1607330762041.gif
三阶贝塞尔曲线
cubicTo(控制点1x坐标,控制点1y坐标,控制点2x坐标,控制点2y坐标,终点x坐标,终点y坐标)
实现控件分为两部分
- 心形控件-自定义view
- 存放心形控件的容器 - 自定义ViewGroup
1. 心形控件(可以使用ImageView代替)
因为正在学习自定义view的知识,尽量不适用图片资源。而且画爱心图案需要用到三阶贝塞尔曲线,正好练习
class HeartView : View {
private var radius = 0f
val paint = Paint() // 画笔
private val pointStart = PointF() // 画心需要三阶贝塞尔曲线,是path的起点
private val point1 = PointF() // 控制点1
private val point2 = PointF() // 控制点2
private val pointEnd = PointF() // 终点
// 右半边心的两个控制点
private val point1Right = PointF() // 控制点1
private val point2Right = PointF() // 控制点2
val path = Path()
// HeartView的中心点
// downX 、downY 名称起得不好
private var downX = 0f
private var downY = 0f
constructor(context: Context?) : this(context, null)
constructor(context: Context?, attrs: AttributeSet?) : this(context, attrs, 0)
constructor(context: Context?, attrs: AttributeSet?, defStyleAttr: Int) : super(
context,
attrs,
defStyleAttr
) {
paint.apply {
isAntiAlias = true
color = Color.RED
}
// setBackgroundColor(Color.BLACK)
}
override fun onMeasure(widthMeasureSpec: Int, heightMeasureSpec: Int) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec)
/**
* 此处测量实现的效果是
* 1. 当宽高都为wrap_content时,宽高都设置为240px
* 2. 当宽或高有一个为wrap_content ,另一个为具体值时,比较具体值和240px的大小,取较小值
* 3. 当都为具体值时,比较大小,取小值
**/
val widthMode = MeasureSpec.getMode(widthMeasureSpec)
val heightMode = MeasureSpec.getMode(heightMeasureSpec)
var width = MeasureSpec.getSize(widthMeasureSpec)
var height = MeasureSpec.getSize(heightMeasureSpec)
if (widthMode == MeasureSpec.AT_MOST || heightMode == MeasureSpec.AT_MOST) {
if (widthMode == MeasureSpec.AT_MOST) {
width = getSmallSize(240,height)
}
if (heightMode == MeasureSpec.AT_MOST) {
height = getSmallSize(width,240)
}
setMeasuredDimension(width,height)
}else {
val size = getSmallSize(width,height)
setMeasuredDimension(size,size)
}
}
// 比较两个参数的大小,返回较小的值
private fun getSmallSize(width:Int, height:Int):Int{
return if (width > height) {
height
} else {
width
}
}
override fun onDraw(canvas: Canvas) {
super.onDraw(canvas)
Log.e("宽","$measuredWidth")
Log.e("高","$measuredHeight")
// 此处radius是控件中心点到贝塞尔曲线控制点的计算尺度
// 可以随意指定,不用计较具体的计算方法,这里是试出来的
// 这样画出来的爱心比较好看
radius = measuredHeight/2.6f
val xinR = measuredHeight/1.5f
val xinR2 = measuredHeight / 2.4f
downX = measuredWidth/2f
downY = measuredHeight/2f
canvas.apply {
if (downX == 0f) {
return
}
// 画左半边的心
pointStart.x = downX
pointStart.y = (downY - radius)
point1.x = pointStart.x - xinR
point1.y = pointStart.y - xinR2
point2.x = pointStart.x - xinR
point2.y = pointStart.y + xinR2 / 5 * 6
pointEnd.x = downX
pointEnd.y = (downY + radius)
path.moveTo(pointStart.x, pointStart.y)
path.cubicTo(
point1.x,
point1.y,
point2.x,
point2.y,
pointEnd.x,
pointEnd.y
)
// 画右半边的心
point1Right.x = pointStart.x + xinR
point1Right.y = pointStart.y + xinR2 / 5 * 6
point2Right.x = pointStart.x + xinR
point2Right.y = pointStart.y - xinR2
path.cubicTo(
point1Right.x,
point1Right.y,
point2Right.x,
point2Right.y,
pointStart.x,
pointStart.y
)
drawPath(path, paint)
path.close()
path.reset()
}
}
}
需要注意的地方
- 最开始画爱心的方案是先画左边半块,然后通过moveTo移动path的起始点,再画右边半块,左边和右边分别是一个三阶贝塞尔曲线,这样画出的爱心中间有一条缝隙,就算起点和终点一样也还是存在
- 现在的方案是一笔画下来,最后调用一次drawPath(),中间不调用moveTo()。
这样的话,画右边的贝塞尔曲线时,起点和终点是反着的,控制点1和控制点2也要调换位置
2. 存放心形控件,响应双击事件的容器
class DianZanView : RelativeLayout {
var gestureDetector: GestureDetector
