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Add ViewPager2 fragment
Update DynamicFrameLayout to support nested scrolling in same direction inside a ViewPager2.
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‎dynamic-support/src/main/java/com/pranavpandey/android/dynamic/support/fragment/DynamicViewPager2Fragment.java

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/*
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* Copyright 2019 Pranav Pandey
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.pranavpandey.android.dynamic.support.fragment;
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import android.os.Bundle;
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import android.view.LayoutInflater;
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import android.view.View;
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import android.view.ViewGroup;
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import androidx.annotation.NonNull;
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import androidx.annotation.Nullable;
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import androidx.fragment.app.Fragment;
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import androidx.viewpager.widget.ViewPager;
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import androidx.viewpager2.widget.ViewPager2;
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import com.google.android.material.tabs.TabLayout;
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import com.google.android.material.tabs.TabLayoutMediator;
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import com.pranavpandey.android.dynamic.support.R;
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import com.pranavpandey.android.dynamic.support.activity.DynamicActivity;
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import com.pranavpandey.android.dynamic.support.adapter.DynamicFragmentStateAdapter;
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import com.pranavpandey.android.dynamic.support.listener.DynamicViewPagerCallback;
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/**
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* An abstract {@link ViewPager} fragment to display multiple fragments inside the view pager
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* along with the tabs.
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* <p>Just extend this fragment and implement the necessary methods to use it inside an activity.
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*/
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public abstract class DynamicViewPager2Fragment extends
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DynamicFragment implements DynamicViewPagerCallback {
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/**
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* Fragment argument key to set the initial view pager page.
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*/
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public static String ADS_ARGS_VIEW_PAGER_PAGE = "ads_args_view_pager_page";
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/**
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* View pager used by this fragment.
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*/
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private ViewPager2 mViewPager;
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/**
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* Tab layout used by this fragment.
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*/
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private TabLayout mTabLayout;
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/**
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* View pager adapter used by this fragment.
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*/
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private ViewPagerAdapter mAdapter;
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@Override
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public void onCreate(@Nullable Bundle savedInstanceState) {
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super.onCreate(savedInstanceState);
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setRetainInstance(false);
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}
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@Override
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public View onCreateView(@NonNull LayoutInflater inflater,
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@Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
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return inflater.inflate(R.layout.ads_fragment_view_pager_2, container, false);
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}
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@Override
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public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
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super.onViewCreated(view, savedInstanceState);
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mViewPager = view.findViewById(R.id.ads_view_pager);
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}
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@Override
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public void onActivityCreated(@Nullable Bundle savedInstanceState) {
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super.onActivityCreated(savedInstanceState);
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((DynamicActivity) getActivity()).addHeader(R.layout.ads_tabs, true);
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mTabLayout = getActivity().findViewById(R.id.ads_tab_layout);
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mAdapter = new ViewPagerAdapter(this, this);
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mViewPager.setOffscreenPageLimit(mAdapter.getItemCount());
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mViewPager.setAdapter(mAdapter);
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new TabLayoutMediator(mTabLayout, mViewPager,
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new TabLayoutMediator.TabConfigurationStrategy() {
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@Override
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public void onConfigureTab(@NonNull TabLayout.Tab tab, int position) {
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tab.setText(getTitle(position));
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}
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}).attach();
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if (getArguments() != null && getArguments().containsKey(ADS_ARGS_VIEW_PAGER_PAGE)) {
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setPage(getArguments().getInt(ADS_ARGS_VIEW_PAGER_PAGE));
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}
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}
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/**
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* Get the tab layout used by this fragment.
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*
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* @return The tab layout used by this fragment.
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*/
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public TabLayout getTabLayout() {
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return mTabLayout;
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}
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/**
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* Get the view pager used by this fragment.
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*
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* @return The view pager used by this fragment.
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*/
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public ViewPager2 getViewPager() {
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return mViewPager;
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}
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/**
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* Returns the currently selected view pager page or position.
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*
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* @return The currently selected view pager page or position.
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*/
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public int getCurrentPage() {
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return mViewPager.getCurrentItem();
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}
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/**
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* Set the current page or position for the view pager.
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*
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* @param page The current position for the view pager.
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*/
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public void setPage(final int page) {
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mViewPager.setCurrentItem(page);
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}
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/**
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* View pager adapter to display the supplied fragments with tab titles.
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*/
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static class ViewPagerAdapter extends DynamicFragmentStateAdapter {
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private final DynamicViewPagerCallback dynamicViewPagerCallback;
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/**
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* Constructor to initialize an object of this class.
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*
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* @param fragment The fragment manager to get the child fragment manager.
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* @param dynamicViewPagerCallback The view pager callback to return the data.
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*/
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ViewPagerAdapter(@NonNull Fragment fragment,
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@NonNull DynamicViewPagerCallback dynamicViewPagerCallback) {
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super(fragment);
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this.dynamicViewPagerCallback = dynamicViewPagerCallback;
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}
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@Override
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public @NonNull Fragment createFragment(int position) {
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return dynamicViewPagerCallback.createFragment(position);
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}
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@Override
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public int getItemCount() {
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return dynamicViewPagerCallback.getItemCount();
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}
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}
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}

‎dynamic-support/src/main/java/com/pranavpandey/android/dynamic/support/listener/DynamicViewPagerCallback.java

