如何在 swift 中为路径设置 fillColor 和 strokColor

Question

我正在使用MKMapSnapshotter获取某个区域的图像。

我使用UIGraphicsGetCurrentContext()在图像上画线来显示多边形，

我可以设置线条颜色，但无法为多边形设置填充颜色。

下面是代码

private func drawLineOnImage(snapshot: MKMapSnapshotter.Snapshot, coordinates: [CLLocationCoordinate2D]) -> UIImage {
    let image = snapshot.image
    UIGraphicsBeginImageContextWithOptions(getMapFrameSize(), true, 0)
    image.draw(at: CGPoint.zero)
    let context = UIGraphicsGetCurrentContext()
    context!.setLineWidth(2.0)
    context!.setStrokeColor(UIColor.red.cgColor)
    context!.move(to: snapshot.point(for: coordinates[0]))
    for i in 0...coordinates.count-1 {
        context!.addLine(to: snapshot.point(for: coordinates[i]))
        context!.move(to: snapshot.point(for: coordinates[i]))
    }
    context!.strokePath()
    context!.setFillColor(UIColor.green.cgColor)
    context!.fillPath()
    let resultImage = UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext()
    return resultImage!
}

我怎样才能做到这一点？

溶液：

private func drawLineOnImage(snapshot: MKMapSnapshotter.Snapshot, coordinates: [CLLocationCoordinate2D]) -> UIImage {
    let image = snapshot.image
    UIGraphicsBeginImageContextWithOptions(getMapFrameSize(), true, 0)
    image.draw(at: CGPoint.zero)
    let context = UIGraphicsGetCurrentContext()!
    context.setLineWidth(2.0)
    context.setStrokeColor(annotationColor.cgColor)
    context.setFillColor(annotationColor.withAlphaComponent(0.5).cgColor)
    var coordinates = coordinates
    if let firstPoint = coordinates.first { context.move(to: snapshot.point(for: firstPoint)) }
    context.move(to: snapshot.point(for: coordinates[0]))
    coordinates.removeFirst()
    coordinates.forEach { context.addLine(to: snapshot.point(for: $0)) }
    context.drawPath(using: .fillStroke)
    context.fillPath()
    let resultImage = UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext()
    return resultImage!
}

Answer 1

来自strokePath和fillPath的文档

清除当前路径作为调用此函数的副作用。

这意味着在调用strokePath之后，路径被清除，因此在调用fillPath时要注意绘制

相反，您应该致电context!.drawPath(using: .fillStroke)