TimelineDetailScrollView.java

package org.aisen.weibo.sina.ui.widget;

import android.content.Context;
import android.support.v4.view.MotionEventCompat;
import android.support.v4.view.ViewCompat;
import android.support.v4.view.ViewPager;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewGroup;
import android.widget.LinearLayout;
import android.widget.ScrollView;

import org.aisen.weibo.sina.R;

/**
 * Created by wangdan on 16/2/1.
 */
public class TimelineDetailScrollView extends ScrollView {

    static final String TAG = "TimelineDetailScrollView";

    private static final int INVALID_POINTER = -1;
    private int mActivePointerId = INVALID_POINTER;
    private float mInitialMotionY;

    private ViewGroup layHeader;
    private ViewGroup layBar;
    private ViewPager viewPager;
    private View refreshView;

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

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

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

    public void setRefreshView(View refreshView) {
        this.refreshView = refreshView;
    }

    @Override
    public void requestChildFocus(View child, View focused) {
        // 包含了TabLayout时，拿到焦点总会自动滚动到TabLayout位置
//        super.requestChildFocus(child, focused);
    }

    @Override
    protected void onLayout(boolean changed, int l, int t, int r, int b) {
        super.onLayout(changed, l, t, r, b);

        layHeader = (ViewGroup) findViewById(R.id.layHeader);
        if (layHeader == null || layHeader.getChildCount() == 0 || layHeader.getHeight() == 0) {
            return;
        }

        if (layBar == null) {
            layBar = (ViewGroup) findViewById(R.id.layBar);
            viewPager = (ViewPager) findViewById(R.id.viewPager);
            viewPager.setLayoutParams(new LinearLayout.LayoutParams(LinearLayout.LayoutParams.MATCH_PARENT, getHeight() - layBar.getHeight()));

//            Logger.d(TAG, "HeaderViewHeight = " + layHeader.getHeight() + ", BarHeight = " + layBar.getHeight() + ", top = " + getScrollY());
        }
    }

    @Override
    public boolean onInterceptTouchEvent(MotionEvent ev) {
        final int action = MotionEventCompat.getActionMasked(ev);

        if (refreshView != null) {
            boolean canChildScrollUp = ViewCompat.canScrollVertically(refreshView, -1);
//            Logger.d(TAG, String.format("canChildScrollUp = %s", String.valueOf(canChildScrollUp)));
            if (canChildScrollUp) {
                return false;
            }
        }

        switch (action) {
            case MotionEvent.ACTION_DOWN:
                mActivePointerId = MotionEventCompat.getPointerId(ev, 0);
                final float initialMotionY = getMotionEventY(ev, mActivePointerId);
                if (initialMotionY == -1) {
                    return false;
                }
                mInitialMotionY = initialMotionY;
                break;
            case MotionEvent.ACTION_MOVE:
                if (mActivePointerId == INVALID_POINTER) {
//                    Logger.e(TAG, "Got ACTION_MOVE event but don't have an active pointer id.");
                    return false;
                }

                final float y = getMotionEventY(ev, mActivePointerId);
                if (y == -1) {
                    return false;
                }
                final float yDiff = y - mInitialMotionY;
                if (yDiff < 0) {
                    if (getChildAt(0).getHeight() <= getHeight() + getScrollY()) {
                        return false;
                    }
                }
                break;
            case MotionEvent.ACTION_UP:
            case MotionEvent.ACTION_CANCEL:
                mActivePointerId = INVALID_POINTER;
                break;
        }

        return super.onInterceptTouchEvent(ev);
    }

    private float getMotionEventY(MotionEvent ev, int activePointerId) {
        final int index = MotionEventCompat.findPointerIndex(ev, activePointerId);
        if (index < 0) {
            return -1;
        }
        return MotionEventCompat.getY(ev, index);
    }

}