首先来看一个UI动效图。
效果图是是Dribbble上看到的，原作品在此。
我所实现的效果如下： Watch on YouTube
为了使用起来简单，我将动画封装成CircularAnimUtil.
现在，让按钮收缩只需一行代码，如下：
CircularAnimUtil.hide(mChangeBtn);
同理，让按钮伸展开：
CircularAnimUtil.show(mChangeBtn);
水波般铺满指定颜色并启动一个Activity:
CircularAnimUtil.startActivity(MainActivity.this, EmptyActivity.class, view, R.color.colorPrimary);
这里，你还可以放图片：
CircularAnimUtil.startActivity(MainActivity.this, EmptyActivity.class, view, R.mipmap.img_huoer_black);
也许在显示或隐藏视图时，你想要设置半径和时长，你可以调用这个方法：
显示：show(View myView, float startRadius, long durationMills)
隐藏：hide(final View myView, float endRadius, long durationMills)
以及，你可以在startActivity时带上Intent:
startActivity(Activity thisActivity, Intent intent, View triggerView, int colorOrImageRes)
还可以startActivityForResult:
startActivityForResult(Activity thisActivity, Intent intent, Integer requestCode, View triggerView, int colorOrImageRes)
同理，startActivity同样可以设置时长。
用起来非常的方便，一切逻辑性的东西都由帮助类搞定。
下面贡献源码。你可以直接新建一个CircularAnimUtil的类，然后把下面的代码复制进去就OK了。
另外，GitHub Demo 地址在此，欢迎Star,欢迎喜欢，欢迎关注，哈哈哈 ^ ^ ~
import android.animation.Animator;
import android.animation.AnimatorListenerAdapter;
import android.annotation.SuppressLint;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.view.ViewAnimationUtils;
import android.view.ViewGroup;
import android.widget.ImageView;
/**
* 对 ViewAnimationUtils.createCircularReveal() 方法的封装.
* <p/>
* Created on 16/7/20.
* GitHub: https://github.com/XunMengWinter
*
* @author ice
*/
public class CircularAnimUtil {
public static final long PERFECT_MILLS = 618;
public static final int MINI_RADIUS = 0;
/**
* 向四周伸张，直到完成显示。
*/
@SuppressLint("NewApi")
public static void show(View myView, float startRadius, long durationMills) {
if (android.os.Build.VERSION.SDK_INT < android.os.Build.VERSION_CODES.LOLLIPOP) {
myView.setVisibility(View.VISIBLE);
return;
}
int cx = (myView.getLeft() + myView.getRight()) / 2;
int cy = (myView.getTop() + myView.getBottom()) / 2;
int w = myView.getWidth();
int h = myView.getHeight();
// 勾股定理 & 进一法
int finalRadius = (int) Math.sqrt(w * w + h * h) + 1;
Animator anim =
ViewAnimationUtils.createCircularReveal(myView, cx, cy, startRadius, finalRadius);
myView.setVisibility(View.VISIBLE);
anim.setDuration(durationMills);
anim.start();
}
/**
* 由满向中间收缩，直到隐藏。
*/
@SuppressLint("NewApi")
public static void hide(final View myView, float endRadius, long durationMills) {
if (android.os.Build.VERSION.SDK_INT < android.os.Build.VERSION_CODES.LOLLIPOP) {
myView.setVisibility(View.INVISIBLE);
return;
}
int cx = (myView.getLeft() + myView.getRight()) / 2;
int cy = (myView.getTop() + myView.getBottom()) / 2;
int w = myView.getWidth();
int h = myView.getHeight();
// 勾股定理 & 进一法
int initialRadius = (int) Math.sqrt(w * w + h * h) + 1;
Animator anim =
ViewAnimationUtils.createCircularReveal(myView, cx, cy, initialRadius, endRadius);
anim.setDuration(durationMills);
anim.addListener(new AnimatorListenerAdapter() {
@Override
public void onAnimationEnd(Animator animation) {
super.onAnimationEnd(animation);
myView.setVisibility(View.INVISIBLE);
}
});
anim.start();
}
/**
* 从指定View开始向四周伸张(伸张颜色或图片为colorOrImageRes), 然后进入另一个Activity,
* 返回至 @thisActivity 后显示收缩动画。
*/
@SuppressLint("NewApi")
public static void startActivityForResult(
final Activity thisActivity, final Intent intent, final Integer requestCode, final Bundle bundle,
final View triggerView, int colorOrImageRes, long durationMills) {
if (android.os.Build.VERSION.SDK_INT < android.os.Build.VERSION_CODES.LOLLIPOP) {
