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Android自定義View實現時鐘功能_Android

作者：skylarliuu ? 更新時間： 2022-11-04 編程語言

最近在練習自定義view, 想起之前面試的時候筆試有道題是寫出自定義一個時鐘的關鍵代碼. 今天就來實現一下. 步驟依然是先分析, 再上代碼.

實現效果

View分析

時鐘主要分為五個部分:

1、中心點: 圓心位置

2、圓盤: 以中心點為圓心,drawCircle畫個圓

3、刻度:

paint有個aip, setPathEffect可以根據path畫特效, 那么刻度就可以根據圓的path畫一個矩形path的特效, 并且這個api只會畫特效, 不會畫出圓.

/**
* shape: 特效的path, 這里傳一個矩形
* advance: 兩個特效path之間的間距, 即兩個矩形的left間距
* phase: 特效起始位置的偏移
* style: 原始path拐彎的時候特效path的轉換方式,這里用ROTATE跟著旋轉即可
*/
PathDashPathEffect(Path shape, float advance, float phase,
? ? ? ? ? ? ? ? ? ? ? ? ? ? ? Style style)

刻度又分兩種, 粗一點刻度: 3、6、9、12, 和細一點的刻度. 兩種特效又可以用SumPathEffect合起來畫

SumPathEffect(PathEffect first, PathEffect second)?

4、時分秒指針

時分秒指針都是一個圓角矩形, 先把他們的位置計算出來, 然后旋轉圓心去繪制不同角度的指針.

5、動畫效果

TimerTask每隔一秒計算時間, 根據時間去換算當前時分秒指針的角度, 動態變量只有三個角度.

實現源碼

//
// Created by skylar on 2022/4/19.
//
class ClockView : View {
? ? private var mTimer: Timer? = null
? ? private val mCirclePaint: Paint = Paint()
? ? private val mPointerPaint: Paint = Paint()
? ? private val mTextPaint: Paint = Paint()

? ? private val mCirclePath: Path = Path()
? ? private val mHourPath: Path = Path()
? ? private val mMinutePath: Path = Path()
? ? private val mSecondPath: Path = Path()

? ? private lateinit var mPathMeasure: PathMeasure
? ? private lateinit var mSumPathEffect: SumPathEffect

? ? private var mViewWidth = 0
? ? private var mViewHeight = 0
? ? private var mCircleWidth = 6f
? ? private var mRadius = 0f
? ? private var mRectRadius = 20f
? ? private var mHoursDegree = 0f
? ? private var mMinutesDegree = 0f
? ? private var mSecondsDegree = 0f
? ? private var mCurrentTimeInSecond = 0L

? ? constructor(context: Context) : super(context)

? ? constructor(context: Context, attrs: AttributeSet?) : this(context, attrs, 0)

? ? constructor(
? ? ? ? context: Context, attrs: AttributeSet?,
? ? ? ? defStyleAttr: Int
? ? ) : super(context, attrs, defStyleAttr)

? ? init {
? ? ? ? mCirclePaint.color = Color.BLACK
? ? ? ? mCirclePaint.isAntiAlias = true
? ? ? ? mCirclePaint.style = Paint.Style.STROKE
? ? ? ? mCirclePaint.strokeWidth = mCircleWidth

? ? ? ? mPointerPaint.color = Color.BLACK
? ? ? ? mPointerPaint.isAntiAlias = true
? ? ? ? mPointerPaint.style = Paint.Style.FILL

? ? ? ? mTextPaint.color = Color.BLACK
? ? ? ? mTextPaint.isAntiAlias = true
? ? ? ? mTextPaint.style = Paint.Style.FILL
? ? ? ? mTextPaint.textSize = 40f
? ? }

? ? override fun onSizeChanged(w: Int, h: Int, oldw: Int, oldh: Int) {
? ? ? ? super.onSizeChanged(w, h, oldw, oldh)
? ? ? ? mViewWidth = measuredWidth - paddingLeft - paddingRight
? ? ? ? mViewHeight = measuredHeight - paddingTop - paddingBottom

? ? ? ? mRadius = mViewWidth / 2 - mCircleWidth
? ? ? ? mCirclePath.addCircle(0f, 0f, mRadius, Path.Direction.CW)

? ? ? ? mPathMeasure = PathMeasure(mCirclePath, false)
? ? ? ? val minutesShapePath = Path()
? ? ? ? val quarterShapePath = Path()
? ? ? ? minutesShapePath.addRect(0f, 0f, mRadius * 0.01f, mRadius * 0.06f, Path.Direction.CW)
? ? ? ? quarterShapePath.addRect(0f, 0f, mRadius * 0.02f, mRadius * 0.06f, Path.Direction.CW)
? ? ? ? val minutesDashPathEffect = PathDashPathEffect(
? ? ? ? ? ? minutesShapePath,
? ? ? ? ? ? mPathMeasure.length / 60,
? ? ? ? ? ? 0f,
? ? ? ? ? ? PathDashPathEffect.Style.ROTATE
? ? ? ? )
? ? ? ? val quarterDashPathEffect = PathDashPathEffect(
? ? ? ? ? ? quarterShapePath,
? ? ? ? ? ? mPathMeasure.length / 12,
? ? ? ? ? ? 0f,
? ? ? ? ? ? PathDashPathEffect.Style.ROTATE
? ? ? ? )
? ? ? ? mSumPathEffect = SumPathEffect(minutesDashPathEffect, quarterDashPathEffect)

