自定义TextView实现多个文案切换炫酷动画

当显示2个或2个以上文案时，每隔2秒切换气泡文案

核心实现代码如下：

import android.animation.ValueAnimator
import android.content.Context
import android.util.AttributeSet
import android.util.Log
import androidx.appcompat.widget.AppCompatTextView

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

    private var strs: List<String>? = null
    private var startPos: Int = 0
    private val timeStep = 2000L // 2S
    private val TAG = "TextViewSwitcher"

    private val showNext = Runnable {
        showNextStr()
    }

    override fun onAttachedToWindow() {
        Log.d(TAG, "onAttachedToWindow: ")
        super.onAttachedToWindow()
        val size = strs?.size ?: 0
        if (size > 1) {
            handler.postDelayed(showNext, timeStep)
        }
    }

    override fun onDetachedFromWindow() {
        Log.d(TAG, "onDetachedFromWindow: ")
        handler.removeCallbacks(showNext)
        super.onDetachedFromWindow()
    }

    fun setTextList(strs: List<String>?, startPos: Int = 0) {
        Log.d(TAG, "setTextList: ")
        if (strs.isNullOrEmpty()) return
        this.strs = strs
        this.startPos = startPos
        if (strs.size == 1) {
            text = strs[0]
        } else {
            this.startPos = startPos % strs.size
            text = strs[this.startPos]
        }
    }

    private fun showNextStr() {
        var startPos = this.startPos + 1
        val size = strs?.size ?: 0
        if (size <= 1) return
        if (startPos >= size) startPos %= size

        this.startPos = startPos
        changeTextWithAnimator(this, strs?.get(startPos))

        handler.postDelayed(showNext, timeStep)
    }

    private fun changeTextWithAnimator(
        textView: AppCompatTextView?,
        nextContent: String?
    ) {
        if (textView != null) {
            val animator = ValueAnimator.ofFloat(0f, 2f)
            animator.duration = 400
            var changed = false
            textView.pivotX = 0f
            val height = textView.measuredHeight
            if (height > 0) {
                textView.pivotY = height.toFloat()
            }

            val startWidth = textView.measuredWidth
            var endWidth = 0
            val params = textView.layoutParams
            animator.addUpdateListener { animation ->
                val value = animation.animatedValue as Float
                when {
                    value < 1f -> {
                        textView.rotation = 360 - value * 60
                        textView.alpha = 1 - value
                    }
                    value > 1f -> {
                        textView.alpha = value - 1
                        textView.rotation = 360 - (2 - value) * 60
                        if (!changed) {
                            changed = true
                            textView.text = nextContent

                            val measureSpec = MeasureSpec.makeMeasureSpec(
                                0,
                                MeasureSpec.UNSPECIFIED
                            )
                            textView.measure(measureSpec, measureSpec)
                            endWidth = textView.measuredWidth

                            Log.d(TAG, "changeTextWithAnimator: endWidth=$endWidth")
                        } else {
                            if (endWidth > 0) {
                                params.width =
                                    (startWidth + (endWidth - startWidth) * (value - 1)).toInt()
                                textView.layoutParams = params
                            }
                        }
                    }
                }
            }
            animator.start()
        }
    }
}

由于动画要在顶部浮层，这样动画才能不被父类容器的大小所限制和切割，所以，直接在PopWindow中显示。
具体代码如下：

import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import android.widget.PopupWindow

object HomePromptView {
    @JvmStatic
    fun showTipPopView(view: View, typedStr: String?): PopupWindow {

        val rootView = LayoutInflater.from(view.context).inflate(R.layout.home_prompt_layout, null)
        val promptTv = rootView.findViewById<TextViewSwitcher>(R.id.tv_prompt)
        promptTv.setTextList(typedStr?.split("|"))
        rootView.isClickable = false

        // PopWindow
        val popTipWid = PopupWindow(
            rootView,
            ViewGroup.LayoutParams.MATCH_PARENT,
            ViewGroup.LayoutParams.MATCH_PARENT
        )
        popTipWid.isTouchable = false

        // android.view.WindowManager$BadTokenException:
        // Unable to add window -- token null is not valid;
        // is your activity running?
        try {
            popTipWid.showAtLocation(view.rootView, 0, 0, 0)
            layoutPromptLocation(promptTv, view)
//            popTipWid.showAsDropDown(view, UiUtils.dip2px(39), -UiUtils.dip2px(48))
            view.addOnLayoutChangeListener { view, i, i2, i3, i4, i5, i6, i7, i8 ->
                layoutPromptLocation(promptTv, view)
            }
        } catch (e: Exception) {
            e.printStackTrace()
        }
        return popTipWid
    }


    private fun layoutPromptLocation(
        promptTv: TextViewSwitcher,
        view: View
    ) {
        try {
            val params = promptTv.layoutParams as ViewGroup.MarginLayoutParams
            val location = IntArray(2)
            view.getLocationInWindow(location)
            params.topMargin =
                location[1] - UiUtils.getStatusBarHeight(view.context) + UiUtils.dip2px(4)
            params.leftMargin = location[0] + UiUtils.dip2px(25)
            promptTv.layoutParams = params
        } catch (e: Exception) {
            e.printStackTrace()
        }
    }

    @JvmStatic
    fun dismissTipPopView(popTipWid: PopupWindow?) {
        popTipWid?.dismiss()
    }

}

添加布局代码如下：

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@color/transparent">

    <******.TextViewSwitcher
        android:id="@+id/tv_prompt"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:background="@drawable/common_ui_shape_red_heavy_prompt"
        android:maxLines="1"
        android:paddingStart="5dp"
        android:paddingTop="1.5dp"
        android:paddingEnd="5dp"
        android:paddingBottom="1.5dp"
        android:textColor="@color/white"
        android:textSize="10sp"
        tools:text="硬核安利">

    </******.TextViewSwitcher>

</FrameLayout>

drawable:

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="rectangle">
    <corners
        android:bottomRightRadius="9dp"
        android:topLeftRadius="9dp"
        android:topRightRadius="9dp" />
    <solid android:color="#FF5E79" />
    <stroke
        android:width="0.5dp"
        android:color="@color/white" />
</shape>