Android 两种方式实现类似水波扩散效果

两种方式实现类似水波扩散效果，先上图为敬

1. 自定义view实现
2. 动画实现

自定义view实现

思路分析：通过canvas画圆，每次改变圆半径和透明度，当半径达到一定程度，再次从中心开始绘圆，达到不同层级的效果，通过不断绘制达到view扩散效果

private Paint centerPaint; //中心圆paint private int radius = 100; //中心圆半径 private Paint spreadPaint; //扩散圆paint private float centerX;//圆心x private float centerY;//圆心y private int distance = 5; //每次圆递增间距 private int maxRadius = 80; //最大圆半径 private int delayMilliseconds = 33;//扩散延迟间隔，越大扩散越慢 private List<Integer> spreadRadius = new ArrayList<>();//扩散圆层级数，元素为扩散的距离 private List<Integer> alphas = new ArrayList<>();//对应每层圆的透明度 

style文件里自定义属性

<declare-styleable name="SpreadView"> <!--中心圆颜色--> <attr name="spread_center_color" format="color" /> <!--中心圆半径--> <attr name="spread_radius" format="integer" /> <!--扩散圆颜色--> <attr name="spread_spread_color" format="color" /> <!--扩散间距--> <attr name="spread_distance" format="integer" /> <!--扩散最大半径--> <attr name="spread_max_radius" format="integer" /> <!--扩散延迟间隔--> <attr name="spread_delay_milliseconds" format="integer" /> </declare-styleable> 

初始化

 public SpreadView(Context context) { this(context, null, 0); } public SpreadView(Context context, @Nullable AttributeSet attrs) { this(context, attrs, 0); } public SpreadView(Context context, @Nullable AttributeSet attrs, int defStyleAttr) { super(context, attrs, defStyleAttr); TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.SpreadView, defStyleAttr, 0); radius = a.getInt(R.styleable.SpreadView_spread_radius, radius); maxRadius = a.getInt(R.styleable.SpreadView_spread_max_radius, maxRadius); int centerColor = a.getColor(R.styleable.SpreadView_spread_center_color, ContextCompat.getColor(context, R.color.colorAccent)); int spreadColor = a.getColor(R.styleable.SpreadView_spread_spread_color, ContextCompat.getColor(context, R.color.colorAccent)); distance = a.getInt(R.styleable.SpreadView_spread_distance, distance); a.recycle(); centerPaint = new Paint(); centerPaint.setColor(centerColor); centerPaint.setAntiAlias(true); //最开始不透明且扩散距离为0 alphas.add(255); spreadRadius.add(0); spreadPaint = new Paint(); spreadPaint.setAntiAlias(true); spreadPaint.setAlpha(255); spreadPaint.setColor(spreadColor); } 

确定圆心位置

@Override protected void onSizeChanged(int w, int h, int oldw, int oldh) { super.onSizeChanged(w, h, oldw, oldh); //圆心位置 centerX = w / 2; centerY = h / 2; } 

自定义view的绘制

 @Override protected void onDraw(Canvas canvas) { super.onDraw(canvas); for (int i = 0; i < spreadRadius.size(); i++) { int alpha = alphas.get(i); spreadPaint.setAlpha(alpha); int width = spreadRadius.get(i); //绘制扩散的圆 canvas.drawCircle(centerX, centerY, radius + width, spreadPaint); //每次扩散圆半径递增，圆透明度递减 if (alpha > 0 && width < 300) { alpha = alpha - distance > 0 ? alpha - distance : 1; alphas.set(i, alpha); spreadRadius.set(i, width + distance); } } //当最外层扩散圆半径达到最大半径时添加新扩散圆 if (spreadRadius.get(spreadRadius.size() - 1) > maxRadius) { spreadRadius.add(0); alphas.add(255); } //超过8个扩散圆，删除最先绘制的圆，即最外层的圆 if (spreadRadius.size() >= 8) { alphas.remove(0); spreadRadius.remove(0); } //中间的圆 canvas.drawCircle(centerX, centerY, radius, centerPaint); //TODO 可以在中间圆绘制文字或者图片 //延迟更新，达到扩散视觉差效果 postInvalidateDelayed(delayMilliseconds); } 

