appcompat/appcompat/src/main/java/androidx/appcompat/widget/ScrollingTabContainerView.java - platform/frameworks/support - Git at Google

 /*
  * Copyright (C) 2011 The Android Open Source Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *      http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
 package androidx.appcompat.widget;

 import static androidx.annotation.RestrictTo.Scope.LIBRARY_GROUP_PREFIX;

 import android.animation.Animator;
 import android.animation.AnimatorListenerAdapter;
 import android.content.Context;
 import android.content.res.Configuration;
 import android.graphics.drawable.Drawable;
 import android.text.TextUtils;
 import android.text.TextUtils.TruncateAt;
 import android.view.Gravity;
 import android.view.View;
 import android.view.ViewGroup;
 import android.view.ViewParent;
 import android.view.ViewPropertyAnimator;
 import android.view.accessibility.AccessibilityEvent;
 import android.view.accessibility.AccessibilityNodeInfo;
 import android.view.animation.DecelerateInterpolator;
 import android.view.animation.Interpolator;
 import android.widget.AdapterView;
 import android.widget.BaseAdapter;
 import android.widget.HorizontalScrollView;
 import android.widget.ImageView;
 import android.widget.LinearLayout;
 import android.widget.ListView;
 import android.widget.Spinner;
 import android.widget.TextView;

 import androidx.annotation.NonNull;
 import androidx.annotation.RestrictTo;
 import androidx.appcompat.R;
 import androidx.appcompat.app.ActionBar;
 import androidx.appcompat.view.ActionBarPolicy;
 import androidx.core.view.GravityCompat;

 /**
  * This widget implements the dynamic action bar tab behavior that can change across different
  * configurations or circumstances.
  *
  * @hide
  */
 @RestrictTo(LIBRARY_GROUP_PREFIX)
 public class ScrollingTabContainerView extends HorizontalScrollView
         implements AdapterView.OnItemSelectedListener {

     private static final String TAG = "ScrollingTabContainerView";
     Runnable mTabSelector;
     private TabClickListener mTabClickListener;

     LinearLayoutCompat mTabLayout;
     private Spinner mTabSpinner;
     private boolean mAllowCollapse;

     int mMaxTabWidth;
     int mStackedTabMaxWidth;
     private int mContentHeight;
     private int mSelectedTabIndex;

     protected ViewPropertyAnimator mVisibilityAnim;
     protected final VisibilityAnimListener mVisAnimListener = new VisibilityAnimListener();

     private static final Interpolator sAlphaInterpolator = new DecelerateInterpolator();

     private static final int FADE_DURATION = 200;

     public ScrollingTabContainerView(@NonNull Context context) {
         super(context);

         setHorizontalScrollBarEnabled(false);

         ActionBarPolicy abp = ActionBarPolicy.get(context);
         setContentHeight(abp.getTabContainerHeight());
         mStackedTabMaxWidth = abp.getStackedTabMaxWidth();

         mTabLayout = createTabLayout();
         addView(mTabLayout, new ViewGroup.LayoutParams(ViewGroup.LayoutParams.WRAP_CONTENT,
                 ViewGroup.LayoutParams.MATCH_PARENT));
     }

     @Override
     public void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
         final int widthMode = MeasureSpec.getMode(widthMeasureSpec);
         final boolean lockedExpanded = widthMode == MeasureSpec.EXACTLY;
         setFillViewport(lockedExpanded);

         final int childCount = mTabLayout.getChildCount();
         if (childCount > 1 &&
                 (widthMode == MeasureSpec.EXACTLY || widthMode == MeasureSpec.AT_MOST)) {
             if (childCount > 2) {
                 mMaxTabWidth = (int) (MeasureSpec.getSize(widthMeasureSpec) * 0.4f);
             } else {
                 mMaxTabWidth = MeasureSpec.getSize(widthMeasureSpec) / 2;
             }
             mMaxTabWidth = Math.min(mMaxTabWidth, mStackedTabMaxWidth);
         } else {
             mMaxTabWidth = -1;
         }

         heightMeasureSpec = MeasureSpec.makeMeasureSpec(mContentHeight, MeasureSpec.EXACTLY);

         final boolean canCollapse = !lockedExpanded && mAllowCollapse;

         if (canCollapse) {
             // See if we should expand
             mTabLayout.measure(MeasureSpec.UNSPECIFIED, heightMeasureSpec);
             if (mTabLayout.getMeasuredWidth() > MeasureSpec.getSize(widthMeasureSpec)) {
                 performCollapse();
             } else {
                 performExpand();
             }
         } else {
             performExpand();
         }

         final int oldWidth = getMeasuredWidth();
         super.onMeasure(widthMeasureSpec, heightMeasureSpec);
         final int newWidth = getMeasuredWidth();

         if (lockedExpanded && oldWidth != newWidth) {
             // Recenter the tab display if we're at a new (scrollable) size.
             setTabSelected(mSelectedTabIndex);
         }
     }

