参考代码 酷炫粒子效果合成图片 code4app
为了实现项目中的一些特效，最近就扒了一些代码，无意中发现了这个特效，感觉效果很酷，本来感觉实现起来应该是非常有难度的，但是看了源码过后，发现实现的方式十分的简单。主要的步骤就是：先把图片分解为像素点，然后再利用 CADisplayLink 与屏幕同步刷新动画。源代码是OC 的，而我需要使用 Swfit 版的，所以就将整个代码又用 Swift3.0 写了一遍。由于 Swift 的一些原因，中途也遇见到了一些问题，所以就在此再记录一遍，温故而知新吗！
这是最终的效果图，粒子的发射速度，时间，起点等都是可以控制的。
问题
遇到的一个问题就是，需要如何解析 UnsafeMutableRawPointer 的数据，解决的方法如下
let rawData: UnsafeMutableRawPointer = calloc(imageH*imageW*bytesPerPixel, MemoryLayout.size(ofValue: CChar()))
.
.
.
let bufferData = UnsafeRawBufferPointer(start: rawData, count: imageH*imageW*bytesPerPixel)
通过 UnsafeRawBufferPointer 来将数据解析出来，count 后是数据所占的字节大小
代码示例
//
// BZEmitterLayer.swift
// BZEmitter
//
// Copyright © 2017 SSBun. All rights reserved.
//
import Foundation
import QuartzCore
import UIKit
struct BZParticle {
var color: UIColor
var point: CGPoint
var customColor: UIColor? {
set {
if let value = newValue {
color = value
}
}
get {
return color
}
}
var randomPointRange: CGFloat? {
set {
let value = newValue ?? 0
if value != 0 {
point.x = point.x - value + CGFloat(arc4random_uniform(UInt32(value) * 2))
point.y = point.y - value + CGFloat(arc4random_uniform(UInt32(value) * 2))
}
}
get {
return 0
}
}
let delayTime: UInt32 = arc4random_uniform(30)
let delayDuration: UInt32 = arc4random_uniform(10)
}
protocol BZEmitterLayerDelegate {
func emitterLayerEndAnimation()
}
class BZEmitterLayer: CALayer {
public var beginPoint: CGPoint = .zero// 粒子发射起点
public var ignoredBlack: Bool = false// 忽略黑色粒子
public var ignoredWhite: Bool = false// 忽略白色粒子
public var customColor: UIColor? // 覆盖原粒子颜色，最后会是一个图片的纯色图片
public var randomPointRange: CGFloat = 0// 不能等于0
public var maxParticleCount: UInt32 = 0 // 每行最大的粒子数量
public var image: UIImage? { // 待渲染的图片
didSet {
if let image = image {
particleArray = self.getRGBAs(from: image)
}
}
}
public var emitterDelegate: BZEmitterLayerDelegate?
private var animationTime: CGFloat = 0
private var animationDuration: CGFloat = 2
private var displayLink:CADisplayLink?
private var particleArray:[BZParticle] = []
override init() {
super.init()
self.masksToBounds = false
displayLink = CADisplayLink(target: self, selector: #selector(BZEmitterLayer.emitterAnimation))
displayLink?.add(to: .current, forMode: .commonModes)
}
required init?(coder aDecoder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
func emitterAnimation() {
self.setNeedsDisplay()
animationTime += 0.6
}
override func draw(in ctx: CGContext) {
var count = 0
for particle in particleArray {
if CGFloat(particle.delayTime) > animationTime {
continue
}
var curTime = animationTime - CGFloat(particle.delayTime)
if curTime > animationDuration + CGFloat(particle.delayDuration) {
curTime = animationDuration + CGFloat(particle.delayDuration)
count += 1
}
let curX = self.easeInOutQuad(curTime, beginPoint.x, particle.point.x + self.bounds.size.width/2 - CGFloat(image!.cgImage!.width/2), animationDuration + CGFloat(particle.delayDuration))
let curY = self.easeInOutQuad(curTime, beginPoint.y, particle.point.y + self.bounds.size.height/2 - CGFloat(image!.cgImage!.height/2), animationDuration + CGFloat(particle.delayDuration))
ctx.addRect(CGRect(x:curX, y:curY, width:1, height:1))
let components = particle.color.cgColor.components!
ctx.setFillColor(red: components[0], green: components[1], blue: components[2], alpha: components[3])
ctx.fillPath()
}
if (count == particleArray.count) {
self.reset()
self.emitterDelegate?.emitterLayerEndAnimation()
}
}
func easeInOutQuad(_ time: CGFloat, _ begin: CGFloat, _ end: CGFloat, _ duration: CGFloat) -> CGFloat {
let coverDistance = end - begin
var newTime = time / (duration/2)
if newTime < 1 {
return coverDistance/2.0 * pow(newTime, 2) + begin
}
newTime -= 1
return -coverDistance/2.0 * (newTime * (newTime - 2) - 1) + begin
}
func getRGBAs(from image: UIImage) -> [BZParticle] {
let imageRef = image.cgImage!
let imageW = imageRef.width
let imageH = imageRef.height
let colorSpace = CGColorSpaceCreateDeviceRGB()
let bytesPerPixel = 4 // 一个像素4个字节
let bytesPerRow = bytesPerPixel * imageW
let rawData: UnsafeMutableRawPointer = calloc(imageH*imageW*bytesPerPixel, MemoryLayout.size(ofValue: CChar()))
let bitsPerComponent = 8
let context = CGContext(data: rawData, width: imageW, height: imageH, bitsPerComponent: bitsPerComponent, bytesPerRow: bytesPerRow, space: colorSpace, bitmapInfo: CGImageByteOrderInfo.order32Big.rawValue | CGImageAlphaInfo.premultipliedLast.rawValue)
context?.draw(imageRef, in: CGRect(x: 0, y: 0, width: imageW, height: imageH))
let addY = maxParticleCount == 0 ? 1 : imageH / Int(maxParticleCount)
let addX = maxParticleCount == 0 ? 1 : imageW / Int(maxParticleCount)
var result = [BZParticle]()
let bufferData = UnsafeRawBufferPointer(start: rawData, count: imageH*imageW*bytesPerPixel)
for y in stride(from: 0, to: imageH, by: addY) {
for x in stride(from: 0, to: imageW, by: addX) {
let byteIndex = bytesPerRow*y + bytesPerPixel*x
let red = CGFloat(bufferData[byteIndex]) / 255.0
let green = CGFloat(bufferData[byteIndex + 1]) / 255.0
let blue = CGFloat(bufferData[byteIndex + 2]) / 255.0
let alpha = CGFloat(bufferData[byteIndex + 3]) / 255.0
if alpha == 0 || (ignoredWhite && (red+green+blue == 3)) || (ignoredBlack && (red+green+blue == 0)) {
continue
}
let color = UIColor(red: red, green: green, blue: blue, alpha: alpha)
let point = CGPoint(x: x, y: y)
var particle = BZParticle(color: color, point: point)
if let custom = customColor {
particle.customColor = custom
}
if randomPointRange > 0 {
particle.randomPointRange = randomPointRange
}
result.append(particle)
}
}
free(rawData)
return result
}
func pause() {
displayLink?.isPaused = true
}
func resume() {
displayLink?.isPaused = false
}
func reset() {
displayLink?.invalidate()
displayLink = nil
animationTime = 0
}
func restart() {
self.reset()
displayLink = CADisplayLink(target: self, selector: #selector(BZEmitterLayer.emitterAnimation))
displayLink?.add(to: .current, forMode: .commonModes)
}
}
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