iphone石英在彼此的顶部绘制2条线导致蠕虫效应

Question

我正在使用iPhone的Quartz-2D在地图上显示路线。路线根据温度着色。由于某些街​​道的颜色是黄色，因此我在路线下方使用稍厚的黑色线条来创建边框效果，以便黄色街道上的黄色部分能够被点亮。但是，即使黑线与路线一样粗糙，整条路线看起来像是一条蠕虫（非常丑陋）。我想这是因为我正在绘制从航点到航点的线路，而不是使用最后一个航点作为下一个起点。这样，如果有几个路标遗失，路线仍然没有削减。

我需要做什么来显示两条线没有蠕虫效应？

-(void) drawRect:(CGRect) rect 
{ 
CSRouteAnnotation* routeAnnotation = (CSRouteAnnotation*)self.routeView.annotation; 

// only draw our lines if we're not int he moddie of a transition and we 
// acutally have some points to draw. 
if(!self.hidden && nil != routeAnnotation.points && routeAnnotation.points.count > 0) 
{ 
    CGContextRef context = UIGraphicsGetCurrentContext(); 

    Waypoint* fromWaypoint = [[Waypoint alloc] initWithDictionary:[routeAnnotation.points objectAtIndex:0]]; 
    Waypoint* toWaypoint; 

    for(int idx = 1; idx < routeAnnotation.points.count; idx++) 
    { 
     toWaypoint = [[Waypoint alloc] initWithDictionary:[routeAnnotation.points objectAtIndex:idx]]; 


     CLLocation* fromLocation = [fromWaypoint getLocation]; 
     CGPoint fromPoint = [self.routeView.mapView convertCoordinate:fromLocation.coordinate toPointToView:self]; 

     CLLocation* toLocation = [toWaypoint getLocation]; 
     CGPoint toPoint = [self.routeView.mapView convertCoordinate:toLocation.coordinate toPointToView:self]; 

     routeAnnotation.lineColor = [fromWaypoint.weather getTemperatureColor]; 

     CGContextBeginPath(context); 
     CGContextSetLineWidth(context, 3.0); 
     CGContextSetStrokeColorWithColor(context, [UIColor blackColor].CGColor); 
     CGContextMoveToPoint(context, fromPoint.x, fromPoint.y); 
     CGContextAddLineToPoint(context, toPoint.x, toPoint.y); 
     CGContextStrokePath(context); 
     CGContextClosePath(context); 

     CGContextBeginPath(context); 
     CGContextSetLineWidth(context, 3.0); 
     CGContextSetStrokeColorWithColor(context, routeAnnotation.lineColor.CGColor); 
     CGContextMoveToPoint(context, fromPoint.x, fromPoint.y); 
     CGContextAddLineToPoint(context, toPoint.x, toPoint.y); 
     CGContextStrokePath(context); 
     CGContextClosePath(context); 


     fromWaypoint = toWaypoint; 
    } 

    [fromWaypoint release]; 
    [toWaypoint release];  
} 
} 

而且，我得到一个

<Error>: CGContextClosePath: no current point. 

错误，我认为这是废话。

请提示我！ :)

---

Answer 1

听起来像这可能是与线帽有关。尝试绘制平坦的端盖，并看到它有帮助。

更新： 我明白现在发生了什么。它只是与前面的“背景”+“场景”画线所覆盖的像素重叠的“背景”线。您所做的更改将绘制所有“背景”线，然后所有“前景”线将避免此问题。 你的线仍然透支一些像素，但只有相同的颜色，所以你不会注意到。 （请注意，大部分线条端盖样式延伸线的实际点，使效果更明显 - 更重叠像素。）

Answer 2

而不是画两条线，你可以只画一条线，并使用the Shadows ability？

Answer 3

谢谢你们！所以，简单地添加一个阴影或线条上限没有帮助，效果保持不变。然而，我只是玩了一段代码，结果是，如果我分别在完整路径中绘制两条线（两条for循环），效果就消失了！然后我在背景线上添加了方形线条帽，使其稍微好一些。

现在我唯一想知道的是......对此有什么解释？下面是新的代码，我将在后面对其进行优化...

-(void) drawRect:(CGRect) rect { 
CSRouteAnnotation* routeAnnotation = (CSRouteAnnotation*)self.routeView.annotation; 

// only draw our lines if we're not int he moddie of a transition and we 
// acutally have some points to draw. 
if(!self.hidden && nil != routeAnnotation.points && routeAnnotation.points.count > 0) 
{ 
    CGContextRef context = UIGraphicsGetCurrentContext(); 


    Waypoint* fromWaypoint = [[Waypoint alloc] initWithDictionary:[routeAnnotation.points objectAtIndex:0]]; 
    Waypoint* toWaypoint; 

    for(int idx = 1; idx < routeAnnotation.points.count; idx++) 
    { 
     toWaypoint = [[Waypoint alloc] initWithDictionary:[routeAnnotation.points objectAtIndex:idx]]; 


     CLLocation* fromLocation = [fromWaypoint getLocation]; 
     CGPoint fromPoint = [self.routeView.mapView convertCoordinate:fromLocation.coordinate toPointToView:self]; 

     CLLocation* toLocation = [toWaypoint getLocation]; 
     CGPoint toPoint = [self.routeView.mapView convertCoordinate:toLocation.coordinate toPointToView:self]; 

     routeAnnotation.lineColor = [fromWaypoint.weather getTemperatureColor]; 

     CGContextBeginPath(context); 
     CGContextSetLineWidth(context, 3.5); 
     CGContextSetStrokeColorWithColor(context, [UIColor blackColor].CGColor); 
     CGContextSetLineCap(context, kCGLineCapSquare); 
     CGContextMoveToPoint(context, fromPoint.x, fromPoint.y); 
     CGContextAddLineToPoint(context, toPoint.x, toPoint.y); 
     CGContextStrokePath(context); 
     CGContextClosePath(context); 

     fromWaypoint = toWaypoint; 

    } 

    // zweite for schleife 
    for(int idx = 1; idx < routeAnnotation.points.count; idx++) 
    { 
     toWaypoint = [[Waypoint alloc] initWithDictionary:[routeAnnotation.points objectAtIndex:idx]]; 


     CLLocation* fromLocation = [fromWaypoint getLocation]; 
     CGPoint fromPoint = [self.routeView.mapView convertCoordinate:fromLocation.coordinate toPointToView:self]; 

     CLLocation* toLocation = [toWaypoint getLocation]; 
     CGPoint toPoint = [self.routeView.mapView convertCoordinate:toLocation.coordinate toPointToView:self]; 

     routeAnnotation.lineColor = [fromWaypoint.weather getTemperatureColor]; 

     CGContextBeginPath(context); 

     CGContextSetLineWidth(context, 3.0); 
     CGContextSetStrokeColorWithColor(context, routeAnnotation.lineColor.CGColor); 
     CGContextSetLineCap(context, kCGLineCapSquare); 
     CGContextMoveToPoint(context, fromPoint.x, fromPoint.y); 
     CGContextAddLineToPoint(context, toPoint.x, toPoint.y); 
     CGContextStrokePath(context); 
     CGContextClosePath(context); 

    } 

    [fromWaypoint release]; 
    } 
}  

Answer 4

而且，我得到一个

<错误>：CGContextClosePath：没有当前点。

抚摸路径结束当前路径上下文。