ViewPager实现应用的欢迎界面

来源：互联网发布：linux more cat 编辑：程序博客网时间：2024/05/17 20:30

在前一篇博客中介绍了Animation实现应用的欢迎界面，本篇博客介绍ViewPager实现应用的欢迎引导界面，并且实现继续向左滑动最后一张图片进入新的Activity的效果。

实现效果：
这里写图片描述

项目结构：
这里写图片描述

1.在activity_main.xml中添加ViewPager控件

<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="${relativePackage}.${activityClass}" >    <android.support.v4.view.ViewPager        android:id="@+id/id_viewpager"        android:layout_width="match_parent"        android:layout_height="match_parent" >    </android.support.v4.view.ViewPager></RelativeLayout>

2.添加要显示的三张欢迎图片到drawable文件夹中
这里写图片描述

3.MainActivity

package com.example.viewpager1;import java.util.ArrayList;import java.util.List;import android.app.Activity;import android.content.Intent;import android.os.Bundle;import android.support.v4.view.PagerAdapter;import android.support.v4.view.ViewPager;import android.support.v4.view.ViewPager.OnPageChangeListener;import android.view.View;import android.view.ViewGroup;import android.view.Window;import android.widget.ImageView;import android.widget.ImageView.ScaleType;public class MainActivity extends Activity {    // 声明ViewPager控件    private ViewPager mViewPager;    // 声明图片的id    private int[] mImgIds = new int[] { R.drawable.a, R.drawable.b,            R.drawable.c };    // 定义存储ImageView的集合    private List<ImageView> mImages = new ArrayList<ImageView>();    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        // 去除标题        requestWindowFeature(Window.FEATURE_NO_TITLE);        setContentView(R.layout.activity_main);        // 初始化ViewPager        mViewPager = (ViewPager) findViewById(R.id.id_viewpager);        // ========================为ViewPager添加切换动画效果开始========================        // 动画效果1 - DepthPageTransformer        // mViewPager.setPageTransformer(true, new DepthPageTransformer());        // 动画效果2 - ZoomOutPageTransformer        mViewPager.setPageTransformer(true, new ZoomOutPageTransformer());        // ========================为ViewPager添加切换动画效果结束========================        // 设置适配器        mViewPager.setAdapter(new PagerAdapter() {            @Override            public Object instantiateItem(ViewGroup container, int position) {                ImageView imageView = new ImageView(MainActivity.this);                // 设置图片                imageView.setImageResource(mImgIds[position]);                imageView.setScaleType(ScaleType.CENTER_CROP);                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 isViewFromObject(View view, Object object) {                // TODO Auto-generated method stub                return view == object;            }            @Override            public int getCount() {                // TODO Auto-generated method stub                return mImgIds.length;            }        });        // 绑定事件        mViewPager.setOnPageChangeListener(new OnPageChangeListener() {            @Override            public void onPageSelected(int arg0) {                // TODO Auto-generated method stub            }            @Override            public void onPageScrolled(int arg0, float arg1, int arg2) {                // 当滑动到最后一张图片打开新的activity                if (arg0 == mImgIds.length - 1) {                    Intent intent = new Intent(MainActivity.this,                            SecondActivity.class);                    startActivity(intent);                    finish();                }            }            @Override            public void onPageScrollStateChanged(int arg0) {                // TODO Auto-generated method stub            }        });    }}

官方API: http://developer.android.com/training/animation/screen-slide.html

提供了两种ViewPager的切换动画
这里写图片描述

DepthPageTransformer.java

package com.example.viewpager1;import android.annotation.SuppressLint;import android.support.v4.view.ViewPager;import android.view.View;@SuppressLint("NewApi")public class DepthPageTransformer implements ViewPager.PageTransformer {    private static final float MIN_SCALE = 0.75f;    @SuppressLint("NewApi")    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);        }    }}

ZoomOutPageTransformer.java

package com.example.viewpager1;import android.annotation.SuppressLint;import android.support.v4.view.ViewPager;import android.view.View;@SuppressLint("NewApi")public class ZoomOutPageTransformer implements ViewPager.PageTransformer {    private static final float MIN_SCALE = 0.85f;    private static final float MIN_ALPHA = 0.5f;    @SuppressLint("NewApi")    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);        }    }}

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