屬性動畫

ViewPropertyAnimator

 imageView.animate()
            .translationX(200.dp)
            .translationY(100.dp)
            .scaleX(2f)
            .scaleY(2f)
            .alpha(0.5f)
            .setStartDelay(1000)

缺點(diǎn)：

• 有局限性，只能改變其中的幾個屬性，橫向縱向 漸變旋轉(zhuǎn)
• 比如需要更改圓半徑大小的動畫，對于這種自定義的屬性不能實(shí)現(xiàn)

優(yōu)點(diǎn)：

• 使用方便

ObjectAnimator

class CircleView @JvmOverloads constructor(
    context: Context, attrs: AttributeSet? = null, defStyleAttr: Int = 0
) : View(context, attrs, defStyleAttr) {

    var radius = 50.dp
    set(value) {
        field = value
        invalidate()
    }

    private val paint = Paint(Paint.ANTI_ALIAS_FLAG).apply {
        color = Color.GREEN
    }

    override fun onDraw(canvas: Canvas) {
        super.onDraw(canvas)
        canvas.drawCircle(width/2f,height/2f,radius,paint)
    }
}

val animtor = ObjectAnimator.ofFloat(imageView, "radius", 150.dp)
animtor.startDelay = 1000
animtor.start()

優(yōu)點(diǎn)：

• 支持自定義的屬性值

缺點(diǎn)：

• 一次只支持一個屬性值，如果操作多個屬性值的話，需要設(shè)置多個，然后一起執(zhí)行。

AnimatorSet 動畫集(對多個動畫進(jìn)行合成)

animtor,animtor1,animtor2 三個ObjectAnimator動畫順序執(zhí)行

val animatorSet = AnimatorSet()
animatorSet.playSequentially(animtor,animtor1,animtor2)
animatorSet.start()

PropertyValuesHolder

• 用法

val propertyValuesHolder = PropertyValuesHolder.ofFloat("radius", 150.dp)

        val objectAnimator = ObjectAnimator.ofPropertyValuesHolder(imageView,propertyValuesHolder)
        objectAnimator.startDelay = 1000
        objectAnimator.duration = 2000
        objectAnimator.start()

優(yōu)點(diǎn)

• 支持更精細(xì)的動畫控制，可以支持多個自定義屬性值（ObjectAnimator.ofPropertyValuesHolder此方法支持多個holder）

和AnimatorSet區(qū)別

• 不支持多個屬性值動畫按順序執(zhí)行

Keyframe

使用方式

val distance = 200.dp
val keyframe = Keyframe.ofFloat(0f, 0f * distance)
val keyframe1 = Keyframe.ofFloat(0.2f, 0.4f * distance)
val keyframe2 = Keyframe.ofFloat(0.8f, 0.6f * distance)
val keyframe3 = Keyframe.ofFloat(1f, 1f * distance)
val holder = PropertyValuesHolder.ofKeyframe(
            "translationX",
            keyframe,
            keyframe1,
            keyframe2,
            keyframe3
        )
val animator = ObjectAnimator.ofPropertyValuesHolder(imageView,holder)
animator.startDelay = 2000
animator.start()

優(yōu)點(diǎn)

• 更加精準(zhǔn)的控制動畫執(zhí)行的快慢進(jìn)度，實(shí)現(xiàn)特殊的動畫效果

Interpolator 插值器

使用方式

val animator = ObjectAnimator.ofFloat(imageView,"translationX",200.dp)
animator.interpolator = LinearInterpolator()
animator.startDelay = 2000
animator.start()

總結(jié)

1. 適用于場景內(nèi)的動畫AccelerateDecelerateInterpolator()
2. 適用于出場動畫 AccelerateInterpolator
3. 適用于入場動畫 DecelerateInterpolator

TypeEvaluator

使用方式

 val animtor =
            ObjectAnimator.ofObject(imageView, "point", PointFEvaluator(), PointF(100.dp, 200.dp))
animtor.startDelay = 1000
animtor.start()

private class PointFEvaluator :TypeEvaluator<PointF>{
        override fun evaluate(fraction: Float, startValue: PointF, endValue: PointF): PointF {

            val startX = startValue.x
            val startY = startValue.y
            val endX = endValue.x
            val endY = endValue.y
            val currentX = startX + (endX-startX)*fraction
            val currentY = startY + (endY-startY)*fraction
            return PointF(currentX,currentY)
        }

    }

class PointFView @JvmOverloads constructor(
    context: Context, attrs: AttributeSet? = null, defStyleAttr: Int = 0
) : View(context, attrs, defStyleAttr) {

    private val mPaint = Paint(Paint.ANTI_ALIAS_FLAG).apply {
        strokeWidth = 20.dp
        strokeCap = Paint.Cap.ROUND
    }

    var point = PointF(0f,0f)
    set(value) {
        field = value
        invalidate()
    }

    override fun onDraw(canvas: Canvas) {
        super.onDraw(canvas)
        canvas.drawPoint(point.x,point.y,mPaint)
    }
}

Listeners

各種動畫的監(jiān)聽器，監(jiān)聽動畫開始啦 結(jié)束啦等

ValueAnimator

不常用

硬件加速

利用GPU提高視圖渲染的速度？ 沒搞明白