Android自定義View系列之Path繪制仿支付寶支付成功動畫

前言

使用支付寶付款時，我們可以看到成功或者失敗都會有個動畫提示，如果我們需要做這樣的效果的話，當然，你可以讓設計師給你做個GIF，但是我們知道圖像比較耗內存的，我們自己可以用代碼實現還是代碼實現好點吧。

效果

實現方法

首先我們需要了解PathMeasure這個類，這個類我們可以理解為用來管理Path。我們主要看幾個方法。

PathMeasure()： 構造方法 ，實例化一個對象

PathMeasure(Path path,boolean isClosed)：傳入Path對象和是否閉合，path對象不能為空

getLength()：獲取當前輪廓、外形的總長度， 如果沒有設置Path對象，返回0

getSegment(float startD,float stopD,Path dst,boolean startWithMoveTo)：調用這個方法，我們可以獲取到指定范圍內的一段輪廓，存入到dst參數中。所以，這個方法傳入的參數分別為長度起始值、結束值、裝這一段路徑的Path對象、是否MoveTo。另外，這個方法返回值為Boolean類型，如果getLength為0的話，返回false，或者startD > stopD，同樣返回false。

setPath(Path path , boolean isClosed)：給當前PathMeasure對象設置Path

nextContour()：移動到下一個輪廓

然後我們需要動起來，我們知道invalidate()方法可以刷新界面，也就是重新調用onDraw()方法，所以我們要不停調用invalidate方法，在onDraw方法中改變參數，這樣實現動的效果。所以可以用到剛剛介紹的getSegment方法，不斷改變獲取的范圍，從0 * getLength，到1 * getLength，最後繪制完整。所以我們需要一個在一秒內或兩秒內一個從0到1的值的變化，so，我們使用ValueAnimator這個類來實現。

//實例化對象
mCircleAnimator = ValueAnimator.ofFloat(0, 1);
//設置時長為1000ms
mCircleAnimator.setDuration(1000);
//開始動畫
mCircleAnimator.start();
//設置動畫監聽
mCircleAnimator.addUpdateListener(this);

動畫開始後，在監聽方法中獲取當前進度並且重繪圖像

mCirclePercent = (float)animation.getAnimatedValue();
invalidate();

在onDraw方法中，繪制圖像

//畫圓
mPathCircle.addCircle(getWidth() / 2, getWidth() / 2, getWidth() / 2 - mLineWidth, Path.Direction.CW);
mPathMeasure.setPath(mPathCircle, false);
mPathMeasure.getSegment(0, mCirclePercent * mPathMeasure.getLength(), mPathCircleDst, true);
canvas.drawPath(mPathCircleDst, mPaint);

附上源碼，歡迎點評

package com.mintmedical.wavedemo;

import android.animation.ValueAnimator;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Path;
import android.graphics.PathMeasure;
import android.util.AttributeSet;
import android.util.Log;
import android.view.View;

/**
 * Created by MooreLi on 2016/12/12.
 */

public class ResultAnimation extends View implements ValueAnimator.AnimatorUpdateListener {
 private Context mContext;
 /**
  * paint對象
  */
 private Paint mPaint;
 /**
  * Path和對應的空Path用來填充
  */
 private Path mPathCircle;
 private Path mPathCircleDst;
 private Path mPathRight;
 private Path mPathRightDst;
 private Path mPathWrong1;
 private Path mPathWrong2;
 private Path mPathWrong1Dst;
 private Path mPathWrong2Dst;
 /**
  * Path管理
  */
 private PathMeasure mPathMeasure;
 /**
  * 動畫
  */
 private ValueAnimator mCircleAnimator;
 private ValueAnimator mRightAnimator;
 private ValueAnimator mWrong1Animator;
 private ValueAnimator mWrong2Animator;
 /**
  * 當前繪制進度占總Path長度百分比
  */
 private float mCirclePercent;
 private float mRightPercent;
 private float mWrong1Percent;
 private float mWrong2Percent;
 /**
  * 線寬
  */
 private int mLineWidth;
 /**
  * 正確動畫 錯誤動畫
  */
 public static final int RESULT_RIGHT = 1;
 public static final int RESULT_WRONG = 2;
 /**
  * 當前結果類型
  */
 private int mResultType = RESULT_WRONG;

 public ResultAnimation(Context context) {
  super(context);
  mContext = context;
  init();
 }

 public ResultAnimation(Context context, AttributeSet attrs) {
  super(context, attrs);
  mContext = context;
  init();
 }

 public ResultAnimation(Context context, AttributeSet attrs, int defStyleAttr) {
  super(context, attrs, defStyleAttr);
  mContext = context;
  init();
 }

 private void init() {
  mLineWidth = dp2px(3);
  mPaint = new Paint();
  mPaint.setAntiAlias(true);
  mPaint.setStrokeWidth(mLineWidth);
  mPaint.setStyle(Paint.Style.STROKE);
  mPaint.setColor(Color.GREEN);

  initPath();
 }

 private void initPath() {
  mPathCircle = new Path();
  mPathCircleDst = new Path();
  mPathRight = new Path();
  mPathRightDst = new Path();
  mPathWrong1 = new Path();
  mPathWrong2 = new Path();
  mPathWrong1Dst = new Path();
  mPathWrong2Dst = new Path();

  mPathMeasure = new PathMeasure();

