Android UI(继承控件)--VerticalViewPager 垂直方向的viewpager

package com.wzq.verticalViewPager;

import android.content.Context;
import android.util.AttributeSet;
import android.util.DisplayMetrics;
import android.util.Log;
import android.view.MotionEvent;
import android.view.VelocityTracker;
import android.view.View;
import android.view.ViewGroup;
import android.view.WindowManager;
import android.widget.Scroller;

/**
 * 垂直方向上的ViewPager
 */
public class VerticalViewPager extends ViewGroup {

    /**
     * 屏幕的高度
     */
    private int mScreenHeight;
    /**
     * 手指按下时的getScrollY
     */
    private int mScrollStart;
    /**
     * 手指抬起时的getScrollY
     */
    private int mScrollEnd;
    /**
     * 记录移动时的Y
     */
    private int mLastY;
    /**
     * 滚动的辅助类
     */
    private Scroller mScroller;
    /**
     * 是否正在滚动
     */
    private boolean isScrolling;
    /**
     * 加速度检测
     */
    private VelocityTracker mVelocityTracker;
    /**
     * 记录当前页
     */
    private int currentPage = 0;

    private OnPageChangeListener mOnPageChangeListener;

    /**
     * 回调接口
     */
    public interface OnPageChangeListener {
        void onPageChange(int currentPage);
    }

    /**
     * 设置回调接口
     * 
     * @param listener
     */
    public void setOnPageChangeListener(OnPageChangeListener listener) {
        mOnPageChangeListener = listener;
    }

    public VerticalViewPager(Context context, AttributeSet attrs) {
        super(context, attrs);
        /**
         * 获取屏幕高度
         */
        DisplayMetrics dm = new DisplayMetrics();
        WindowManager wm = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);
        wm.getDefaultDisplay().getMetrics(dm);
        mScreenHeight = dm.heightPixels;
        // 初始化滚动辅助类
        mScroller = new Scroller(context);
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        int count = getChildCount();
        for (int i = 0; i < count; i++) {
            View childView = getChildAt(i);
            measureChild(childView, widthMeasureSpec, heightMeasureSpec);
        }
    }

    @Override
    protected void onLayout(boolean changed, int l, int t, int r, int b) {
        if (changed) {
            childCount = getChildCount();

            // 1， 设置主布局的高度(孩子个数 * 屏幕高度)
            MarginLayoutParams lp = (MarginLayoutParams) getLayoutParams();
            lp.height = mScreenHeight * childCount;
            setLayoutParams(lp);
            // 2，调整每个孩子的高度
            for (int i = 0; i < childCount; i++) {
                View child = getChildAt(i);
                if (child.getVisibility() != View.GONE) {
                    child.layout(l, i * mScreenHeight, r, (i + 1) * mScreenHeight);
                }
            }
        }
    }

    private String TAG = "VerticalViewPager";
    private int childCount;

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        // 如果当前正在滚动，调用父类的onTouchEvent
        if (isScrolling)
            return super.onTouchEvent(event);
        int action = event.getAction();
        int y = (int) event.getY();
        obtainVelocity(event);
        switch (action) {
        case MotionEvent.ACTION_DOWN:
            mScrollStart = getScrollY();
            mLastY = y;
            Log.i(TAG, "111111---ACTION_DOWN getScrollY = " + mScrollStart + " ; mLastY = "
                    + mLastY);
            break;
        case MotionEvent.ACTION_MOVE:
            if (!mScroller.isFinished()) {
                mScroller.abortAnimation();
            }
            int dy = mLastY - y;
            int scrollY = getScrollY();
            // 边界值检查
            Log.i(TAG, "2---ACTION_MOVE ; dy =  " + dy + " scrollY = " + scrollY);
            // 已经到达控件最顶端，此时下拉，拉拽速度减半
            if (dy < 0 && scrollY <= 0) {
                dy = dy / 2;// 控件移动速度减半
            }
            // 已经到达控件最底部，此时上拉，拉拽速度减半
            // if (dy > 0 && scrollY + dy > getHeight() - mScreenHeight) {
            if (dy > 0 && scrollY > (childCount - 1) * mScreenHeight) {
                dy = dy / 2;// 控件移动速度减半
            }
            scrollBy(0, dy);
            mLastY = y;
            break;
        case MotionEvent.ACTION_UP:
            mScrollEnd = getScrollY();
            int dScrollY = mScrollEnd - mScrollStart;
            Log.i(TAG, "333333---ACTION_UP_UP getScrollY = " + mScrollEnd + " ; dScrollY = "
                    + dScrollY);
            if (wantScrollToNext()) {// 往上滑动
                if (mScrollStart == (childCount - 1) * mScreenHeight) {// 已经在整个控件的最底部了
                    mScroller.startScroll(0, getScrollY(), 0, -dScrollY);// 回弹(用户不想换页)
                } else {
                    if (shouldScrollToNext()) {
                        mScroller.startScroll(0, getScrollY(), 0, mScreenHeight - dScrollY);// 换页
                    } else {
                        mScroller.startScroll(0, getScrollY(), 0, -dScrollY);// 回弹
                    }
                }
            }
            if (wantScrollToPre()) {// 往下滑动
                if (mScrollStart == 0) {// 已经在整个控件的最顶部了
                    mScroller.startScroll(0, getScrollY(), 0, -dScrollY);// 回弹
                } else {
                    if (shouldScrollToPre()) {
                        mScroller.startScroll(0, getScrollY(), 0, -mScreenHeight - dScrollY);// 换页
                    } else {
                        mScroller.startScroll(0, getScrollY(), 0, -dScrollY);// 回弹
                    }
                }
            }
            isScrolling = true;
            postInvalidate();
            recycleVelocity();
            break;
        }
        return true;
    }

