淺談Android PathMeasure詳解和應(yīng)用

PathMeasure()

PathMeasure(Path path, boolean forceClosed)

public class PathMeasureView extends View {

 private static final String TAG = "lwj";
 private int mViewHeight;
 private int mViewWidth;
 private Paint paint;

 public PathMeasureView(Context context) {
  super(context);
  init(context);
 }

 private void init(Context context) {
  paint = new Paint();
  paint.setColor(Color.RED);
  paint.setStyle(Paint.Style.STROKE);
  paint.setStrokeWidth(10);
 }


 @Override
 protected void onDraw(Canvas canvas) {
  super.onDraw(canvas);
  canvas.translate(mViewWidth/2, mViewHeight/2);

  Path path = new Path();
		path.lineTo(0, 300);
		path.lineTo(300, 300);
		path.lineTo(300, 0);

		PathMeasure measure = new PathMeasure(path, false);
		PathMeasure measure2 = new PathMeasure(path, true);
		Log.i(TAG, "length:"+measure.getLength());//900
		Log.i(TAG,"length:"+ measure2.getLength());//1200
  canvas.drawPath(path, paint);

 }

 //該方法在當(dāng)前View尺寸變化時(shí)被調(diào)用
 @Override
 protected void onSizeChanged(int w, int h, int oldw, int oldh) {
  super.onSizeChanged(w, h, oldw, oldh);
  mViewHeight = h;
  mViewWidth = w;
 }
}

setLayerType(View.LAYER_TYPE_SOFTWARE, null);
Path path = new Path();
path.addRect(-200, -200, 200, 200, Path.Direction.CW);
path.addRect(-100, -100, 100, 100, Path.Direction.CW);
PathMeasure measure = new PathMeasure(path, false);
float length = measure.getLength();
//獲取下一個(gè)路徑，有可能沒有多個(gè)路徑了，返回false
boolean nextContour = measure.nextContour();
float length3 = measure.getLength();
Log.i("damon", "length2:"+length);
Log.i("damon", "length3:"+length3);
canvas.drawPath(path, paint);

Path path = new Path();
//多路徑的效果需要關(guān)閉硬件加速??！
path.addRect(-200, -200, 200, 200, Path.Direction.CW);
PathMeasure measure = new PathMeasure(path, false);
float length = measure.getLength();
Log.i("damon", "length2:"+length);
canvas.drawPath(path, paint);
Path dst = new Path();
dst.lineTo(-300, -300);
//startWithMoveTo:false，代表該起始點(diǎn)是否位上一個(gè)的結(jié)束點(diǎn)(是否保持連續(xù)性)。
measure.getSegment(200, 600, dst , false);
paint.setColor(Color.RED);
canvas.drawPath(dst, paint);

Path path = new Path();
path.addCircle(0, 0, 300, Path.Direction.CW);
PathMeasure measure = new PathMeasure(path, false);
float[] pos = new float[2];
float[] tan = new float[2];//tan=y/x
measure.getPosTan(measure.getLength()/4, pos , tan );
Log.i("damon", "position:x-"+pos[0]+", y-"+pos[1]);
Log.i("damon", "tan:x-"+tan[0]+", y-"+tan[1]);
canvas.drawPath(path, paint);

public class SearchView extends View {

 // 畫筆
 private Paint mPaint;

 // View 寬高
 private int mViewWidth;
 private int mViewHeight;

 // 這個(gè)視圖擁有的狀態(tài)
 public static enum State {
  NONE,
  STARTING,
  SEARCHING,
  ENDING
 }

 // 當(dāng)前的狀態(tài)(非常重要)
 private State mCurrentState = State.NONE;

 // 放大鏡與外部圓環(huán)
 private Path path_srarch;
 private Path path_circle;

 // 測(cè)量Path 并截取部分的工具
 private PathMeasure mMeasure;

 // 默認(rèn)的動(dòng)效周期 2s
 private int defaultDuration = 2000;

 // 控制各個(gè)過程的動(dòng)畫
 private ValueAnimator mStartingAnimator;
 private ValueAnimator mSearchingAnimator;
 private ValueAnimator mEndingAnimator;

 // 動(dòng)畫數(shù)值(用于控制動(dòng)畫狀態(tài),因?yàn)橥粫r(shí)間內(nèi)只允許有一種狀態(tài)出現(xiàn),具體數(shù)值處理取決于當(dāng)前狀態(tài))
 private float mAnimatorValue = 0;

 // 動(dòng)效過程監(jiān)聽器
 private ValueAnimator.AnimatorUpdateListener mUpdateListener;
 private Animator.AnimatorListener mAnimatorListener;

 // 用于控制動(dòng)畫狀態(tài)轉(zhuǎn)換
 private Handler mAnimatorHandler;

 // 判斷是否已經(jīng)搜索結(jié)束
 private boolean isOver = false;

 private int count = 0;

 public SearchView(Context context) {
  super(context);

  initPaint();

  initPath();

  initListener();

  initHandler();

  initAnimator();

  // 進(jìn)入開始動(dòng)畫
  mCurrentState = State.STARTING;
  mStartingAnimator.start();