  //實例化對象
  mCircleAnimator = ValueAnimator.ofFloat(0, 1);
  //設置時長為1000ms
  mCircleAnimator.setDuration(1000);
  //開始動畫
  mCircleAnimator.start();
  //設置動畫監聽
  mCircleAnimator.addUpdateListener(this);

  mRightAnimator = ValueAnimator.ofFloat(0, 1);
  mRightAnimator.setDuration(500);
  mRightAnimator.addUpdateListener(this);

  mWrong1Animator = ValueAnimator.ofFloat(0, 1);
  mWrong1Animator.setDuration(300);
  mWrong1Animator.addUpdateListener(this);
  mWrong2Animator = ValueAnimator.ofFloat(0, 1);
  mWrong2Animator.setDuration(300);
  mWrong2Animator.addUpdateListener(this);

 }

 @Override
 protected void onDraw(Canvas canvas) {
  super.onDraw(canvas);
  if (mResultType == RESULT_RIGHT) {
   mPaint.setColor(Color.GREEN);
  } else {
   mPaint.setColor(Color.RED);
  }

  //畫圓
  mPathCircle.addCircle(getWidth() / 2, getWidth() / 2, getWidth() / 2 - mLineWidth, Path.Direction.CW);
  mPathMeasure.setPath(mPathCircle, false);
  mPathMeasure.getSegment(0, mCirclePercent * mPathMeasure.getLength(), mPathCircleDst, true);
  canvas.drawPath(mPathCircleDst, mPaint);
  if (mResultType == RESULT_RIGHT) {
   //畫對勾
   mPathRight.moveTo(getWidth() / 4, getWidth() / 2);
   mPathRight.lineTo(getWidth() / 2, getWidth() / 4 * 3);
   mPathRight.lineTo(getWidth() / 4 * 3, getWidth() / 4);
   if (mCirclePercent == 1) {
    mPathMeasure.nextContour();
    mPathMeasure.setPath(mPathRight, false);
    mPathMeasure.getSegment(0, mRightPercent * mPathMeasure.getLength(), mPathRightDst, true);
    canvas.drawPath(mPathRightDst, mPaint);
   }
  } else {
   mPathWrong1.moveTo(getWidth() / 4 * 3, getWidth() / 4);
   mPathWrong1.lineTo(getWidth() / 4, getWidth() / 4 * 3);

   mPathWrong2.moveTo(getWidth() / 4, getWidth() / 4);
   mPathWrong2.lineTo(getWidth() / 4 * 3, getWidth() / 4 * 3);

   if (mCirclePercent == 1) {
    mPathMeasure.nextContour();
    mPathMeasure.setPath(mPathWrong1, false);
    mPathMeasure.getSegment(0, mWrong1Percent * mPathMeasure.getLength(), mPathWrong1Dst, true);
    canvas.drawPath(mPathWrong1Dst, mPaint);
   }
   if (mWrong1Percent == 1) {
    mPathMeasure.nextContour();
    mPathMeasure.setPath(mPathWrong2, false);
    mPathMeasure.getSegment(0, mWrong2Percent * mPathMeasure.getLength(), mPathWrong2Dst, true);
    canvas.drawPath(mPathWrong2Dst, mPaint);
   }
  }
 }

 private int dp2px(int dp) {
  float scale = mContext.getResources().getDisplayMetrics().density;
  return (int) (scale * dp + 0.5f);
 }

 @Override
 public void onAnimationUpdate(ValueAnimator animation) {
  //圓形動畫
  if (animation.equals(mCircleAnimator)) {
   mCirclePercent = (float) animation.getAnimatedValue();
   invalidate();
   Log.e("TEST","percent:"+mCirclePercent);
   if (mCirclePercent == 1) {
    if (mResultType == RESULT_RIGHT)
     mRightAnimator.start();
    else
     mWrong1Animator.start();
   }
  }
  //正確時 對勾動畫
  else if (animation.equals(mRightAnimator)) {
   mRightPercent = (float) animation.getAnimatedValue();
   invalidate();
  }
  //錯誤時 右側動畫
  else if (animation.equals(mWrong1Animator)) {
   mWrong1Percent = (float) animation.getAnimatedValue();
   invalidate();
   if (mWrong1Percent == 1) {
    mWrong2Animator.start();
   }
  }
  //錯誤時 左側動畫
  else if (animation.equals(mWrong2Animator)) {
   mWrong2Percent = (float) animation.getAnimatedValue();
   invalidate();
  }
 }

 public void setmResultType(int mResultType) {
  this.mResultType = mResultType;
  invalidate();
 }

 /**
  * 固定寫死了寬高，可重新手動調配
  *
  * @param widthMeasureSpec
  * @param heightMeasureSpec
  */
 @Override
 protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
  super.onMeasure(widthMeasureSpec, heightMeasureSpec);
  setMeasuredDimension(dp2px(50), dp2px(50));
 }
}

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