百度地图步行箭头和路线一致

最近又重新再过一遍百度地图的相关东西，之前有一些细节没有注意到，其中有一个路线规划的步行中，把大头针设置成一个箭头，然后这个箭头的方向与路线方向一致，这个就需要自己来写一下。

1 把大头针设置成箭头图片

在实现BMKMapView的Delegate中实现如下方法，然后自定义一个getRouteAnnotation函数。

- (BMKAnnotationView *)mapView:(BMKMapView *)mapView viewForAnnotation:(id<BMKAnnotation>)annotation
{
if ([annotation isKindOfClass:[RouteAnnotation class]]) {
return [self getRouteAnnotationView:mapView viewForAnnotation:(RouteAnnotation *)annotation];
}
return nil;
}

2 自定义的getRouteAnnotationView

- (BMKAnnotationView *)getRouteAnnotationView:(BMKMapView *)mapView viewForAnnotation:(RouteAnnotation *)routeAnnotation
{
view = [mapView dequeueReusableAnnotationViewWithIdentifier:@"route_node"];
if (view == nil) {
view = [[BMKAnnotationView alloc]initWithAnnotation:routeAnnotation reuseIdentifier:@"route_node"];
view.canShowCallout = TRUE;
} else {
[view setNeedsDisplay];
}

UIImage* image = [UIImage imageWithContentsOfFile:[self getMyBundlePath:@"images/icon_direction.png"]];
view.image = [image imageRotatedByDegrees:routeAnnotation.degree];
view.annotation = routeAnnotation;
}

3 进行箭头和路线的调整

- (UIImage*)imageRotatedByDegrees:(CGFloat)degrees
{

CGFloat width = CGImageGetWidth(self.CGImage);
CGFloat height = CGImageGetHeight(self.CGImage);

CGSize rotatedSize;

rotatedSize.width = width;
rotatedSize.height = height;

UIGraphicsBeginImageContext(rotatedSize);
CGContextRef bitmap = UIGraphicsGetCurrentContext();
CGContextTranslateCTM(bitmap, rotatedSize.width/2, rotatedSize.height/2);
CGContextRotateCTM(bitmap, degrees * M_PI / 180);
CGContextRotateCTM(bitmap, M_PI);
CGContextScaleCTM(bitmap, -1.0, 1.0);
CGContextDrawImage(bitmap, CGRectMake(-rotatedSize.width/2, -rotatedSize.height/2, rotatedSize.width, rotatedSize.height), self.CGImage);
UIImage* newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return newImage;
}

这样，就实现了如图所示的效果