序言
当前Android 主流的系统中粒子的实现方式大致可以分为两类三种
1. 继承普通的View，主线程刷新绘制
2. 使用surfaceView，子线程刷新绘制
3. 使用surfaceView+openGl，子线程刷新绘制
因为第三种方式不是很常用，这里使用前两种方式实现粒子
效果图（视频转GIf有点卡）
image
实现功能
1. 可以自定义粒子刷新的频率，每次刷新的数量
2. 粒子自己维护自己的生命周期
3. 可以预先自己定义的粒子数量加载粒子 避免一加载就是满屏粒子的尴尬
4. 复用消亡粒子
5. 实现粒子的高度自定义 避免过度封装
理论概述
两种实现方式 对粒子的处理大致相同 不同的是绘制的位置区别
这里以第一种方式为例 画出粒子的UML框架：
image
如上图所示
ParticleView继承Runnable 使用handler定时刷新，每次刷新进行以下一个步骤
1. 新增粒子 从cacheItems集合中获取缓存粒子 如果没有则调用adapter进行创建
2. 调用transForms 移动粒子并将消亡粒子移除绘制集合中
3. 调用drawItems方法绘制所有的粒子
使用
这里因为是高度资质粒子，所以如果我们想要绘制粒子需要首先继承BaseItem接口定义自己的粒子类：
然后实现适配器ParticleAdapter
如：
particle.setAdapter(object : ParticleAdapter() {
override fun newItem(parentWidth: Int, parentHeight: Int): BaseItem {
//返回自己实现的粒子
return BubbleItem(parentWidth, parentHeight, this@MainActivity)
}
override fun preCreateCount(): Int {
return 50
}
})
particle.setIncreaseParticleInterval(100)
particle.setRenderTime(16)
particle.setIncreaseParticleCount(1)
我这里实现的粒子如下：BubbleItem.kotlin
class BubbleItem(private val parentWidth: Int, private val parentHeight: Int,context: Context) :
BaseItem {
companion object {
const val STATE_LIVE = 1
const val STATE_DIE = 0
}
private val baseBubbleRadius = ScreenUtil.dip2px(context,2f)
private val intervalBubbleRadius = ScreenUtil.dip2px(context,3f)
//起点
private var origX: Float = 0f
private var origY: Float = parentHeight.toFloat()
//终点
private var desY: Float = 0f
//当前的位置
private var curX = 0f
private var curY = 0f
//每次刷新 在Y轴的偏移量
private var speedY = ScreenUtil.dip2px(context,2f)
private val baseSpeedX =ScreenUtil.dip2px(context,0.5f)
//每次刷新 在X轴的偏移量
private var speedX = 0f
var radius = 20f
//透明的距离
private var alphaDis = 0f
var state = STATE_DIE
private val paint = Paint(Paint.ANTI_ALIAS_FLAG)
private var drawBitmap: Bitmap? = null
private var resRect: Rect? = null
init {
paint.style = Paint.Style.FILL_AND_STROKE
paint.color = Color.BLUE
}
/**
* 初始化 随机生成气泡的出生地点
*/
override fun init(context: Context) {
//获取气泡的bitmap
if (drawBitmap == null) {
drawBitmap = BitmapFactory.decodeResource(context.resources, R.drawable.bubble)
resRect = Rect(0, 0, drawBitmap?.width ?: 0, drawBitmap?.height ?: 0)
}
origX = Random.nextInt(100, parentWidth - 100).toFloat()
desY = 2 * parentHeight / 3 - Random.nextInt(0, parentHeight / 2).toFloat()
alphaDis = (origY - desY) * 0.2f
radius = Random.nextFloat() * intervalBubbleRadius + baseBubbleRadius
speedX = baseSpeedX * Random.nextFloat() * if (Random.nextBoolean()) {
1
} else {
-1
}
curX = origX
curY = origY
state = STATE_LIVE
//在边界处的粒子 没有横向速度
if (curX <= 200 || curX > (parentWidth - 200)) {
speedX = 0f
}
paint.alpha = 255
}
override fun preInit(context: Context) {
//起点的X轴坐标
init(context)
curY = desY + max((origY - desY) * Random.nextFloat(), 0f)
}
override fun move(): Boolean {
curY -= speedY
curX += speedX
val diff = curY - desY
if (diff <= alphaDis) {
if (diff <= alphaDis * 0.4 && diff >=0.3 * alphaDis) {
paint.alpha = 255
} else {
//开始透明
paint.alpha = (255 * diff / alphaDis + 0.5f).toInt()
}
}
if (curY < desY) {
state = STATE_DIE
return false
}
if (curX <= 20 || curX >= parentWidth - 20) {
state = STATE_DIE
return false
}
return true
}
override fun reset() {
}
override fun draw(canvas: Canvas) {
drawBitmap?.apply {
if (!isRecycled) {
canvas.drawBitmap(this, resRect, RectF(curX - radius, curY - radius, curX + radius, curY + radius), paint)
}
}
}
override fun isLive(): Boolean {
return state == STATE_LIVE
}
override fun destroy() {
drawBitmap?.recycle()
drawBitmap = null
}
}
使用普通View 主线程刷新绘制
普通的View绘制就是 使用handler主线程绘制刷新实现如下：
class ParticleView(context: Context, attributeSet: AttributeSet) : View(context, attributeSet),
