仿京东样式下拉查看图文详情效果

其他 2018-11-29 09:51:02 阅读次数: 0

用到的两个类:

package com.example.administrator.permissiondemo.activity;

import android.content.Context;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.VelocityTracker;
import android.view.View;
import android.view.ViewConfiguration;
import android.view.ViewGroup;
import android.widget.Scroller;

/**
 * Created by baoyunlong on 16/6/8.
 */
public class PullUpToLoadMore extends ViewGroup {

    private ScrollViewListener scrollViewListener = null;

    public void setOnScrollListener(ScrollViewListener scrollViewListener) {
        this.scrollViewListener = scrollViewListener;
    }

    @Override
    protected void onScrollChanged(int x, int y, int oldx, int oldy) {
        super.onScrollChanged(x, y, oldx, oldy);
        if (scrollViewListener != null) {

            if (oldy < y) {// 手指向上滑动，屏幕内容下滑
                scrollViewListener.onScroll(oldy, y, false);

            } else if (oldy > y) {// 手指向下滑动，屏幕内容上滑
                scrollViewListener.onScroll(oldy, y, true);
            }

        }
    }

    public interface ScrollViewListener {//dy Y轴滑动距离，isUp 是否返回顶部

        void onScroll(int oldy, int dy, boolean isUp);
    }

    public static String TAG = PullUpToLoadMore.class.getName();
    MyScrollView topScrollView, bottomScrollView;
    VelocityTracker velocityTracker = VelocityTracker.obtain();
    Scroller scroller = new Scroller(getContext());
    int currPosition = 0;
    int position1Y;
    int lastY;
    public int scaledTouchSlop;//最小滑动距离
    int speed = 200;
    boolean isIntercept;
    public boolean bottomScrollVIewIsInTop = false;
    public boolean topScrollViewIsBottom = false;

    public PullUpToLoadMore(Context context) {
        super(context);
        init();
    }

    public PullUpToLoadMore(Context context, AttributeSet attrs) {
        super(context, attrs);
        init();
    }

    public PullUpToLoadMore(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        init();
    }

    private void init() {
        post(new Runnable() {
            @Override
            public void run() {
                topScrollView = (MyScrollView) getChildAt(0);
                bottomScrollView = (MyScrollView) getChildAt(1);
                topScrollView.setScrollListener(new MyScrollView.ScrollListener() {
                    @Override
                    public void onScrollToBottom() {
                        topScrollViewIsBottom = true;
                    }

                    @Override
                    public void onScrollToTop() {
                    }

                    @Override
                    public void onScroll(int scrollY) {
                    }

                    @Override
                    public void notBottom() {
                        topScrollViewIsBottom = false;
                    }
                });

                bottomScrollView.setScrollListener(new MyScrollView.ScrollListener() {
                    @Override
                    public void onScrollToBottom() {
                    }

                    @Override
                    public void onScrollToTop() {
                    }

                    @Override
                    public void onScroll(int scrollY) {
                        if (scrollY == 0) {
                            bottomScrollVIewIsInTop = true;
                        } else {
                            bottomScrollVIewIsInTop = false;
                        }
                    }

                    @Override
                    public void notBottom() {
                    }
                });
                position1Y = topScrollView.getBottom();
                scaledTouchSlop = ViewConfiguration.get(getContext()).getScaledTouchSlop();
            }
        });
    }

    @Override
    public boolean dispatchTouchEvent(MotionEvent ev) {
        //防止子View禁止父view拦截事件
        this.requestDisallowInterceptTouchEvent(false);
        return super.dispatchTouchEvent(ev);
    }