val listHeart = mutableListOf<HeartView>()
constructor(context: Context?) : this(context, null)
constructor(context: Context?, attrs: AttributeSet?) : this(context, attrs, 0)
constructor(context: Context?, attrs: AttributeSet?, defStyleAttr: Int) : super(
context,
attrs,
defStyleAttr
) {
gestureDetector =
GestureDetector(context, object : GestureDetector.SimpleOnGestureListener() {
override fun onDoubleTap(e: MotionEvent): Boolean {
// 处理双击事件
// 在点击位置生成一个心图案
val heartView = HeartView(context, e.x, e.y).apply {
// layoutParams = LayoutParams(320, 1040)
layoutParams =
LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT)
visibility = INVISIBLE // 因为要知道控件本身的宽高,来计算他的坐标,所以必须在能看到它时,设置它的x,y
// 但是这样,在一开始的坐标会显示在左上角,闪一下,再出现在给定坐标位置,所以先隐藏
// 等能看到时,在显示
post {
x = e.x - measuredWidth / 2 // 设置heartView的x轴坐标
y = e.y - measuredHeight / 2 // 设置heartView的Y轴坐标
// 在heartView可见时,开启动画
startUpAnimator(this) // 向上移动的路径是一个三阶贝塞尔曲线
// startUpAlphaZoomAnimator(this) // 向上平移,放大,透明度变化
visibility = VISIBLE
}
}
addView(heartView)
listHeart.add(heartView)
invalidate()
return super.onDoubleTap(e)
}
})
}
// 开启动画,向上移动,轨迹是一个三阶贝塞尔曲线,伴随透明度变化
private fun startUpAnimator(view: HeartView) {
// 创建移动的路径,一个贝塞尔曲线
val path = Path()
path.moveTo(view.x,view.y)
path.cubicTo(view.x- measuredWidth/3,view.y- measuredHeight/3,view.x+measuredWidth/3,view.y-measuredHeight/2,view.x,0f)
val pathMeasure = PathMeasure(path,false)
val pathLength = pathMeasure.length
val pathAnim = ValueAnimator.ofInt(1,pathLength.toInt()).apply {
addUpdateListener {
val value = it.animatedValue as Int
val xy = FloatArray(2)
val aa = FloatArray(2)
// 执行完毕,xy即为横纵坐标
pathMeasure.getPosTan(value.toFloat(), xy, aa)
view.x = xy[0]
view.y = xy[1]
invalidate()
}
}
val alphaAnim = ValueAnimator.ofFloat(1f, 0f).apply {
addUpdateListener {
val value = it.animatedValue as Float
var alpha = value
if (alpha <= 0) {
alpha = 0f
}
view.alpha = alpha
invalidate()
}
}
AnimatorSet().apply {
duration = 1000
playTogether(pathAnim,alphaAnim)
addListener(object : AnimatorListenerAdapter() {
override fun onAnimationEnd(animation: Animator?) {
super.onAnimationEnd(animation)
this@DianZanView.removeView(view)
}
})
start()
}
}
// 向上,放大,透明
private fun startUpAlphaZoomAnimator(view: HeartView) {
view.translationY
view.scaleX
val targetY = view.y
val upAnimator = ObjectAnimator.ofFloat(view,"translationY",targetY,targetY-measuredHeight/5)
val scaleXAnimator = ObjectAnimator.ofFloat(view,"scaleX",1f,2f)
val scaleYAnimator = ObjectAnimator.ofFloat(view,"scaleY",1f,2f)
val alphaAnimator = ObjectAnimator.ofFloat(view,"alpha",1f,0f)
AnimatorSet().apply {
playTogether(upAnimator,scaleXAnimator,scaleYAnimator,alphaAnimator)
duration = 1000
addListener(object : AnimatorListenerAdapter() {
override fun onAnimationEnd(animation: Animator?) {
super.onAnimationEnd(animation)
this@DianZanView.removeView(view)
Log.e("DianZanView","子view数量为:${this@DianZanView.childCount}")
}
})
start()
}
}
@SuppressLint("ClickableViewAccessibility")
override fun onTouchEvent(ev: MotionEvent): Boolean {
gestureDetector.onTouchEvent(ev)
return super.onTouchEvent(ev)
}
}
实现思路:
监听双击事件,用户双击时,创建一个HeartView,在HeratView可见时,设置它的坐标(双击的位置),并开启动画。
在设置HeartView坐标时,需要减去HeartView自身的宽高,所以需要HeartView.post{} 在内部设置x,y
效果如下:更新:新增按照路径移动的动画,同时伴随透明度变化
1607414741725[1].gif