common/list/ViewPagerTabs.java

/*
 * Copyright (C) 2014 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 com.android.contacts.common.list;

import android.content.Context;
import android.content.res.ColorStateList;
import android.content.res.TypedArray;
import android.graphics.Outline;
import android.support.v4.view.PagerAdapter;
import android.support.v4.view.ViewPager;
import android.util.AttributeSet;
import android.util.TypedValue;
import android.view.Gravity;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewOutlineProvider;
import android.widget.FrameLayout;
import android.widget.HorizontalScrollView;
import android.widget.LinearLayout;
import android.widget.TextView;
import android.widget.Toast;
import com.android.contacts.common.R;

/**
 * Lightweight implementation of ViewPager tabs. This looks similar to traditional actionBar tabs,
 * but allows for the view containing the tabs to be placed anywhere on screen. Text-related
 * attributes can also be assigned in XML - these will get propogated to the child TextViews
 * automatically.
 */
public class ViewPagerTabs extends HorizontalScrollView implements ViewPager.OnPageChangeListener {

  private static final ViewOutlineProvider VIEW_BOUNDS_OUTLINE_PROVIDER =
      new ViewOutlineProvider() {
        @Override
        public void getOutline(View view, Outline outline) {
          outline.setRect(0, 0, view.getWidth(), view.getHeight());
        }
      };
  private static final int TAB_SIDE_PADDING_IN_DPS = 10;
  // TODO: This should use <declare-styleable> in the future
  private static final int[] ATTRS =
      new int[] {
        android.R.attr.textSize,
        android.R.attr.textStyle,
        android.R.attr.textColor,
        android.R.attr.textAllCaps
      };

  /**
   * Linearlayout that will contain the TextViews serving as tabs. This is the only child of the
   * parent HorizontalScrollView.
   */
  final int mTextStyle;

  final ColorStateList mTextColor;
  final int mTextSize;
  final boolean mTextAllCaps;
  ViewPager mPager;
  int mPrevSelected = -1;
  int mSidePadding;
  private ViewPagerTabStrip mTabStrip;
  private int[] mTabIcons;
  // For displaying the unread count next to the tab icon.
  private int[] mUnreadCounts;

  public ViewPagerTabs(Context context) {
    this(context, null);
  }

  public ViewPagerTabs(Context context, AttributeSet attrs) {
    this(context, attrs, 0);
  }

  public ViewPagerTabs(Context context, AttributeSet attrs, int defStyle) {
    super(context, attrs, defStyle);
    setFillViewport(true);

    mSidePadding = (int) (getResources().getDisplayMetrics().density * TAB_SIDE_PADDING_IN_DPS);

    final TypedArray a = context.obtainStyledAttributes(attrs, ATTRS);
    mTextSize = a.getDimensionPixelSize(0, 0);
    mTextStyle = a.getInt(1, 0);
    mTextColor = a.getColorStateList(2);
    mTextAllCaps = a.getBoolean(3, false);

    mTabStrip = new ViewPagerTabStrip(context);
    addView(
        mTabStrip,
        new FrameLayout.LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.MATCH_PARENT));
    a.recycle();

    // enable shadow casting from view bounds
    setOutlineProvider(VIEW_BOUNDS_OUTLINE_PROVIDER);
  }

  public void setViewPager(ViewPager viewPager) {
    mPager = viewPager;
    addTabs(mPager.getAdapter());
  }

  /**
   * Set the tab icons and initialize an array for unread counts the same length as the icon array.
   *
   * @param tabIcons An array representing the tab icons in order.
   */
  public void configureTabIcons(int[] tabIcons) {
    mTabIcons = tabIcons;
    mUnreadCounts = new int[tabIcons.length];
  }

  public void setUnreadCount(int count, int position) {
    if (mUnreadCounts == null || position >= mUnreadCounts.length) {
      return;
    }
    mUnreadCounts[position] = count;
  }

  private void addTabs(PagerAdapter adapter) {
    mTabStrip.removeAllViews();

    final int count = adapter.getCount();
    for (int i = 0; i < count; i++) {
      addTab(adapter.getPageTitle(i), i);
    }
  }

  private void addTab(CharSequence tabTitle, final int position) {
    View tabView;
    if (mTabIcons != null && position < mTabIcons.length) {
      View layout = LayoutInflater.from(getContext()).inflate(R.layout.unread_count_tab, null);
      View iconView = layout.findViewById(R.id.icon);
      iconView.setBackgroundResource(mTabIcons[position]);
      iconView.setContentDescription(tabTitle);
      TextView textView = (TextView) layout.findViewById(R.id.count);
      if (mUnreadCounts != null && mUnreadCounts[position] > 0) {
        textView.setText(Integer.toString(mUnreadCounts[position]));
        textView.setVisibility(View.VISIBLE);
        iconView.setContentDescription(
            getResources()
                .getQuantityString(
                    R.plurals.tab_title_with_unread_items,
                    mUnreadCounts[position],
                    tabTitle.toString(),
                    mUnreadCounts[position]));
      } else {
        textView.setVisibility(View.INVISIBLE);
        iconView.setContentDescription(getResources().getString(R.string.tab_title, tabTitle));
      }
      tabView = layout;
    } else {
      final TextView textView = new TextView(getContext());
      textView.setText(tabTitle);
      textView.setBackgroundResource(R.drawable.view_pager_tab_background);