    @Override
    public boolean onInterceptTouchEvent(MotionEvent ev) {
        int y = (int) ev.getY();
        switch (ev.getAction()) {
            case MotionEvent.ACTION_DOWN:
                lastY = y;
                break;
            case MotionEvent.ACTION_MOVE:
                //判断是否已经滚动到了底部
                if (topScrollViewIsBottom) {
                    int dy = lastY - y;
                    //判断是否是向上滑动和是否在第一屏
                    if (dy > 0 && currPosition == 0) {
                        if (dy >= scaledTouchSlop) {
                            isIntercept = true;//拦截事件
                            lastY = y;
                        }
                    }
                }
                if (bottomScrollVIewIsInTop) {
                    int dy = lastY - y;
                    //判断是否是向下滑动和是否在第二屏
                    if (dy < 0 && currPosition == 1) {
                        if (Math.abs(dy) >= scaledTouchSlop) {
                            isIntercept = true;
                        }
                    }
                }
                break;
        }
        return isIntercept;
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        int y = (int) event.getY();
        velocityTracker.addMovement(event);
        switch (event.getAction()) {
            case MotionEvent.ACTION_MOVE:
                int dy = lastY - y;
                if (getScrollY() + dy < 0) {
                    dy = getScrollY() + dy + Math.abs(getScrollY() + dy);
                }
                if (getScrollY() + dy + getHeight() > bottomScrollView.getBottom()) {
                    dy = dy - (getScrollY() + dy - (bottomScrollView.getBottom() - getHeight()));
                }
                scrollBy(0, dy);
                break;
            case MotionEvent.ACTION_UP:
                isIntercept = false;
                velocityTracker.computeCurrentVelocity(1000);
                float yVelocity = velocityTracker.getYVelocity();
                if (currPosition == 0) {
                    if (yVelocity < 0 && yVelocity < -speed) {
                        smoothScroll(position1Y);
                        currPosition = 1;
                    } else {
                        smoothScroll(0);
                    }
                } else {
                    if (yVelocity > 0 && yVelocity > speed) {
                        smoothScroll(0);
                        currPosition = 0;
                    } else {
                        smoothScroll(position1Y);
                    }
                }
                break;
        }
        lastY = y;
        return true;
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        measureChildren(widthMeasureSpec, heightMeasureSpec);
    }

    @Override
    protected void onLayout(boolean changed, int l, int t, int r, int b) {
        int childCount = getChildCount();
        int childTop = 0;
        for (int i = 0; i < childCount; i++) {
            View child = getChildAt(i);
            child.layout(l, childTop, r, childTop + child.getMeasuredHeight());
            childTop += child.getMeasuredHeight();
        }
    }

    //通过Scroller实现弹性滑动
    private void smoothScroll(int tartY) {
        int dy = tartY - getScrollY();
        scroller.startScroll(getScrollX(), getScrollY(), 0, dy);
        invalidate();
    }

    //滚动到顶部
    public void scrollToTop() {
        smoothScroll(0);
        currPosition = 0;
        topScrollView.smoothScrollTo(0, 0);
    }

    @Override
    public void computeScroll() {
        if (scroller.computeScrollOffset()) {
            scrollTo(scroller.getCurrX(), scroller.getCurrY());
            postInvalidate();
        }
    }
}

and:

package com.example.administrator.permissiondemo.activity;

import android.content.Context;
import android.util.AttributeSet;
import android.util.Log;
import android.view.MotionEvent;
import android.widget.ScrollView;

/**
 * Created by baoyunlong on 16/6/8.
 */
public class MyScrollView extends ScrollView {
    private ScrollViewListener scrollViewListener = null;

    public void setOnScrollListener(ScrollViewListener scrollViewListener) {
        this.scrollViewListener = scrollViewListener;
    }

    @Override
    protected void onScrollChanged(int x, int y, int oldx, int oldy) {
        super.onScrollChanged(x, y, oldx, oldy);
        if (scrollViewListener != null) {

            if (oldy < y) {// 手指向上滑动，屏幕内容下滑
                scrollViewListener.onScroll(oldy, y, false);

            } else if (oldy > y) {// 手指向下滑动，屏幕内容上滑
                scrollViewListener.onScroll(oldy, y, true);
            }
        }
    }

    public interface ScrollViewListener {//dy Y轴滑动距离，isUp 是否返回顶部

        void onScroll(int oldy, int dy, boolean isUp);
    }

    private static String TAG = MyScrollView.class.getName();

    public void setScrollListener(ScrollListener scrollListener) {
        this.mScrollListener = scrollListener;
    }

    private ScrollListener mScrollListener;

    public MyScrollView(Context context) {
        super(context);
    }

    public MyScrollView(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    public MyScrollView(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
    }

