import android.content.Context;
import android.content.res.TypedArray;
import android.support.v4.view.ViewCompat;
import android.support.v4.view.ViewPager;
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.view.animation.DecelerateInterpolator;
import android.widget.LinearLayout;
import android.widget.Scroller;
import com.snail.labaffinity.R;
import com.snail.labaffinity.adapter.SlideFragmentPagerAdapter;
/**
* 1 ViewPager+TabLayout as content
* 2 FragmentTabHost+Fragment as content
* 3 bug :can not assertain which View is inTouch
*/
public class DragScrollDetailsLayout extends LinearLayout {
public interface OnSlideFinishListener {
void onStatueChanged(CurrentTargetIndex status);
}
public enum CurrentTargetIndex {
UPSTAIRS,
DOWNSTAIRS;
public static CurrentTargetIndex valueOf(int index) {
return 1 == index ? DOWNSTAIRS : UPSTAIRS;
}
}
private static final float DEFAULT_PERCENT = 0.3f;
private static final int DEFAULT_DURATION = 400;
private int mMaxFlingVelocity;
private int mMiniFlingVelocity;
private int mDefaultPanel = 0;
private int mDuration = DEFAULT_DURATION;
private float mTouchSlop;
private float mDownMotionY;
private float mDownMotionX;
private float mInitialInterceptY;
public void setPercent(float percent) {
mPercent = percent;
}
private float mPercent = DEFAULT_PERCENT;
/**
* flag for listview or scrollview ,if child overscrolled ,do not judge view region 滚过头了，还是可以滚动
*/
private boolean mChildHasScrolled;
private View mUpstairsView;
private View mDownstairsView;
private View mCurrentTargetView;
private Scroller mScroller;
private VelocityTracker mVelocityTracker;
private OnSlideFinishListener mOnSlideDetailsListener;
private CurrentTargetIndex mCurrentViewIndex = CurrentTargetIndex.UPSTAIRS;
public DragScrollDetailsLayout(Context context) {
this(context, null);
}
public DragScrollDetailsLayout(Context context, AttributeSet attrs) {
this(context, attrs, 0);
}
public DragScrollDetailsLayout(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.DragScrollDetailsLayout, defStyleAttr, 0);
mPercent = a.getFloat(R.styleable.DragScrollDetailsLayout_percent, DEFAULT_PERCENT);
mDuration = a.getInt(R.styleable.DragScrollDetailsLayout_duration, DEFAULT_DURATION);
mDefaultPanel = a.getInt(R.styleable.DragScrollDetailsLayout_default_panel, 0);
a.recycle();
mScroller = new Scroller(getContext(),new DecelerateInterpolator());
mTouchSlop = ViewConfiguration.get(getContext()).getScaledTouchSlop();
mMaxFlingVelocity = ViewConfiguration.get(getContext()).getScaledMaximumFlingVelocity();
mMiniFlingVelocity = ViewConfiguration.get(getContext()).getScaledMinimumFlingVelocity();
setOrientation(VERTICAL);
}
public void setOnSlideDetailsListener(OnSlideFinishListener listener) {
this.mOnSlideDetailsListener = listener;
}
@Override
protected void onFinishInflate() {
super.onFinishInflate();
final int childCount = getChildCount();
if (1 >= childCount) {
throw new RuntimeException("SlideDetailsLayout only accept childs more than 1!!");
}
mUpstairsView = getChildAt(0);
mDownstairsView = getChildAt(1);
}
/**
* requestDisallowInterceptTouchEvent guarantee DragScrollDetailsLayout intercept event as wish
*/
@Override
public boolean dispatchTouchEvent(MotionEvent ev) {
requestDisallowInterceptTouchEvent(false);
return super.dispatchTouchEvent(ev);
}
/**
* intercept rules：
* 1. The vertical displacement is larger than the horizontal displacement;
* 2. Panel stauts is UPSTAIRS： slide up
* 3. Panel status is DOWNSTAIRS：slide down
* 4. child can requestDisallowInterceptTouchEvent();
*/
@Override
public boolean onInterceptTouchEvent(MotionEvent ev) {
switch (ev.getActionMasked()) {
case MotionEvent.ACTION_DOWN:
mDownMotionX = ev.getX();
mDownMotionY = ev.getY();
if (mVelocityTracker == null) {
mVelocityTracker = VelocityTracker.obtain();
}
mVelocityTracker.clear();
mChildHasScrolled=false;
break;
case MotionEvent.ACTION_MOVE:
adjustValidDownPoint(ev);
return checkCanInterceptTouchEvent(ev);
default:
break;
}
return false;
}
@Override
public boolean onTouchEvent(MotionEvent ev) {
switch (ev.getActionMasked()) {
case MotionEvent.ACTION_UP:
case MotionEvent.ACTION_CANCEL:
flingToFinishScroll();
recycleVelocityTracker();
break;
case MotionEvent.ACTION_MOVE:
scroll(ev);
break;
default:
break;
}
return true;
}
private boolean checkCanInterceptTouchEvent(MotionEvent ev) {
final float xDiff = ev.getX() - mDownMotionX;
final float yDiff = ev.getY() - mDownMotionY;
if (!canChildScrollVertically((int) yDiff,ev)) {
mInitialInterceptY = (int) ev.getY();
if (Math.abs(yDiff) > mTouchSlop && Math.abs(yDiff) >= Math.abs(xDiff)
&& !(mCurrentViewIndex == CurrentTargetIndex.UPSTAIRS && yDiff > 0
|| mCurrentViewIndex == CurrentTargetIndex.DOWNSTAIRS && yDiff < 0)) {
return true;
}
}
return false;
}
