為了買彩票，我寫了這個控制元件

安卓開發 · 發表 2019-03-10 22:48:36

摘要： 0. 最近偶爾會買個雙色球，一週買個6塊錢的，也不多，就是湊個熱鬧，為生活添加個小情趣。因為不會選號，每次都是機選，作為一個陰謀論者，我覺得機選可能不夠“隨機”，為此我決定自己寫個程式為我選號，為此我模仿老虎機寫了一個控制元件。先上圖 image ...

0.

最近偶爾會買個雙色球，一週買個6塊錢的，也不多，就是湊個熱鬧，為生活添加個小情趣。因為不會選號，每次都是機選，作為一個陰謀論者，我覺得機選可能不夠“隨機”，為此我決定自己寫個程式為我選號，為此我模仿老虎機寫了一個控制元件。先上圖

image

1.

先設計一下

1.1支援從數字和陣列獲取資料

1.2繪製兩個數字，當前數字和下一個數字

1.3設定便宜量，並實現加速

1.4開始和停止，停止時添加回調

1.5支援設定文字大小與顏色

2.

廢話少說，上程式碼

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

//開始時的數字或者陣列下標
var min = 0
//最大的數字或者陣列下標
var max = 0
//當前要繪製數字或者陣列下標
private var now = min
//每次重新整理移動的距離
private var offset = 0

private var paint = Paint(Paint.ANTI_ALIAS_FLAG)

private var isStart = false

var maxSpeed = 10f
//當前移動速度
private var curSpeed = 0f
//加速度增量
private var speedOffset = 0.1f

var dataList: List<Int>? = 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)
}
}

程式碼比較簡單，沒什麼難度，先看onDraw方法

override fun onDraw(canvas: Canvas?) {
super.onDraw(canvas)
canvas?.let {
drawNow(it)
drawNext(it)
calCurSpeed()
calOffset()
}
}

繪製當前數字，繪製下一個數字，計算當前速度，計算偏移量，這個速度主要是用來看起來開始時數字的翻轉有一個加速的過程。看一下drawNow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)
}

首先根據資料來源的不同獲取的資料，然後計算文字繪製的位置，然後繪製

drawNext大同小異，無非就是一個下一個數字的判斷問題

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)
}
}
}
}
}

如果處於執行狀態，先判斷控制元件當前偏移量，如果等於控制元件高度，那麼就重置為0，然後將now置為下一個數，否則就加上速度重新計算偏移量。如果不處於執行狀態，那麼判斷當前的偏移量，如果既不等於0也不等於控制元件高度，說明處於一箇中間狀態，那麼就讓它移到下一個位置，並呼叫回撥函式。其他的也沒什麼關鍵了，各位有需要的看程式碼就好了

3.

github