在Android开发中使用View制作一个引导动画

这篇文章将为大家详细讲解有关在Android开发中使用View制作一个引导动画，文章内容质量较高，因此小编分享给大家做个参考，希望大家阅读完这篇文章后对相关知识有一定的了解。

一、实现效果图

关于贝塞尔曲线

二、实现代码

自定义view

package com.czhappy.showintroduce.view;import android.content.Context;import android.graphics.Bitmap;import android.graphics.canvas;import android.graphics.Color;import android.graphics.Paint;import android.graphics.Path;import android.util.AttributeSet;import android.view.View;import android.widget.RelativeLayout;public class RippleIntroView extends RelativeLayout implements Runnable { private int mMaxRadius = 70; private int mInterval = 20; private int count = 0; private Bitmap mCacheBitmap; private Paint mRipplePaint; private Paint mCirclePaint; private Path mArcPath; public RippleIntroView(Context context) {  this(context, null); } public RippleIntroView(Context context, AttributeSet attrs) {  this(context, attrs, 0); } public RippleIntroView(Context context, AttributeSet attrs, int defStyleAttr) {  super(context, attrs, defStyleAttr);  init(); } private void init() {  mRipplePaint = new Paint();  mRipplePaint.setAntiAlias(true);  mRipplePaint.setStyle(Paint.Style.STROKE);  mRipplePaint.setColor(Color.WHITE);  mRipplePaint.setStrokeWidth(2.f);  mCirclePaint = new Paint();  mCirclePaint.setAntiAlias(true);  mCirclePaint.setStyle(Paint.Style.FILL);  mCirclePaint.setColor(Color.WHITE);  mArcPath = new Path(); }  @Override protected void onSizeChanged(int w, int h, int oldw, int oldh) {  super.onSizeChanged(w, h, oldw, oldh);  if (mCacheBitmap != null) {   mCacheBitmap.recycle();   mCacheBitmap = null;  } } @Override protected void onDraw(Canvas canvas) {  //获取加号图片view  View mPlusChild = getChildAt(0);  //获取提示图片view  View mRefsChild = getChildAt(1);  if (mPlusChild == null || mRefsChild == null) return;  //获取加号图片大小  final int pw = mPlusChild.getWidth();  final int ph = mPlusChild.getHeight();  //获取提示图片大小  final int fw = mRefsChild.getWidth();  final int fh = mRefsChild.getHeight();  if (pw == 0 || ph == 0) return;  //加号图片中心点坐标  final float px = mPlusChild.getX() + pw / 2;  final float py = mPlusChild.getY() + ph / 2;  //提示图片左上角坐标  final float fx = mRefsChild.getX();  final float fy = mRefsChild.getY();  final int rw = pw / 2;  final int rh = ph / 2;  if (mCacheBitmap == null) {   mCacheBitmap = Bitmap.createBitmap(getWidth(), getHeight(), Bitmap.Config.ARGB_8888);   Canvas cv = new Canvas(mCacheBitmap);   super.onDraw(cv);   //清空所有已经画过的path至原始状态   mArcPath.reset();   //起始轮廓点移至x，y坐标点,即加号图片正下方再往下20位置   mArcPath.moveTo(px, py + rh + mInterval);   //设置二次贝塞尔，实现平滑曲线，前两个参数为操作点坐标，后两个参数为结束点坐标   mArcPath.quadTo(px, fy - mInterval, fx + fw * 0.618f, fy - mInterval);   //0~255，数值越小越透明   mRipplePaint.setAlpha(255);   cv.drawPath(mArcPath, mRipplePaint);   //绘制半径为6的实心圆点   cv.drawCircle(px, py + rh + mInterval, 6, mCirclePaint);  }  //绘制背景图片  canvas.drawBitmap(mCacheBitmap, 0, 0, mCirclePaint);  //保存画布当前的状态  int save = canvas.save();  for (int step = count; step <= mMaxRadius; step += mInterval) {   //step越大越靠外就越透明   mRipplePaint.setAlpha(255 * (mMaxRadius - step) / mMaxRadius);   canvas.drawCircle(px, py, (float) (rw + step), mRipplePaint);  }  //恢复Canvas的状态  canvas.restoreToCount(save);  //延迟80毫秒后开始运行  postDelayed(this, 80); } @Override public void run() {  //把run对象的引用从队列里拿出来，这样，他就不会执行了，但 run 没有销毁  removeCallbacks(this);  count += 2;  count %= mInterval;  invalidate();//重绘 }  @Override protected void onDetachedFromWindow() {  super.onDetachedFromWindow();  if (mCacheBitmap != null) {   mCacheBitmap.recycle();   mCacheBitmap = null;  } }}