ios – 使用MKOverlayRenderer绘制带孔的圆圈效果不佳

2023年11月6日 337次阅读

我想在mapview上画一个带孔的圆圈(比如甜甜圈).

我的代码在这里.

- (void)drawMapRect:(MKMapRect)mapRect zoomScale:(MKZoomScale)zoomScale inContext:(CG    ContextRef)context {

WPCircleOverlay * circleOverlay = self.overlay;

CGPoint centerPoint = [self pointForMapPoint:MKMapPointForCoordinate(circleOverlay.coordinate)];

CGFloat innerRadius = MKMapPointsPerMeterAtLatitude(circleOverlay.coordinate.latitude) * circleOverlay.innerRadius;
CGFloat outerRadius = MKMapPointsPerMeterAtLatitude(circleOverlay.coordinate.latitude) * circleOverlay.outerRadius;
CGMutablePathRef path = CGPathCreateMutable();

//CGPathMoveToPoint(path, ...);
CGPathAddArc(path, NULL, centerPoint.x, centerPoint.y, outerRadius, 0, 2 * M_PI, true);
CGPathCloseSubpath(path);

// Add the inner arc to the path (later used to substract the inner area)
CGPathAddArc(path, NULL, centerPoint.x, centerPoint.y, innerRadius, 0, 2 * M_PI, true);
CGPathCloseSubpath(path);

// Add the path to the context
CGContextAddPath(context, path);

CGContextSetFillColorWithColor(context, self.fillColor.CGColor);
CGContextEOFillPath(context);

CGPathRelease(path);

它在模拟器中运行良好,但在设备上却没有.

在设备上,外圈充满颜色,内圈没有被剪裁.
如何修改我的代码才能在设备上正常运行？

最佳答案 我使用CGContextAddEllipseInRect方法而不是CGContextAddArc修复它.

WPCircleOverlay * circleOverlay = self.overlay;

CGRect rectForMapRect = [self rectForMapRect:mapRect];
CGPoint centerPoint = [self pointForMapPoint:MKMapPointForCoordinate(circleOverlay.coordinate)];

CGFloat innerRadius = MKMapPointsPerMeterAtLatitude(circleOverlay.coordinate.latitude) * circleOverlay.innerRadius;
CGFloat outerRadius = MKMapPointsPerMeterAtLatitude(circleOverlay.coordinate.latitude) * circleOverlay.outerRadius;

CGRect innerRect = CGRectMake(centerPoint.x - innerRadius, centerPoint.y - innerRadius, innerRadius * 2.0, innerRadius * 2.0);
CGRect outerRect = CGRectMake(centerPoint.x - outerRadius, centerPoint.y - outerRadius, outerRadius * 2.0, outerRadius * 2.0);

if (CGRectIntersectsRect(rectForMapRect, outerRect)) {

    CGContextAddRect(context, rectForMapRect);

    CGContextSaveGState(context);
    CGContextClip(context);

    CGContextAddEllipseInRect(context, outerRect);
    CGContextAddEllipseInRect(context, innerRect);

    CGContextSaveGState(context);
    CGContextEOClip(context);

    UIColor * color = [self.fillColor copy];
    CGContextSetFillColorWithColor(context, color.CGColor);
    CGContextFillRect(context, outerRect);

    CGContextRestoreGState(context);
    CGContextRestoreGState(context);

    UIGraphicsPopContext();
}
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