自定义LoadingViewkotlin实现

package com.example.mylibrary.view import android.animation.ValueAnimator import android.content.ContentValues import android.content.Context import android.graphics.Canvas import android.graphics.Color import android.graphics.Paint import android.util.AttributeSet import android.util.Log import android.view.View import android.view.animation.LinearInterpolator import com.example.mylibrary.log.LogUtils import kotlin.math.max import kotlin.math.sin class LoadingView @JvmOverloads constructor(context: Context, attrs: AttributeSet? = null, defStyleAttr: Int = 0) : View(context, attrs, defStyleAttr) { var paint: Paint = Paint() private val count = 4 var defaultSize = 200 var lineHeight = 150f var defaultHeight = 150f var lineWidth = 0f private val space = 20f init { paint.color = Color.RED paint.isAntiAlias = true paint.style = Paint.Style.FILL setBackgroundColor(Color.TRANSPARENT) } override fun onMeasure(widthMeasureSpec: Int, heightMeasureSpec: Int) { super.onMeasure(widthMeasureSpec, heightMeasureSpec) //view根据xml中layout_width和layout_height测量出对应的宽度和高度值， val widthSpecMode = MeasureSpec.getMode(widthMeasureSpec) val widthSpecSize = MeasureSpec.getSize(widthMeasureSpec) when (widthSpecMode) { MeasureSpec.UNSPECIFIED -> defaultSize = widthSpecSize MeasureSpec.AT_MOST -> defaultSize = getContentWidth() MeasureSpec.EXACTLY -> defaultSize = max(getContentWidth(), widthSpecSize) } lineHeight = max(0f, defaultSize - 80f) lineWidth = (defaultSize - (count + 1) * space) * 1f / count LogUtils.d("宽度:$defaultSize") setMeasuredDimension(defaultSize, defaultSize) } open fun getContentHeight(): Int { val contentHeight = height + paddingTop + paddingBottom.toFloat() Log.d(ContentValues.TAG, "getContentWidth: contentHeight=$contentHeight") return contentHeight.toInt() } private fun getContentWidth(): Int { val contentWidth = width + paddingLeft + paddingRight.toFloat() Log.d(ContentValues.TAG, "getContentWidth: contentWidth=$contentWidth") return contentWidth.toInt() } override fun onDraw(canvas: Canvas?) { super.onDraw(canvas) canvas?.translate(0f, defaultSize * 1.0f) paint.strokeWidth = lineWidth val wave = lineHeight for (i in 0 until count) { val startX = i * (lineWidth + space) + space val endY = wave * sin(progress * 360 + startX / defaultSize * 360) canvas?.drawLine(startX, 0f, startX, endY.toFloat(), paint) } } override fun onAttachedToWindow() { super.onAttachedToWindow() startAnimation() } override fun onDetachedFromWindow() { super.onDetachedFromWindow() if (valueAnimator != null) { valueAnimator.cancel() } } var progress = 0f lateinit var valueAnimator: ValueAnimator private fun startAnimation() { valueAnimator = ValueAnimator.ofFloat(0f, 1f) valueAnimator?.duration = 60000 valueAnimator.interpolator = LinearInterpolator() valueAnimator.repeatCount = -1 valueAnimator.repeatMode = ValueAnimator.REVERSE valueAnimator.addUpdateListener { progress = it.animatedValue as Float postInvalidate() } valueAnimator.start() } }

利用sin函数实现波浪上下水波起伏