android----------用ViewPage实现滑动效果

野性酷女 2022-08-19 04:52 241阅读 0赞

# 一、效果图    #

先上实现效果：

![Center][]

实现滑动效果主要用到的类是：**android.support.v4.view.****ViewPager**

# **二、代码实现** #

布局代码

<?xml version="1.0" encoding="utf-8"?>
    <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
        android:layout_width="match_parent" android:layout_height="match_parent">
    
        <android.support.v4.view.ViewPager
            android:id="@+id/welcome_viewpager"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_gravity="center" />
    </RelativeLayout>

主要代码（从项目中扣出来）

public class WelcomeActivity extends BasicActivity{
        @ViewInject(id = R.id.welcome_viewpager)
        private ViewPager wel_viewPager;
    
        private PagerAdapter pagerAdapter;
        private ArrayList<View> viewlist;
        private Preference preference;
        //三张图片
        private int[] pic_ids = { R.mipmap.welcome_v1, R.mipmap.welcome_v2,
                R.mipmap.welcome_v3 };
        // 位移量
        private int offset;
        // 记录当前的位置
        private int curpos = 0;
        // 记录滑动手势的按下和抬起的位置，用于判断最后一页是否左滑从而进入主页面
        private float lastx = 0, curx = 0;
    
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_welcome);
            // 判断首次使用
            preference = Preference.instance(this);
            initviewpage();
            handler.postDelayed(runnable, 2000);
        }
    
        private void initviewpage() {
            viewlist = new ArrayList<View>();
    
            for (int i = 0; i < pic_ids.length; i++) {
                ImageView iv = new ImageView(this);
                iv.setImageResource(pic_ids[i]);
                ViewGroup.LayoutParams params = new ViewGroup.LayoutParams(
                        ViewGroup.LayoutParams.MATCH_PARENT,
                        ViewGroup.LayoutParams.MATCH_PARENT);
                iv.setLayoutParams(params);
                iv.setScaleType(ImageView.ScaleType.CENTER_CROP);// 图片按等比缩放
                viewlist.add(iv);
            }
    
            // 设置wel_viewPager的Adapter
            initAdapter();
        }
    
        private void initAdapter() {
            pagerAdapter=new PagerAdapter() {
                @Override
                public int getCount() {
                    return viewlist.size();
                }
    
                @Override
                public boolean isViewFromObject(View view, Object o) {
                    return view==o;// 官方提示这样写
                }
    
                @Override
                public int getItemPosition(Object object) {
                    return super.getItemPosition(object);
                }
    
                @Override
                public void destroyItem(ViewGroup container, int position, Object object) {
                    container.removeView(viewlist.get(position));
                }
    
                @Override
                public Object instantiateItem(ViewGroup container, int position) {
                    container.addView(viewlist.get(position));
                    return viewlist.get(position);
                }
            };
    
            wel_viewPager.setAdapter(pagerAdapter);
    
            /**
             * 在最后一页 判断左滑还是右滑
             */
            wel_viewPager.setOnTouchListener(new View.OnTouchListener() {
    
                @Override
                public boolean onTouch(View v, MotionEvent event) {
                    if ((curpos == viewlist.size() - 1)) {// 是否是最后一页
                        switch (event.getAction()) {
                            case MotionEvent.ACTION_DOWN:
                                lastx = event.getX();
                                break;
                            case MotionEvent.ACTION_MOVE:
                                curx = event.getX();
                                if (lastx - curx > 100) {
                                    skipActivity();
                                }
                                break;
                        }
                    }
                    return false;
                }
            });
    
            wel_viewPager.setOnPageChangeListener(new ViewPager.OnPageChangeListener() {
    
                @Override
                public void onPageSelected(int arg0) {
                    // // 转移到下一个view时 原点移动到下一个位置
                    // if (arg0 < viewlist.size()) {
                    // moveCurdot(arg0);
                    // }
                    curpos = arg0;
                }
    
                @Override
                public void onPageScrolled(int arg0, float arg1, int arg2) {
                }
    
                @Override
                public void onPageScrollStateChanged(int arg0) {
                }
    
            });
        }
        private Handler handler = new Handler();
        private boolean isEnd = false;
        private Runnable runnable = new Runnable() {
            @Override
            public void run() {
                if (!isEnd) {
                    if (curpos < 2) {
                        handler.postDelayed(this, 2000);
                        curpos++;
                        wel_viewPager.setCurrentItem(curpos);
                    } else {
                        skipActivity();
                        isEnd = true;
                    }
                }
            }
        };
    
        /**
         * 跳转到指定Activity
         */
        private void skipActivity() {
            startActivity(null, MainActivity.class);
            preference.putBoolean(Preference.FIRST_IN, true);
            finishSimple();
        }
    }

[Center]: /images/20220731/25ecb45c4d2b4a58bebf813628c5b232.png