Android自定义View制作仪表盘界面

郗欣嘉

2023-03-14

本文向大家介绍Android自定义View制作仪表盘界面，包括了Android自定义View制作仪表盘界面的使用技巧和注意事项，需要的朋友参考一下

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：

Android自定义View制作仪表盘界面

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