     /**
      * Indicates whether this view is collapsed into a dropdown menu instead
      * of traditional tabs.
      * @return true if showing as a spinner
      */
     private boolean isCollapsed() {
         return mTabSpinner != null && mTabSpinner.getParent() == this;
     }

     public void setAllowCollapse(boolean allowCollapse) {
         mAllowCollapse = allowCollapse;
     }

     private void performCollapse() {
         if (isCollapsed()) return;

         if (mTabSpinner == null) {
             mTabSpinner = createSpinner();
         }
         removeView(mTabLayout);
         addView(mTabSpinner, new ViewGroup.LayoutParams(ViewGroup.LayoutParams.WRAP_CONTENT,
                 ViewGroup.LayoutParams.MATCH_PARENT));
         if (mTabSpinner.getAdapter() == null) {
             mTabSpinner.setAdapter(new TabAdapter());
         }
         if (mTabSelector != null) {
             removeCallbacks(mTabSelector);
             mTabSelector = null;
         }
         mTabSpinner.setSelection(mSelectedTabIndex);
     }

     private boolean performExpand() {
         if (!isCollapsed()) return false;

         removeView(mTabSpinner);
         addView(mTabLayout, new ViewGroup.LayoutParams(ViewGroup.LayoutParams.WRAP_CONTENT,
                 ViewGroup.LayoutParams.MATCH_PARENT));
         setTabSelected(mTabSpinner.getSelectedItemPosition());
         return false;
     }

     public void setTabSelected(int position) {
         mSelectedTabIndex = position;
         final int tabCount = mTabLayout.getChildCount();
         for (int i = 0; i < tabCount; i++) {
             final View child = mTabLayout.getChildAt(i);
             final boolean isSelected = i == position;
             child.setSelected(isSelected);
             if (isSelected) {
                 animateToTab(position);
             }
         }
         if (mTabSpinner != null && position >= 0) {
             mTabSpinner.setSelection(position);
         }
     }

     public void setContentHeight(int contentHeight) {
         mContentHeight = contentHeight;
         requestLayout();
     }

     private LinearLayoutCompat createTabLayout() {
         final LinearLayoutCompat tabLayout = new LinearLayoutCompat(getContext(), null,
                 R.attr.actionBarTabBarStyle);
         tabLayout.setMeasureWithLargestChildEnabled(true);
         tabLayout.setGravity(Gravity.CENTER);
         tabLayout.setLayoutParams(new LinearLayoutCompat.LayoutParams(
                 LinearLayoutCompat.LayoutParams.WRAP_CONTENT, LinearLayoutCompat.LayoutParams.MATCH_PARENT));
         return tabLayout;
     }

     private Spinner createSpinner() {
         final Spinner spinner = new AppCompatSpinner(getContext(), null,
                 R.attr.actionDropDownStyle);
         spinner.setLayoutParams(new LinearLayoutCompat.LayoutParams(
                 LinearLayoutCompat.LayoutParams.WRAP_CONTENT,
                 LinearLayoutCompat.LayoutParams.MATCH_PARENT));
         spinner.setOnItemSelectedListener(this);
         return spinner;
     }

     @Override
     protected void onConfigurationChanged(Configuration newConfig) {
         super.onConfigurationChanged(newConfig);

         ActionBarPolicy abp = ActionBarPolicy.get(getContext());
         // Action bar can change size on configuration changes.
         // Reread the desired height from the theme-specified style.
         setContentHeight(abp.getTabContainerHeight());
         mStackedTabMaxWidth = abp.getStackedTabMaxWidth();
     }

     public void animateToVisibility(int visibility) {
         if (mVisibilityAnim != null) {
             mVisibilityAnim.cancel();
         }
         if (visibility == VISIBLE) {
             if (getVisibility() != VISIBLE) {
                 setAlpha(0f);
             }

             ViewPropertyAnimator anim = animate().alpha(1f);
             anim.setDuration(FADE_DURATION);

             anim.setInterpolator(sAlphaInterpolator);
             anim.setListener(mVisAnimListener.withFinalVisibility(anim, visibility));
             anim.start();
         } else {
             ViewPropertyAnimator anim = animate().alpha(0f);
             anim.setDuration(FADE_DURATION);

             anim.setInterpolator(sAlphaInterpolator);
             anim.setListener(mVisAnimListener.withFinalVisibility(anim, visibility));
             anim.start();
         }
     }

     public void animateToTab(final int position) {
         final View tabView = mTabLayout.getChildAt(position);
         if (mTabSelector != null) {
             removeCallbacks(mTabSelector);
         }
         mTabSelector = new Runnable() {
             @Override
             public void run() {
                 final int scrollPos = tabView.getLeft() - (getWidth() - tabView.getWidth()) / 2;
                 smoothScrollTo(scrollPos, 0);
                 mTabSelector = null;
             }
         };
         post(mTabSelector);
     }

