Android自定义view实现圆环效果实例代码

public class CirclePercentBar extends View{
  private Context mContext;
  private int mArcColor;
  private int mArcWidth;
  private int mCenterTextColor;
  private int mCenterTextSize;
  private int mCircleRadius;
  private Paint arcPaint;
  private Paint arcCirclePaint;
  private Paint centerTextPaint;
  private RectF arcRectF;
  private Rect textBoundRect;
  private float mCurData=0;
  private int arcStartColor;
  private int arcEndColor;
  private Paint startCirclePaint;
  public CirclePercentBar(Context context) {
    this(context, null);
  }
  public CirclePercentBar(Context context, AttributeSet attrs) {
    this(context, attrs, 0);
  }
  public CirclePercentBar(Context context, AttributeSet attrs, int defStyleAttr) {
    super(context, attrs, defStyleAttr);
    mContext=context;
    TypedArray typedArray=context.obtainStyledAttributes(attrs,R.styleable.CirclePercentBar,defStyleAttr,0);
    mArcColor = typedArray.getColor(R.styleable.CirclePercentBar_arcColor,0xff0000);
    mArcWidth = typedArray.getDimensionPixelSize(R.styleable.CirclePercentBar_arcWidth, DisplayUtil.dp2px(context, 20));
    mCenterTextColor = typedArray.getColor(R.styleable.CirclePercentBar_centerTextColor, 0x0000ff);
    mCenterTextSize = typedArray.getDimensionPixelSize(R.styleable.CirclePercentBar_centerTextSize, DisplayUtil.dp2px(context, 20));
    mCircleRadius = typedArray.getDimensionPixelSize(R.styleable.CirclePercentBar_circleRadius, DisplayUtil.dp2px(context, 100));
    arcStartColor = typedArray.getColor(R.styleable.CirclePercentBar_arcStartColor,
        ContextCompat.getColor(mContext, R.color.green));
    arcEndColor = typedArray.getColor(R.styleable.CirclePercentBar_arcEndColor,
        ContextCompat.getColor(mContext, R.color.yellow));
    typedArray.recycle();
    initPaint();
  }
  private void initPaint() {
    startCirclePaint = new Paint(Paint.ANTI_ALIAS_FLAG);
    startCirclePaint.setStyle(Paint.Style.FILL);
    //startCirclePaint.setStrokeWidth(mArcWidth);
    startCirclePaint.setColor(arcStartColor);
    arcCirclePaint = new Paint(Paint.ANTI_ALIAS_FLAG);
    arcCirclePaint.setStyle(Paint.Style.STROKE);
    arcCirclePaint.setStrokeWidth(mArcWidth);
    arcCirclePaint.setColor(ContextCompat.getColor(mContext,R.color.colorAccent));
    arcCirclePaint.setStrokeCap(Paint.Cap.ROUND);
    arcPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
    arcPaint.setStyle(Paint.Style.STROKE);
    arcPaint.setStrokeWidth(mArcWidth);
    arcPaint.setColor(mArcColor);
    arcPaint.setStrokeCap(Paint.Cap.ROUND);
    centerTextPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
    centerTextPaint.setStyle(Paint.Style.STROKE);
    centerTextPaint.setColor(mCenterTextColor);
    centerTextPaint.setTextSize(mCenterTextSize);
    //圓弧的外接矩形
    arcRectF = new RectF();
    //文字的边界矩形
    textBoundRect = new Rect();
  }
  @Override
  protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
    super.onMeasure(widthMeasureSpec, heightMeasureSpec);
    setMeasuredDimension(measureDimension(widthMeasureSpec),measureDimension(heightMeasureSpec));
  }
  private int measureDimension(int measureSpec) {
    int result;
    int specMode=MeasureSpec.getMode(measureSpec);
    int specSize=MeasureSpec.getSize(measureSpec);
    if(specMode==MeasureSpec.EXACTLY){
      result=specSize;
    }else{
      result=mCircleRadius*2;
      if(specMode==MeasureSpec.AT_MOST){
        result=Math.min(result,specSize);
      }
    }
    return result;
  }
  @Override
  protected void onDraw(Canvas canvas) {
    canvas.rotate(-90, getWidth()/ 2, getHeight()/ 2);
    arcRectF.set(getWidth()/2-mCircleRadius+mArcWidth/2,getHeight()/2-mCircleRadius+mArcWidth/2
        ,getWidth()/2+mCircleRadius-mArcWidth/2,getHeight()/2+mCircleRadius-mArcWidth/2);
    canvas.drawArc(arcRectF, 0,360,false,arcCirclePaint);
    arcPaint.setShader(new SweepGradient(getWidth()/2,getHeight()/2,arcStartColor,arcEndColor));
    canvas.drawArc(arcRectF, 0,360* mCurData /100,false,arcPaint);
    canvas.rotate(90, getWidth()/ 2, getHeight()/ 2);
    canvas.drawCircle(getWidth()/2,getHeight()/2-mCircleRadius+mArcWidth/2,mArcWidth/2,startCirclePaint);
    String data= String.valueOf(mCurData) +"%";
    centerTextPaint.getTextBounds(data,0,data.length(),textBoundRect);
    canvas.drawText(data,getWidth()/2-textBoundRect.width()/2,getHeight()/2+textBoundRect.height()/2,centerTextPaint);
  }
  public void setPercentData(float data, TimeInterpolator interpolator){
    ValueAnimator valueAnimator=ValueAnimator.ofFloat(mCurData,data);
    valueAnimator.setDuration((long) (Math.abs(mCurData-data)*30));
    valueAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
      @Override
      public void onAnimationUpdate(ValueAnimator valueAnimator) {
        float value= (float) valueAnimator.getAnimatedValue();
        mCurData=(float)(Math.round(value*10))/10;
        invalidate();
      }
    });
    valueAnimator.setInterpolator(interpolator);
    valueAnimator.start();
  }
}

public class DisplayUtil {
  public static int px2dp(Context context,float pxValue){
    final float scale=context.getResources().getDisplayMetrics().density;
    return (int)(pxValue/scale+0.5f);
  }
  public static int dp2px(Context context,float dpValue){
    final float scale=context.getResources().getDisplayMetrics().density;
    return (int)(dpValue*scale+0.5f);
  }
}

public class MainActivity extends AppCompatActivity {
  CirclePercentBar circlePercentBar;
  Button startBtn;
  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    circlePercentBar= (CirclePercentBar) findViewById(R.id.circle_bar);
    circlePercentBar.setPercentData(55.2f,new DecelerateInterpolator());
    startBtn= (Button) findViewById(R.id.start_btn);
    startBtn.setOnClickListener(new View.OnClickListener() {
      @Override
      public void onClick(View view) {
        circlePercentBar.setPercentData((float) (100*Math.random()),new DecelerateInterpolator());
      }
    });
  }
}