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/*
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* Copyright 2020 Pranav Pandey
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.pranavpandey.android.dynamic.support.listener;
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import androidx.annotation.NonNull;
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import androidx.annotation.Nullable;
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import androidx.fragment.app.Fragment;
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/**
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* An interface to return the data for {@link androidx.viewpager2.widget.ViewPager2} using
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* {@link com.pranavpandey.android.dynamic.support.adapter.DynamicFragmentStateAdapter}.
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*/
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public interface DynamicViewPagerCallback {
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/**
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* This method will be called to return the tab title for the supplied position.
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*
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* @param position The current position of the adapter.
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*
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* @return The tab title for the supplied position.
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*/
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@Nullable String getTitle(int position);
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/**
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* This method will be called on creating the fragment for the supplied position.
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*
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* @param position The current position of the adapter.
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*
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* @return The fragment for the supplied position.
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*/
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@NonNull Fragment createFragment(int position);
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/**
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* This method will be called to get the item count for the adapter.
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*
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* @return The item count for the adapter.
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*/
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int getItemCount();
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}

‎dynamic-support/src/main/java/com/pranavpandey/android/dynamic/support/widget/DynamicFrameLayout.java

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import android.content.res.TypedArray;
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import android.graphics.drawable.ColorDrawable;
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import android.util.AttributeSet;
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import android.view.MotionEvent;
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import android.view.View;
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import android.view.ViewConfiguration;
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import android.widget.FrameLayout;
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import androidx.annotation.AttrRes;
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import androidx.annotation.ColorInt;
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import androidx.annotation.NonNull;
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import androidx.annotation.Nullable;
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import androidx.viewpager2.widget.ViewPager2;
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import com.pranavpandey.android.dynamic.support.R;
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import com.pranavpandey.android.dynamic.support.theme.DynamicTheme;
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*/
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private @Theme.BackgroundAware int mBackgroundAware;
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/**
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* Scaled touch slop used by the view configuration.
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*/
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private int mTouchSlop;
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/**
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* Initial horizontal position.
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*/
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private float mInitialX;
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/**
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* Initial vertical position.
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*/
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private float mInitialY;
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public DynamicFrameLayout(@NonNull Context context) {
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this(context, null);
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}
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a.recycle();
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}
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mTouchSlop = ViewConfiguration.get(getContext()).getScaledTouchSlop();
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initialize();
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}
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DynamicDrawableUtils.setBackground(this, new ColorDrawable(mColor));
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}
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}
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@Override
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public boolean onInterceptTouchEvent(MotionEvent ev) {
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handleInterceptTouchEvent(ev);
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return super.onInterceptTouchEvent(ev);
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}
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/**
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* Checks whether a child can be scrolled.
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*
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* @param orientation The current orientation of the view.
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* @param delta The delta to check the scrolling.
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*
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* @return Returns {@code true} if a child can be scrolled.
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*/
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private boolean canChildScroll(int orientation, float delta) {
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if (getChildCount() <= 0) {
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return false;
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}
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int direction = -((int) Math.signum(delta));
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switch (orientation) {
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default:
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throw new IllegalArgumentException();
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case ViewPager2.ORIENTATION_HORIZONTAL:
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return getChildAt(0).canScrollHorizontally(direction);
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case ViewPager2.ORIENTATION_VERTICAL:
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return getChildAt(0).canScrollVertically(direction);
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}
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}
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/**
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* Returns the parent view pager for this view.
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*/
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private @Nullable ViewPager2 getParentViewPager() {
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if (!(getParent() instanceof View)) {
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return null;
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}
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View view = (View) getParent();
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while (view != null && !(view instanceof ViewPager2)) {
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if (view.getParent() instanceof View) {
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view = (View) view.getParent();
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} else {
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view = null;
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}
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}
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return (view instanceof ViewPager2) ? (ViewPager2) view : null;
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}
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/**
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* Handle touch event to support nested {@link ViewPager2} scrolling.
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*
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* @param ev The motion event being dispatched down the hierarchy.
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*/
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private void handleInterceptTouchEvent(@Nullable MotionEvent ev) {
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ViewPager2 viewPager2 = getParentViewPager();
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if (ev == null || viewPager2 == null) {
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return;
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}
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int orientation = viewPager2.getOrientation();
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// Early return if child can't scroll in same direction as parent.
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if (!canChildScroll(orientation, -1.0f) && !canChildScroll(orientation, 1.0f)) {
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return;
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}
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if (ev.getAction() == MotionEvent.ACTION_DOWN) {
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mInitialX = ev.getX();
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mInitialY = ev.getY();
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getParent().requestDisallowInterceptTouchEvent(true);
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} else if (ev.getAction() == MotionEvent.ACTION_MOVE) {
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float dx = ev.getX() - mInitialX;
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float dy = ev.getY() - mInitialY;
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boolean isVpHorizontal = orientation == ViewPager2.ORIENTATION_HORIZONTAL;
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// Assuming ViewPager2 touch-slop is 2x touch-slop of child.
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float scaledDx = Math.abs(dx) * (isVpHorizontal ? 0.5f : 1.0f);
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float scaledDy = Math.abs(dy) * (isVpHorizontal ? 1.0f : 0.5f);
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if (scaledDx > mTouchSlop || scaledDy > mTouchSlop) {
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if (isVpHorizontal == (scaledDy > scaledDx)) {
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// Gesture is perpendicular, allow all parents to intercept.
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getParent().requestDisallowInterceptTouchEvent(false);
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} else {
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if (canChildScroll(orientation, isVpHorizontal ? dx : dy)) {
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// Child can scroll, disallow all parents to intercept.
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getParent().requestDisallowInterceptTouchEvent(true);
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} else {
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// Child cannot scroll, allow all parents to intercept.
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getParent().requestDisallowInterceptTouchEvent(false);
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}
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}
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}
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}
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}
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}

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