     @Override
     public void onAttachedToWindow() {
         super.onAttachedToWindow();
         if (mTabSelector != null) {
             // Re-post the selector we saved
             post(mTabSelector);
         }
     }

     @Override
     public void onDetachedFromWindow() {
         super.onDetachedFromWindow();
         if (mTabSelector != null) {
             removeCallbacks(mTabSelector);
         }
     }

     TabView createTabView(ActionBar.Tab tab, boolean forAdapter) {
         final TabView tabView = new TabView(getContext(), tab, forAdapter);
         if (forAdapter) {
             tabView.setBackgroundDrawable(null);
             tabView.setLayoutParams(new ListView.LayoutParams(ListView.LayoutParams.MATCH_PARENT,
                     mContentHeight));
         } else {
             tabView.setFocusable(true);

             if (mTabClickListener == null) {
                 mTabClickListener = new TabClickListener();
             }
             tabView.setOnClickListener(mTabClickListener);
         }
         return tabView;
     }

     public void addTab(ActionBar.Tab tab, boolean setSelected) {
         TabView tabView = createTabView(tab, false);
         mTabLayout.addView(tabView, new LinearLayoutCompat.LayoutParams(0,
                 LayoutParams.MATCH_PARENT, 1));
         if (mTabSpinner != null) {
             ((TabAdapter) mTabSpinner.getAdapter()).notifyDataSetChanged();
         }
         if (setSelected) {
             tabView.setSelected(true);
         }
         if (mAllowCollapse) {
             requestLayout();
         }
     }

     public void addTab(ActionBar.Tab tab, int position, boolean setSelected) {
         final TabView tabView = createTabView(tab, false);
         mTabLayout.addView(tabView, position, new LinearLayoutCompat.LayoutParams(
                 0, LayoutParams.MATCH_PARENT, 1));
         if (mTabSpinner != null) {
             ((TabAdapter) mTabSpinner.getAdapter()).notifyDataSetChanged();
         }
         if (setSelected) {
             tabView.setSelected(true);
         }
         if (mAllowCollapse) {
             requestLayout();
         }
     }

     public void updateTab(int position) {
         ((TabView) mTabLayout.getChildAt(position)).update();
         if (mTabSpinner != null) {
             ((TabAdapter) mTabSpinner.getAdapter()).notifyDataSetChanged();
         }
         if (mAllowCollapse) {
             requestLayout();
         }
     }

     public void removeTabAt(int position) {
         mTabLayout.removeViewAt(position);
         if (mTabSpinner != null) {
             ((TabAdapter) mTabSpinner.getAdapter()).notifyDataSetChanged();
         }
         if (mAllowCollapse) {
             requestLayout();
         }
     }

     public void removeAllTabs() {
         mTabLayout.removeAllViews();
         if (mTabSpinner != null) {
             ((TabAdapter) mTabSpinner.getAdapter()).notifyDataSetChanged();
         }
         if (mAllowCollapse) {
             requestLayout();
         }
     }

     @Override
     public void onItemSelected(AdapterView<?> adapterView, View view, int position, long id) {
         TabView tabView = (TabView) view;
         tabView.getTab().select();
     }

     @Override
     public void onNothingSelected(AdapterView<?> adapterView) {
         // no-op
     }

     private class TabView extends LinearLayout {
         private final int[] BG_ATTRS = {
                 android.R.attr.background
         };

         private ActionBar.Tab mTab;
         private TextView mTextView;
         private ImageView mIconView;
         private View mCustomView;

         // Class name may be obfuscated by Proguard. Hardcode the string for accessibility usage.
         private static final String ACCESSIBILITY_CLASS_NAME =
                 "androidx.appcompat.app.ActionBar$Tab";

         public TabView(Context context, ActionBar.Tab tab, boolean forList) {
             super(context, null, R.attr.actionBarTabStyle);
             mTab = tab;

             TintTypedArray a = TintTypedArray.obtainStyledAttributes(context, null, BG_ATTRS,
                     R.attr.actionBarTabStyle, 0);
             if (a.hasValue(0)) {
                 setBackgroundDrawable(a.getDrawable(0));
             }
             a.recycle();

             if (forList) {
                 setGravity(GravityCompat.START | Gravity.CENTER_VERTICAL);
             }

             update();
         }

         public void bindTab(ActionBar.Tab tab) {
             mTab = tab;
             update();
         }

         @Override
         public void setSelected(boolean selected) {
             final boolean changed = (isSelected() != selected);
             super.setSelected(selected);
             if (changed && selected) {
                 sendAccessibilityEvent(AccessibilityEvent.TYPE_VIEW_SELECTED);
             }
         }

         @Override
         public void onInitializeAccessibilityEvent(AccessibilityEvent event) {
             super.onInitializeAccessibilityEvent(event);
             // This view masquerades as an action bar tab.
             event.setClassName(ACCESSIBILITY_CLASS_NAME);
         }

         @Override
         public void onInitializeAccessibilityNodeInfo(AccessibilityNodeInfo info) {
             super.onInitializeAccessibilityNodeInfo(info);

