自定义进度条Android，kotlin

1：效果

           

 一运行起来，红色是下载的部分，蓝色是为下载部分，下载完之后先缩成一个椭圆，在缩成一个圆

GitHub地址：https://github.com/luofangli/MyDrawProgress

详细代码：

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <com.example.my.CustomProgress
        android:id="@+id/custom_progress"
        android:layout_width="0dp"
        android:layout_height="100dp"
        android:layout_marginStart="20dp"
        android:layout_marginTop="200dp"
        android:layout_marginEnd="20dp"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.5"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>

package com.example.my

import android.animation.AnimatorSet
import android.animation.ValueAnimator
import android.content.Context
import android.graphics.Canvas
import android.graphics.Color
import android.graphics.Paint
import android.graphics.Path
import android.util.AttributeSet
import android.util.Log
import android.view.View

class CustomProgress : View {
    //运行起来的背景画笔
    private val paintFirst:Paint by lazy {
        Paint().apply {
            style = Paint.Style.FILL
            color = Color.BLUE
        }
    }
    //移动的进度条的画笔
    private val paintSecond:Paint by lazy {
        Paint().apply {
            style = Paint.Style.FILL
            color = Color.RED
        }
    }
    //勾勾的画笔
    private val paintPath:Paint by lazy {
        Paint().apply {
            style = Paint.Style.STROKE
            color = Color.WHITE
            strokeWidth = 6f
        }
    }
    //勾勾的路径
    private val path:Path by lazy {
        Path().apply {
            moveTo(startpathX,startpathY)
            lineTo(centerpathX,centerpathY)
        }
    }
    //定义动画因子
    //路径移动的起点和尾点
    private var startpathX = 0f
    private var startpathY = 0f
    private var centerpathX = 0f
    private var centerpathY = 0f
    //两边向中间移动成一个圆的距离
    private var centerDistance = 0f
    //圆矩形圆的半径
    private var radius = 0f
    //进度条的总长度
    private var progressLength = 0f
    //进度条下载过程中的动画因子
   private var allDistance = 0f
    //外部下载的进度
    var loadProgress = 0f
    set(value) {
        field = value
        progressGo(field)
    }

    constructor(context: Context):super(context){}
    constructor(context: Context,attributeSet: AttributeSet):super(context,attributeSet){}

    override fun onSizeChanged(w: Int, h: Int, oldw: Int, oldh: Int) {
        super.onSizeChanged(w, h, oldw, oldh)
        progressLength = measuredWidth.toFloat()
//        startpathX = measuredWidth/2f-measuredHeight*3/10f
//        startpathY = measuredHeight/2f
//        centerpathX = measuredWidth/2f-measuredHeight*3/10f
//       centerpathY = measuredHeight/2f
        startpathX = measuredWidth/2f-radius/2
        startpathY = measuredHeight/2f
        centerpathX =measuredWidth/2f-radius/2
        centerpathY = measuredHeight/2f

    }
    override fun onDraw(canvas: Canvas?) {
        super.onDraw(canvas)
        //运行起来就有的背景
        canvas?.drawRoundRect(allDistance,0f,measuredWidth.toFloat(),measuredHeight.toFloat(),
        0f,0f,paintFirst)
        //移动的进度条
        canvas?.drawRoundRect(0f+centerDistance,0f,allDistance-centerDistance,measuredHeight.toFloat(),
            radius,radius,paintSecond)
        //画勾勾
        canvas?.drawPath(path,paintPath)
    }
    //进度条前进的动画
    private fun progressGo(load:Float){
        allDistance = progressLength*load
        //下载完之后执行
        if (allDistance == progressLength){
            afterProgress()
        }
        invalidate()
    }
    //进度条完了之后的动画
    private fun afterProgress(){
        //如果进度条完了则开启下面的动画
        //由长方形变成一个圆矩形的动画
        val radiusValueAnimator = ValueAnimator.ofFloat(0f,measuredHeight/2f).apply {
            duration = 2000
            addUpdateListener {
                Log.v("lfl","长方形变成圆矩形")
                val value = it.animatedValue as Float
                radius = value
                invalidate()
            }
        }
        //由两边向中间移动成一个圆的距离
        val centerValueAnimator = ValueAnimator.ofFloat(0f,(measuredWidth-measuredHeight)/2f).apply {
            duration = 2000
            addUpdateListener {
                Log.v("lfl","从两边缩成一个圆")
                val value = it.animatedValue as Float
                centerDistance = value
                invalidate()
            }
        }
        //画钩钩
        // measuredWidth/2f-measuredHeight*3/20f,
        val pathXValueAnimator = ValueAnimator.ofFloat(measuredWidth/2f-radius/2f,
           measuredWidth/2f+radius/2f).apply {
            duration = 2000
            addUpdateListener {
                val value = it.animatedValue as Float
                centerpathX = value
                Log.v("lfl","勾勾尾巴的位置X:$centerpathX")
                invalidate()
            }
        }

        val pathYValueAnimator = ValueAnimator.ofFloat(measuredHeight/2f,
           measuredHeight/2f+radius/2f,
            measuredHeight/2f-radius/2f).apply {
            duration = 2000
            addUpdateListener {
                val value = it.animatedValue as Float
                centerpathY = value
                invalidate()
            }
        }
        val path = AnimatorSet().apply {
            playTogether(pathXValueAnimator,pathYValueAnimator)
            Log.v("lfl","圆的区域为：左：${measuredWidth/2-radius},上：${measuredHeight/2-radius}," +
                    "右：${measuredWidth/2+radius},下：${measuredHeight/2+radius}")

        }
        val ValueAnimator = AnimatorSet().apply {
           playSequentially(radiusValueAnimator,centerValueAnimator)
        }
        val all = AnimatorSet().apply {
            playSequentially(ValueAnimator,path)
        }.start()
    }
}

package com.example.my

import android.animation.ValueAnimator
import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.util.Log
import kotlinx.android.synthetic.main.activity_main.*

class MainActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        ValueAnimator.ofFloat(0f,1f).apply {
            duration = 1000
            addUpdateListener {
                val value = it.animatedValue as Float
                custom_progress.loadProgress = value
            }
        }.start()
    }
}