Android实现旋转动画的两种方式案例详解

这篇文章主要介绍了Android实现旋转动画的两种方式,需要的朋友可以参考下

练习案例

效果展示

前期准备

第一步：准备好颜色数组 res => values => colors.xml

 #FF9600#02D1AC#FFD200#00C6FF#00E099#FF3891 @color/orange@color/aqua@color/yellow@color/bule@color/green@color/pink

自定义 View java代码编写

方法一

关键思想：属性动画 + 计算圆心

 package com.wust.mydialog; import android.animation.ObjectAnimator; import android.animation.ValueAnimator; import android.content.Context; import android.graphics.Canvas; import android.graphics.Paint; import android.util.AttributeSet; import android.view.View; import android.view.animation.LinearInterpolator; import androidx.annotation.Nullable; /** * ClassName: com.wust.mydialog.MyRotateView 
 * Description: 
 * date: 2021/8/7 12:13
 * * @author yiqi
 * @QQ 1820762465 * @微信 yiqiideallife * @技术交流QQ群 928023749 */ public class MyRotateView extends View { //设置旋转间隔时间 private int SPLASH_CIRCLE_ROTATE_TIME = 3000; //设置中心圆半径 private float CENTER_CIRCLE_RADIUS; private float SMALL_CIRCLE_RADIUS; private float mCurrentSingle = 0f; private int[] mColorArray; private Paint mCirclePaint; private ValueAnimator va; public MyRotateView(Context context) { super(context); } public MyRotateView(Context context, @Nullable AttributeSet attrs) { super(context, attrs); } public MyRotateView(Context context, @Nullable AttributeSet attrs, int defStyleAttr) { super(context, attrs, defStyleAttr); } @Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { int width = MeasureSpec.getSize(widthMeasureSpec); int height = MeasureSpec.getSize(heightMeasureSpec); //初始化参数 initParams(width,height); setMeasuredDimension(width,height); } private void initParams(int w, int h) { //设置中心圆半径 CENTER_CIRCLE_RADIUS = 1/4.0f * w; //设置小圆的半径 SMALL_CIRCLE_RADIUS = 1/25.0f * w; //获取小球颜色 mColorArray = getResources().getIntArray(R.array.splash_circle_colors); //初始化画笔 mCirclePaint = new Paint(); mCirclePaint.setDither(true); mCirclePaint.setAntiAlias(true); } @Override protected void onDraw(Canvas canvas) { super.onDraw(canvas); //绘制圆 drawSplashCircle(canvas); } private void drawSplashCircle(Canvas canvas) { //设置属性动画，让小圆转起来 //这里得注意，是个坑，你如果不判断那球就不会动 因为会陷入死循环 值动画将值设置为0 -> invalidate()重绘 -> 执行draw 又将值设为0 if (va == null){ va = ObjectAnimator.ofFloat(0f, 2 * (float) Math.PI); va.setDuration(SPLASH_CIRCLE_ROTATE_TIME); va.setRepeatCount(ValueAnimator.INFINITE); va.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() { @Override public void onAnimationUpdate(ValueAnimator animation) { mCurrentSingle = (float) animation.getAnimatedValue(); //                    System.out.println("mCurrentSingle ->" + mCurrentSingle); invalidate(); } }); va.setInterpolator(new LinearInterpolator()); va.start(); } //计算每个小球的间隔 double spaceAngle = Math.PI*2/mColorArray.length; for (int i = 0; i

