最近需要做个类似于水波纹动画的效果，思考了一下不需要UI切个动态图，Android原生的技术利用动画或者自定义控件都可以实现，下面上个图类似于这样的效果
下面请看第一种动画实现，这种方式较为简单些，就是利用3个ImageView不断地做缩放和渐变的动画。
布局文件定义一下
android:id="@+id/rl"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:gravity="center"
android:layout_marginBottom="160dp">
android:id="@+id/iv_wave"
android:layout_width="150dp"
android:layout_height="150dp"
android:layout_centerHorizontal="true"
android:background="@drawable/shape_circle" />
android:id="@+id/iv_wave_1"
android:layout_width="150dp"
android:layout_height="150dp"
android:layout_centerHorizontal="true"
android:background="@drawable/shape_circle" />
android:id="@+id/iv_wave_2"
android:layout_width="150dp"
android:layout_height="150dp"
android:layout_centerHorizontal="true"
android:background="@drawable/shape_circle" />
接下来中间的ImageView保持不变，通过操作另外两个ImageView达到效果
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);
}
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);
}
接下来就是第二种自定义动画实现
首先定义style文件自定义属性--在values下创建attrs.xml文件
接下来创建SpreadView继承view,初始化构造方法
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);
}
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);
//延迟更新，达到扩散视觉差效果
postInvalidateDelayed(delayMilliseconds);
}
最后在activity的布局文件中引用自定义属性：
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="150"
app:spread_spread_color="@color/colorAccent" />
以上两种方法就实现了水波纹的效果，下载完整的demo请点击链接，希望对大家有所帮助。
以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持脚本之家。
