SeniorUI_目录
SeniorUI1001_PathMeasure语法

一、Rendering

二、Principe

• 利用Path、PathMeasure、Animation实现
• 将动画 START,END,NONE,SEARCHING 四个不同的阶段
• 利用状态和动画的值，取对应的Path，绘制

三、Core Code

public class SearchView extends View {
    private static final String TAG = "SearchView";

    private Paint mPaint;

    private Context mContext;

    private int mWidth,mHeight;

    private Path mPathCircle;

    private Path mPathSearch;

    private PathMeasure mMeasure;

    private ValueAnimator mValueAnimator;

    private long DEFAULT_DURATION =3000;

    private float mCurAnimValue;

    private SearchState mState = SearchState.NONE;

    public SearchView(Context context) {
        this(context,null);
    }

    public SearchView(Context context, AttributeSet attrs) {
        this(context, attrs,0);
    }

    public SearchView(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        init(context);
    }

    public void init(Context context){
        this.mContext = context;
        initPaint();
        initPath();
        initAnimation();

    }
    public void initPaint(){
        mPaint = new Paint();
        mPaint.setDither(true);
        mPaint.setStrokeCap(Paint.Cap.ROUND);//设置笔头效果
        mPaint.setAntiAlias(true);
        mPaint.setColor(Color.RED);
        mPaint.setStrokeWidth(3);
        mPaint.setStyle(Paint.Style.STROKE);
    }

    public void initPath(){
        mPathSearch = new Path();
        mPathCircle = new Path();

        mMeasure = new PathMeasure();

        // 注意,不要到360度,否则内部会自动优化,测量不能取到需要的数值
        RectF oval1 = new RectF(-50, -50, 50, 50);     // 放大镜圆环
        mPathSearch.addArc(oval1, 45, 359.9f);

        RectF oval2 = new RectF(-100, -100, 100, 100);   // 外部圆环
        mPathCircle.addArc(oval2, 45, -359.9f);

        float[] pos = new float[2];

        mMeasure.setPath(mPathCircle, false);        // 放大镜把手的位置
        mMeasure.getPosTan(0, pos, null);

        mPathSearch.lineTo(pos[0], pos[1]);         // 放大镜把手

        Log.d(TAG, "pos=" + pos[0] + ":" + pos[1]);

    }

    public void initAnimation(){
        mValueAnimator = ValueAnimator.ofFloat(0f,1.0f).setDuration(DEFAULT_DURATION);

        mValueAnimator.addUpdateListener(updateListener);

        mValueAnimator.addListener(animationListener);
    }
    private ValueAnimator.AnimatorUpdateListener updateListener = new ValueAnimator.AnimatorUpdateListener() {
        @Override
        public void onAnimationUpdate(ValueAnimator animation) {
            mCurAnimValue = (float) animation.getAnimatedValue();
            invalidate();
        }
    };

    private Animator.AnimatorListener animationListener = new Animator.AnimatorListener() {
        @Override
        public void onAnimationStart(Animator animation) {

        }

        @Override
        public void onAnimationEnd(Animator animation) {
            if(mState == SearchState.START){
                setState(SearchState.SEARCHING);
            }
        }

        @Override
        public void onAnimationCancel(Animator animation) {

        }

        @Override
        public void onAnimationRepeat(Animator animation) {

        }
    };
    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        Log.d(TAG,"onDraw");
        drawPath(canvas);
    }

    @Override
    protected void onSizeChanged(int w, int h, int oldw, int oldh) {
        super.onSizeChanged(w, h, oldw, oldh);
        mWidth = w;
        mHeight = h;

    }

    private void drawPath(Canvas canvas) {
        canvas.translate(mWidth / 2, mHeight / 2);
        switch (mState){

            case NONE:
                canvas.drawPath(mPathSearch,mPaint);
                break;

            case START:
                mMeasure.setPath(mPathSearch,true);
                Path path = new Path();
                mMeasure.getSegment(mMeasure.getLength() * mCurAnimValue,mMeasure.getLength(),path, true);
                canvas.drawPath(path,mPaint);
                break;

            case SEARCHING:
                mMeasure.setPath(mPathCircle,true);
                Path pathSearch = new Path();
                mMeasure.getSegment(mMeasure.getLength()* mCurAnimValue -30,mMeasure.getLength()* mCurAnimValue,pathSearch,true);
                canvas.drawPath(pathSearch,mPaint);
                break;

            case END:
                mMeasure.setPath(mPathSearch,true);
                Path pathView = new Path();

                mMeasure.getSegment(0,mMeasure.getLength()* mCurAnimValue,pathView,true);
                canvas.drawPath(pathView,mPaint);
                break;
        }

    }


    public void setState(SearchState state){
        this.mState = state;
        startSearch();
    }

    public void startSearch(){
        switch (mState){
            case START:
                mValueAnimator.setRepeatCount(0);
                break;

            case SEARCHING:
                mValueAnimator.setRepeatCount(ValueAnimator.INFINITE);
                mValueAnimator.setRepeatMode(ValueAnimator.REVERSE);
                break;

            case END:
                mValueAnimator.setRepeatCount(0);
                break;
        }
        mValueAnimator.start();
    }
    public  enum SearchState {
        START,END,NONE,SEARCHING
    }
}

四、Demo

SearchView