    @Override
    public boolean onTouchEvent(MotionEvent ev) {

        switch (ev.getAction()) {
            case MotionEvent.ACTION_MOVE:

                if (mScrollListener != null) {
                    int contentHeight = getChildAt(0).getHeight();
                    int scrollHeight = getHeight();
                    Log.d(TAG, "scrollY:" + getScrollY() + "contentHeight:" + contentHeight + " scrollHeight" + scrollHeight + "object:" + this);
                    int scrollY = getScrollY();
                    mScrollListener.onScroll(scrollY);
                    if (scrollY + scrollHeight >= contentHeight || contentHeight <= scrollHeight) {
                        mScrollListener.onScrollToBottom();
                    } else {
                        mScrollListener.notBottom();
                    }
                    if (scrollY == 0) {
                        mScrollListener.onScrollToTop();
                    }
                }
                break;
        }
        boolean result = super.onTouchEvent(ev);
        requestDisallowInterceptTouchEvent(false);
        return result;
    }

    public interface ScrollListener {
        void onScrollToBottom();

        void onScrollToTop();

        void onScroll(int scrollY);

        void notBottom();
    }
}

其中MyScrollView相当于一个页面,由PullUpToLoadMore包裹:布局代码:

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <com.example.administrator.permissiondemo.activity.PullUpToLoadMore
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical">

        <com.example.administrator.permissiondemo.activity.MyScrollView
            android:id="@+id/ceshi2"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:fillViewport="true">


            <LinearLayout
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:orientation="vertical">

                <LinearLayout
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"
                    android:orientation="vertical">

                    <LinearLayout
                        android:id="@+id/lv_header"
                        android:layout_width="match_parent"
                        android:layout_height="wrap_content"
                        android:orientation="vertical">

                        <ImageView
                            android:id="@+id/iv_header"
                            android:layout_width="match_parent"
                            android:layout_height="@dimen/head_height3"
                            android:layout_gravity="center"
                            android:scaleType="centerCrop"
                            android:src="@drawable/a1" />
                    </LinearLayout>

                    <TextView
                        android:id="@+id/cd_name"
                        android:layout_width="match_parent"
                        android:layout_height="wrap_content"
                        android:layout_weight="1"
                        android:text="儿童基础级钢琴课1\n\n儿童基础级钢琴课2\n\n儿童基础级钢琴课3\n\n儿童基础级钢琴课4\n\n儿童基础级钢琴课5\n\n儿童基础级钢琴课6\n\n儿童基础级钢琴课7\n\n儿童基础级钢琴课8\n\n儿童基础级钢琴课9\n\n儿童基础级钢琴课10\n\n儿童基础级钢琴课11\n\n儿童基础级钢琴课12\n\n儿童基础级钢琴课13\n\n儿童基础级钢琴课14\n\n儿童基础级钢琴课15\n\n儿童基础级钢琴课16\n\n儿童基础级钢琴课17\n\n儿童基础级钢琴课18\n\n儿童基础级钢琴课19\n\n儿童基础级钢琴课20\n\n儿童基础级钢琴课21\n\n"
                        android:textColor="#000000"
                        android:textSize="@dimen/textSize20" />

                    <TextView
                        android:layout_width="match_parent"
                        android:layout_height="wrap_content"
                        android:gravity="center"
                        android:padding="15dp"
                        android:text="继续下滑看图文详情"
                        android:textColor="#f00" />

                </LinearLayout>
            </LinearLayout>

        </com.example.administrator.permissiondemo.activity.MyScrollView>

        <com.example.administrator.permissiondemo.activity.MyScrollView
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:fillViewport="true">

            <LinearLayout
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:gravity="center"
                android:orientation="vertical">


                <ImageView
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:src="@drawable/a1" />

                <ImageView
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:src="@drawable/a3" />

                <ImageView
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:src="@drawable/a4" />

                <ImageView
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:src="@drawable/a5" />

                <ImageView
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:src="@drawable/a9" />

                <ImageView
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:src="@drawable/a8" />

                <ImageView
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:src="@drawable/a10" />


            </LinearLayout>
        </com.example.administrator.permissiondemo.activity.MyScrollView>
    </com.example.administrator.permissiondemo.activity.PullUpToLoadMore>


    <include layout="@layout/title_coursededails" />

</RelativeLayout>

完成

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