             // This view masquerades as an action bar tab.
             info.setClassName(ACCESSIBILITY_CLASS_NAME);
         }

         @Override
         public void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
             super.onMeasure(widthMeasureSpec, heightMeasureSpec);

             // Re-measure if we went beyond our maximum size.
             if (mMaxTabWidth > 0 && getMeasuredWidth() > mMaxTabWidth) {
                 super.onMeasure(MeasureSpec.makeMeasureSpec(mMaxTabWidth, MeasureSpec.EXACTLY),
                         heightMeasureSpec);
             }
         }

         public void update() {
             final ActionBar.Tab tab = mTab;
             final View custom = tab.getCustomView();
             if (custom != null) {
                 final ViewParent customParent = custom.getParent();
                 if (customParent != this) {
                     if (customParent != null) ((ViewGroup) customParent).removeView(custom);
                     addView(custom);
                 }
                 mCustomView = custom;
                 if (mTextView != null) mTextView.setVisibility(GONE);
                 if (mIconView != null) {
                     mIconView.setVisibility(GONE);
                     mIconView.setImageDrawable(null);
                 }
             } else {
                 if (mCustomView != null) {
                     removeView(mCustomView);
                     mCustomView = null;
                 }

                 final Drawable icon = tab.getIcon();
                 final CharSequence text = tab.getText();

                 if (icon != null) {
                     if (mIconView == null) {
                         ImageView iconView = new AppCompatImageView(getContext());
                         LayoutParams lp = new LayoutParams(LayoutParams.WRAP_CONTENT,
                                 LayoutParams.WRAP_CONTENT);
                         lp.gravity = Gravity.CENTER_VERTICAL;
                         iconView.setLayoutParams(lp);
                         addView(iconView, 0);
                         mIconView = iconView;
                     }
                     mIconView.setImageDrawable(icon);
                     mIconView.setVisibility(VISIBLE);
                 } else if (mIconView != null) {
                     mIconView.setVisibility(GONE);
                     mIconView.setImageDrawable(null);
                 }

                 final boolean hasText = !TextUtils.isEmpty(text);
                 if (hasText) {
                     if (mTextView == null) {
                         TextView textView = new AppCompatTextView(getContext(), null,
                                 R.attr.actionBarTabTextStyle);
                         textView.setEllipsize(TruncateAt.END);
                         LayoutParams lp = new LayoutParams(LayoutParams.WRAP_CONTENT,
                                 LayoutParams.WRAP_CONTENT);
                         lp.gravity = Gravity.CENTER_VERTICAL;
                         textView.setLayoutParams(lp);
                         addView(textView);
                         mTextView = textView;
                     }
                     mTextView.setText(text);
                     mTextView.setVisibility(VISIBLE);
                 } else if (mTextView != null) {
                     mTextView.setVisibility(GONE);
                     mTextView.setText(null);
                 }

                 if (mIconView != null) {
                     mIconView.setContentDescription(tab.getContentDescription());
                 }
                 TooltipCompat.setTooltipText(this, hasText ? null : tab.getContentDescription());
             }
         }

         public ActionBar.Tab getTab() {
             return mTab;
         }
     }

     private class TabAdapter extends BaseAdapter {
         TabAdapter() {
         }

         @Override
         public int getCount() {
             return mTabLayout.getChildCount();
         }

         @Override
         public Object getItem(int position) {
             return ((TabView) mTabLayout.getChildAt(position)).getTab();
         }

         @Override
         public long getItemId(int position) {
             return position;
         }

         @Override
         public View getView(int position, View convertView, ViewGroup parent) {
             if (convertView == null) {
                 convertView = createTabView((ActionBar.Tab) getItem(position), true);
             } else {
                 ((TabView) convertView).bindTab((ActionBar.Tab) getItem(position));
             }
             return convertView;
         }
     }

     private class TabClickListener implements OnClickListener {
         TabClickListener() {
         }

         @Override
         public void onClick(View view) {
             TabView tabView = (TabView) view;
             tabView.getTab().select();
             final int tabCount = mTabLayout.getChildCount();
             for (int i = 0; i < tabCount; i++) {
                 final View child = mTabLayout.getChildAt(i);
                 child.setSelected(child == view);
             }
         }
     }

     protected class VisibilityAnimListener extends AnimatorListenerAdapter {
         private boolean mCanceled = false;
         private int mFinalVisibility;

         public VisibilityAnimListener withFinalVisibility(ViewPropertyAnimator animation,
                 int visibility) {
             mFinalVisibility = visibility;
             mVisibilityAnim = animation;
             return this;
         }

         @Override
         public void onAnimationStart(Animator animator) {
             setVisibility(VISIBLE);
             mCanceled = false;
         }