方法二

关键思想：旋转画布法

 package com.wust.mydialog; import android.animation.ObjectAnimator; import android.animation.ValueAnimator; import android.content.Context; import android.graphics.Canvas; import android.graphics.Paint; import android.util.AttributeSet; import android.view.View; import android.view.animation.LinearInterpolator; import androidx.annotation.Nullable; /** * ClassName: com.wust.mydialog.MyRotateView 
 * Description: 
 * date: 2021/8/7 12:13
 * * @author yiqi
 * @QQ 1820762465 * @微信 yiqiideallife * @技术交流QQ群 928023749 */ public class MyRotateView extends View { //设置旋转间隔时间 private int SPLASH_CIRCLE_ROTATE_TIME = 3000; //设置中心圆半径 private float CENTER_CIRCLE_RADIUS; private float SMALL_CIRCLE_RADIUS; private float mCurrentSingle = 0f; private int[] mColorArray; private Paint mCirclePaint; private ValueAnimator va; public MyRotateView(Context context) { super(context); } public MyRotateView(Context context, @Nullable AttributeSet attrs) { super(context, attrs); } public MyRotateView(Context context, @Nullable AttributeSet attrs, int defStyleAttr) { super(context, attrs, defStyleAttr); } @Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { int width = MeasureSpec.getSize(widthMeasureSpec); int height = MeasureSpec.getSize(heightMeasureSpec); //初始化参数 initParams(width,height); setMeasuredDimension(width,height); } private void initParams(int w, int h) { //设置中心圆半径 CENTER_CIRCLE_RADIUS = 1/4.0f * w; //设置小圆的半径 SMALL_CIRCLE_RADIUS = 1/25.0f * w; //获取小球颜色 mColorArray = getResources().getIntArray(R.array.splash_circle_colors); //初始化画笔 mCirclePaint = new Paint(); mCirclePaint.setDither(true); mCirclePaint.setAntiAlias(true); } @Override protected void onDraw(Canvas canvas) { super.onDraw(canvas); //绘制圆 drawSplashCircle(canvas); } private void drawSplashCircle(Canvas canvas) { //设置属性动画，让小圆转起来 //这里得注意，是个坑，你如果不判断那球就不会动 因为会陷入死循环 值动画将值设置为0 -> invalidate()重绘 -> 执行draw 又将值设为0 if (va == null){ //            va = ObjectAnimator.ofFloat(0f, 2 * (float) Math.PI); va = ObjectAnimator.ofFloat(0f, 360.0f); va.setDuration(SPLASH_CIRCLE_ROTATE_TIME); va.setRepeatCount(ValueAnimator.INFINITE); va.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() { @Override public void onAnimationUpdate(ValueAnimator animation) { mCurrentSingle = (float) animation.getAnimatedValue(); //                    System.out.println("mCurrentSingle ->" + mCurrentSingle); invalidate(); } }); va.setInterpolator(new LinearInterpolator()); va.start(); } //计算每个小球的间隔 //        double spaceAngle = Math.PI*2/mColorArray.length; double spaceAngle = 360.0d/mColorArray.length; System.out.println("spaceAngle -> " + spaceAngle); //利用旋转画布法 canvas.save(); canvas.rotate(mCurrentSingle,getWidth()/2,getHeight()/2); for (int i = 0; i

易错点总结：

1、canvas.rotate(mCurrentSingle,getWidth()/2,getHeight()/2);中第一个参数传的是角度（360度的那种），而 Math.cos();中参数传的是一个弧度（2π的那种）

2、canvas.rotate() 函数执行之后对后续画布上的操作都是有影响的，所以，得配合 canvas.save();和 canvas.restore();使用。因此，里面的canvas.rotate((float) spaceAngle,getWidth()/2,getHeight()/2);中spaceAngle不能乘 i 。

3、画布的旋转除了 canvas.rotate() 函数可以实现外，还可以利用矩阵。代码如下：

 //创建矩阵 private Matrix mSpaceMatrix; //初始化旋转矩阵 mSpaceMatrix = new Matrix(); //初始化旋转矩阵 mSpaceMatrix.reset(); mSpaceMatrix.postRotate((float) spaceAngle,getWidth()/2,getHeight()/2); //画布旋转角度 canvas.concat(mSpaceMatrix);