thisActivity.startActivity(intent);
return;
}
int[] location = new int[2];
triggerView.getLocationInWindow(location);
final int cx = location[0] + triggerView.getWidth() / 2;
final int cy = location[1] + triggerView.getHeight() / 2;
final ImageView view = new ImageView(thisActivity);
view.setScaleType(ImageView.ScaleType.CENTER_CROP);
view.setImageResource(colorOrImageRes);
final ViewGroup decorView = (ViewGroup) thisActivity.getWindow().getDecorView();
int w = decorView.getWidth();
int h = decorView.getHeight();
decorView.addView(view, w, h);
// 计算中心点至view边界的最大距离
int maxW = Math.max(cx, w - cx);
int maxH = Math.max(cy, h - cy);
final int finalRadius = (int) Math.sqrt(maxW * maxW + maxH * maxH) + 1;
Animator
anim = ViewAnimationUtils.createCircularReveal(view, cx, cy, 0, finalRadius);
int maxRadius = (int) Math.sqrt(w * w + h * h) + 1;
// 若使用默认时长，则需要根据水波扩散的距离来计算实际时间
if (durationMills == PERFECT_MILLS) {
// 算出实际边距与最大边距的比率
double rate = 1d * finalRadius / maxRadius;
// 水波扩散的距离与扩散时间成正比
durationMills = (long) (PERFECT_MILLS * rate);
}
final long finalDuration = durationMills;
anim.setDuration(finalDuration);
anim.addListener(new AnimatorListenerAdapter() {
@Override
public void onAnimationEnd(Animator animation) {
super.onAnimationEnd(animation);
if (requestCode == null)
thisActivity.startActivity(intent);
else if (bundle == null)
thisActivity.startActivityForResult(intent, requestCode);
else
thisActivity.startActivityForResult(intent, requestCode, bundle);
// 默认渐隐过渡动画.
thisActivity.overridePendingTransition(android.R.anim.fade_in, android.R.anim.fade_out);
// 默认显示返回至当前Activity的动画.
triggerView.postDelayed(new Runnable() {
@Override
public void run() {
Animator anim =
ViewAnimationUtils.createCircularReveal(view, cx, cy, finalRadius, 0);
anim.setDuration(finalDuration);
anim.addListener(new AnimatorListenerAdapter() {
@Override
public void onAnimationEnd(Animator animation) {
super.onAnimationEnd(animation);
try {
decorView.removeView(view);
} catch (Exception e) {
e.printStackTrace();
}
}
});
anim.start();
}
}, 1000);
}
});
anim.start();
}
/*下面的方法全是重载，用简化上面方法的构建*/
public static void startActivityForResult(
Activity thisActivity, Intent intent, Integer requestCode, View triggerView, int colorOrImageRes) {
startActivityForResult(thisActivity, intent, requestCode, null, triggerView, colorOrImageRes, PERFECT_MILLS);
}
public static void startActivity(
Activity thisActivity, Intent intent, View triggerView, int colorOrImageRes, long durationMills) {
startActivityForResult(thisActivity, intent, null, null, triggerView, colorOrImageRes, durationMills);
}
public static void startActivity(
Activity thisActivity, Intent intent, View triggerView, int colorOrImageRes) {
startActivity(thisActivity, intent, triggerView, colorOrImageRes, PERFECT_MILLS);
}
public static void startActivity(Activity thisActivity, Class<?> targetClass, View triggerView, int colorOrImageRes) {
startActivity(thisActivity, new Intent(thisActivity, targetClass), triggerView, colorOrImageRes, PERFECT_MILLS);
}
public static void show(View myView) {
show(myView, MINI_RADIUS, PERFECT_MILLS);
}
public static void hide(View myView) {
hide(myView, MINI_RADIUS, PERFECT_MILLS);
}
}
需要注意的是，该帮助类适配了api 19以下的版本，因此你不需要判断版本号，但在这些低版本设备上是没有水波动画效果的，不过好的是并不会影响交互逻辑。
另外，有木有手机版或者Mac版好用的Gif转换器推荐，表示好难找。 (感谢im_brucezz、AkiossDev推荐的GIF录制器：licecap，非常好用，上面的gif已经用这个录制了～)
And有没有傻瓜式发布项目到JCenter的教程推荐？看过几篇都不管用。囧 ~