在iOS上绘制圆角图像时遇到奇怪的锯齿

Question

我正在尝试创建带圆角的缩略图，并在iOS的图像底部添加一个条形图。

我有以下代码：

java -jar jacoco-0.8.1/lib/jacococli.jar report jacoco.exec --classfiles directory_with_classes --html directory_for_report

最后，我得到了一个带有尖角圆角的图像，就像下面的快照一样。

有否建议消除圆角的锯齿？

=======添加了解决方案======

感谢@ wj2061的回答，问题解决了。这是代码：

extension UIImage {
  func thumbnails(with options: SomeDrawingOptions) -> UIImage? {
    // ...

    UIGraphicsBeginImageContextWithOptions(targetRect.size, false, 0)
    defer {
      UIGraphicsEndImageContext()
    }
    let context = UIGraphicsGetCurrentContext()!

    UIColor.white.setFill()
    context.fill(targetRect)

    UIBezierPath(roundedRect: targetRect, cornerRadius: 8).addClip()

    // Drawing image
    draw(in: targetRect)

    // Drawing a transparent mask
    UIColor.black.withAlphaComponent(0.4).setFill()
    context.fill(targetRect)

    // Drawing bar
    UIColor.white.setFill()
    context.fill(someBarRect)

    return UIGraphicsGetImageFromCurrentImageContext()
  }
}

Answer 1

所以看起来这个陷阱与UIBezierPath(roundedRect: targetRect, cornerRadius: 8).addClip()有关，我尝试在步骤1中为图像添加遮罩，在步骤2中为图像添加角落。代码就像这样

extension UIImage {
func thumbnails() -> UIImage? {
    let targetRect = CGRect(x: 0, y: 0, width: 100, height: 150)

    UIGraphicsBeginImageContextWithOptions(targetRect.size, false, 0)
    defer {
        UIGraphicsEndImageContext()
    }

    UIBezierPath(roundedRect: targetRect, cornerRadius: 8).addClip()

    let makedImage = self.makedImage()

    makedImage?.draw(in : targetRect)

    return UIGraphicsGetImageFromCurrentImageContext()
}


func makedImage()->UIImage?{
    let targetRect = CGRect(x: 0, y: 0, width: 100, height: 150)
    let someBarRect = CGRect(x: 0, y: 100, width: 100, height: 50)

    UIGraphicsBeginImageContextWithOptions(targetRect.size, false, 0)
    defer {
        UIGraphicsEndImageContext()
    }
    let context = UIGraphicsGetCurrentContext()!

    draw(in : targetRect)


    // Drawing a transparent mask
    UIColor.black.withAlphaComponent(0.4).setFill()
    context.fill(targetRect)

    // Drawing bar
    UIColor.white.withAlphaComponent(1).setFill()
    context.fill(someBarRect)

    return UIGraphicsGetImageFromCurrentImageContext()
 }
}