         @Override
         public void onAnimationEnd(Animator animator) {
             if (mCanceled) return;

             mVisibilityAnim = null;
             setVisibility(mFinalVisibility);
         }

         @Override
         public void onAnimationCancel(Animator animator) {
             mCanceled = true;
         }
     }
 }
	/*
	* Copyright (C) 2011 The Android Open Source Project
	*
	* Licensed under the Apache License, Version 2.0 (the "License");
	* you may not use this file except in compliance with the License.
	* You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/
	package androidx.appcompat.widget;

	import static androidx.annotation.RestrictTo.Scope.LIBRARY_GROUP_PREFIX;

	import android.animation.Animator;
	import android.animation.AnimatorListenerAdapter;
	import android.content.Context;
	import android.content.res.Configuration;
	import android.graphics.drawable.Drawable;
	import android.text.TextUtils;
	import android.text.TextUtils.TruncateAt;
	import android.view.Gravity;
	import android.view.View;
	import android.view.ViewGroup;
	import android.view.ViewParent;
	import android.view.ViewPropertyAnimator;
	import android.view.accessibility.AccessibilityEvent;
	import android.view.accessibility.AccessibilityNodeInfo;
	import android.view.animation.DecelerateInterpolator;
	import android.view.animation.Interpolator;
	import android.widget.AdapterView;
	import android.widget.BaseAdapter;
	import android.widget.HorizontalScrollView;
	import android.widget.ImageView;
	import android.widget.LinearLayout;
	import android.widget.ListView;
	import android.widget.Spinner;
	import android.widget.TextView;

	import androidx.annotation.NonNull;
	import androidx.annotation.RestrictTo;
	import androidx.appcompat.R;
	import androidx.appcompat.app.ActionBar;
	import androidx.appcompat.view.ActionBarPolicy;
	import androidx.core.view.GravityCompat;

	/**
	* This widget implements the dynamic action bar tab behavior that can change across different
	* configurations or circumstances.
	*
	* @hide
	*/
	@RestrictTo(LIBRARY_GROUP_PREFIX)
	public class ScrollingTabContainerView extends HorizontalScrollView
	implements AdapterView.OnItemSelectedListener {

	private static final String TAG = "ScrollingTabContainerView";
	Runnable mTabSelector;
	private TabClickListener mTabClickListener;

	LinearLayoutCompat mTabLayout;
	private Spinner mTabSpinner;
	private boolean mAllowCollapse;

	int mMaxTabWidth;
	int mStackedTabMaxWidth;
	private int mContentHeight;
	private int mSelectedTabIndex;

	protected ViewPropertyAnimator mVisibilityAnim;
	protected final VisibilityAnimListener mVisAnimListener = new VisibilityAnimListener();

	private static final Interpolator sAlphaInterpolator = new DecelerateInterpolator();

	private static final int FADE_DURATION = 200;

	public ScrollingTabContainerView(@NonNull Context context) {
	super(context);

	setHorizontalScrollBarEnabled(false);

	ActionBarPolicy abp = ActionBarPolicy.get(context);
	setContentHeight(abp.getTabContainerHeight());
	mStackedTabMaxWidth = abp.getStackedTabMaxWidth();

	mTabLayout = createTabLayout();
	addView(mTabLayout, new ViewGroup.LayoutParams(ViewGroup.LayoutParams.WRAP_CONTENT,
	ViewGroup.LayoutParams.MATCH_PARENT));
	}

	@Override
	public void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
	final int widthMode = MeasureSpec.getMode(widthMeasureSpec);
	final boolean lockedExpanded = widthMode == MeasureSpec.EXACTLY;
	setFillViewport(lockedExpanded);

	final int childCount = mTabLayout.getChildCount();
	if (childCount > 1 &&
	(widthMode == MeasureSpec.EXACTLY \|\| widthMode == MeasureSpec.AT_MOST)) {
	if (childCount > 2) {
	mMaxTabWidth = (int) (MeasureSpec.getSize(widthMeasureSpec) * 0.4f);
	} else {
	mMaxTabWidth = MeasureSpec.getSize(widthMeasureSpec) / 2;
	}
	mMaxTabWidth = Math.min(mMaxTabWidth, mStackedTabMaxWidth);
	} else {
	mMaxTabWidth = -1;
	}

	heightMeasureSpec = MeasureSpec.makeMeasureSpec(mContentHeight, MeasureSpec.EXACTLY);

	final boolean canCollapse = !lockedExpanded && mAllowCollapse;

	if (canCollapse) {
	// See if we should expand
	mTabLayout.measure(MeasureSpec.UNSPECIFIED, heightMeasureSpec);
	if (mTabLayout.getMeasuredWidth() > MeasureSpec.getSize(widthMeasureSpec)) {
	performCollapse();
	} else {
	performExpand();
	}
	} else {
	performExpand();
	}

	final int oldWidth = getMeasuredWidth();
	super.onMeasure(widthMeasureSpec, heightMeasureSpec);
	final int newWidth = getMeasuredWidth();

	if (lockedExpanded && oldWidth != newWidth) {
	// Recenter the tab display if we're at a new (scrollable) size.
	setTabSelected(mSelectedTabIndex);
	}
	}