      // Assign various text appearance related attributes to child views.
      if (mTextStyle > 0) {
        textView.setTypeface(textView.getTypeface(), mTextStyle);
      }
      if (mTextSize > 0) {
        textView.setTextSize(TypedValue.COMPLEX_UNIT_PX, mTextSize);
      }
      if (mTextColor != null) {
        textView.setTextColor(mTextColor);
      }
      textView.setAllCaps(mTextAllCaps);
      textView.setGravity(Gravity.CENTER);

      tabView = textView;
    }

    tabView.setOnClickListener(
        new OnClickListener() {
          @Override
          public void onClick(View v) {
            mPager.setCurrentItem(getRtlPosition(position));
          }
        });

    tabView.setOnLongClickListener(new OnTabLongClickListener(position));

    tabView.setPadding(mSidePadding, 0, mSidePadding, 0);

    mTabStrip.addView(
        tabView,
        position,
        new LinearLayout.LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.MATCH_PARENT, 1));

    // Default to the first child being selected
    if (position == 0) {
      mPrevSelected = 0;
      tabView.setSelected(true);
    }
  }

  /**
   * Remove a tab at a certain index.
   *
   * @param index The index of the tab view we wish to remove.
   */
  public void removeTab(int index) {
    View view = mTabStrip.getChildAt(index);
    if (view != null) {
      mTabStrip.removeView(view);
    }
  }

  /**
   * Refresh a tab at a certain index by removing it and reconstructing it.
   *
   * @param index The index of the tab view we wish to update.
   */
  public void updateTab(int index) {
    removeTab(index);

    if (index < mPager.getAdapter().getCount()) {
      addTab(mPager.getAdapter().getPageTitle(index), index);
    }
  }

  @Override
  public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
    position = getRtlPosition(position);
    int tabStripChildCount = mTabStrip.getChildCount();
    if ((tabStripChildCount == 0) || (position < 0) || (position >= tabStripChildCount)) {
      return;
    }

    mTabStrip.onPageScrolled(position, positionOffset, positionOffsetPixels);
  }

  @Override
  public void onPageSelected(int position) {
    position = getRtlPosition(position);
    int tabStripChildCount = mTabStrip.getChildCount();
    if ((tabStripChildCount == 0) || (position < 0) || (position >= tabStripChildCount)) {
      return;
    }

    if (mPrevSelected >= 0 && mPrevSelected < tabStripChildCount) {
      mTabStrip.getChildAt(mPrevSelected).setSelected(false);
    }
    final View selectedChild = mTabStrip.getChildAt(position);
    selectedChild.setSelected(true);

    // Update scroll position
    final int scrollPos = selectedChild.getLeft() - (getWidth() - selectedChild.getWidth()) / 2;
    smoothScrollTo(scrollPos, 0);
    mPrevSelected = position;
  }

  @Override
  public void onPageScrollStateChanged(int state) {}

  private int getRtlPosition(int position) {
    if (getLayoutDirection() == View.LAYOUT_DIRECTION_RTL) {
      return mTabStrip.getChildCount() - 1 - position;
    }
    return position;
  }

  /** Simulates actionbar tab behavior by showing a toast with the tab title when long clicked. */
  private class OnTabLongClickListener implements OnLongClickListener {

    final int mPosition;

    public OnTabLongClickListener(int position) {
      mPosition = position;
    }

    @Override
    public boolean onLongClick(View v) {
      final int[] screenPos = new int[2];
      getLocationOnScreen(screenPos);

      final Context context = getContext();
      final int width = getWidth();
      final int height = getHeight();
      final int screenWidth = context.getResources().getDisplayMetrics().widthPixels;

      Toast toast =
          Toast.makeText(context, mPager.getAdapter().getPageTitle(mPosition), Toast.LENGTH_SHORT);

      // Show the toast under the tab
      toast.setGravity(
          Gravity.TOP | Gravity.CENTER_HORIZONTAL,
          (screenPos[0] + width / 2) - screenWidth / 2,
          screenPos[1] + height);

      toast.show();
      return true;
    }
  }
}