前言

最近我跟自定义View杠上了，甚至说有点上瘾到走火入魔了。身为菜鸟的我自然要查阅大量的资料，学习大神们的代码，这不，前两天正好在郭神在微信公众号里推送一片自定义控件的文章——一步步实现精美的钟表界面。正适合我这种菜鸟来学习，闲着没事，我就差不多依葫芦画瓢也写了一个自定义表盘View，现在纯粹最为笔记记录下来。先展示下效果图：

下面进入正题

自定义表盘属性

老规矩，先在attrs文件里添加表盘自定义属性

<declare-styleable name="WatchView"> <attr name="watchRadius" format="dimension"/> //表盘半径 <attr name="watchPadding" format="dimension"/> //表盘相对控件边框距离 <attr name="watchScalePadding" format="dimension"/> //刻度相对表盘距离 <attr name="watchScaleColor" format="color|reference"/> //常规刻度颜色 <attr name="watchScaleLength" format="dimension|reference"/> //常规刻度长度 <attr name="watchHourScaleColor" format="dimension|reference"/> //整点刻度颜色 <attr name="watchHourScaleLength" format="dimension|reference"/> //整点刻度长度 <attr name="hourPointColor" format="color|reference"/> //时针颜色 <attr name="hourPointLength" format="dimension|reference"/> //时针长度 <attr name="minutePointColor" format="color|reference"/> //分针颜色 <attr name="minutePointLength" format="dimension|reference"/> //分针长度 <attr name="secondPointColor" format="color|reference"/> //秒针颜色 <attr name="secondPointLength" format="dimension|reference"/> //秒针长度 <attr name="timeTextSize" format="dimension|reference"/> //表盘字体大小 <attr name="timeTextColor" format="color|reference"/> //表盘字体颜色 </declare-styleable>

在自定义View的构造方法种获取自定义属性

先将属性变量声明如下：

<span style="font-size:14px;"> /**表盘边距*/ private float mWatchPadding = 5; /**表盘与刻度边距*/ private float mWatchScalePadding = 5; /**表盘半径*/ private float mWatchRadius = 250; /**表盘刻度长度*/ private float mWatchScaleLength; /**表盘刻度颜色*/ private int mWatchScaleColor = Color.BLACK; /**表盘整点刻度长度*/ private float mHourScaleLength = 8; /**表盘整点刻度颜色*/ private int mHourScaleColor = Color.BLUE; /**表盘时针颜色*/ private int mHourPointColor = Color.BLACK; /**表盘时针长度*/ private float mHourPointLength = 100; /**表盘分针颜色*/ private int mMinutePointColor = Color.BLACK; /**表盘分针长度*/ private float mMinutePointLength = 130; /**表盘秒针颜色*/ private int mSecondPointColor = Color.RED; /**表盘秒针长度*/ private float mSecondPointLength = 160; /**表盘尾部指针长度*/ private float mEndPointLength; /**表盘数字颜色*/ private int mTimeTextColor = Color.BLACK; /**表盘数字大小*/ private int mTimeTextSize = 15;</span>

在构造方法种获取自定义属性

<span style="font-size:14px;"> public WatchView(Context context, AttributeSet attrs) { super(context, attrs); TypedArray array = context.obtainStyledAttributes(attrs,R.styleable.WatchView); int n = array.getIndexCount(); for (int i = 0;i<n;i++){ int attr = array.getIndex(i); switch (attr){ case R.styleable.WatchView_watchRadius: mWatchRadius = array.getDimensionPixelSize(attr,MyUtil.dip2px(context,60)); break; case R.styleable.WatchView_watchPadding: mWatchPadding = array.getDimensionPixelSize(attr,MyUtil.dip2px(context,5)); break; case R.styleable.WatchView_watchScalePadding: mWatchScalePadding = array.getDimensionPixelSize(attr,MyUtil.dip2px(context,3)); break; case R.styleable.WatchView_watchScaleLength: mWatchScaleLength = array.getDimensionPixelSize(attr,MyUtil.dip2px(context,5)); break; case R.styleable.WatchView_watchScaleColor: mWatchScaleColor = array.getColor(attr, Color.parseColor("#50000000")); break; case R.styleable.WatchView_watchHourScaleLength: mHourScaleLength = array.getDimensionPixelSize(attr,MyUtil.dip2px(context,10)); break; case R.styleable.WatchView_watchHourScaleColor: mHourScaleColor = array.getColor(attr,Color.BLACK); break; case R.styleable.WatchView_hourPointLength: mHourPointLength = array.getDimensionPixelSize(attr,MyUtil.dip2px(context,35)); break; case R.styleable.WatchView_hourPointColor: mHourPointColor = array.getColor(attr,Color.BLACK); break; case R.styleable.WatchView_minutePointLength: mMinutePointLength = array.getDimensionPixelSize(attr,MyUtil.dip2px(context,40)); break; case R.styleable.WatchView_minutePointColor: mMinutePointColor = array.getColor(attr,Color.BLACK); break; case R.styleable.WatchView_secondPointLength: mSecondPointLength = array.getDimensionPixelSize(attr,MyUtil.dip2px(context,50)); break; case R.styleable.WatchView_secondPointColor: mSecondPointColor = array.getColor(attr,Color.BLUE); break; case R.styleable.WatchView_timeTextSize: mTimeTextSize = array.getDimensionPixelSize(attr,MyUtil.dip2px(context,15)); break; case R.styleable.WatchView_timeTextColor: mTimeTextColor = array.getColor(attr,Color.BLACK); break; } } array.recycle(); }</span>

