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android自定義view實(shí)現(xiàn)鐘表效果

 更新時(shí)間：2019年12月20日 11:05:10   作者：_implements  
這篇文章主要為大家詳細(xì)介紹了android自定義view實(shí)現(xiàn)鐘表效果，文中示例代碼介紹的非常詳細(xì)，具有一定的參考價(jià)值，感興趣的小伙伴們可以參考一下

本文實(shí)例為大家分享了android view實(shí)現(xiàn)鐘表的具體代碼，供大家參考，具體內(nèi)容如下

先看效果圖：

自定義view大家肯定已經(jīng)不陌生了，所以直接今天直接步入正題：如何利用canvas去繪制出一個(gè)鐘表

當(dāng)然繪制之前我們必須進(jìn)行測(cè)量（重寫onMeasure），根據(jù)自己的規(guī)則去測(cè)量，這暫時(shí)是將控件限制為一個(gè)正方形。

首先我們先把鐘表分解，看它由哪幾部分組成。如上圖：鐘表包括表盤（刻度）和表針還有文字構(gòu)成。

分清結(jié)構(gòu)之后我們?cè)倜鞔_canvas需要畫什么，表盤的構(gòu)成其實(shí)就是外層一個(gè)圓，然后上面是有規(guī)律的線段，表針就是三個(gè)長(zhǎng)短不一的線段，再加上12個(gè)鐘點(diǎn)文字。這樣一分析是不是發(fā)現(xiàn)調(diào)用canvas的drawCircle、drawLine和drawText就可以完成鐘表的繪制了。

既然明確了我們繪制所需要的方法，那么就開始重頭戲了，告訴canvas在哪繪制這些零件。

最外層的圓是最簡(jiǎn)單的，我們只需要以控件的中心為圓心，控件的寬度一半為半徑畫一個(gè)圓就可以了。

接下來就是難點(diǎn)一了，這些刻度怎么辦呢，其實(shí)我們不難發(fā)現(xiàn)其中的規(guī)律，每個(gè)刻度之間的弧度是一樣的，那這樣我們是不是可以通過旋轉(zhuǎn)畫布就可以實(shí)現(xiàn)這些刻度的繪制呢，答案是肯定的。

難點(diǎn)二，文字又該如何繪制，難道也通過旋轉(zhuǎn)畫布嗎，但是你想一下，假如通過旋轉(zhuǎn)畫布去繪制文字，那有些文字可是會(huì)顛倒的，這并不是我們想要的結(jié)果，那該怎么辦，這時(shí)候我們只能通過數(shù)學(xué)計(jì)算老老實(shí)實(shí)的計(jì)算每個(gè)文字的起始坐標(biāo)，這些坐標(biāo)并沒有想象中的復(fù)雜，我們可以根據(jù)中心點(diǎn)的位置和偏移角度（當(dāng)然還需要考慮文字的寬度）算出。

難點(diǎn)三，繪制表針，其實(shí)文字繪制出來，那么同樣可以根據(jù)中心點(diǎn)和偏移角度算出表針的起始坐標(biāo)和結(jié)束坐標(biāo)
表心就是一個(gè)實(shí)體的圓，這個(gè)就簡(jiǎn)單了。

好像還沒說時(shí)分秒是怎么確定的，這當(dāng)然是通過系統(tǒng)時(shí)間獲取的了。說到這里似乎一個(gè)靜態(tài)鐘表已經(jīng)繪制出來了，接下來讓它動(dòng)起來就可以了。在這我們啟動(dòng)一個(gè)線程，讓它隔一秒鐘進(jìn)行一次重繪即可。

下面我直接貼一下代碼把，代碼是用kotlin實(shí)現(xiàn)（這不是重點(diǎn)）的

package com.example.commonui.widget
 
import android.annotation.SuppressLint
import android.content.Context
import android.graphics.Canvas
import android.graphics.Color
import android.graphics.Paint
import android.os.Handler
import android.os.Message
import android.util.AttributeSet
import android.view.View
import java.util.*
 
/**
 * Created by zhang on 2017/12/20.
 */
class ClockView(context: Context?, attrs: AttributeSet? = null, defStyleAttr: Int = 0) : View(context, attrs, defStyleAttr) {
 
  companion object {
    private const val DEFAULT_WIDTH = 200 //默認(rèn)寬度
  }
 
  private lateinit var mBlackPaint: Paint//黑色畫筆
  private lateinit var mRedPaint: Paint //紅色畫筆
  private lateinit var mBlackPaint2: Paint//黑色畫筆
  private lateinit var mTextPaint: Paint
  private var hour: Int? = null
  private var minute: Int? = null
  private var second: Int? = null
  private val textArray = arrayOf("12", "1", "2", "3", "4", "5", "6", "7", "8", "9", "10", "11")
  private var refreshThread: Thread? = null
  private var mHandler = @SuppressLint("HandlerLeak")
  object : Handler() {
    override fun handleMessage(msg: Message?) {
      super.handleMessage(msg)
      when (msg?.what) {
        0 -> {
          invalidate()
        }
      }
 
