练习案例
视差动画 - 雅虎新闻摘要加载
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 < mColorArray.length; i++) { //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)); canvas.drawCircle(cx,cy,SMALL_CIRCLE_RADIUS,mCirclePaint); } } }
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 < mColorArray.length; i++) { canvas.rotate((float) spaceAngle,getWidth()/2,getHeight()/2); //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(); } }
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 < mColorArray.length; i++) { // canvas.rotate((float) spaceAngle,getWidth()/2,getHeight()/2); // System.out.println("spaceAngle -> " + 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
说set、pre、post的区别之前，先说说Matrix。
Matrix包含一个3 X 3的矩阵，专门用于图像变换匹配。
Matrix提供了四种操作：
- translate(平移)
- rotate(旋转)
- scale(缩放)
- skew(倾斜)
也就是说这4种操作都是对这个3 X 3的矩阵设值来达到变换的效果。
Matrix没有结构体，它必须被初始化，通过reset或set方法。
OK，Matrix介绍完了，我们来看看set、pre、post的区别。
pre是在队列最前面插入，post是在队列最后面追加，而set先清空队列在添加（这也是上文提到的“Matrix没有结构体，它必须被初始化，通过reset或set方法”的原因）。
下面通过一些例子具体说明：
- matrix.preScale(2f,1f);
- matrix.preTranslate(5f, 0f);
- matrix.postScale(0.2f, 1f);
- matrix.postTranslate(0.5f, 0f);
执行顺序：translate(5, 0) -> scale(2f, 1f) -> scale(0.2f, 1f) -> translate(0.5f, 0f)
- matrix.postTranslate(2f, 0f);
- matrix.preScale(0.2f, 1f);
- matrix.setScale(1f, 1f);
- matrix.postScale(5f, 1f);
- matrix.preTranslate(0.5f, 0f);
执行顺序：translate(0.5f, 0f) -> scale(1f, 1f) -> scale(5f, 1)
到此这篇关于Android实现旋转动画的两种方式的文章就介绍到这了,更多相关android旋转动画内容请搜索脚本之家以前的文章或继续浏览下面的相关文章希望大家以后多多支持脚本之家！