? ? ? ? val hourPointerHeight = mRadius * 0.5f
? ? ? ? val hourPointerWidth = mRadius * 0.07f
? ? ? ? val hourRect = RectF(
? ? ? ? ? ? -hourPointerWidth / 2,
? ? ? ? ? ? -hourPointerHeight * 0.7f,
? ? ? ? ? ? hourPointerWidth / 2,
? ? ? ? ? ? hourPointerHeight * 0.3f
? ? ? ? )
? ? ? ? mHourPath.addRoundRect(hourRect, mRectRadius, mRectRadius, Path.Direction.CW)

? ? ? ? val minutePointerHeight = mRadius * 0.7f
? ? ? ? val minutePointerWidth = mRadius * 0.05f
? ? ? ? val minuteRect = RectF(
? ? ? ? ? ? -minutePointerWidth / 2,
? ? ? ? ? ? -minutePointerHeight * 0.8f,
? ? ? ? ? ? minutePointerWidth / 2,
? ? ? ? ? ? minutePointerHeight * 0.2f
? ? ? ? )
? ? ? ? mMinutePath.addRoundRect(minuteRect, mRectRadius, mRectRadius, Path.Direction.CW)

? ? ? ? val secondPointerHeight = mRadius * 0.9f
? ? ? ? val secondPointerWidth = mRadius * 0.03f
? ? ? ? val secondRect = RectF(
? ? ? ? ? ? -secondPointerWidth / 2,
? ? ? ? ? ? -secondPointerHeight * 0.8f,
? ? ? ? ? ? secondPointerWidth / 2,
? ? ? ? ? ? secondPointerHeight * 0.2f
? ? ? ? )
? ? ? ? mSecondPath.addRoundRect(secondRect, mRectRadius, mRectRadius, Path.Direction.CW)

? ? ? ? startAnimator()
? ? }

? ? override fun onDraw(canvas: Canvas?) {
? ? ? ? super.onDraw(canvas)
? ? ? ? if (canvas == null) {
? ? ? ? ? ? return
? ? ? ? }
? ? ? ? canvas.translate((mViewWidth / 2).toFloat(), (mViewHeight / 2).toFloat())

? ? ? ? //畫圓盤
? ? ? ? mCirclePaint.pathEffect = null
? ? ? ? canvas.drawPath(mCirclePath, mCirclePaint)

? ? ? ? //畫刻度
? ? ? ? mCirclePaint.pathEffect = mSumPathEffect
? ? ? ? canvas.drawPath(mCirclePath, mCirclePaint)

? ? ? ? //時分秒指針
? ? ? ? mPointerPaint.color = Color.BLACK

? ? ? ? canvas.save()
? ? ? ? canvas.rotate(mHoursDegree)
? ? ? ? canvas.drawPath(mHourPath, mPointerPaint)
? ? ? ? canvas.restore()

? ? ? ? canvas.save()
? ? ? ? canvas.rotate(mMinutesDegree)
? ? ? ? canvas.drawPath(mMinutePath, mPointerPaint)
? ? ? ? canvas.restore()

? ? ? ? canvas.save()
? ? ? ? canvas.rotate(mSecondsDegree)
? ? ? ? canvas.drawPath(mSecondPath, mPointerPaint)
? ? ? ? canvas.restore()

? ? ? ? //畫中心點
? ? ? ? mPointerPaint.color = Color.WHITE
? ? ? ? canvas.drawCircle(0f, 0f, mRadius * 0.02f, mPointerPaint)
? ? }


? ? private fun startAnimator() {
? ? ? ? val cal = Calendar.getInstance()
? ? ? ? val hour = cal.get(Calendar.HOUR) ?//小時
? ? ? ? val minute = cal.get(Calendar.MINUTE) ?//分
? ? ? ? val second = cal.get(Calendar.SECOND) ?//秒
? ? ? ? mCurrentTimeInSecond = (hour * 60 * 60 + minute * 60 + second).toLong()

? ? ? ? if (mTimer == null) {
? ? ? ? ? ? mTimer = Timer()
? ? ? ? } else {
? ? ? ? ? ? mTimer?.cancel()
? ? ? ? ? ? mTimerTask.cancel()
? ? ? ? }
? ? ? ? mTimer?.schedule(mTimerTask, 0, 1000)
? ? }

? ? private var mTimerTask: TimerTask = object : TimerTask() {
? ? ? ? override fun run() {
? ? ? ? ? ? mCurrentTimeInSecond++
? ? ? ? ? ? computeDegree()
? ? ? ? ? ? invalidate()
? ? ? ? }
? ? }

? ? //12小時 00:00:00 ~ 12:00:00
? ? private fun computeDegree() {
? ? ? ? val secondsInOneRoll = 12 * 60 * 60
? ? ? ? val currentSeconds = mCurrentTimeInSecond % secondsInOneRoll

? ? ? ? var leftSeconds = currentSeconds
? ? ? ? val hours = currentSeconds / 60 / 60
? ? ? ? leftSeconds = currentSeconds - hours * 60 * 60
? ? ? ? val minutes = leftSeconds / 60
? ? ? ? leftSeconds -= minutes * 60
? ? ? ? val seconds = leftSeconds % 60

? ? ? ? mHoursDegree = hours * 30f
? ? ? ? mMinutesDegree = minutes * 6f
? ? ? ? mSecondsDegree = seconds * 6f

? ? }
}

原文鏈接：https://blog.csdn.net/qq_29125669/article/details/124452399

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