ViewPager添加动画效果（一行代码）

首先建立一个普通的ViewPager

普通的ViewPager



加有动画效果的Viewpager



1.布局文件

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"
android:layout_height="match_parent" tools:context=".MainActivity">
<android.support.v4.view.ViewPager
android:id="@+id/viewpager"
android:layout_width="match_parent"
android:layout_height="match_parent"></android.support.v4.view.ViewPager>

</RelativeLayout>

2.MainActivity

package com.example.administrator.viewpageraddanimation;

import android.support.v4.view.PagerAdapter;
import android.support.v4.view.ViewPager;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;

import java.util.ArrayList;
import java.util.List;

public class MainActivity extends AppCompatActivity {
private ViewPager mViewPager;
private int[] mImagIds = new int[]{R.drawable.guide_image1
, R.drawable.guide_image2, R.drawable.guide_image3};
private List<ImageView> mImages = new ArrayList<ImageView>();

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mViewPager = (ViewPager) findViewById(R.id.viewpager);
//为ViewPager添加动画效果
mViewPager.setPageTransformer(true,new ZoomOutPageTransformer());
mViewPager.setAdapter(new PagerAdapter() {
@Override
public int getCount() {
return mImagIds.length;
}

@Override
public boolean isViewFromObject(View view, Object object) {
return view == object;
}

@Override
public Object instantiateItem(ViewGroup container, int position) {
ImageView imageView = new ImageView(MainActivity.this);
imageView.setImageResource(mImagIds[position]);
imageView.setScaleType(ImageView.ScaleType.CENTER_CROP);//为了不让图片变形
container.addView(imageView);
mImages.add(imageView);
return imageView;
}

@Override
public void destroyItem(ViewGroup container, int position, Object object) {

container.removeView(mImages.get(position));
}
});
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_main, menu);
return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();

//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}

return super.onOptionsItemSelected(item);
}
}

为ViewPager添加动画

只需一个方法：

mViewPager.setPageTransformer(，)

先看一眼API





此方法只在3.0以上的版本有效，3.0以下是没有效果的。

这个方法要传两个参数：

第一个直接传true

第二个就是传动画效果，这里google给了两个例子（工具类），使用时只需要将这个类导入到你的工程中，然后直接调用即可。

例如：

mViewPager.setPageTransformer(true,new ZoomOutPageTransformer())

这样动画效果就实现了

第一种：Zoom-out Page Transformer 当在相邻界面滑动时，这个page transformer使页面收缩

public class ZoomOutPageTransformer implements ViewPager.PageTransformer {
private static final float MIN_SCALE = 0.85f;
private static final float MIN_ALPHA = 0.5f;

public void transformPage(View view, float position) {
int pageWidth = view.getWidth();
int pageHeight = view.getHeight();

if (position < -1) { // [-Infinity,-1)
// This page is way off-screen to the left.
view.setAlpha(0);

} else if (position <= 1) { // [-1,1]
// Modify the default slide transition to shrink the page as well
float scaleFactor = Math.max(MIN_SCALE, 1 - Math.abs(position));
float vertMargin = pageHeight * (1 - scaleFactor) / 2;
float horzMargin = pageWidth * (1 - scaleFactor) / 2;
if (position < 0) {
view.setTranslationX(horzMargin - vertMargin / 2);
} else {
view.setTranslationX(-horzMargin + vertMargin / 2);
}

// Scale the page down (between MIN_SCALE and 1)
view.setScaleX(scaleFactor);
view.setScaleY(scaleFactor);

// Fade the page relative to its size.
view.setAlpha(MIN_ALPHA +
(scaleFactor - MIN_SCALE) /
(1 - MIN_SCALE) * (1 - MIN_ALPHA));

} else { // (1,+Infinity]
// This page is way off-screen to the right.
view.setAlpha(0);
}
}
}

2.Depth Page Transformer 这个page transformer使用默认动画的屏幕左滑动画。但是为右

public class DepthPageTransformer implements ViewPager.PageTransformer {
private static final float MIN_SCALE = 0.75f;

public void transformPage(View view, float position) {
int pageWidth = view.getWidth();

if (position < -1) { // [-Infinity,-1)
// This page is way off-screen to the left.
view.setAlpha(0);

} else if (position <= 0) { // [-1,0]
// Use the default slide transition when moving to the left page
view.setAlpha(1);
view.setTranslationX(0);
view.setScaleX(1);
view.setScaleY(1);

} else if (position <= 1) { // (0,1]
// Fade the page out.
view.setAlpha(1 - position);

// Counteract the default slide transition
view.setTranslationX(pageWidth * -position);

// Scale the page down (between MIN_SCALE and 1)
float scaleFactor = MIN_SCALE
+ (1 - MIN_SCALE) * (1 - Math.abs(position));
view.setScaleX(scaleFactor);
view.setScaleY(scaleFactor);

} else { // (1,+Infinity]
// This page is way off-screen to the right.
view.setAlpha(0);
}
}
}