Android程序员用控件玩彩票，告诉网友什么叫真正的随机

为了买彩票，我写了这个控件

0.

最近偶尔会买个双色球，一周买个6块钱的，也不多，就是凑个热闹，为生活添加个小情趣

因为不会选号，每次都是机选，作为一个阴谋论者，我觉得机选可能不够"随机"，为此我决定自己写个程序为我选号，学过Java会Android的我模仿老虎机写了一个控件。先上图

1.

先设计一下

1.1支持从数字和数组获取数据

1.2绘制两个数字，当前数字和下一个数字

1.3设置便宜量，并实现加速

1.4开始和停止，停止时添加回调

1.5支持设置文字大小与颜色

2.

废话少说，上代码

package com.skateboard.numberrunningview

import android.content.Context

import android.graphics.Canvas

import android.graphics.Color

import android.graphics.Paint

import android.support.v4.view.ViewCompat

import android.util.AttributeSet

import android.view.View

class NumberRunningView(context: Context, attributes: AttributeSet?) : View(context, attributes) {

private var numberColor = Color.WHITE

private var numberSize = 15.0f

//开始时的数字或者数组下标

var min = 0

//最大的数字或者数组下标

var max = 0

//当前要绘制数字或者数组下标

private var now = min

//每次刷新移动的距离

private var offset = 0

private var paint = Paint(Paint.ANTI_ALIAS_FLAG)

private var isStart = false

var maxSpeed = 10f

//当前移动速度

private var curSpeed = 0f

//加速度增量

private var speedOffset = 0.1f

var dataList: List? = null

set(value) {

field = value

min = 0

max = (value?.size ?: 1) - 1

now = min

offset = 0

}

var onNumberSelectedListener: OnNumberSelectedListenern? = null

init {

if (attributes != null) {

parseAttrs(attributes)

}

initPaint()

}

constructor(context: Context) : this(context, null)

private fun parseAttrs(attributes: AttributeSet) {

val typedArray = context.obtainStyledAttributes(attributes, R.styleable.NumberRunningView)

min = typedArray.getInt(R.styleable.NumberRunningView_min, min)

max = typedArray.getInt(R.styleable.NumberRunningView_max, max)

maxSpeed = typedArray.getFloat(R.styleable.NumberRunningView_maxSpeed, maxSpeed)

numberColor = typedArray.getColor(R.styleable.NumberRunningView_numberColor, numberColor)

numberSize = typedArray.getDimension(R.styleable.NumberRunningView_numberSize, numberSize)

speedOffset = typedArray.getFloat(R.styleable.NumberRunningView_speedOffset, 0.1f)

typedArray.recycle()

now = min

}

private fun initPaint() {

paint.textSize = numberSize

paint.color = numberColor

}

override fun onDraw(canvas: Canvas?) {

super.onDraw(canvas)

canvas?.let {

drawNow(it)

drawNext(it)

calCurSpeed()

calOffset()

}

}

private fun calCurSpeed() {

curSpeed += speedOffset

if (curSpeed > maxSpeed) curSpeed = maxSpeed

}

private fun drawNow(canvas: Canvas) {

val curDataList = dataList

var nowNum = "0"

nowNum = if (curDataList != null) {

curDataList[now].toString()

} else {

now.toString()

}

val numWidth = paint.measureText(nowNum)

canvas.drawText(nowNum, width / 2 - numWidth / 2, height / 2 - offset + paint.textSize / 2, paint)

}

private fun drawNext(canvas: Canvas) {

val curDataList = dataList

var nextNum = ""

if (curDataList == null) {

nextNum = if (now + 1 > max) {

min.toString()

} else {

(now + 1).toString()

}

} else {

nextNum = if (now + 1 > max) {

curDataList[min].toString()

} else {

(curDataList[now + 1]).toString()

}

}

val numWidth = paint.measureText(nextNum)

canvas.drawText(nextNum, width / 2 - numWidth / 2, 1.5f * height - offset + paint.textSize / 2, paint)

}

private fun calOffset() {

if (isStart) {

if (offset == height) {

offset = 0

if (now + 1 > max) {

now = min

} else {

now += 1

}

} else if (offset + curSpeed > height) {

offset = height

} else {

offset = (offset + curSpeed).toInt()

}

postInvalidate()

} else {

if (offset != 0 && offset != height) {

offset = if (offset + curSpeed > height) {

height

} else {

(offset + curSpeed).toInt()

}

postInvalidate()

} else {

if (offset == 0) {

val curDataList = dataList

if (curDataList != null) {

onNumberSelectedListener?.onNumberSelected(curDataList[now])

} else {

onNumberSelectedListener?.onNumberSelected(now)

}

} else {

val curDataList = dataList

if (curDataList != null) {

onNumberSelectedListener?.onNumberSelected(if (now == max) curDataList[min] else curDataList[now + 1])

} else {

onNumberSelectedListener?.onNumberSelected(if (now == max) min else now + 1)

}

}

}

}

}

fun start() {

if (isStart) {

return

}

curSpeed = 0f

isStart = true

if (ViewCompat.isAttachedToWindow(this)) {

postInvalidate()

}

}

fun stop() {

isStart = false

}

interface OnNumberSelectedListenern {

fun onNumberSelected(num: Int)

}

}

---

• 代码比较简单，没什么难度，先看onDraw方法

• • *

private fun drawNow(canvas: Canvas) {

val curDataList = dataList

var nowNum = "0"

nowNum = if (curDataList != null) {

curDataList[now].toString()

} else {

now.toString()

}

val numWidth = paint.measureText(nowNum)

canvas.drawText(nowNum, width / 2 - numWidth / 2, height / 2 - offset + paint.textSize / 2, paint)

}

---

• 首先根据数据源的不同获取的数据，然后计算文字绘制的位置，然后绘制 drawNext大同小异，无非就是一个下一个数字的判断问题 calOffset方法

• • *

private fun calOffset() {

if (isStart) {

if (offset == height) {

offset = 0

if (now + 1 > max) {

now = min

} else {

now += 1

}

} else if (offset + curSpeed > height) {

offset = height

} else {

offset = (offset + curSpeed).toInt()

}

postInvalidate()

} else {

if (offset != 0 && offset != height) {

offset = if (offset + curSpeed > height) {

height

} else {

(offset + curSpeed).toInt()

}

postInvalidate()

} else {

if (offset == 0) {

val curDataList = dataList

if (curDataList != null) {

onNumberSelectedListener?.onNumberSelected(curDataList[now])

} else {

onNumberSelectedListener?.onNumberSelected(now)

}

} else {

val curDataList = dataList

if (curDataList != null) {

onNumberSelectedListener?.onNumberSelected(if (now == max) curDataList[min] else curDataList[now + 1])

} else {

onNumberSelectedListener?.onNumberSelected(if (now == max) min else now + 1)

}

}

}

}

}

---

1. 如果处于运行状态，先判断控件当前偏移量，如果等于控件高度，那么就重置为0，然后将now置为下一个数，否则就加上速度重新计算偏移量。
2. 如果不处于运行状态，那么判断当前的偏移量，如果既不等于0也不等于控件高度，说明处于一个中间状态，那么就让它移到下一个位置，并调用回调函数。其他的也没什么关键了，各位有需要的看代码就好了

3.

控件代码就全部告诉大家了，感受一把随机的乐趣，至于彩票，这是薛定谔的彩票。也不要太沉迷，要不然，最后就是西湖的水，我的泪。

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