画线动画 [英] Draw line animated

问题描述

我想在屏幕中央有一条线，让它像一条蛇一样动画

I want to have a line in the center of the screen and animate it like a snake

这是我想做的一步一步的动画

This is step by step animation I want to make

我该怎么做?

推荐答案

您可以为 CAShapeLayer 上的 path 的笔划末端设置动画，例如，>

You can animate the end of the stroke of a path on a CAShapeLayer, e.g.,

weak var shapeLayer: CAShapeLayer?

@IBAction func didTapButton(_ sender: Any) {
    // remove old shape layer if any

    self.shapeLayer?.removeFromSuperlayer()

    // create whatever path you want

    let path = UIBezierPath()
    path.move(to: CGPoint(x: 10, y: 50))
    path.addLine(to: CGPoint(x: 200, y: 50))
    path.addLine(to: CGPoint(x: 200, y: 240))

    // create shape layer for that path

    let shapeLayer = CAShapeLayer()
    shapeLayer.fillColor = #colorLiteral(red: 0, green: 0, blue: 0, alpha: 0).cgColor
    shapeLayer.strokeColor = #colorLiteral(red: 1, green: 0, blue: 0, alpha: 1).cgColor
    shapeLayer.lineWidth = 4
    shapeLayer.path = path.cgPath

    // animate it

    view.layer.addSublayer(shapeLayer)
    let animation = CABasicAnimation(keyPath: "strokeEnd")
    animation.fromValue = 0
    animation.duration = 2
    shapeLayer.add(animation, forKey: "MyAnimation")

    // save shape layer

    self.shapeLayer = shapeLayer
}

结果:

显然，您可以将 UIBezierPath 更改为适合您兴趣的任何内容.例如，路径中可以有空格.或者你甚至不需要直线路径:

Clearly, you can change the UIBezierPath to whatever suits your interests. For example, you could have spaces in the path. Or you don't even need to have rectilinear paths:

let path = UIBezierPath()
path.move(to: CGPoint(x: 10, y: 130))
path.addCurve(to: CGPoint(x: 210, y: 200), controlPoint1: CGPoint(x: 50, y: -100), controlPoint2: CGPoint(x: 100, y: 350))

您还可以在 CAAnimationGroup 中组合笔画开始和结束的动画:

You can also combine animation of both the start and end of the stroke in a CAAnimationGroup:

// create shape layer for that path (this defines what the path looks like when the animation is done)

let shapeLayer = CAShapeLayer()
shapeLayer.fillColor = #colorLiteral(red: 0, green: 0, blue: 0, alpha: 0).cgColor
shapeLayer.strokeColor = #colorLiteral(red: 1, green: 0, blue: 0, alpha: 1).cgColor
shapeLayer.lineWidth = 5
shapeLayer.path = path.cgPath
shapeLayer.strokeStart = 0.8

let startAnimation = CABasicAnimation(keyPath: "strokeStart")
startAnimation.fromValue = 0
startAnimation.toValue = 0.8

let endAnimation = CABasicAnimation(keyPath: "strokeEnd")
endAnimation.fromValue = 0.2
endAnimation.toValue = 1.0

let animation = CAAnimationGroup()
animation.animations = [startAnimation, endAnimation]
animation.duration = 2
shapeLayer.add(animation, forKey: "MyAnimation")

产量:

CoreAnimation 使您可以对描边路径的渲染方式进行大量控制.

CoreAnimation gives you a lot of control over how the stroked path is rendered.

这篇关于画线动画的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！