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@Dmuasya

Dmuasya/StickyNavLayout.java Secret

Created Dec 23, 2020
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package com.quick.lib;
import android.content.Context;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentPagerAdapter;
import android.support.v4.app.FragmentStatePagerAdapter;
import android.support.v4.view.PagerAdapter;
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.widget.LinearLayout;
import android.widget.OverScroller;
import android.widget.ScrollView;
public class StickyNavLayout extends LinearLayout {
private View mTop;
private View mNav;
private ViewPager mViewPager;
private int mTopViewHeight;
OverScroller mScroller;
private boolean isTopHidden = false;
private ScrollView mInnerScrollView;
private VelocityTracker mVelocityTracker;
private int mMaximumVelocity, mMinimumVelocity;
float lastX=0;
float lastY = 0;
float dy = 0;
float dx=0;
private int mTouchSlop;
boolean onIntercept;
public StickyNavLayout(Context context, AttributeSet attrs) {
super(context, attrs);
setOrientation(LinearLayout.VERTICAL);
mScroller = new OverScroller(context);
mTouchSlop = ViewConfiguration.get(context).getScaledTouchSlop();//获得能够进行手势滑动的距离
mMaximumVelocity = ViewConfiguration.get(context)
.getScaledMaximumFlingVelocity();
mMinimumVelocity = ViewConfiguration.get(context)
.getScaledMinimumFlingVelocity();
}
private void getCurrentScrollView() {
int currentItem = mViewPager.getCurrentItem();
PagerAdapter a = mViewPager.getAdapter();
if (a instanceof FragmentPagerAdapter) {
FragmentPagerAdapter fadapter = (FragmentPagerAdapter) a;
Fragment item = (Fragment) fadapter.instantiateItem(mViewPager,
currentItem);
mInnerScrollView = (ScrollView) (item.getView()
.findViewById(R.id.id_stickynavlayout_innerscrollview));
} else if (a instanceof FragmentStatePagerAdapter) {
FragmentStatePagerAdapter fsAdapter = (FragmentStatePagerAdapter) a;
Fragment item = (Fragment) fsAdapter.instantiateItem(mViewPager,
currentItem);
mInnerScrollView = (ScrollView) (item.getView()
.findViewById(R.id.id_stickynavlayout_innerscrollview));
}
}
@Override
protected void onFinishInflate() {
super.onFinishInflate();
mTop = findViewById(R.id.id_stickynavlayout_topview);
mNav = findViewById(R.id.id_stickynavlayout_indicator);
View view = findViewById(R.id.id_stickynavlayout_viewpager);
if (!(view instanceof ViewPager)) {
throw new RuntimeException(
"id_stickynavlayout_viewpager show used by ViewPager !");
}
mViewPager = (ViewPager) view;
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
ViewGroup.LayoutParams params = mViewPager.getLayoutParams();
/**Because StickyNavLayout is match_parent, getMeasuredHeight() is equal to screen height-status bar height
*
*/
params.height = getMeasuredHeight() - mNav.getMeasuredHeight();
mTopViewHeight = mTop.getMeasuredHeight();
}
/**
* When is it necessary to intercept and when does it need to be intercepted?
*/
@Override
public boolean dispatchTouchEvent(MotionEvent ev) {
int action = ev.getAction();
float x = ev.getX();
float y = ev.getY();
switch (action) {
case MotionEvent.ACTION_DOWN:
lastX=x;
lastY = y;
break;
case MotionEvent.ACTION_MOVE:
dx=x-lastX;
dy = y - lastY;
lastX = x;
lastY = y;
getCurrentScrollView();
if(onIntercept){
//If it is horizontal sliding
if(Math.abs(dx)>Math.abs(dy)){
onIntercept =false;
}else{
// If the topView is hidden and slides up, the current event is changed to ACTION_DOWN
if (isTopHidden && dy < 0) {
onIntercept = false;
ev.setAction(MotionEvent.ACTION_DOWN); //Manually call the dispatch event
dispatchTouchEvent(ev);//Send events manually
}
}
}else{
//Vertical sliding
if(Math.abs(dy)>Math.abs(dx)){
// If topView is not hidden
// Or sc listView at the top && topView hide && drop down, then intercept
if(!isTopHidden||(isTopHidden&&dy > 0 && mInnerScrollView.getScrollY() == 0 )){
onIntercept=true;
ev.setAction(MotionEvent.ACTION_DOWN);
dispatchTouchEvent(ev);
}
}
}
break;
}
return super.dispatchTouchEvent(ev);
}
@Override
public boolean onInterceptTouchEvent(MotionEvent ev) {
int action = ev.getAction();
switch (action) {
case MotionEvent.ACTION_MOVE:
if (onIntercept) {
return true;
}
}
return super.onInterceptTouchEvent(ev);
}
@Override
public boolean onTouchEvent(MotionEvent event) {
initVelocityTrackerIfNotExists();
mVelocityTracker.addMovement(event);
int action = event.getAction();
switch (action) {
case MotionEvent.ACTION_DOWN:
if (!mScroller.isFinished()) {
mScroller.abortAnimation();
}
break;
case MotionEvent.ACTION_MOVE:
scrollBy(0, (int) -dy);
break;
case MotionEvent.ACTION_CANCEL:
recycleVelocityTracker();
if (!mScroller.isFinished()) {
mScroller.abortAnimation();
}
break;
case MotionEvent.ACTION_UP:
mVelocityTracker.computeCurrentVelocity(1000, mMaximumVelocity);//How many pixels are moved in a unit time of 1 second
int velocityY = (int) mVelocityTracker.getYVelocity();//Get speed in y direction
if (Math.abs(velocityY) > mMinimumVelocity) {
fling(-velocityY);
}
recycleVelocityTracker();
break;
}
return true;
}
public void fling(int velocityY) {
/*
fling(int startX, int startY, int velocityX, int velocityY,int minX, int maxX, int minY, int maxY)
*/
mScroller.fling(0, getScrollY(), 0, velocityY, 0, 0, 0, mTopViewHeight);
invalidate();
}
@Override
public void scrollTo(int x, int y) {
super.scrollTo(x, y);
if (getScrollY() > mTopViewHeight) {
setScrollY(mTopViewHeight);
}
if (getScrollY() < 0) {
setScrollY(0);
}
isTopHidden = (getScrollY() == mTopViewHeight);
}
@Override
public void computeScroll() {
super.computeScroll();
if (mScroller.computeScrollOffset()) {
scrollTo(0, mScroller.getCurrY());
invalidate();
}
}
private void initVelocityTrackerIfNotExists() {
if (mVelocityTracker == null) {
mVelocityTracker = VelocityTracker.obtain();
}
}
private void recycleVelocityTracker() {
if (mVelocityTracker != null) {
mVelocityTracker.recycle();
mVelocityTracker = null;
}
}
}
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