BaseParticle, Runnable {
private var particleAdapter: ParticleAdapter? = null
private var isAutoPlay = true
private var intervalTime = 10 * Constant.RENDER_TIME
private var renderTime = Constant.RENDER_TIME
private var increaseParticleCount = 1
private var childTotal = Int.MAX_VALUE
private var temTime = -1
//缓存的view
private var cacheItems = LinkedList<BaseItem>()
//要绘制的所有View
private var drawItems = ArrayList<BaseItem>()
private var renderHandler: Handler = Handler()
private var isInit: Boolean = false
override fun preCreate() {
repeat(particleAdapter?.preCreateCount() ?: 0) {
val newItem = particleAdapter!!.newItem(measuredWidth, measuredHeight)
newItem.preInit(context)
drawItems.add(newItem)
}
}
override fun getItem(): BaseItem {
val newItem = if (cacheItems.size > 0) {
cacheItems.removeFirst()
} else {
particleAdapter!!.newItem(measuredWidth, measuredHeight)
}
newItem.init(context)
return newItem
}
override fun drawItems(canvas: Canvas) {
if (drawItems.size < childTotal) {
if (temTime == -1) {
temTime = ((intervalTime / renderTime.toFloat() + 0.5).toInt())
} else if (temTime == 0) {
repeat(increaseParticleCount) {
drawItems.add(getItem())
}
}
temTime--
}
drawItems.forEach {
it.draw(canvas)
}
}
override fun transForms() {
val iterator = drawItems.iterator()
while (iterator.hasNext()) {
val next = iterator.next()
val isLive = next.move()
if (!isLive) {
iterator.remove()
cacheItems.add(next)
}
}
}
override fun destroyAllView() {
drawItems.forEach {
it.destroy()
}
cacheItems.forEach {
it.destroy()
}
}
override fun startAnimation() {
renderHandler.removeCallbacks(this)
renderHandler.post(this)
}
override fun stopAnimation() {
renderHandler.removeCallbacks(this)
}
override fun setAdapter(adapter: ParticleAdapter) {
particleAdapter = adapter
if (particleAdapter!!.maxParticleCount() <= 0) {
return
}
childTotal = particleAdapter!!.maxParticleCount()
}
override fun setRenderTime(renderTime: Long) {
if (intervalTime < renderTime || renderTime < 0) {
return
}
this.renderTime = renderTime
}
override fun setIncreaseParticleInterval(intervalTime: Long) {
if (intervalTime < renderTime || renderTime < 0) {
return
}
this.intervalTime = intervalTime
}
override fun setIncreaseParticleCount(count: Int) {
if (count <= 0) {
return
}
increaseParticleCount = count
}
override fun setIsAutoPlay(isAuto: Boolean) {
isAutoPlay = isAuto
}
/**
* 设置大小则按照设置的大小计算 否则按照屏幕的宽高来计算
*/
override fun onMeasure(widthMeasureSpec: Int, heightMeasureSpec: Int) {
//获取屏幕宽高
val screenWidth = ScreenUtil.getScreenWidth(context)
val screenHeight = ScreenUtil.getScreenRealHeight(context)
setMeasuredDimension(
getDefaultSize(screenWidth, widthMeasureSpec),
getDefaultSize(screenHeight, screenHeight)
)
}
override fun onLayout(changed: Boolean, left: Int, top: Int, right: Int, bottom: Int) {
super.onLayout(changed, left, top, right, bottom)
if (!isInit) {
isInit = true
preCreate()
}
}
override fun onDraw(canvas: Canvas?) {
if (visibility != VISIBLE) {
return
}
if (canvas == null) {
renderHandler.removeCallbacks(this)
return
}
drawItems(canvas)
}
override fun run() {
transForms()
invalidate()
renderHandler.postDelayed(this, renderTime)
}
override fun setVisibility(visibility: Int) {
super.setVisibility(visibility)
if (isAutoPlay) {
if (visibility == VISIBLE) {
startAnimation()
} else {
renderHandler.removeCallbacksAndMessages(null)
}
}
}
override fun onDetachedFromWindow() {
super.onDetachedFromWindow()
renderHandler.removeCallbacks(this)
}
override fun onAttachedToWindow() {
super.onAttachedToWindow()
renderHandler.post(this)
}
}
使用surfaceView，子线程刷新绘制
实现如下：
