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| 导读 | 这篇文章主要为大家详细介绍了 Android 自定义 View 实现时钟功能，文中示例代码介绍的非常详细，具有一定的参考价值，感兴趣的小伙伴们可以参考一下 |
最近在练习自定义 view, 想起之前面试的时候笔试有道题是写出自定义一个时钟的关键代码. 今天就来实现一下. 步骤依然是先分析, 再上代码.
实现效果
View 分析
时钟主要分为五个部分:
1、中心点: 圆心位置
2、圆盘: 以中心点为圆心,drawCircle 画个圆
3、刻度:
paint 有个 aip, setPathEffect 可以根据 path 画特效, 那么刻度就可以根据圆的 path 画一个矩形 path 的特效, 并且这个 api 只会画特效, 不会画出圆.
/**
* shape: 特效的 path, 这里传一个矩形
* advance: 两个特效 path 之间的间距, 即两个矩形的 left 间距
* phase: 特效起始位置的偏移
* style: 原始 path 拐弯的时候特效 path 的转换方式, 这里用 ROTATE 跟着旋转即可
*/
PathDashPathEffect(Path shape, float advance, float phase,
Style style)刻度又分两种, 粗一点刻度: 3、6、9、12, 和细一点的刻度. 两种特效又可以用 SumPathEffect 合起来画
SumPathEffect(PathEffect first, PathEffect second)4、时分秒指针
时分秒指针都是一个圆角矩形, 先把他们的位置计算出来, 然后旋转圆心去绘制不同角度的指针.
5、动画效果
TimerTask 每隔一秒计算时间, 根据时间去换算当前时分秒指针的角度, 动态变量只有三个角度.
实现源码
//
// 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())
// 画圆盘
mCirclePaint.pathEffect = null
canvas.drawPath(mCirclePath, mCirclePaint)
// 画刻度
mCirclePaint.pathEffect = mSumPathEffect
canvas.drawPath(mCirclePath, mCirclePaint)
// 时分秒指针
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()
// 画中心点
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) // 小时
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 小时 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
}
}以上就是本文的全部内容，希望对大家的学习有所帮助。
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