    }
  }
 
  init {
    initPaints()
  }
 
  /**
   * 初始化畫筆
   */
  private fun initPaints() {
    mBlackPaint = Paint()
    with(mBlackPaint) {
      color = Color.BLACK
      strokeWidth = 5f
      isAntiAlias = true
      style = Paint.Style.STROKE
    }
    //用于畫表心
    mBlackPaint2 = Paint()
    with(mBlackPaint2) {
      color = Color.BLACK
      isAntiAlias = true
      style = Paint.Style.FILL
    }
    mRedPaint = Paint()
    with(mRedPaint) {
      color = Color.RED
      strokeWidth = 5f
      isAntiAlias = true
    }
 
    mTextPaint = Paint()
    with(mTextPaint) {
      color = Color.BLACK
      textSize = 30f
      isAntiAlias = true
    }
  }
 
  override fun onDraw(canvas: Canvas?) {
    super.onDraw(canvas)
    //獲取當(dāng)前時(shí)間
    getCurrentTime()
 
    //先畫最外層的圓圈
    drawOuterCircle(canvas)
 
    //畫刻度
    drawScale(canvas)
 
    //繪制文字
    drawTimeText(canvas)
 
    //繪制表針
    drawHand(canvas)
 
    //繪制表心
    drawCenter(canvas)
  }
 
  private fun getCurrentTime() {
    val calendar = Calendar.getInstance()
    hour = calendar.get(Calendar.HOUR)
    minute = calendar.get(Calendar.MINUTE)
    second = calendar.get(Calendar.SECOND)
  }
 
  private fun drawOuterCircle(canvas: Canvas?) {
    mBlackPaint.strokeWidth = 5f
    canvas?.drawCircle(measuredWidth / 2.toFloat(), measuredHeight / 2.toFloat(), (measuredWidth / 2 - 5).toFloat(), mBlackPaint)
  }
 
  private fun drawCenter(canvas: Canvas?) {
    canvas?.drawCircle(measuredWidth / 2.toFloat(), measuredHeight / 2.toFloat(), 20f, mBlackPaint2)
  }
 
  private fun drawHand(canvas: Canvas?) {
    drawSecond(canvas, mRedPaint)
    mBlackPaint.strokeWidth = 10f
    drawMinute(canvas, mBlackPaint)
    mBlackPaint.strokeWidth = 15f
    drawHour(canvas, mBlackPaint)
  }
 
  private fun drawTimeText(canvas: Canvas?) {
    val textR = (measuredWidth / 2 - 50).toFloat()//文字構(gòu)成的圓的半徑
    for (i in 0..11) {
      //繪制文字的起始坐標(biāo)
      val startX = (measuredWidth / 2 + textR * Math.sin(Math.PI / 6 * i) - mTextPaint.measureText(textArray[i]) / 2).toFloat()
      val startY = (measuredHeight / 2 - textR * Math.cos(Math.PI / 6 * i) + mTextPaint.measureText(textArray[i]) / 2).toFloat()
      canvas?.drawText(textArray[i], startX, startY, mTextPaint)
    }
  }
 
  private fun drawScale(canvas: Canvas?) {
    var scaleLength: Float?
    canvas?.save()
    //0..59代表[0,59]
    for (i in 0..59) {
      if (i % 5 == 0) {
        //大刻度
        mBlackPaint.strokeWidth = 5f
        scaleLength = 20f
      } else {
        //小刻度
        mBlackPaint.strokeWidth = 3f
        scaleLength = 10f
      }
      canvas?.drawLine(measuredWidth / 2.toFloat(), 5f, measuredWidth / 2.toFloat(), (5 + scaleLength), mBlackPaint)
      canvas?.rotate(360 / 60.toFloat(), measuredWidth / 2.toFloat(), measuredHeight / 2.toFloat())
    }
    //恢復(fù)原來狀態(tài)
    canvas?.restore()
  }
 