class ParticleSurfaceView(context: Context, attributeSet: AttributeSet) :
SurfaceView(context, attributeSet), BaseParticle, SurfaceHolder.Callback, Runnable {
private var particleAdapter: ParticleAdapter? = null
private var isAutoPlay = true
private var intervalTime = 10 * Constant.RENDER_TIME
private var renderTime = Constant.RENDER_TIME
private var increaseParticleCount = 1
private var childTotal = Int.MAX_VALUE
private var temTime = -1
private val surfaceHolder: SurfaceHolder = holder
private lateinit var handlerThread: HandlerThread
private lateinit var renderHandler: Handler
//缓存的view
private var cacheItems = LinkedList<BaseItem>()
//要绘制的所有View
private var drawItems = ArrayList<BaseItem>()
init {
surfaceHolder.setKeepScreenOn(true)
surfaceHolder.addCallback(this)
isFocusable = true
isFocusableInTouchMode = true
setZOrderOnTop(true)
//设置背景为透明色
surfaceHolder.setFormat(PixelFormat.TRANSPARENT)
}
override fun preCreate() {
repeat(particleAdapter?.preCreateCount() ?: 0) {
val newItem = particleAdapter!!.newItem(measuredWidth, measuredHeight)
newItem.preInit(context)
drawItems.add(newItem)
}
}
override fun getItem(): BaseItem {
val newItem = if (cacheItems.size > 0) {
cacheItems.removeFirst()
} else {
particleAdapter!!.newItem(measuredWidth, measuredHeight)
}
newItem.init(context)
return newItem
}
override fun drawItems(canvas: Canvas) {
if (drawItems.size < childTotal) {
if (temTime == -1) {
temTime = ((intervalTime / renderTime.toFloat() + 0.5).toInt())
} else if (temTime == 0) {
repeat(increaseParticleCount) {
drawItems.add(getItem())
}
}
temTime--
}
drawItems.forEach {
it.draw(canvas)
}
}
override fun transForms() {
val iterator = drawItems.iterator()
while (iterator.hasNext()) {
val next = iterator.next()
val isLive = next.move()
if (!isLive) {
iterator.remove()
cacheItems.add(next)
}
}
}
override fun destroyAllView() {
drawItems.forEach {
it.destroy()
}
cacheItems.forEach {
it.destroy()
}
}
override fun startAnimation() {
renderHandler.removeCallbacks(this)
renderHandler.post(this)
}
override fun stopAnimation() {
renderHandler.removeCallbacks(this)
}
override fun setAdapter(adapter: ParticleAdapter) {
particleAdapter = adapter
if (particleAdapter!!.maxParticleCount() <= 0) {
return
}
childTotal = particleAdapter!!.maxParticleCount()
}
override fun setRenderTime(renderTime: Long) {
if (intervalTime < renderTime || renderTime < 0) {
return
}
this.renderTime = renderTime
}
override fun setIncreaseParticleInterval(intervalTime: Long) {
if (intervalTime < renderTime || renderTime < 0) {
return
}
this.intervalTime = intervalTime
}
override fun setIncreaseParticleCount(count: Int) {
if (count <= 0) {
return
}
increaseParticleCount = count
}
override fun setIsAutoPlay(isAuto: Boolean) {
isAutoPlay = isAuto
}
override fun surfaceChanged(holder: SurfaceHolder?, format: Int, width: Int, height: Int) {
}
override fun surfaceDestroyed(holder: SurfaceHolder?) {
renderHandler.removeCallbacks(this)
destroyAllView()
}
override fun surfaceCreated(holder: SurfaceHolder?) {
if (particleAdapter == null) {
throw NullPointerException("particleAdapter must not be null")
}
handlerThread = HandlerThread("BaseSurfaceView")
handlerThread.start()
renderHandler = Handler(handlerThread.looper)
preCreate()
if (isAutoPlay) {
renderHandler.post(this)
}
}
override fun run() {
transForms()
val lockCanvas = surfaceHolder.lockCanvas(null)
lockCanvas.drawColor(Color.TRANSPARENT, PorterDuff.Mode.CLEAR)
drawItems(lockCanvas)
surfaceHolder.unlockCanvasAndPost(lockCanvas)
renderHandler.postDelayed(this, renderTime)
}
}
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