    @Override
    public void computeScroll() {
        super.computeScroll();
        // the animation is not yet finished
        if (mScroller.computeScrollOffset()) {
            scrollTo(0, mScroller.getCurrY());
            postInvalidate();
            Log.i(TAG, "44---computeScroll  animation is not not not not not yet finished");
        } else {// animation is finished
            Log.i(TAG, "44---computeScroll  animation finished");
            int position = getScrollY() / mScreenHeight;
            Log.i(TAG, "~~~~~~~~~computeScroll  position = " + position + " , currentPage = "
                    + currentPage);
            if (position != currentPage) {
                if (mOnPageChangeListener != null) {
                    currentPage = position;
                    mOnPageChangeListener.onPageChange(currentPage);
                }
            }
            isScrolling = false;
        }
    }

    /**
     * 根据滚动距离判断是否能够滚到下一页
     * 
     * @return
     */
    private boolean shouldScrollToNext() {
        return mScrollEnd - mScrollStart > mScreenHeight / 2 || Math.abs(getVelocity()) > 600;
    }

    /**
     * 根据滚动距离判断是否能够滚动到上一页
     * 
     * @return
     */
    private boolean shouldScrollToPre() {
        return -mScrollEnd + mScrollStart > mScreenHeight / 2 || Math.abs(getVelocity()) > 600;
    }

    /**
     * 根据用户滑动，判断用户的意图是否是滚动到上一页，即手向下滑动。
     * 
     * @return
     */
    private boolean wantScrollToPre() {
        return mScrollEnd < mScrollStart;
    }

    /**
     * 根据用户滑动，判断用户的意图是否是滚到到下一页，即手向上滑动。
     * 
     * @return
     */
    private boolean wantScrollToNext() {
        return mScrollEnd > mScrollStart;
    }

    /**
     * 获取Y方向的加速度
     * 
     * @return
     */
    private int getVelocity() {
        mVelocityTracker.computeCurrentVelocity(1000);
        return (int) mVelocityTracker.getYVelocity();
    }

    /**
     * 初始化加速度检测器
     * 
     * @param event
     */
    private void obtainVelocity(MotionEvent event) {
        if (mVelocityTracker == null) {
            mVelocityTracker = VelocityTracker.obtain();
        }
        mVelocityTracker.addMovement(event);
    }

    /**
     * 是否资源
     */
    private void recycleVelocity() {
        if (mVelocityTracker != null) {
            mVelocityTracker.recycle();
            mVelocityTracker = null;
        }
    }

}

xml文件 

<?xml version="1.0" encoding="utf-8"?>
<com.wzq.verticalViewPager.VerticalViewPager xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/id_main_ly"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >

    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:background="@drawable/introduce" >

        <Button
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="position = 0" />
    </RelativeLayout>

    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:background="@drawable/introduce" >

        <Button
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="position = 1" />
    </RelativeLayout>

    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:background="@drawable/introduce" >

        <Button
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="position = 2" />
    </RelativeLayout>

    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:background="@drawable/introduce" >

        <Button
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="position = 3" />
    </RelativeLayout>

</com.wzq.verticalViewPager.VerticalViewPager>

引用

public class VerticalViewPagerActivity extends Activity {
    private VerticalViewPager mMianLayout;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.a_vertical_viewpager);

        mMianLayout = (VerticalViewPager) findViewById(R.id.id_main_ly);
        mMianLayout.setOnPageChangeListener(new OnPageChangeListener() {
            @Override
            public void onPageChange(int currentPage) {
                // TODO
            }
        });
    }

}

参考：http://blog.csdn.net/lmj623565791/article/details/23692439