	/**
	* Indicates whether this view is collapsed into a dropdown menu instead
	* of traditional tabs.
	* @return true if showing as a spinner
	*/
	private boolean isCollapsed() {
	return mTabSpinner != null && mTabSpinner.getParent() == this;
	}

	public void setAllowCollapse(boolean allowCollapse) {
	mAllowCollapse = allowCollapse;
	}

	private void performCollapse() {
	if (isCollapsed()) return;

	if (mTabSpinner == null) {
	mTabSpinner = createSpinner();
	}
	removeView(mTabLayout);
	addView(mTabSpinner, new ViewGroup.LayoutParams(ViewGroup.LayoutParams.WRAP_CONTENT,
	ViewGroup.LayoutParams.MATCH_PARENT));
	if (mTabSpinner.getAdapter() == null) {
	mTabSpinner.setAdapter(new TabAdapter());
	}
	if (mTabSelector != null) {
	removeCallbacks(mTabSelector);
	mTabSelector = null;
	}
	mTabSpinner.setSelection(mSelectedTabIndex);
	}

	private boolean performExpand() {
	if (!isCollapsed()) return false;

	removeView(mTabSpinner);
	addView(mTabLayout, new ViewGroup.LayoutParams(ViewGroup.LayoutParams.WRAP_CONTENT,
	ViewGroup.LayoutParams.MATCH_PARENT));
	setTabSelected(mTabSpinner.getSelectedItemPosition());
	return false;
	}

	public void setTabSelected(int position) {
	mSelectedTabIndex = position;
	final int tabCount = mTabLayout.getChildCount();
	for (int i = 0; i < tabCount; i++) {
	final View child = mTabLayout.getChildAt(i);
	final boolean isSelected = i == position;
	child.setSelected(isSelected);
	if (isSelected) {
	animateToTab(position);
	}
	}
	if (mTabSpinner != null && position >= 0) {
	mTabSpinner.setSelection(position);
	}
	}

	public void setContentHeight(int contentHeight) {
	mContentHeight = contentHeight;
	requestLayout();
	}

	private LinearLayoutCompat createTabLayout() {
	final LinearLayoutCompat tabLayout = new LinearLayoutCompat(getContext(), null,
	R.attr.actionBarTabBarStyle);
	tabLayout.setMeasureWithLargestChildEnabled(true);
	tabLayout.setGravity(Gravity.CENTER);
	tabLayout.setLayoutParams(new LinearLayoutCompat.LayoutParams(
	LinearLayoutCompat.LayoutParams.WRAP_CONTENT, LinearLayoutCompat.LayoutParams.MATCH_PARENT));
	return tabLayout;
	}

	private Spinner createSpinner() {
	final Spinner spinner = new AppCompatSpinner(getContext(), null,
	R.attr.actionDropDownStyle);
	spinner.setLayoutParams(new LinearLayoutCompat.LayoutParams(
	LinearLayoutCompat.LayoutParams.WRAP_CONTENT,
	LinearLayoutCompat.LayoutParams.MATCH_PARENT));
	spinner.setOnItemSelectedListener(this);
	return spinner;
	}

	@Override
	protected void onConfigurationChanged(Configuration newConfig) {
	super.onConfigurationChanged(newConfig);

	ActionBarPolicy abp = ActionBarPolicy.get(getContext());
	// Action bar can change size on configuration changes.
	// Reread the desired height from the theme-specified style.
	setContentHeight(abp.getTabContainerHeight());
	mStackedTabMaxWidth = abp.getStackedTabMaxWidth();
	}

	public void animateToVisibility(int visibility) {
	if (mVisibilityAnim != null) {
	mVisibilityAnim.cancel();
	}
	if (visibility == VISIBLE) {
	if (getVisibility() != VISIBLE) {
	setAlpha(0f);
	}

	ViewPropertyAnimator anim = animate().alpha(1f);
	anim.setDuration(FADE_DURATION);

	anim.setInterpolator(sAlphaInterpolator);
	anim.setListener(mVisAnimListener.withFinalVisibility(anim, visibility));
	anim.start();
	} else {
	ViewPropertyAnimator anim = animate().alpha(0f);
	anim.setDuration(FADE_DURATION);

	anim.setInterpolator(sAlphaInterpolator);
	anim.setListener(mVisAnimListener.withFinalVisibility(anim, visibility));
	anim.start();
	}
	}

	public void animateToTab(final int position) {
	final View tabView = mTabLayout.getChildAt(position);
	if (mTabSelector != null) {
	removeCallbacks(mTabSelector);
	}
	mTabSelector = new Runnable() {
	@Override
	public void run() {
	final int scrollPos = tabView.getLeft() - (getWidth() - tabView.getWidth()) / 2;
	smoothScrollTo(scrollPos, 0);
	mTabSelector = null;
	}
	};
	post(mTabSelector);
	}

