先看效果：
代码是老外写滴，本文将它实现的过程做了解析，并将代码中大部分的注释翻译为中文，同时贴出资源和代码。需要的同学自己动手啦。
代码就是一个类：ActivitySplitAnimationUtil
有一个继承了imageview 的内部类MyImageView：功能是把图片的一部分内容画出来，有截图的感觉。
有一个重要的步骤就是将activity的内容放到一个bitmap中去，代码是这样的：
// Get the content of the activity and put in a bitmap
//获取一个activity的内容并把它放到一个bitmap中
View root = currActivity.getWindow().getDecorView().findViewById(android.R.id.content);
root.setDrawingCacheEnabled(true);
mBitmap = root.getDrawingCache();分割完之后就用属性动画开始分割动画的过程(属性动画的教程可以去找一下大神的文章或者看官方文档学习学习，基本的使用也是非常简单的)。
所以总结一下他的实现步骤：
1.将activity的内容解析到bitmap
2.用自定义的MyImageiew分别绘制出bitmap内容的一部分，完成内容分割
3.使用属性动画绘制出分割部分bitmap的动画过程，完成动画效果
其实也不难，但是可以从中学习的基础知识点也是不少……
ActivitySplitAnimationUtil类代码如下，注释我已经作了翻译：
package com.duguang.baseanimation.utils;
import android.animation.Animator;
import android.animation.AnimatorSet;
import android.animation.ObjectAnimator;
import android.animation.TimeInterpolator;
import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.PixelFormat;
import android.graphics.Rect;
import android.graphics.drawable.BitmapDrawable;
import android.graphics.drawable.Drawable;
import android.os.Handler;
import android.view.Gravity;
import android.view.View;
import android.view.WindowManager;
import android.view.animation.DecelerateInterpolator;
import android.widget.ImageView;
/**
* Utility class to create a split activity animation
* 实现步骤：将activity的内容解析到bitmap 用自定义的MyImageiew分别绘制出bitmap内容的一部分，然后使用属性动画绘制出分割部分bitmap的动画过程
* @author Udi Cohen (@udinic)
*/
public class ActivitySplitAnimationUtil {
public static Bitmap mBitmap = null;
private static int[] mLoc1;
private static int[] mLoc2;
private static ImageView mTopImage;
private static ImageView mBottomImage;
private static AnimatorSet mSetAnim;
/**
* Start a new Activity with a Split animation
* 动画开启一个新的页面
* @param currActivity The current Activity 当前页面
* @param intent The Intent needed tot start the new Activity 开启页面的intent
* @param splitYCoord The Y coordinate where we want to split the Activity on the animation. -1 will split the Activity equally
* 动画分割的y坐标点，-1则从中间开始分割
*/
public static void startActivity(Activity currActivity, Intent intent, int splitYCoord) {
// Preparing the bitmaps that we need to show
prepare(currActivity, splitYCoord);
currActivity.startActivity(intent);
currActivity.overridePendingTransition(0, 0);
}
/**
* Start a new Activity with a Split animation right in the middle of the Activity
* 启动一个新页面，从中间开启分割动画
* @param currActivity The current Activity 当前页面
* @param intent The Intent needed tot start the new Activity 开启页面的intent
*/
public static void startActivity(Activity currActivity, Intent intent) {
startActivity(currActivity, intent, -1);
}
/**
* Preparing the graphics on the destination Activity.
* Should be called on the destination activity on Activity#onCreate() BEFORE setContentView()
* 准备页面动画的数据计算工作，要在页面的onCreate方法中的setContentView()之前调用
*
* @param destActivity the destination Activity 开启页面的activity
*/
public static void prepareAnimation(final Activity destActivity) {
mTopImage = createImageView(destActivity, mBitmap, mLoc1);
mBottomImage = createImageView(destActivity, mBitmap, mLoc2);
}
/**
* Start the animation the reveals the destination Activity
* Should be called on the destination activity on Activity#onCreate() AFTER setContentView()
* 开启动画显示目标页面，在页面的onCreate方法中的setContentView()之后调用
*
* @param destActivity the destination Activity 开启页面的activity
* @param duration The duration of the animation 动画时间长度
* @param interpolator The interpulator to use for the animation. null for no interpulation.