private void adjustValidDownPoint(MotionEvent event) {
if (mCurrentViewIndex == CurrentTargetIndex.UPSTAIRS && event.getY() > mDownMotionY
|| mCurrentViewIndex == CurrentTargetIndex.DOWNSTAIRS && event.getY() < mDownMotionY) {
mDownMotionX = event.getX();
mDownMotionY = event.getY();
}
}
private void scroll(MotionEvent event) {
if (mCurrentViewIndex == CurrentTargetIndex.UPSTAIRS) {
if (getScrollY() <= 0 && event.getY() > mInitialInterceptY) {
mInitialInterceptY = (int) event.getY();
}
scrollTo(0, (int) (mInitialInterceptY - event.getY()));
} else {
if (getScrollY() >= mUpstairsView.getMeasuredHeight() && event.getY() < mInitialInterceptY) {
mInitialInterceptY = (int) event.getY();
}
scrollTo(0, (int) (mInitialInterceptY - event.getY() + mUpstairsView.getMeasuredHeight()));
}
mVelocityTracker.addMovement(event);
}
private void recycleVelocityTracker() {
if (mVelocityTracker != null) {
mVelocityTracker.clear();
mVelocityTracker.recycle();
mVelocityTracker = null;
}
}
/**
* if speed is enough even though offset is not enough go
*/
private void flingToFinishScroll() {
final int pHeight = mUpstairsView.getMeasuredHeight();
final int threshold = (int) (pHeight * mPercent);
float scrollY = getScrollY();
if (CurrentTargetIndex.UPSTAIRS == mCurrentViewIndex) {
if (scrollY <= 0) {
scrollY = 0;
} else if (scrollY <= threshold) {
if (needFlingToToggleView()) {
scrollY = pHeight - getScrollY();
mCurrentViewIndex = CurrentTargetIndex.DOWNSTAIRS;
} else
scrollY = -getScrollY();
} else {
scrollY = pHeight - getScrollY();
mCurrentViewIndex = CurrentTargetIndex.DOWNSTAIRS;
}
} else if (CurrentTargetIndex.DOWNSTAIRS == mCurrentViewIndex) {
if (pHeight - scrollY <= threshold) {
if (needFlingToToggleView()) {
scrollY = -getScrollY();
mCurrentViewIndex = CurrentTargetIndex.UPSTAIRS;
} else
scrollY = pHeight - scrollY;
} else if (scrollY < pHeight) {
scrollY = -getScrollY();
mCurrentViewIndex = CurrentTargetIndex.UPSTAIRS;
}
}
mScroller.startScroll(0, getScrollY(), 0, (int) scrollY, mDuration);
if (mOnSlideDetailsListener != null) {
mOnSlideDetailsListener.onStatueChanged(mCurrentViewIndex);
}
postInvalidate();
}
private boolean needFlingToToggleView() {
mVelocityTracker.computeCurrentVelocity(1000, mMaxFlingVelocity);
if (mCurrentViewIndex == CurrentTargetIndex.UPSTAIRS) {
if (-mVelocityTracker.getYVelocity() > mMiniFlingVelocity) {
return true;
}
} else {
if (mVelocityTracker.getYVelocity() > mMiniFlingVelocity) {
return true;
}
}
return false;
}
private View getCurrentTargetView() {
return mCurrentViewIndex == CurrentTargetIndex.UPSTAIRS
? mUpstairsView : mDownstairsView;
}
@Override
public void computeScroll() {
super.computeScroll();
if (mScroller.computeScrollOffset()) {
scrollTo(0, mScroller.getCurrY());
postInvalidate();
}
}
/***
* 复用已经实现的View，省却了测量布局之类的麻烦
*/
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
measureChildren(widthMeasureSpec, heightMeasureSpec);
setMeasuredDimension(getMeasuredWidth(), getMeasuredHeight());
}
protected boolean canChildScrollVertically(int offSet,MotionEvent ev) {
mCurrentTargetView = getCurrentTargetView();
return canScrollVertically(mCurrentTargetView, -offSet, ev);
}
/***
* judge is event is in current view
* 判断MotionEvent是否处于View上面
*/
protected boolean isTransformedTouchPointInView(MotionEvent ev, View view) {
float x = ev.getRawX();
float y = ev.getRawY();
int[] rect = new int[2];
view.getLocationInWindow(rect);
float localX = x - rect[0];
float localY = y - rect[1];
return localX >= 0 && localX < (view.getRight() - view.getLeft())
&& localY >= 0 && localY < (view.getBottom() - view.getTop());
}
/***
* first can view self ScrollVertically
* seconde if View is ViewPager only judge current page
* third if view is viewgroup check it`s children
*/
private boolean canScrollVertically(View view, int offSet, MotionEvent ev) {
if (!mChildHasScrolled && !isTransformedTouchPointInView(ev, view)) {
return false;
}
if (ViewCompat.canScrollVertically(view, offSet)) {
mChildHasScrolled = true;
return true;
}
if (view instanceof ViewPager) {
return canViewPagerScrollVertically((ViewPager) view, offSet, ev);
}
if (view instanceof ViewGroup) {
ViewGroup vGroup = (ViewGroup) view;
for (int i = 0; i < vGroup.getChildCount(); i++) {
if (canScrollVertically(vGroup.getChildAt(i), offSet, ev)) {
mChildHasScrolled = true;
return true;
}
}
}
return false;
}
private boolean canViewPagerScrollVertically(ViewPager viewPager, int offset,MotionEvent ev) {
View showView = ((SlideFragmentPagerAdapter) viewPager.getAdapter()).getPrimaryItem();
return showView != null && canScrollVertically(showView, offset, ev);
}
@Override
protected void onScrollChanged(int l, int t, int oldl, int oldt) {
super.onScrollChanged(l, t, oldl, oldt);
}
}
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