Java tutorial
/* * Copyright (C) 2011 The Android Open Source Project * Copyright (C) 2011 Jake Wharton * * 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.dwdesign.tweetings.view; import com.dwdesign.tweetings.R; import android.content.Context; import android.graphics.drawable.Drawable; import android.support.v4.view.PagerAdapter; import android.util.AttributeSet; import android.view.LayoutInflater; import android.view.View; import android.view.ViewGroup; import android.widget.HorizontalScrollView; import android.widget.ImageView; import android.widget.LinearLayout; import android.widget.TextView; /** * This widget implements the dynamic action bar tab behavior that can change * across different configurations or circumstances. */ public class TabPageIndicator extends HorizontalScrollView implements ExtendedViewPager.OnPageChangeListener { private Runnable mTabSelector; private int mCurrentItem; private TitleProvider mAdapter; private final OnClickListener mTabClickListener = new OnClickListener() { @Override public void onClick(final View view) { if (!mPagingEnabled) return; final TabView tabView = (TabView) view; if (mCurrentItem == tabView.getIndex()) { mAdapter.onPageReselected(mCurrentItem); } mCurrentItem = tabView.getIndex(); mViewPager.setCurrentItem(mCurrentItem); } }; private final OnLongClickListener mTabLongClickListener = new OnLongClickListener() { @Override public boolean onLongClick(final View view) { if (!mPagingEnabled) return false; final TabView tabView = (TabView) view; return mAdapter.onTabLongClick(tabView.getIndex()); } }; private LinearLayout mTabLayout; private ExtendedViewPager mViewPager; private ExtendedViewPager.OnPageChangeListener mListener; private LayoutInflater mInflater; int mMaxTabWidth; private int mSelectedTabIndex; private boolean mPagingEnabled = true; public TabPageIndicator(final Context context) { super(context); } public TabPageIndicator(final Context context, final AttributeSet attrs) { super(context, attrs); setHorizontalScrollBarEnabled(false); mInflater = LayoutInflater.from(context); mTabLayout = new LinearLayout(getContext()); addView(mTabLayout, new ViewGroup.LayoutParams(ViewGroup.LayoutParams.WRAP_CONTENT, ViewGroup.LayoutParams.MATCH_PARENT)); } public void notifyDataSetChanged() { if (mTabLayout == null || mViewPager == null) return; mTabLayout.removeAllViews(); mAdapter = (TitleProvider) mViewPager.getAdapter(); if (mAdapter == null) return; final int count = ((PagerAdapter) mAdapter).getCount(); for (int i = 0; i < count; i++) { final String title = mAdapter.getTitle(i); final Drawable icon = mAdapter.getIcon(i); if (title != null && icon != null) { addTab(title, icon, i); } else if (title == null && icon != null) { addTab(icon, i); } else if (title != null && icon == null) { addTab(title, i); } } if (mSelectedTabIndex > count) { mSelectedTabIndex = count - 1; } setCurrentItem(mSelectedTabIndex); requestLayout(); } @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); } } @Override public void onMeasure(final int widthMeasureSpec, final 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; } } else { mMaxTabWidth = -1; } 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. setCurrentItem(mSelectedTabIndex); } } @Override public void onPageScrolled(final int arg0, final float arg1, final int arg2) { if (mListener != null) { mListener.onPageScrolled(arg0, arg1, arg2); } } @Override public void onPageScrollStateChanged(final int arg0) { if (mListener != null) { mListener.onPageScrollStateChanged(arg0); } } @Override public void onPageSelected(final int position) { setCurrentItem(position); mAdapter.onPageSelected(position); if (mListener != null) { mListener.onPageSelected(position); } } public void setCurrentItem(final int item) { if (mViewPager == null) return; // throw new IllegalStateException("ViewPager has not been bound."); mCurrentItem = item; mViewPager.setCurrentItem(item); mSelectedTabIndex = item; final int tabCount = mTabLayout.getChildCount(); for (int i = 0; i < tabCount; i++) { final View child = mTabLayout.getChildAt(i); final boolean isSelected = i == item; child.setSelected(isSelected); if (isSelected) { animateToTab(item); } } } public void setOnPageChangeListener(final ExtendedViewPager.OnPageChangeListener listener) { mListener = listener; } public void setPagingEnabled(final boolean enabled) { mViewPager.setPagingEnabled(enabled); mPagingEnabled = enabled; } public void setViewPager(final ExtendedViewPager pager) { final PagerAdapter adapter = pager.getAdapter(); if (adapter == null) return; // throw new IllegalStateException("ViewPager has not been bound."); if (!(adapter instanceof TitleProvider)) throw new IllegalStateException( "ViewPager adapter must implement TitleProvider to be used with TitlePageIndicator."); mViewPager = pager; pager.setOnPageChangeListener(this); notifyDataSetChanged(); } public void setViewPager(final ExtendedViewPager pager, final int initialPosition) { setViewPager(pager); setCurrentItem(initialPosition); } private void addTab(final Drawable icon, final int index) { addTab(null, icon, index); } private void addTab(final String text, final Drawable icon, final int index) { // Workaround for not being able to pass a defStyle on pre-3.0 final TabView tabView = (TabView) mInflater.inflate(R.layout.vpi__tab, null); tabView.init(this, text, icon, index); tabView.setFocusable(true); tabView.setOnClickListener(mTabClickListener); tabView.setOnLongClickListener(mTabLongClickListener); mTabLayout.addView(tabView, new LinearLayout.LayoutParams(0, LayoutParams.MATCH_PARENT, 1)); } private void addTab(final String text, final int index) { addTab(text, null, index); } private 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); } public static class TabView extends LinearLayout { private TabPageIndicator mParent; private int mIndex; public TabView(final Context context, final AttributeSet attrs) { super(context, attrs); } public int getIndex() { return mIndex; } public void init(final TabPageIndicator parent, final Drawable icon, final int index) { init(parent, null, icon, index); } public void init(final TabPageIndicator parent, final String text, final Drawable icon, final int index) { mParent = parent; mIndex = index; final ImageView imageView = (ImageView) findViewById(android.R.id.icon); imageView.setVisibility(icon != null ? View.VISIBLE : View.GONE); imageView.setImageDrawable(icon); final TextView textView = (TextView) findViewById(android.R.id.text1); textView.setVisibility(text != null ? View.VISIBLE : View.GONE); textView.setText(text); } public void init(final TabPageIndicator parent, final String text, final int index) { init(parent, text, null, index); } @Override public void onMeasure(final int widthMeasureSpec, final int heightMeasureSpec) { super.onMeasure(widthMeasureSpec, heightMeasureSpec); // Re-measure if we went beyond our maximum size. if (mParent.mMaxTabWidth > 0 && getMeasuredWidth() > mParent.mMaxTabWidth) { super.onMeasure(MeasureSpec.makeMeasureSpec(mParent.mMaxTabWidth, MeasureSpec.EXACTLY), heightMeasureSpec); } } } /** * A TitleProvider provides the title to display according to a view. */ public interface TitleProvider { /** * Returns the icon of the view at position * * @param position * @return */ public Drawable getIcon(int position); public void setIcon(int position, Drawable icon); /** * Returns the title of the view at position * * @param position * @return */ public String getTitle(int position); public void onPageReselected(int position); public void onPageSelected(int position); public boolean onTabLongClick(int position); } }