package cn.ittiger.uc.view.behavior;
import cn.ittiger.uc.R;
import cn.ittiger.uc.view.behavior.base.ViewOffsetBehavior;
import android.content.Context;
import android.support.design.widget.CoordinatorLayout;
import android.support.v4.view.ViewCompat;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;
import android.widget.OverScroller;
import java.lang.ref.WeakReference;
/**
* Created by ylhu on 17-2-23.
*/
public class UCViewHeaderBehavior extends ViewOffsetBehavior<View> {
private int mTitleViewHeight = 0;
private OverScroller mOverScroller;
private WeakReference<View> mChild;
public static final int STATE_OPENED = 0;
public static final int STATE_CLOSED = 1;
public static final int DURATION_SHORT = 300;
public static final int DURATION_LONG = 600;
private int mCurState = STATE_OPENED;
public UCViewHeaderBehavior() {
super();
}
public UCViewHeaderBehavior(Context context, AttributeSet attrs) {
super(context, attrs);
mOverScroller = new OverScroller(context);
}
@Override
protected void layoutChild(CoordinatorLayout parent, View child, int layoutDirection) {
super.layoutChild(parent, child, layoutDirection);
mTitleViewHeight = parent.findViewById(R.id.news_view_title_layout).getMeasuredHeight();
mChild = new WeakReference<>(child);
}
@Override
public boolean onStartNestedScroll(CoordinatorLayout coordinatorLayout, View child, View directTargetChild, View target, int nestedScrollAxes) {
//开始滑动的条件，垂直方向滑动，滑动未结束
return nestedScrollAxes == ViewCompat.SCROLL_AXIS_VERTICAL && canScroll(child, 0) && !isClosed(child);
}
/**
* 当前是否可以滑动
* @param child
* @param pendingDy Y轴方向滑动的translationY
* @return
*/
private boolean canScroll(View child, float pendingDy) {
int pendingTranslationY = (int) (child.getTranslationY() - pendingDy);
if (pendingTranslationY >= getHeaderOffsetRange() && pendingTranslationY <= 0) {
return true;
}
return false;
}
@Override
public void onNestedPreScroll(CoordinatorLayout coordinatorLayout, View child, View target, int dx, int dy, int[] consumed) {
super.onNestedPreScroll(coordinatorLayout, child, target, dx, dy, consumed);
//开始滑动之前的逻辑处理
//dy>0 向上滑
//dy<0 向下滑
float halfOfDis = dy / 4.0f;
if (!canScroll(child, halfOfDis)) {//滑动结束
if(halfOfDis > 0) {
child.setVisibility(View.GONE);//滑动结束后，隐藏此视图
child.setTranslationY(getHeaderOffsetRange());
} else {
child.setTranslationY(0);
}
} else {//滑动未结束
if(halfOfDis <= 0) {
child.setVisibility(View.VISIBLE);
}
//滑动
child.setTranslationY(child.getTranslationY() - halfOfDis);
}
//消耗掉当前垂直方向上的滑动距离
consumed[1] = dy;
}
/**
* 向上滑动过程时translationY的最小值
* @return
*/
private int getHeaderOffsetRange() {
return -mTitleViewHeight;
}
@Override
public boolean onInterceptTouchEvent(CoordinatorLayout parent, View child, MotionEvent ev) {
if(ev.getAction() == MotionEvent.ACTION_UP) {
//对松开手指时进行处理，如果松开时滑动滑动了1/4则自动滑动到结束，否则则回归原位
handlerActionUp(child);
}
return super.onInterceptTouchEvent(parent, child, ev);
}
private void handlerActionUp(View child) {
if (mFlingRunnable != null) {
child.removeCallbacks(mFlingRunnable);
mFlingRunnable = null;
}
mFlingRunnable = new FlingRunnable(child);
if (child.getTranslationY() < getHeaderOffsetRange() / 4.0f) {
mFlingRunnable.scrollToClosed(DURATION_SHORT);
} else {
mFlingRunnable.scrollToOpen(DURATION_SHORT);
}
}
private void onFlingFinished(View layout) {
boolean isClosed = isClosed(layout);
mCurState = isClosed ? STATE_CLOSED : STATE_OPENED;
if(isClosed) {
layout.setVisibility(View.GONE);
}
}
/**
* 是否滑动结束
* @param child
* @return
*/
private boolean isClosed(View child) {
return child.getTranslationY() == getHeaderOffsetRange();
}
public boolean isClosed() {
return mCurState == STATE_CLOSED;
}
public void openPager() {
openPager(DURATION_LONG);
}
/**
* @param duration open animation duration
*/
public void openPager(int duration) {
View child = mChild.get();
if (isClosed() && child != null) {
if(child.getVisibility() == View.GONE) {
child.setVisibility(View.VISIBLE);
}
if (mFlingRunnable != null) {
child.removeCallbacks(mFlingRunnable);
mFlingRunnable = null;
}
mFlingRunnable = new FlingRunnable(child);
mFlingRunnable.scrollToOpen(duration);
}
}
public void closePager() {
closePager(DURATION_LONG);
}
/**
* @param duration close animation duration
*/
public void closePager(int duration) {
View child = mChild.get();
if (!isClosed()) {
if (mFlingRunnable != null) {
child.removeCallbacks(mFlingRunnable);
mFlingRunnable = null;
}
mFlingRunnable = new FlingRunnable(child);
mFlingRunnable.scrollToClosed(duration);
}
}
private FlingRunnable mFlingRunnable;
private class FlingRunnable implements Runnable {
private final View mLayout;
FlingRunnable(View layout) {
mLayout = layout;
}
public void scrollToClosed(int duration) {
float curTranslationY = ViewCompat.getTranslationY(mLayout);
float dy = getHeaderOffsetRange() - curTranslationY;
mOverScroller.startScroll(0, Math.round(curTranslationY - 0.1f), 0, Math.round(dy + 0.1f), duration);
start();
}
public void scrollToOpen(int duration) {
float curTranslationY = ViewCompat.getTranslationY(mLayout);
mOverScroller.startScroll(0, (int) curTranslationY, 0, (int) -curTranslationY, duration);
start();
}
private void start() {
if (mOverScroller.computeScrollOffset()) {
mFlingRunnable = new FlingRunnable(mLayout);
ViewCompat.postOnAnimation(mLayout, mFlingRunnable);
} else {
onFlingFinished(mLayout);
}
}
@Override
public void run() {
if (mLayout != null && mOverScroller != null) {
if (mOverScroller.computeScrollOffset()) {
ViewCompat.setTranslationY(mLayout, mOverScroller.getCurrY());
ViewCompat.postOnAnimation(mLayout, this);
} else {
onFlingFinished(mLayout);
}
}
}
}
}
