Java tutorial
/* * 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; import com.android.contacts.common.compat.CompatUtils; /** * 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 { ViewPager mPager; private ViewPagerTabStrip mTabStrip; /** * 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; int mPrevSelected = -1; int mSidePadding; private int[] mTabIcons; // For displaying the unread count next to the tab icon. private int[] mUnreadCounts; private static final ViewOutlineProvider VIEW_BOUNDS_OUTLINE_PROVIDER; static { if (CompatUtils.isLollipopCompatible()) { VIEW_BOUNDS_OUTLINE_PROVIDER = new ViewOutlineProvider() { @Override public void getOutline(View view, Outline outline) { outline.setRect(0, 0, view.getWidth(), view.getHeight()); } }; } else { VIEW_BOUNDS_OUTLINE_PROVIDER = null; } } 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 }; /** * 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; } } 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(); if (CompatUtils.isLollipopCompatible()) { // 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(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; } }