android自定義view實(shí)現(xiàn)鐘表效果
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(xiě)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(pán)(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(huà)什么,表盤(pán)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(kāi)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(huà)一個(gè)圓就可以了。
接下來(lái)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(guò)旋轉(zhuǎn)畫(huà)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(guò)旋轉(zhuǎn)畫(huà)布嗎,但是你想一下,假如通過(guò)旋轉(zhuǎn)畫(huà)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(guò)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(méi)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(lái),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(méi)說(shuō)時(shí)分秒是怎么確定的,這當(dāng)然是通過(guò)系統(tǒng)時(shí)間獲取的了。說(shuō)到這里似乎一個(gè)靜態(tài)鐘表已經(jīng)繪制出來(lái)了,接下來(lái)讓它動(dòng)起來(lái)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(huà)筆 private lateinit var mRedPaint: Paint //紅色畫(huà)筆 private lateinit var mBlackPaint2: Paint//黑色畫(huà)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(huà)筆 */ private fun initPaints() { mBlackPaint = Paint() with(mBlackPaint) { color = Color.BLACK strokeWidth = 5f isAntiAlias = true style = Paint.Style.STROKE } //用于畫(huà)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(huà)最外層的圓圈 drawOuterCircle(canvas) //畫(huà)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(lái)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(guò)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(méi)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我們。
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