	@Override
	public void onAttachedToWindow() {
	super.onAttachedToWindow();
	if (mTabSelector != null) {
	// Re-post the selector we saved
	post(mTabSelector);
	}
	}

	@Override
	public void onDetachedFromWindow() {
	super.onDetachedFromWindow();
	if (mTabSelector != null) {
	removeCallbacks(mTabSelector);
	}
	}

	TabView createTabView(ActionBar.Tab tab, boolean forAdapter) {
	final TabView tabView = new TabView(getContext(), tab, forAdapter);
	if (forAdapter) {
	tabView.setBackgroundDrawable(null);
	tabView.setLayoutParams(new ListView.LayoutParams(ListView.LayoutParams.MATCH_PARENT,
	mContentHeight));
	} else {
	tabView.setFocusable(true);

	if (mTabClickListener == null) {
	mTabClickListener = new TabClickListener();
	}
	tabView.setOnClickListener(mTabClickListener);
	}
	return tabView;
	}

	public void addTab(ActionBar.Tab tab, boolean setSelected) {
	TabView tabView = createTabView(tab, false);
	mTabLayout.addView(tabView, new LinearLayoutCompat.LayoutParams(0,
	LayoutParams.MATCH_PARENT, 1));
	if (mTabSpinner != null) {
	((TabAdapter) mTabSpinner.getAdapter()).notifyDataSetChanged();
	}
	if (setSelected) {
	tabView.setSelected(true);
	}
	if (mAllowCollapse) {
	requestLayout();
	}
	}

	public void addTab(ActionBar.Tab tab, int position, boolean setSelected) {
	final TabView tabView = createTabView(tab, false);
	mTabLayout.addView(tabView, position, new LinearLayoutCompat.LayoutParams(
	0, LayoutParams.MATCH_PARENT, 1));
	if (mTabSpinner != null) {
	((TabAdapter) mTabSpinner.getAdapter()).notifyDataSetChanged();
	}
	if (setSelected) {
	tabView.setSelected(true);
	}
	if (mAllowCollapse) {
	requestLayout();
	}
	}

	public void updateTab(int position) {
	((TabView) mTabLayout.getChildAt(position)).update();
	if (mTabSpinner != null) {
	((TabAdapter) mTabSpinner.getAdapter()).notifyDataSetChanged();
	}
	if (mAllowCollapse) {
	requestLayout();
	}
	}

	public void removeTabAt(int position) {
	mTabLayout.removeViewAt(position);
	if (mTabSpinner != null) {
	((TabAdapter) mTabSpinner.getAdapter()).notifyDataSetChanged();
	}
	if (mAllowCollapse) {
	requestLayout();
	}
	}

	public void removeAllTabs() {
	mTabLayout.removeAllViews();
	if (mTabSpinner != null) {
	((TabAdapter) mTabSpinner.getAdapter()).notifyDataSetChanged();
	}
	if (mAllowCollapse) {
	requestLayout();
	}
	}

	@Override
	public void onItemSelected(AdapterView<?> adapterView, View view, int position, long id) {
	TabView tabView = (TabView) view;
	tabView.getTab().select();
	}

	@Override
	public void onNothingSelected(AdapterView<?> adapterView) {
	// no-op
	}

	private class TabView extends LinearLayout {
	private final int[] BG_ATTRS = {
	android.R.attr.background
	};

	private ActionBar.Tab mTab;
	private TextView mTextView;
	private ImageView mIconView;
	private View mCustomView;

	// Class name may be obfuscated by Proguard. Hardcode the string for accessibility usage.
	private static final String ACCESSIBILITY_CLASS_NAME =
	"androidx.appcompat.app.ActionBar$Tab";

	public TabView(Context context, ActionBar.Tab tab, boolean forList) {
	super(context, null, R.attr.actionBarTabStyle);
	mTab = tab;

	TintTypedArray a = TintTypedArray.obtainStyledAttributes(context, null, BG_ATTRS,
	R.attr.actionBarTabStyle, 0);
	if (a.hasValue(0)) {
	setBackgroundDrawable(a.getDrawable(0));
	}
	a.recycle();

	if (forList) {
	setGravity(GravityCompat.START \| Gravity.CENTER_VERTICAL);
	}

	update();
	}

	public void bindTab(ActionBar.Tab tab) {
	mTab = tab;
	update();
	}

	@Override
	public void setSelected(boolean selected) {
	final boolean changed = (isSelected() != selected);
	super.setSelected(selected);
	if (changed && selected) {
	sendAccessibilityEvent(AccessibilityEvent.TYPE_VIEW_SELECTED);
	}
	}

	@Override
	public void onInitializeAccessibilityEvent(AccessibilityEvent event) {
	super.onInitializeAccessibilityEvent(event);
	// This view masquerades as an action bar tab.
	event.setClassName(ACCESSIBILITY_CLASS_NAME);
	}