xml样式

<com.airsaid.diffuseview.widget.SpreadView android:id="@+id/spreadView" android:layout_width="match_parent" android:layout_height="wrap_content" app:spread_center_color="@color/colorAccent" app:spread_delay_milliseconds="35" app:spread_distance="5" app:spread_max_radius="90" app:spread_radius="100" app:spread_spread_color="@color/colorAccent" /> 

效果图

中心圆处可以自定义写文字，画图片等等...

动画实现

思路分析：通过动画实现，imageView不停做动画缩放+渐变
最中心的imageView保持不变
中间一层imageView从原始放大到1.4倍，同时从不透明变为半透明
最外层的imageView从1.4倍放大到1.8倍，同时从半透明变为全透明
利用shape画一个圆，作为动画基础视图

<?xml version="1.0" encoding="utf-8"?> <shape xmlns:android="http://schemas.android.com/apk/res/android"> <corners android:radius="65dp"/> <solid android:color="@color/colorAccent"/> </shape> 

布局视图

<FrameLayout android:layout_width="match_parent" android:layout_height="match_parent"> <!--中心imageView--> <ImageView android:id="@+id/iv_wave" android:layout_width="130dp" android:layout_height="130dp" android:layout_gravity="center" android:background="@drawable/shape_circle" /> <!--中间的imageView--> <ImageView android:id="@+id/iv_wave_1" android:layout_width="130dp" android:layout_height="130dp" android:layout_gravity="center" android:background="@drawable/shape_circle" /> <!--最外层imageView--> <ImageView android:id="@+id/iv_wave_2" android:layout_width="130dp" android:layout_height="130dp" android:layout_gravity="center" android:background="@drawable/shape_circle" /> </FrameLayout> 

中间imageView的动画

private void setAnim1() { AnimationSet as = new AnimationSet(true); //缩放动画，以中心从原始放大到1.4倍 ScaleAnimation scaleAnimation = new ScaleAnimation(1.0f, 1.4f, 1.0f, 1.4f, ScaleAnimation.RELATIVE_TO_SELF, 0.5f, ScaleAnimation.RELATIVE_TO_SELF, 0.5f); //渐变动画 AlphaAnimation alphaAnimation = new AlphaAnimation(1.0f, 0.5f); scaleAnimation.setDuration(800); scaleAnimation.setRepeatCount(Animation.INFINITE); alphaAnimation.setRepeatCount(Animation.INFINITE); as.setDuration(800); as.addAnimation(scaleAnimation); as.addAnimation(alphaAnimation); iv1.startAnimation(as); } 

最外层imageView的动画

private void setAnim2() { AnimationSet as = new AnimationSet(true); //缩放动画，以中心从1.4倍放大到1.8倍 ScaleAnimation scaleAnimation = new ScaleAnimation(1.4f, 1.8f, 1.4f, 1.8f, ScaleAnimation.RELATIVE_TO_SELF, 0.5f, ScaleAnimation.RELATIVE_TO_SELF, 0.5f); //渐变动画 AlphaAnimation alphaAnimation = new AlphaAnimation(0.5f, 0.1f); scaleAnimation.setDuration(800); scaleAnimation.setRepeatCount(Animation.INFINITE); alphaAnimation.setRepeatCount(Animation.INFINITE); as.setDuration(800); as.addAnimation(scaleAnimation); as.addAnimation(alphaAnimation); iv2.startAnimation(as); } 

效果图

相比较而言，自定义view的效果更好点，动画实现起来更方便点。

两种方式实现的扩散效果介绍完毕，具体项目里还是要按需变动的。

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