设置控件大小

这里当然就是重写onMeasure方法啦，这里我们处理的简单点，如下面代码所示，当我们将控件的宽高都设定为wrap_content（即MeasureSpec.UNSPECIFED）时，我们将宽高设定为默认值（wrapContentSize）和圆盘半径+圆盘边距（mWatchRadius+mWatchPadding）之间取最大值，其他情况下就取系统自取值。当然作为一个严谨的控件，仅仅这样处理肯定是不行的。项目中，我们要根据我们的需求自行修改里面的代码以适配。

<span style="font-size:14px;"> @Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { int wrapContentSize = 1000; int widthSize = MeasureSpec.getSize(widthMeasureSpec); int widthMode = MeasureSpec.getMode(widthMeasureSpec); int heightSize = MeasureSpec.getSize(heightMeasureSpec); int heightMode = MeasureSpec.getMode(heightMeasureSpec); if (widthMode == MeasureSpec.UNSPECIFIED && heightMode == MeasureSpec.UNSPECIFIED){ wrapContentSize = (int) Math.max(wrapContentSize,mWatchRadius+mWatchPadding); setMeasuredDimension(wrapContentSize,wrapContentSize); }else { setMeasuredDimension(widthSize,heightSize); } }</span>

重写onDraw方法

来到最关键真正画表盘时刻了。一步一步来，首先初始化我们的画笔（我的习惯，写一个initPaint方法）

<span style="font-size:14px;"> private void initPaint(){ mPaint = new Paint(); mPaint.setAntiAlias(true); mPaint.setColor(Color.WHITE); mPaint.setStyle(Paint.Style.FILL); }</span>

为了不显赘述，方便理解，我直接展示代码，在代码中解释

开画之前我们先将画笔移动到控件中心点位置，如下：

<span style="font-size:14px;">@Override protected void onDraw(Canvas canvas) { canvas.translate(getWidth()/2,getHeight()/2); }</span>

第一步，画表盘

<span style="font-size:14px;"> /** * 画表盘 * @param canvas */ private void paintWatchBoard(Canvas canvas){ initPaint(); canvas.save(); canvas.drawCircle(0,0,mWatchRadius,mPaint); //画圆盘 canvas.restore(); }</span>

注：每次画图之前都要先调用canvas.save()方法，保存画笔属性，画完之后要调用canvas.restore()方法，重置画笔属性

这里就不一一展示每次画完之后的效果图了。

第二步，画刻度+整点时间数字（刻度从12点方向开始画）

<span style="font-size:14px;"> /** * 画刻度及整点数字 * @param canvas */ private void paintScale(Canvas canvas){ int lineLength; //刻度线长度 canvas.save(); for (int i = 0;i<60;i++){ if (i%5 == 0){//整点刻度下画笔相关属性 mPaint.setStrokeWidth(MyUtil.dip2px(getContext(),1.5f)); mPaint.setColor(mHourScaleColor); lineLength = MyUtil.dip2px(getContext(),8); canvas.drawLine(0,-mWatchRadius+mWatchScalePadding,0,-mWatchRadius+mWatchScalePadding+lineLength,mPaint); mPaint.setColor(mTimeTextColor); mPaint.setTextSize(mTimeTextSize); canvas.drawText(mTimes[i/5],-mTimeTextSize/2,-mWatchRadius+mWatchScalePadding + lineLength+mTimeTextSize,mPaint);//整点的位置标上整点时间数字 }else {//非整点刻度下画笔相关属性 mPaint.setStrokeWidth(MyUtil.dip2px(getContext(),0.8f)); mPaint.setColor(mWatchScaleColor); lineLength = MyUtil.dip2px(getContext(),5); canvas.drawLine(0,-mWatchRadius+mWatchScalePadding,0,-mWatchRadius+mWatchScalePadding+lineLength,mPaint); } canvas.rotate(6);//每次画完一个刻度线，画笔顺时针旋转6度（360/60，相邻两刻度之间的角度差为6度） } canvas.restore(); }</span>