 }

 private void initPaint() {
  mPaint = new Paint();
  mPaint.setStyle(Paint.Style.STROKE);
  mPaint.setColor(Color.WHITE);
  mPaint.setStrokeWidth(15);
  mPaint.setStrokeCap(Paint.Cap.ROUND);
  mPaint.setAntiAlias(true);
 }

 private void initPath() {
  path_srarch = new Path();
  path_circle = new Path();

  mMeasure = new PathMeasure();

  // 注意,不要到360度,否則內(nèi)部會(huì)自動(dòng)優(yōu)化,測(cè)量不能取到需要的數(shù)值
  RectF oval1 = new RectF(-50, -50, 50, 50);   // 放大鏡圓環(huán)
  path_srarch.addArc(oval1, 45, 359.9f);

  RectF oval2 = new RectF(-100, -100, 100, 100);  // 外部圓環(huán)
  path_circle.addArc(oval2, 45, -359.9f);

  float[] pos = new float[2];

  mMeasure.setPath(path_circle, false);    // 放大鏡把手的位置
  mMeasure.getPosTan(0, pos, null);

  path_srarch.lineTo(pos[0], pos[1]);     // 放大鏡把手

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

 private void initListener() {
  mUpdateListener = new ValueAnimator.AnimatorUpdateListener() {
   @Override
   public void onAnimationUpdate(ValueAnimator animation) {
    mAnimatorValue = (float) animation.getAnimatedValue();
    invalidate();
   }
  };

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

   }

   @Override
   public void onAnimationEnd(Animator animation) {
    // getHandle發(fā)消息通知?jiǎng)赢嫚顟B(tài)更新
    mAnimatorHandler.sendEmptyMessage(0);
   }

   @Override
   public void onAnimationCancel(Animator animation) {

   }

   @Override
   public void onAnimationRepeat(Animator animation) {

   }
  };
 }

 private void initHandler() {
  mAnimatorHandler = new Handler() {
   @Override
   public void handleMessage(Message msg) {
    super.handleMessage(msg);
    switch (mCurrentState) {
     case STARTING:
      // 從開始動(dòng)畫轉(zhuǎn)換好搜索動(dòng)畫
      isOver = false;
      mCurrentState = State.SEARCHING;
      mStartingAnimator.removeAllListeners();
      mSearchingAnimator.start();
      break;
     case SEARCHING:
      if (!isOver) { // 如果搜索未結(jié)束 則繼續(xù)執(zhí)行搜索動(dòng)畫
       mSearchingAnimator.start();
       Log.e("Update", "RESTART");

       count++;
       if (count>2){  // count大于2則進(jìn)入結(jié)束狀態(tài)
        isOver = true;
       }
      } else {  // 如果搜索已經(jīng)結(jié)束 則進(jìn)入結(jié)束動(dòng)畫
       mCurrentState = State.ENDING;
       mEndingAnimator.start();
      }
      break;
     case ENDING:
      // 從結(jié)束動(dòng)畫轉(zhuǎn)變?yōu)闊o狀態(tài)
      mCurrentState = State.NONE;
      break;
    }
   }
  };
 }

 private void initAnimator() {
  mStartingAnimator = ValueAnimator.ofFloat(0, 1).setDuration(defaultDuration);
  mSearchingAnimator = ValueAnimator.ofFloat(0, 1).setDuration(defaultDuration);
  mEndingAnimator = ValueAnimator.ofFloat(1, 0).setDuration(defaultDuration);

  mStartingAnimator.addUpdateListener(mUpdateListener);
  mSearchingAnimator.addUpdateListener(mUpdateListener);
  mEndingAnimator.addUpdateListener(mUpdateListener);

  mStartingAnimator.addListener(mAnimatorListener);
  mSearchingAnimator.addListener(mAnimatorListener);
  mEndingAnimator.addListener(mAnimatorListener);
 }


 @Override
 protected void onSizeChanged(int w, int h, int oldw, int oldh) {
  super.onSizeChanged(w, h, oldw, oldh);
  mViewWidth = w;
  mViewHeight = h;
 }

 @Override
 protected void onDraw(Canvas canvas) {
  super.onDraw(canvas);

  drawSearch(canvas);
 }

 private void drawSearch(Canvas canvas) {

  mPaint.setColor(Color.WHITE);


  canvas.translate(mViewWidth / 2, mViewHeight / 2);

  canvas.drawColor(Color.parseColor("#0082D7"));

  switch (mCurrentState) {
   case NONE:
    canvas.drawPath(path_srarch, mPaint);
    break;
   case STARTING:
    mMeasure.setPath(path_srarch, false);
    Path dst = new Path();
    mMeasure.getSegment(mMeasure.getLength() * mAnimatorValue, mMeasure.getLength(), dst, true);
    canvas.drawPath(dst, mPaint);
    break;
   case SEARCHING:
    mMeasure.setPath(path_circle, false);
    Path dst2 = new Path();
    float stop = mMeasure.getLength() * mAnimatorValue;
    float start = (float) (stop - ((0.5 - Math.abs(mAnimatorValue - 0.5)) * 200f));
//    float start = stop-50;
    mMeasure.getSegment(start, stop, dst2, true);
    canvas.drawPath(dst2, mPaint);
    break;
   case ENDING:
    mMeasure.setPath(path_srarch, false);
    Path dst3 = new Path();
    mMeasure.getSegment(mMeasure.getLength() * mAnimatorValue, mMeasure.getLength(), dst3, true);
    canvas.drawPath(dst3, mPaint);
    break;
  }
 }
}