1

我正在使用 Quartz-2D for iPhone 在地图上显示路线。路线根据温度着色。因为有些街道是黄色的，所以我在路线下方使用了一条稍粗的黑线来创建边框效果，这样路线的黄色部分就可以在黄色街道上看到。但是，即使黑线和路线线一样粗，整条路线看起来也像一条虫子（非常丑陋）。我认为这是因为我在从航点到航点画线，而不是使用最后一个航点作为下一个起始航点。这样，如果缺少几个航点，路线仍然不会有任何削减。

我需要做什么才能在没有蠕虫效果的情况下显示两条线？

-(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];       
}
}

另外，我得到一个

<Error>: CGContextClosePath: no current point.

错误，我认为这是胡说八道。

请提示我！:)

4

4 回答 4

0

多谢你们！因此，简单地添加阴影或线帽并没有帮助，效果保持不变。但是，我只是稍微玩了一下代码，结果发现如果我分别在完整路径中绘制两条线（在两个 for 循环中），效果就消失了！然后我在背景线上添加了方形线帽，使它稍微好一点。

现在我唯一想知道的是……对此有何解释？这是新代码，我稍后会优化它...

-(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];
   }
}
于 2010-01-14T20:50:35.517 回答
0

另外，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。

于 2010-01-15T03:23:31.213 回答
0

不用画两条线，你可以只画一条并使用阴影能力吗？

于 2010-01-14T01:48:43.960 回答
0

听起来这可能与线路上限有关。尝试使用扁平端盖进行绘图，看看是否有帮助。

更新：我知道现在发生了什么。它只是与之前的“背景”+“前景”线绘制覆盖的像素重叠的“背景”线。您绘制所有“背景”线然后所有“前景”线的更改避免了这个问题。你的线条仍然透支了一些像素，但只有相同的颜色，所以你不会注意到。（请注意，大多数线端盖样式延伸到线中的实际点之外，使效果更明显 - 更多重叠像素。）

于 2010-01-14T01:31:42.950 回答