缩放CGPath以适应UIVIew

我需要知道如何缩小或缩小CGPath以便它可以适合UIView？

将背景颜色设置为黄色，以清楚地查看视图

self.frame = CGRectMake(0, 0, 181, 154); self.backgroundColor = [UIColor yellowColor]; 

绘制CAShapeLayer

 CAShapeLayer *shape = [CAShapeLayer layer]; shape.path = aPath; shape.strokeColor = [[UIColor blueColor] CGColor]; shape.lineWidth = 5; shape.fillColor = [[UIColor clearColor] CGColor]; [self.layer addSublayer:shape]; 

然后我得到这个：

我想要的是这个：

谢谢开发人员:)

Answer 1

我假设您想要完全填充（不扭曲）形状以适合您的视图。 我还假设你有一个已经有路径的形状图层，因为问题是标记为CAShapeLayer。

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在这种情况下，您将获得形状图层路径的边界框，并计算要应用于路径的适当比例因子。

根据形状的纵横比和它应该适合的视图，它将是确定比例因子的宽度或高度。

获得比例因子后，您将创建一个转换以应用于路径。 由于路径可能不是从（0,0）开始，因此您还将变换中的路径转换（移动）到边界框原点。

如果您希望新路径位于视图的中心，则需要计算移动路径的数量。 如果您不需要，可以注释掉该代码，但我也将其包含在阅读此答案的其他人中。

最后你有一个新的路径，所以你要做的就是创建一个新的形状图层，分配路径，适当地设置它并将其添加到视图中。

 // I'm assuming that the view and original shape layer is already created CGRect boundingBox = CGPathGetBoundingBox(shapeLayer.path); CGFloat boundingBoxAspectRatio = CGRectGetWidth(boundingBox)/CGRectGetHeight(boundingBox); CGFloat viewAspectRatio = CGRectGetWidth(viewToFitIn.frame)/CGRectGetHeight(viewToFitIn.frame); CGFloat scaleFactor = 1.0; if (boundingBoxAspectRatio > viewAspectRatio) { // Width is limiting factor scaleFactor = CGRectGetWidth(viewToFitIn.frame)/CGRectGetWidth(boundingBox); } else { // Height is limiting factor scaleFactor = CGRectGetHeight(viewToFitIn.frame)/CGRectGetHeight(boundingBox); } // Scaling the path ... CGAffineTransform scaleTransform = CGAffineTransformIdentity; // Scale down the path first scaleTransform = CGAffineTransformScale(scaleTransform, scaleFactor, scaleFactor); // Then translate the path to the upper left corner scaleTransform = CGAffineTransformTranslate(scaleTransform, -CGRectGetMinX(boundingBox), -CGRectGetMinY(boundingBox)); // If you want to be fancy you could also center the path in the view // ie if you don't want it to stick to the top. // It is done by calculating the heigth and width difference and translating // half the scaled value of that in both x and y (the scaled side will be 0) CGSize scaledSize = CGSizeApplyAffineTransform(boundingBox.size, CGAffineTransformMakeScale(scaleFactor, scaleFactor)); CGSize centerOffset = CGSizeMake((CGRectGetWidth(viewToFitIn.frame)-scaledSize.width)/(scaleFactor*2.0), (CGRectGetHeight(viewToFitIn.frame)-scaledSize.height)/(scaleFactor*2.0)); scaleTransform = CGAffineTransformTranslate(scaleTransform, centerOffset.width, centerOffset.height); // End of "center in view" transformation code CGPathRef scaledPath = CGPathCreateCopyByTransformingPath(shapeLayer.path, &scaleTransform); // Create a new shape layer and assign the new path CAShapeLayer *scaledShapeLayer = [CAShapeLayer layer]; scaledShapeLayer.path = scaledPath; scaledShapeLayer.fillColor = [UIColor blueColor].CGColor; [viewToFitIn.layer addSublayer:scaledShapeLayer]; CGPathRelease(scaledPath); // release the copied path 

在我的示例代码（和形状）中，它看起来像这样

Answer 2

swift 4.0版DavidRönnqvist的回答

  func resizepath(Fitin frame : CGRect , path : CGPath) -> CGPath{ let boundingBox = path.boundingBox let boundingBoxAspectRatio = boundingBox.width / boundingBox.height let viewAspectRatio = frame.width / frame.height var scaleFactor : CGFloat = 1.0 if (boundingBoxAspectRatio > viewAspectRatio) { // Width is limiting factor scaleFactor = frame.width / boundingBox.width } else { // Height is limiting factor scaleFactor = frame.height / boundingBox.height } var scaleTransform = CGAffineTransform.identity scaleTransform = scaleTransform.scaledBy(x: scaleFactor, y: scaleFactor) scaleTransform.translatedBy(x: -boundingBox.minX, y: -boundingBox.minY) let scaledSize = boundingBox.size.applying(CGAffineTransform (scaleX: scaleFactor, y: scaleFactor)) let centerOffset = CGSize(width: (frame.width - scaledSize.width ) / scaleFactor * 2.0, height: (frame.height - scaledSize.height) / scaleFactor * 2.0 ) scaleTransform = scaleTransform.translatedBy(x: centerOffset.width, y: centerOffset.height) //CGPathCreateCopyByTransformingPath(path, &scaleTransform) let scaledPath = path.copy(using: &scaleTransform) return scaledPath! }