完整代码

 package com.wust.mydialog; import android.animation.ObjectAnimator; import android.animation.ValueAnimator; import android.content.Context; import android.graphics.Canvas; import android.graphics.Matrix; import android.graphics.Paint; import android.util.AttributeSet; import android.view.View; import android.view.animation.LinearInterpolator; import androidx.annotation.Nullable; /** * ClassName: com.wust.mydialog.MyRotateView 
 * Description: 
 * date: 2021/8/7 12:13
 * * @author yiqi
 * @QQ 1820762465 * @微信 yiqiideallife * @技术交流QQ群 928023749 */ public class MyRotateView extends View { //设置旋转间隔时间 private int SPLASH_CIRCLE_ROTATE_TIME = 3000; //设置中心圆半径 private float CENTER_CIRCLE_RADIUS; private float SMALL_CIRCLE_RADIUS; private float mCurrentSingle = 0f; private int[] mColorArray; private Paint mCirclePaint; private ValueAnimator va; private Matrix mSpaceMatrix; public MyRotateView(Context context) { super(context); } public MyRotateView(Context context, @Nullable AttributeSet attrs) { super(context, attrs); } public MyRotateView(Context context, @Nullable AttributeSet attrs, int defStyleAttr) { super(context, attrs, defStyleAttr); } @Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { int width = MeasureSpec.getSize(widthMeasureSpec); int height = MeasureSpec.getSize(heightMeasureSpec); //初始化参数 initParams(width,height); setMeasuredDimension(width,height); } private void initParams(int w, int h) { //设置中心圆半径 CENTER_CIRCLE_RADIUS = 1/4.0f * w; //设置小圆的半径 SMALL_CIRCLE_RADIUS = 1/25.0f * w; //获取小球颜色 mColorArray = getResources().getIntArray(R.array.splash_circle_colors); //初始化画笔 mCirclePaint = new Paint(); mCirclePaint.setDither(true); mCirclePaint.setAntiAlias(true); //初始化旋转矩阵 mSpaceMatrix = new Matrix(); } @Override protected void onDraw(Canvas canvas) { super.onDraw(canvas); //绘制圆 drawSplashCircle(canvas); } private void drawSplashCircle(Canvas canvas) { //设置属性动画，让小圆转起来 //这里得注意，是个坑，你如果不判断那球就不会动 因为会陷入死循环 值动画将值设置为0 -> invalidate()重绘 -> 执行draw 又将值设为0 if (va == null){ //            va = ObjectAnimator.ofFloat(0f, 2 * (float) Math.PI); va = ObjectAnimator.ofFloat(0f, 360.0f); va.setDuration(SPLASH_CIRCLE_ROTATE_TIME); va.setRepeatCount(ValueAnimator.INFINITE); va.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() { @Override public void onAnimationUpdate(ValueAnimator animation) { mCurrentSingle = (float) animation.getAnimatedValue(); //                    System.out.println("mCurrentSingle ->" + mCurrentSingle); invalidate(); } }); va.setInterpolator(new LinearInterpolator()); va.start(); } //计算每个小球的间隔 //        double spaceAngle = Math.PI*2/mColorArray.length; double spaceAngle = 360.0d/mColorArray.length; //初始化旋转矩阵 mSpaceMatrix.reset(); mSpaceMatrix.postRotate((float) spaceAngle,getWidth()/2,getHeight()/2); //利用旋转画布法 canvas.save(); canvas.rotate(mCurrentSingle,getWidth()/2,getHeight()/2); for (int i = 0; i  " + spaceAngle); canvas.concat(mSpaceMatrix); //为 每个球 画笔 设置颜色 mCirclePaint.setColor(mColorArray[i]); //利用 勾股定理 计算 小圆 中心点 //float cx = getWidth()/2 + (float) (CENTER_CIRCLE_RADIUS*Math.cos(spaceAngle*i+mCurrentSingle)); //float cy = getHeight()/2 + (float) (CENTER_CIRCLE_RADIUS*Math.sin(spaceAngle*i+mCurrentSingle)); //利用旋转画布法 float cx = getWidth()/2 + CENTER_CIRCLE_RADIUS; float cy = getHeight()/2; canvas.drawCircle(cx,cy,SMALL_CIRCLE_RADIUS,mCirclePaint); } canvas.restore(); } }

注意事项：

1、canvas.concat(mSpaceMatrix);对画布的操作也会对后面进行影响

2、Android中Matrix的set、pre、post的区别