* 动画的补间器
*/
public static void animate(final Activity destActivity, final int duration, final TimeInterpolator interpolator) {
// Post this on the UI thread's message queue. It's needed for the items to be already measured
new Handler().post(new Runnable() {
@Override
public void run() {
mSetAnim = new AnimatorSet();
mTopImage.setLayerType(View.LAYER_TYPE_HARDWARE, null);
mBottomImage.setLayerType(View.LAYER_TYPE_HARDWARE, null);
mSetAnim.addListener(new Animator.AnimatorListener() {
@Override
public void onAnimationStart(Animator animation) {
}
@Override
public void onAnimationEnd(Animator animation) {
clean(destActivity);
}
@Override
public void onAnimationCancel(Animator animation) {
clean(destActivity);
}
@Override
public void onAnimationRepeat(Animator animation) {
}
});
// Animating the 2 parts away from each other
Animator anim1 = ObjectAnimator.ofFloat(mTopImage, "translationY", mTopImage.getHeight() * -1);
Animator anim2 = ObjectAnimator.ofFloat(mBottomImage, "translationY", mBottomImage.getHeight());
if (interpolator != null) {
anim1.setInterpolator(interpolator);
anim2.setInterpolator(interpolator);
}
mSetAnim.setDuration(duration);
mSetAnim.playTogether(anim1, anim2);
mSetAnim.start();
}
});
}
/**
* Start the animation that reveals the destination Activity
* Should be called on the destination activity on Activity#onCreate() AFTER setContentView()
* 开启动画显示目标页面，在页面的onCreate方法中的setContentView()之后调用
*
* @param destActivity the destination Activity 开启页面的activity
* @param duration The duration of the animation 动画时间长度
*/
public static void animate(final Activity destActivity, final int duration) {
animate(destActivity, duration, new DecelerateInterpolator());
}
/**
* Cancel an in progress animation
* 取消一个动画
*/
public static void cancel() {
if (mSetAnim != null)
mSetAnim.cancel();
}
/**
* Clean stuff
*
* @param activity The Activity where the animation is occurring
*/
private static void clean(Activity activity) {
if (mTopImage != null) {
mTopImage.setLayerType(View.LAYER_TYPE_NONE, null);
try {
// If we use the regular removeView() we'll get a small UI glitch
activity.getWindowManager().removeViewImmediate(mBottomImage);
} catch (Exception ignored) {
}
}
if (mBottomImage != null) {
mBottomImage.setLayerType(View.LAYER_TYPE_NONE, null);
try {
activity.getWindowManager().removeViewImmediate(mTopImage);
} catch (Exception ignored) {
}
}
mBitmap = null;
}
/**
* Preparing the graphics for the animation
* 动画开启前的绘制数据计算
* @param currActivity the current Activity from where we start the new one 开启新页面的activity
* @param splitYCoord The Y coordinate where we want to split the activity. -1 will split the activity equally y坐标分割点位置，-1则从中间均分
*/
private static void prepare(Activity currActivity, int splitYCoord) {
// Get the content of the activity and put in a bitmap
//获取一个activity的内容并把它放到一个bitmap中
View root = currActivity.getWindow().getDecorView().findViewById(android.R.id.content);
root.setDrawingCacheEnabled(true);
mBitmap = root.getDrawingCache();
// If the split Y coordinate is -1 - We'll split the activity equally
//如果y坐标为-1，从中间均分
splitYCoord = (splitYCoord != -1 ? splitYCoord : mBitmap.getHeight() / 2);
if (splitYCoord > mBitmap.getHeight())
throw new IllegalArgumentException("Split Y coordinate [" + splitYCoord + "] exceeds the activity's height [" + mBitmap.getHeight() + "]");
// Set the location to put the 2 bitmaps on the destination activity
//为bitmap设置在页面上显示的位置坐标
mLoc1 = new int[]{0, splitYCoord, root.getTop()};
mLoc2 = new int[]{splitYCoord, mBitmap.getHeight(), root.getTop()};
}
/**
* Creating the an image, containing one part of the animation on the destination activity
* 创造一个包含部分页面内容的image
* @param destActivity The destination activity 目标页面
* @param bmp The Bitmap of the part we want to add to the destination activity 要被加到目标页面的bitmap
* @param loc The location this part should be on the screen bitmap要被显示到页面上的位置
* @return
*/
private static ImageView createImageView(Activity destActivity, Bitmap bmp, int loc[]) {
MyImageView imageView = new MyImageView(destActivity);
imageView.setImageBitmap(bmp);
imageView.setImageOffsets(bmp.getWidth(), loc[0], loc[1]);
WindowManager.LayoutParams windowParams = new WindowManager.LayoutParams();
windowParams.gravity = Gravity.TOP;
windowParams.x = 0;
windowParams.y = loc[2] + loc[0];
windowParams.height = loc[1] - loc[0];
windowParams.width = bmp.getWidth();
windowParams.flags = WindowManager.LayoutParams.FLAG_LAYOUT_IN_SCREEN;
windowParams.format = PixelFormat.TRANSLUCENT;
windowParams.windowAnimations = 0;
destActivity.getWindowManager().addView(imageView, windowParams);
return imageView;
}
/**
* MyImageView
* Extended ImageView that draws just part of an image, base on start/end position
* 自定义imageview，可根据设定的开始和结束坐标位置画出图片的一部分
*/
private static class MyImageView extends ImageView
{
private Rect mSrcRect;
private Rect mDstRect;
private Paint mPaint;
public MyImageView(Context context)
{
super(context);
mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
}
/**
* Setting the bitmap offests to control the visible area
* 设置宽度和坐标点来控制要切割的可见区域
*
* @param width The bitmap image
* @param bmp The start Y position
* @param loc The end Y position
* @return
*/
public void setImageOffsets(int width, int startY, int endY)
{
mSrcRect = new Rect(0, startY, width, endY);
mDstRect = new Rect(0, 0, width, endY - startY);
}
@Override
protected void onDraw(Canvas canvas)
{
Bitmap bm = null;
Drawable drawable = getDrawable();
if (null != drawable && drawable instanceof BitmapDrawable)
{
bm = ((BitmapDrawable)drawable).getBitmap();
}
if (null == bm)
{
super.onDraw(canvas);
}
else
{
canvas.drawBitmap(bm, mSrcRect, mDstRect, mPaint);
}
}
}
}
ActivitySplitAnimationUtil类的使用也是很简单的了，在页面onCreate方法中描下面的几行代码，就可以实现效果了。
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// Preparing the 2 images to be split
ActivitySplitAnimationUtil.prepareAnimation(this);
setContentView(R.layout.activity_splash_split_two);
findViewById(R.id.two).setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
ActivitySplitAnimationUtil.startActivity(Activity2.this, new Intent(Activity2.this, Activity3.class));
}
});
// Animating the items to be open, revealing the new activity
ActivitySplitAnimationUtil.animate(this, 1000);
}ActivitySplitAnimationUtil类的下载地址：点击进入下载页
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