Android自定义音量调节

先看实现的图形界面如下

这是初始状态，通过上下滑动，改变这些小块的颜色

代码实现如下

资源文件

<?xml version="1.0" encoding="utf-8"?><resources>    <attr name="firstColor" format="color"/>    <attr name="secondColor" format="color"/>    <attr name="circleWidth" format="dimension"/>    <declare-styleable name="CustomView">        <attr name="firstColor"/>        <attr name="secondColor"/>        <attr name="circleWidth"/>    </declare-styleable></resources>

 自定义类

    public class CustomView extends View {    private int mFirstColor;    private int mSecondColor;    private int mCircleWidth;    private Paint mPaint,paint;    private int j=0;    public CustomView(Context context) {        this(context, null);    }    public CustomView(Context context, AttributeSet attrs) {        this(context, attrs, 0);    }    public CustomView(Context context, AttributeSet attrs, int defStyleAttr) {        super(context, attrs, defStyleAttr);        TypedArray a=context.getTheme().obtainStyledAttributes(attrs,R.styleable.CustomView,defStyleAttr,0);        int n=a.getIndexCount();        for(int i=0;i<n;i++){            int attr=a.getIndex(i);            switch(attr)            {                case R.styleable.CustomView_firstColor:                    mFirstColor=a.getColor(attr,Color.BLACK);                    break;                case R.styleable.CustomView_secondColor:                    mSecondColor=a.getColor(attr, Color.BLACK);                    break;                case R.styleable.CustomView_circleWidth:                    mCircleWidth=a.getDimensionPixelSize(attr,(int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_SP,16,getResources().getDisplayMetrics()));                    break;            }        }        a.recycle();        mPaint=new Paint();        paint=new Paint();    }    @Override    protected void onDraw(Canvas canvas) {        int centre=getWidth()/2;        int centre2=getHeight()/2;        int radius=centre-mCircleWidth/2;//半径        mPaint.setStrokeWidth(mCircleWidth);//设置线宽        mPaint.setAntiAlias(true);//消除锯齿        mPaint.setStyle(Paint.Style.STROKE);//设置为空心        mPaint.setStrokeCap(Paint.Cap.ROUND);//设置为线段形状为圆头        //设定一个圆弧的边界矩形        RectF oval=new RectF(centre-radius,centre2-radius,centre+radius,centre2+radius);        mPaint.setColor(mFirstColor);        //注意这个设置的线宽是以半径长度为中线，两边扩展 //       canvas.drawCircle(centre, centre2, radius, mPaint);        for(int i=0;i<12;i++){            canvas.drawArc(oval, (270+30*i)%360, 10, false, mPaint);        }//        canvas.drawArc(oval, 270, 10, false, mPaint);//        canvas.drawArc(oval, 300, 10, false, mPaint);        if(j<0)j=0;        j=j%13;        mPaint.setColor(mSecondColor);        for(int k=0;k<j;k++){            canvas.drawArc(oval,(270+30*k)%360,10,false,mPaint);        }        paint.setColor(Color.LTGRAY);        paint.setStrokeWidth(10);//设置线宽        paint.setStrokeCap(Paint.Cap.ROUND);//设置为线段形状为圆头        canvas.drawLine(centre - 100, centre2 - 50, centre - 100, centre2 + 50, paint);        canvas.drawLine(centre - 100, centre2 - 50, centre - 50, centre2 - 50, paint);        canvas.drawLine(centre - 50, centre2 - 50, centre + 20, centre2 - 100, paint);        canvas.drawLine(centre - 100, centre2 + 50, centre - 50, centre2 + 50, paint);        canvas.drawLine(centre-50,centre2+50,centre+20,centre2+100,paint);        canvas.drawLine(centre+20,centre2-100,centre+20,centre2+100,paint);        canvas.drawLine(centre+40,centre2-50,centre+100,centre2-100,paint);        canvas.drawLine(centre+40,centre2,centre+100,centre2,paint);        canvas.drawLine(centre+40,centre2+50,centre+100,centre2+100,paint);    }    private int xDown,xUp;    @Override    public boolean onTouchEvent(MotionEvent event) {        switch (event.getAction()){            case MotionEvent.ACTION_DOWN:                xDown=(int)event.getY();                break;            case MotionEvent.ACTION_UP:                xUp=(int)event.getY();                if(xUp>xDown){                    j++;                }else{                    j--;                }                postInvalidate();//对于这个还有一点不理解，为什么不直接调用draw呢，而且也没有开启线程吧，为什么不能调用Invalidate()                break;        }        return true;    }}

在布局中引用

       <com.example.administrator.musicplay.CustomView        android:layout_width="match_parent"        android:layout_height="match_parent"        custom:circleWidth="30dp"        custom:firstColor="#D4F668"        custom:secondColor="#2F9DD2"        />