	@Override
	public void onInitializeAccessibilityNodeInfo(AccessibilityNodeInfo info) {
	super.onInitializeAccessibilityNodeInfo(info);

	// This view masquerades as an action bar tab.
	info.setClassName(ACCESSIBILITY_CLASS_NAME);
	}

	@Override
	public void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
	super.onMeasure(widthMeasureSpec, heightMeasureSpec);

	// Re-measure if we went beyond our maximum size.
	if (mMaxTabWidth > 0 && getMeasuredWidth() > mMaxTabWidth) {
	super.onMeasure(MeasureSpec.makeMeasureSpec(mMaxTabWidth, MeasureSpec.EXACTLY),
	heightMeasureSpec);
	}
	}

	public void update() {
	final ActionBar.Tab tab = mTab;
	final View custom = tab.getCustomView();
	if (custom != null) {
	final ViewParent customParent = custom.getParent();
	if (customParent != this) {
	if (customParent != null) ((ViewGroup) customParent).removeView(custom);
	addView(custom);
	}
	mCustomView = custom;
	if (mTextView != null) mTextView.setVisibility(GONE);
	if (mIconView != null) {
	mIconView.setVisibility(GONE);
	mIconView.setImageDrawable(null);
	}
	} else {
	if (mCustomView != null) {
	removeView(mCustomView);
	mCustomView = null;
	}

	final Drawable icon = tab.getIcon();
	final CharSequence text = tab.getText();

	if (icon != null) {
	if (mIconView == null) {
	ImageView iconView = new AppCompatImageView(getContext());
	LayoutParams lp = new LayoutParams(LayoutParams.WRAP_CONTENT,
	LayoutParams.WRAP_CONTENT);
	lp.gravity = Gravity.CENTER_VERTICAL;
	iconView.setLayoutParams(lp);
	addView(iconView, 0);
	mIconView = iconView;
	}
	mIconView.setImageDrawable(icon);
	mIconView.setVisibility(VISIBLE);
	} else if (mIconView != null) {
	mIconView.setVisibility(GONE);
	mIconView.setImageDrawable(null);
	}

	final boolean hasText = !TextUtils.isEmpty(text);
	if (hasText) {
	if (mTextView == null) {
	TextView textView = new AppCompatTextView(getContext(), null,
	R.attr.actionBarTabTextStyle);
	textView.setEllipsize(TruncateAt.END);
	LayoutParams lp = new LayoutParams(LayoutParams.WRAP_CONTENT,
	LayoutParams.WRAP_CONTENT);
	lp.gravity = Gravity.CENTER_VERTICAL;
	textView.setLayoutParams(lp);
	addView(textView);
	mTextView = textView;
	}
	mTextView.setText(text);
	mTextView.setVisibility(VISIBLE);
	} else if (mTextView != null) {
	mTextView.setVisibility(GONE);
	mTextView.setText(null);
	}

	if (mIconView != null) {
	mIconView.setContentDescription(tab.getContentDescription());
	}
	TooltipCompat.setTooltipText(this, hasText ? null : tab.getContentDescription());
	}
	}

	public ActionBar.Tab getTab() {
	return mTab;
	}
	}

	private class TabAdapter extends BaseAdapter {
	TabAdapter() {
	}

	@Override
	public int getCount() {
	return mTabLayout.getChildCount();
	}

	@Override
	public Object getItem(int position) {
	return ((TabView) mTabLayout.getChildAt(position)).getTab();
	}

	@Override
	public long getItemId(int position) {
	return position;
	}

	@Override
	public View getView(int position, View convertView, ViewGroup parent) {
	if (convertView == null) {
	convertView = createTabView((ActionBar.Tab) getItem(position), true);
	} else {
	((TabView) convertView).bindTab((ActionBar.Tab) getItem(position));
	}
	return convertView;
	}
	}

	private class TabClickListener implements OnClickListener {
	TabClickListener() {
	}

	@Override
	public void onClick(View view) {
	TabView tabView = (TabView) view;
	tabView.getTab().select();
	final int tabCount = mTabLayout.getChildCount();
	for (int i = 0; i < tabCount; i++) {
	final View child = mTabLayout.getChildAt(i);
	child.setSelected(child == view);
	}
	}
	}

	protected class VisibilityAnimListener extends AnimatorListenerAdapter {
	private boolean mCanceled = false;
	private int mFinalVisibility;

	public VisibilityAnimListener withFinalVisibility(ViewPropertyAnimator animation,
	int visibility) {
	mFinalVisibility = visibility;
	mVisibilityAnim = animation;
	return this;
	}

	@Override
	public void onAnimationStart(Animator animator) {
	setVisibility(VISIBLE);
	mCanceled = false;
	}

	@Override
	public void onAnimationEnd(Animator animator) {
	if (mCanceled) return;

	mVisibilityAnim = null;
	setVisibility(mFinalVisibility);
	}

	@Override
	public void onAnimationCancel(Animator animator) {
	mCanceled = true;
	}
	}
	}