  /**
   * 繪制秒針
   */
  private fun drawSecond(canvas: Canvas?, paint: Paint?) {
    //秒針長(zhǎng)半徑 (表針會(huì)穿過表心 所以需要根據(jù)兩個(gè)半徑計(jì)算起始和結(jié)束半徑)
    val longR = measuredWidth / 2 - 60
    val shortR = 60
    val startX = (measuredWidth / 2 - shortR * Math.sin(second!!.times(Math.PI / 30))).toFloat()
    val startY = (measuredWidth / 2 + shortR * Math.cos(second!!.times(Math.PI / 30))).toFloat()
    val endX = (measuredWidth / 2 + longR * Math.sin(second!!.times(Math.PI / 30))).toFloat()
    val endY = (measuredWidth / 2 - longR * Math.cos(second!!.times(Math.PI / 30))).toFloat()
    canvas?.drawLine(startX, startY, endX, endY, paint)
  }
 
  /**
   * 繪制分針
   */
  private fun drawMinute(canvas: Canvas?, paint: Paint?) {
    //半徑比秒針小一點(diǎn)
    val longR = measuredWidth / 2 - 90
    val shortR = 50
    val startX = (measuredWidth / 2 - shortR * Math.sin(minute!!.times(Math.PI / 30))).toFloat()
    val startY = (measuredWidth / 2 + shortR * Math.cos(minute!!.times(Math.PI / 30))).toFloat()
    val endX = (measuredWidth / 2 + longR * Math.sin(minute!!.times(Math.PI / 30))).toFloat()
    val endY = (measuredWidth / 2 - longR * Math.cos(minute!!.times(Math.PI / 30))).toFloat()
    canvas?.drawLine(startX, startY, endX, endY, paint)
  }
 
 
  /**
   * 繪制時(shí)針
   */
  private fun drawHour(canvas: Canvas?, paint: Paint?) {
    //半徑比秒針小一點(diǎn)
    val longR = measuredWidth / 2 - 120
    val shortR = 40
    val startX = (measuredWidth / 2 - shortR * Math.sin(hour!!.times(Math.PI / 6))).toFloat()
    val startY = (measuredWidth / 2 + shortR * Math.cos(hour!!.times(Math.PI / 6))).toFloat()
    val endX = (measuredWidth / 2 + longR * Math.sin(hour!!.times(Math.PI / 6))).toFloat()
    val endY = (measuredWidth / 2 - longR * Math.cos(hour!!.times(Math.PI / 6))).toFloat()
    canvas?.drawLine(startX, startY, endX, endY, paint)
  }
 
  /**
   * 進(jìn)行測(cè)量
   */
  override fun onMeasure(widthMeasureSpec: Int, heightMeasureSpec: Int) {
    super.onMeasure(widthMeasureSpec, heightMeasureSpec)
    val widthSpecMode = MeasureSpec.getMode(widthMeasureSpec)
    val widthSpecSize = MeasureSpec.getSize(widthMeasureSpec)
    val heightSpecMode = MeasureSpec.getMode(heightMeasureSpec)
    val heightSpecSize = MeasureSpec.getSize(heightMeasureSpec)
    val result = if (widthSpecMode == MeasureSpec.AT_MOST && heightSpecMode == MeasureSpec.AT_MOST) {
      DEFAULT_WIDTH
    } else {
      Math.min(widthSpecSize, heightSpecSize)
    }
 
    setMeasuredDimension(result, result)
  }
 
  override fun onAttachedToWindow() {
    super.onAttachedToWindow()
    //啟動(dòng)線程 刷新界面
    refreshThread = Thread(Runnable {
      while (true) {
        try {
          Thread.sleep(1000)
          mHandler.sendEmptyMessage(0)
        } catch (e: InterruptedException) {
          break
        }
      }
    })
    refreshThread?.start()
  }
 
  override fun onDetachedFromWindow() {
    super.onDetachedFromWindow()
    mHandler.removeCallbacksAndMessages(null)
    //中斷線程
    refreshThread?.interrupt()
  }
}

在這送上幾點(diǎn)建議，1.盡量不要再ondraw里面創(chuàng)建對(duì)象，因?yàn)関iew可能會(huì)多次重繪，每次都創(chuàng)建新的對(duì)象會(huì)造成不必要的內(nèi)存浪費(fèi)

2.onmeasure方法會(huì)調(diào)用多次，請(qǐng)保證你的邏輯覆蓋性，否則可能會(huì)出現(xiàn)沒有按照你的預(yù)期得到寬高

3.線程的謹(jǐn)慎使用

以上就是本文的全部?jī)?nèi)容，希望對(duì)大家的學(xué)習(xí)有所幫助，也希望大家多多支持腳本之家。

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