其中，整点数字我用了罗马数字来表示

<span style="font-size:14px;">private String[] mTimes = {"XII","Ⅰ","Ⅱ","Ⅲ","Ⅳ","Ⅴ","Ⅵ","Ⅶ","Ⅷ","Ⅸ","Ⅹ","XI"};</span>

第三步，画时针、分针、秒针以及其它修饰图

考虑到时针、分针和秒针大小长度各不一样，我这里特意定义了三支画笔来分别画时针、分针和秒针。

同样的，先初始化指针画笔：

<span style="font-size:14px;">/** * 初始化指针 */ private void initPointPaint(){ mHourPaint = new Paint(); mHourPaint.setAntiAlias(true); mHourPaint.setStyle(Paint.Style.FILL); mHourPaint.setStrokeWidth(16); mHourPaint.setColor(mHourPointColor); mMinutePaint = new Paint(); mMinutePaint.set(mHourPaint); mMinutePaint.setStrokeWidth(12); mMinutePaint.setColor(mMinutePointColor); mSecondPaint = new Paint(); mSecondPaint.set(mHourPaint); mSecondPaint.setStrokeWidth(7); mSecondPaint.setColor(mSecondPointColor); mEndPointLength = mWatchRadius/6; //（修饰部分）指针尾部长度，定义为表盘半径的六分之一 }</span>

画指针

<span style="font-size:14px;">/** * 画指针 * @param canvas */ private void paintPoint(Canvas canvas){ initPointPaint(); Calendar c = Calendar.getInstance(); //取当前时间 int hour = c.get(Calendar.HOUR_OF_DAY); int minute = c.get(Calendar.MINUTE); int second = c.get(Calendar.SECOND); //绘制时针 canvas.save(); canvas.rotate(hour*30); canvas.drawLine(0,0,0,-mHourPointLength,mHourPaint); canvas.drawLine(0,0,0,mEndPointLength,mHourPaint); canvas.restore(); //绘制分针 canvas.save(); canvas.rotate(minute*6); canvas.drawLine(0,0,0,-mMinutePointLength,mMinutePaint); canvas.drawLine(0,0,0,mEndPointLength,mMinutePaint); canvas.restore(); //绘制秒针 canvas.save(); canvas.rotate(second*6); canvas.drawLine(0,0,0,-mSecondPointLength,mSecondPaint); canvas.drawLine(0,0,0,mEndPointLength,mSecondPaint); canvas.restore(); }</span>

OK，该有的差不多都有了，直接在onDraw中调用吧

<span style="font-size:14px;">@Override protected void onDraw(Canvas canvas) { canvas.translate(getWidth()/2,getHeight()/2); paintWatchBoard(canvas); //画表盘 paintScale(canvas); //画刻度 paintPoint(canvas); //画指针 canvas.drawCircle(0,0,15,mSecondPaint); //为了美观，也让表盘更接近我们显示生活中的样子，我在圆盘中心画了一个大红圆点装饰秒针 postInvalidateDelayed(1000); //每隔一秒钟画一次 }</span>

(⊙v⊙)嗯，自定义View大功告成，我们在布局文件里调用看下效果吧

<span style="font-size:14px;"><?xml version="1.0" encoding="utf-8"?> <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:zhusp="http://schemas.android.com/apk/res-auto" android:layout_width="match_parent" android:layout_height="match_parent" android:background="@color/colorAccent"> <com.wondertek.propertyanimatordemo.WatchView android:layout_width="wrap_content" android:layout_height="wrap_content" zhusp:timeTextSize="20dp" zhusp:watchRadius="150dp" zhusp:hourPointLength="80dp" zhusp:minutePointLength="100dp" zhusp:secondPointLength="115dp"/> </RelativeLayout></span>

最后我这里的静态效果是这样的：