到SDK的多边形文件feature request。

Answer 2

有一个办法，你可以得到这样的事情：

的方法是相当简单：

• 添加透明非相互作用的UIView与被覆盖的绘图代码，并将其传递CGPoints为绘制多边形
• 获取多边形的CLLocationCoordinate2D坐标，并将它们转换为CGPoints进行绘制
• 每次地图移动时更新这些CGPoints，以便您可以在正确的位置重新绘制它们，并使UIView自己重绘。

所以，你想要做什么是对你的MapView，这是透明的和非userinteractive，已覆盖drawRect方法的顶部添加UIView。它提供有一个CGPoint的双重阵列，如CGpoint **points,与points[i][j]相符，其中 i是每个封闭多边形，并且 j是每个多边形的单独点。类会是这样，让我们​​把它概述：

#import "OverView.h" 

@interface OverView() 
{ 
    CGPoint **points; 
    int *pointsForPolygon; 
    int count; 
} 

@end 

@implementation OverView 

- (id)initWithFrame:(CGRect)frame andNumberOfPoints:(int)numpoints andPoints:(CGPoint **)passedPoints andPointsForPolygon:(int *)passedPointsForPolygon;{ 
    self = [super initWithFrame:frame]; 
    if (self) { 

     // You want this to be transparent and non-user-interactive 

     self.userInteractionEnabled = NO; 
     self.backgroundColor = [UIColor clearColor]; 

     // Passed data 

     points = passedPoints; // all CGPoints 
     pointsForPolygon = passedPointsForPolygon; // number of cgpoints for each polygon 
     count = numpoints; // Number of polygons 
    } 
    return self; 
} 


// Only override drawRect: if you perform custom drawing. 
// An empty implementation adversely affects performance during animation. 

- (void)drawRect:(CGRect)rect 
{ 

    for(int i=0; i<count; i++) // For each of polygons, like blue ones in picture above 
    { 
     if (pointsForPolygon[i] < 2) // Require at least 3 points 
      continue; 

     CGContextRef context = UIGraphicsGetCurrentContext(); 

     CGContextSetStrokeColorWithColor(context, [UIColor redColor].CGColor); 
     CGContextSetRGBFillColor(context, 0.0, 0.0, 1.0, 1.0); 

     CGContextSetLineWidth(context, 2.0); 

     for(int j = 0; j < pointsForPolygon[i]; j++) 
     { 
      CGPoint point = points[i][j]; 

      if(j == 0) 
      { 
       // Move to the first point 
       CGContextMoveToPoint(context, point.x, point.y); 
      } 
      else 
      { 
       // Line to others 
       CGContextAddLineToPoint(context, point.x, point.y); 
      } 
     } 

     CGContextClosePath(context); // And close the path 
     CGContextFillPath(context); 
     CGContextStrokePath(context); 
    } 
} 


@end 

如今，在原UIViewController与MapView的，你需要有访问，使所有多边形（同一阵列为点所有的坐标，而是由CLLocationCoordinate2D，和其他几个人：无论你得到你的坐标多边形

@interface ViewController() <GMSMapViewDelegate> 
{ 
    CGPoint **points; 
    int howmanypoints; 
    int *pointsForPolygon; 
    CLLocationCoordinate2D **acoordinates; 
} 

acoordinates填充，我解析来自Fusion Tables的响应字符串，我的解析器方法的一部分

- (void)parseResponse2 
{ 
    NSMutableArray *fullArray = [[self.fusionStringBeaches componentsSeparatedByString:@"\n"] mutableCopy]; 

    howmanypoints = fullArray.count; // This is number of polygons 

    pointsForPolygon = (int *)calloc(howmanypoints, sizeof(int)); // Number of points for each of the polygons 
    points = (CGPoint **)calloc(howmanypoints, sizeof(CGPoint *)); 
    acoordinates = (CLLocationCoordinate2D **)calloc(howmanypoints, sizeof(CLLocationCoordinate2D *)); 

    for(int i=0; i<fullArray.count; i++) 
    { 

     // Some parsing skipped here 

     points[i] = (CGPoint *)calloc(koji, sizeof(CGPoint)); 
     acoordinates[i] = (CLLocationCoordinate2D *)calloc(koji, sizeof(CLLocationCoordinate2D)); 
     pointsForPolygon[i] = koji; 

     if (koji > 2) 
     { 
      // Parsing skipped     
      for (int j=0; j<koji; j++) 
      { 
       CLLocationCoordinate2D coordinate = CLLocationCoordinate2DMake(coordinates[j].latitude, coordinates[j].longitude); 

       // Here, you convert coordinate and add it to points array to be passed to overview 
       points[i][j] = [self.mapView.projection pointForCoordinate:coordinate]; 
       // and added that coordinate to array for future access 
       acoordinates[i][j] = coordinate; 
      } 
     } 
    } 

    // Finally, allocate OverView passing points array and polygon and coordinate counts 
    self.overView = [[OverView alloc] initWithFrame:self.view.bounds 
            andNumberOfPoints:howmanypoints 
              andPoints:points 
           andPointsForPolygon:pointsForPolygon]; 

    // And add it to view 
    [self.view addSubview:self.overView]; 

} 

现在，你有多边形你想要他们，但必须遵守- (void)mapView:(GMSMapView *)mapView didChangeCameraPosition:(GMSCameraPosition *)position委托方法为绘制的多边形不会随着地图移动。关键是你有坐标acoordinates你的二维数组，你可以将用户的辅助功能(CGPoint *)[self.mapview.projection pointForCoordinate:(CLLocationCoordinate2D)coordinate]重新计算位置，如：

- (void)mapView:(GMSMapView *)mapView didChangeCameraPosition:(GMSCameraPosition *)position 
{  
    if (points != nil) 
    { 
     // Determine new points to pass 
     for (int i=0; i<howmanypoints; i++) 
     { 
      for(int j=0; j<pointsForPolygon[i]; j++) 
      { 
       // Call method to determine new CGPoint for each coordinate 
       points[i][j] = [self.mapView.projection pointForCoordinate:acoordinates[i][j]]; 
      } 
     } 

     // No need to pass points again as they were passed as pointers, just refresh te view  
     [self.overView setNeedsDisplay]; 
    } 

} 

就是这样。希望你了解它的要点。请评论我是否需要澄清一些事情。我也可以制作一个小型的完整项目并将其上传到github，以便您可以更好地研究它。