使用图案图像在MKMapView上绘制线条

Question

我尝试MKMapView用图案图像在a 上画一条线.通过添加自定义MKMapOverlay视图完成绘图.

我能够绘制线条,但似乎只使用图案图像的左上角像素而不是整个图像来完成绘图.

这是我的绘图程序:

void drawPatternCellCallback(void *info, CGContextRef cgContext)
{
    UIImage *patternImage = [UIImage imageNamed:@"tmpLine"];
    CGContextDrawImage(cgContext, CGRectMake(0, 0, patternImage.size.width, patternImage.size.height), patternImage.CGImage);

}

- (void)drawMapRect:(MKMapRect)mapRect
          zoomScale:(MKZoomScale)zoomScale
          inContext:(CGContextRef)context
{
    float alpha = 1;        
    float tileW = 6.0f;
    float tileH = 4.0f;
    CGFloat lineWidth = MKRoadWidthAtZoomScale(zoomScale)*2;
    CGMutablePathRef path = CGPathCreateMutable();


    if (path != nil)

    {
        //setup styles
        CGContextSetRGBStrokeColor(context, 0.0f, 0.0f, 1.0f, 0.5f);

        const CGPatternCallbacks kPatternCallbacks = {0, drawPatternCellCallback, NULL};
        CGPatternRef strokePattern = CGPatternCreate(
                                                     NULL,
                                                     CGRectMake(0, 0, tileW, tileH), 
                                                     CGAffineTransformIdentity,
                                                     tileW, // horizontal spacing
                                                     tileH,// vertical spacing
                                                     kCGPatternTilingConstantSpacing,
                                                     true,
                                                     &kPatternCallbacks);
        //color sapce
        CGColorSpaceRef patternSpace = CGColorSpaceCreatePattern(NULL);
        CGContextSetStrokeColorSpace(context, patternSpace);

        //pattern
        CGContextSetStrokePattern(context, strokePattern, &alpha);

        //joins/ends
        CGContextSetLineJoin(context, kCGLineJoinMiter);
        CGContextSetLineCap(context, kCGLineCapButt);
        CGContextSetLineWidth(context, lineWidth);

        //OK, let's draw it
        CGPoint firstCGPoint = [self pointForMapPoint:self.point1];    
        CGPoint lastCGPoint = [self pointForMapPoint:self.point2];
        CGPathMoveToPoint(path, NULL, lastCGPoint.x, lastCGPoint.y);    
        CGPathAddLineToPoint(path, NULL, firstCGPoint.x, firstCGPoint.y);
        CGContextAddPath(context, path);
        CGContextStrokePath(context);

        //house hold
        CGPathRelease(path);
        CGPatternRelease(strokePattern);
        CGColorSpaceRelease(patternSpace);
    }
}

知道什么是错的吗？

感谢名单!

Answer 1

我最终得到了一个完全不同的策略.我现在依靠而不是通过自己的叠加添加MKPolyLine.

使用以下代码,我可以在a上添加从A点到B点的伪动画线MKMapView.

该代码为MKMapViews添加了几个叠加层,稍有延迟,给人一种动画效果

不是最美丽的解决方案! - 但它看起来很不错:-)

/*start the animation*/
-(void)plotRouteOnMap
{
    [self.mapView removeOverlays:self.mapView.overlays];
    //calculate a number locations between the two locations
    self.points = [self getPointsOnRouteFrom:<FROM_LOCATION>
                                          to:<TO_LOCATION>
                                   onMapView:self.mapView]; 
    [self addOverlaysFromPointsWithStartFrom:[NSNumber numberWithInt:1]];
}

/*convert a CGPoint to a CLLocation according to a mapView*/
- (CLLocation*)pointToLocation:(MKMapView *)mapView fromPoint:(CGPoint)fromPoint
{
    CLLocationCoordinate2D coord = [mapView convertPoint:fromPoint toCoordinateFromView:mapView];
    return [[[CLLocation alloc] initWithLatitude:coord.latitude longitude:coord.longitude] autorelease];
}

/*get a list of Location objects between from and to*/
-(NSArray*)getPointsOnRouteFrom:(CLLocation*)from to:(CLLocation*)to onMapView:(MKMapView*)mapView
{
    int NUMBER_OF_PIXELS_TO_SKIP =10; //lower number will give a more smooth animation, but will result in more layers 
    NSMutableArray *ret = [NSMutableArray array];
    CGPoint fromPoint = [mapView convertCoordinate:from.coordinate toPointToView:mapView];
    CGPoint toPoint = [mapView convertCoordinate:to.coordinate toPointToView:mapView];

    NSArray *allPixels = [self getAllPointsFromPoint:fromPoint toPoint:toPoint];
    for (int i = 0 ; i < [allPixels count] ; i+=NUMBER_OF_PIXELS_TO_SKIP) {
        NSValue *pointVal = [allPixels objectAtIndex:i];
        [ret addObject:[self pointToLocation:mapView fromPoint:[pointVal CGPointValue]]];  
    } 
    [ret addObject:[self pointToLocation:mapView fromPoint:toPoint]];  
    return ret;
}

/*calulate alle pixels from point to toPint*/
-(NSArray*)getAllPointsFromPoint:(CGPoint)fPoint toPoint:(CGPoint)tPoint
{
    /*Simplyfied implementation of Bresenham's line algoritme */
    NSMutableArray *ret = [NSMutableArray array];
    float deltaX = fabsf(tPoint.x - fPoint.x);
    float deltaY = fabsf(tPoint.y - fPoint.y);
    float x = fPoint.x;
    float y = fPoint.y;
    float err = deltaX-deltaY;

    float sx = -0.5;
    float sy = -0.5;
    if(fPoint.x<tPoint.x)
        sx = 0.5;

    if(fPoint.y<tPoint.y)
        sy = 0.5;
    do {
        [ret addObject:[NSValue valueWithCGPoint:CGPointMake(x, y)]];
        float e = 2*err;
        if(e > -deltaY)
        {
            err -=deltaY;
            x +=sx; 
        }
        if(e < deltaX)
        {
            err +=deltaX;
            y+=sy;
        }
    } while (round(x)  != round(tPoint.x) && round(y) != round(tPoint.y));
    [ret addObject:[NSValue valueWithCGPoint:tPoint]];//add final point
    return ret;

}

/*add a poly line overlay to mapview which start at position 0 and end in 'end' in the array points*/
-(void)addOverlaysFromPointsWithStartFrom:(NSNumber*)end
{
    int intEnd = [end intValue];

    //construct polyline view from start
    CLLocationCoordinate2D *locations = malloc(sizeof(CLLocationCoordinate2D)*2); 
    CLLocation *loc1 = (CLLocation*)[points objectAtIndex:0];
    CLLocation *loc2= (CLLocation*)[points objectAtIndex:intEnd];
    locations[0] = loc1.coordinate;
    locations[1] = loc2.coordinate;
    MKPolyline *line = [MKPolyline polylineWithCoordinates:locations count:2]; 
    [self.mapView addOverlay:line];


    if((intEnd+1) < [points count])//add more overlays after delays unless this is the endpoint
    {        
        [self performSelector:@selector(addOverlaysFromPointsWithStartFrom:) withObject:[NSNumber numberWithInt:intEnd + 1] afterDelay:0.01];
    }

}