Android 两种方式实现类似水波扩散效果

笛里谁知壮士心，沙头空照征人骨。这篇文章主要讲述Android 两种方式实现类似水波扩散效果相关的知识，希望能为你提供帮助。

原文链接 https://mp.weixin.qq.com/s/M19tp_ShOO6esKdozi7Nlg

两种方式实现类似水波扩散效果，先上图为敬

自定义view实现
动画实现

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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

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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>

【Android 两种方式实现类似水波扩散效果】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